Topic:"Infrastructure Planning" in M12696

As expected with a complex capital project, availability levels for the Maritime Link were lower in the first few years after commissioning, with monopole availability of 81 percent NSPML Interim Assessment 2017 (M07718), Decision. M10206,...

AI summary The Maritime Link project experienced lower availability in its early years, but performance improved significantly after 2020. In contrast, NLH faced significant delays and cost overruns in the Lower Churchill Falls Project, which impacted Nova Scotians through higher initial costs.

Recognizing the impact of the delays to customers, NSPML negotiated an August 2021 start to the NS Block through the Acceleration Agreement. At that time, the physical components of the Lower Churchill Project were complete and, while flow...

AI summary NSPML negotiated an August 2021 start to the NS Block through the Acceleration Agreement, but delays in LIL software installation by NLH's contractor led to low delivery levels. A recent $500 million federal guarantee helped mitigate the impact of these delays on NS Power's system planning.

10 Q7. HAVE YOU PREVIOUSLY TESTIFIED IN ANY REGULATORY 11 PROCEEDINGS? 12 A7. Yes. I have provided expert testimony or reports before the Indiana Utility Regulatory 13 Commission, the Federal Energy Regulatory Commission ("FERC"), the Illi...

AI summary The witness confirms prior testimony before multiple regulatory bodies, including FERC and state commissions, focusing on wholesale energy market design, transmission policy, and resource planning.

2 Q9. WHAT IS THE PURPOSE OF YOUR TESTIMONY? 3 A9. I have been asked by NSPML to provide evidence on the expected challenges during early 4 operation of large infrastructure projects, good utility practice as it relates to the 5 maintenanc...

AI summary The testimony discusses challenges in infrastructure projects, emphasizes good utility practices for maintaining high-voltage and undersea transmission lines, and argues that assessing the Labrador Island Link (LIL) performance from May 2023 to April 2024 is appropriate. It also claims that failing to grant relief for 2023 outages and a 2024 weather event would be inappropriate regulatory policy.

15 Q10. PLEASE PROVIDE A SUMMARY OF YOUR TESTIMONY. 16 A10. Section III of my testimony describes the holdback mechanism and my understanding on 17 why it was put in place by the Nova Scotia Utility and Review Board ("Board"). Section 18 I...

AI summary The testimony explains the holdback mechanism, the necessity of planned and unplanned outages for system reliability, and the need for NSPML to receive outage relief in performance metrics calculations. It emphasizes that outages are normal in utility operations and highlights the complexity of maintaining generation and transmission assets for Muskrat Falls energy delivery.

12 IV. MAINTENANCE OF THE GENERATION AND TRANSMISSION ASSETS 13 NEEDED TO SUPPORT THE DELIVERY OF MUSKRAT FALLS ENERGY

AI summary The section discusses the maintenance requirements for generation and transmission assets essential to delivering energy from the Muskrat Falls project. It emphasizes the importance of sustaining infrastructure to ensure reliable energy delivery.

1  Labrador (900 MW) Converter Station (ac/dc) 2  Overhead HVdc transmission line from Muskrat Falls to Strait of Belle 3 Isle 4  Submarine cables across the Strait of Belle Isle (30 km) 5  Overhead HVdc transmission line from the Stra...

AI summary The text outlines the key infrastructure components involved in transmitting energy from Muskrat Falls to Nova Scotia, including converter stations, HVdc and HVac transmission lines, and submarine cables. It also highlights external factors that can impact the reliability of these facilities, such as wildfires and extreme weather events.

26 A23. Asset owners adhere to good utility practice in maintaining assets by implementing a 27 structured and proactive approach that encompasses regular inspections, preventive 28 maintenance, and timely repairs. This involves establishi...

AI summary Asset owners are required to maintain utility infrastructure through structured and proactive approaches, including regular inspections, preventive maintenance, and the use of advanced diagnostic tools. They also ensure staff training, adherence to safety protocols, and compliance with regulatory requirements and industry best practices to enhance reliability and efficiency.

6 Q28. CAN PLANNED OUTAGES BE EXPECTED TO OCCUR EACH YEAR TO 7 ENSURE EQUIPMENT RELIABILITY? 8 A28. Yes. Planned outages for both the generation and transmission assets can be expected each 9 year. Based on the U.S. Hydropower Market Repor...

AI summary Planned outages are expected annually for generation and transmission assets to ensure reliability. Data from the U.S. Department of Energy and NERC show increasing planned outage hours for large hydro units and transmission lines, with NERC reporting an average of 2.7 outages per line annually, including 1.8 planned.

20 Q32. PLEASE DESCRIBE THE OUTAGES THAT TOOK PLACE ON THE LIL IN 21 JULY 2023 AND SEPTEMBER 2023. 22 A32. The July of 2023 planned outage followed a June outage request from NLH to the 23 Newfoundland Labrador System Operator ("NLSO") and...

AI summary The July 2023 LIL outage was planned for software updates and testing, while the September outage focused on preventative maintenance. Both were coordinated with NLH and NLSO, scheduled during low-demand periods to ensure winter reliability.

17 Q33. PLEASE DESCRIBE THE MARCH 2024 PLANNED AND UNPLANNED 18 OUTAGES ON THE LIL. 19 A33. There were two days of planned outages (March 26-27) for corrective maintenance repairs 20 on a variety of systems including the Optical Ground Wir...

AI summary In March 2024, the Labrador-Island Link (LIL) experienced two days of planned outages for maintenance, including OPGW repairs and interference mitigation. An ice storm caused unplanned outages, damaging towers and conductors, leading to a complete shutdown until April 8, 2024, when service was restored in monopole configuration.

15 Q35. WERE ANY OF THESE OUTAGES PART OF THE COMMISSIONING OF THE 16 LIL? 17 A35. No. The LIL was successfully commissioned as of April 14, 2023, meaning that the assets were turned over to the NLSO for regular operation.19 18 The commiss...

AI summary The Labrador-Island Link (LIL) was successfully commissioned by April 14, 2023, with no outages linked to the process. Commissioning involved testing, verification by NLSO and the Independent Engineer, and issuance of a Commissioning Confirmation Certificate. Non-critical 'punch list items' were noted but did not affect reliability or commissioning.

10 Q39. DOES THE LIL'S PLANNED MAINTENANCE WORK REFLECT GOOD 11 UTILITY PRACTICE? 12 A39. Yes. The LIL is a new and complex asset. It is typical and expected that during the initial 13 operation period these types of projects will require...

AI summary Affirms that the LIL's planned maintenance is typical for new complex assets, addressing technical challenges and ensuring reliability. Mentions short-term measures and planning to prevent outages, emphasizing that such adjustments are expected during initial operations.

NON-CONFIDENTIAL 1 Response IR-03: 2 3 a-b) 4 The availability of the Maritime Link for the period 2018 to 2025 is provided in the table 5 below. This includes the Bipole availability (i.e. annual percentage of time when both poles 6 were...

AI summary The text discusses the availability of the Maritime Link transmission line between 2018 and 2025, including metrics such as Bipole and Monopole availability, and Energy Availability. It also describes how NSPML calculates availability using CIGRE guidelines and introduces the concept of Forced Energy Unavailability (FEU).

NSPML 2026 Holdback Mechanism BW IR-04 Attachment 2 Page 3 of 67

AI summary The document discusses the 2026 Holdback Mechanism BW IR-04 Attachment 2, which is related to NSPML's integrated resource planning and capacity management strategies.

stion turbine plant in stand by on day one. Similarly, the incremental additions provide for a more attractive cumulative present worth cost alternative over the single 800 MW up front stand by plant. By comparison, Table 7 provides the im...

AI summary The text compares the cost-effectiveness of incremental combustion turbine additions versus a single 800 MW standby plant, noting that incremental additions offer a more attractive present worth cost. It also highlights the impact of including the Maritime Link on reducing the number of combustion turbines needed to achieve the same level of exposure to permanent loss of the bipole.

Table 7 Level of Exposure and Unsupplied Energy With Maritime Link 50 MW Combustion Turbines Added Year Load Forecast Island Level of Exposure Availability Unsupplied Energy Standby % Load Exceeds Worst 2 wk Window Generation Generation MW...

AI summary Table 7 analyzes the level of exposure and unsupplied energy with the addition of 50 MW combustion turbines from the Maritime Link. It includes data on load forecasts, generation availability, and unsupplied energy for various years from 2017 to 2037.

ound wire on the entire length of the HVdc transmission line will provide acceptable protection to the line from direct lightning strikes, thereby limiting the number of transient pole outages to those listed in the CIGRE statistics. The s...

AI summary The document discusses HVdc line design considerations, emphasizing reliability-based methods for weather loadings and protection against lightning strikes. It references CIGRE statistics for outage frequency and highlights the need for higher reliability standards (1:150 or 1:500 year return periods) for critical lines, citing the Labrador-Island Link's ice thickness requirements as an example.

LO WER CHURCHILL PROJECT ctor/Su EPC(M) Document Number: 505573-480A-47ER-0017 Issue Number: 00

AI summary The document appears to be a technical or engineering document related to the Churchill Project, possibly involving electrical infrastructure or power generation. It includes an EPC(M) document number and an issue number, indicating it may be part of a larger project documentation set.

Date: 10-Apr-2012 Prepared by: Peter Anderson Table 4-5: Variation in Overall FOR with DC Overhead Line Repair Time20

AI summary The document includes a table labeled 'Table 4-5: Variation in Overall FOR with DC Overhead Line Repair Time20' prepared by Peter Anderson. The content is not fully visible, but it appears to relate to repair times for DC overhead lines.

1.1 Overview of the System This Report presents the results of the reliability and availability analysis carried out to determine the expected performance of the ±350 kV, 900 MW HVdc interconnection between Muskrat Falls and Soldiers Pond...

AI summary This section provides an overview of the reliability and availability analysis for the ±350 kV, 900 MW HVdc interconnection between Muskrat Falls and Soldiers Pond (Island Link). The assessment focuses on the performance of the Island Link and excludes other components such as generation and interconnections outside the link.

Table 2-2: Converter Unavailability Item Performance Indicator Spare Transformer No Yes Yes Spare Smoothing Reactor No No Yes Terminal Unavailability 3.04% 0.94% 0.21% Hours/ Year 266 82.5 18.6 Based on the above information, it is recomme...

AI summary The text discusses the reliability performance of converter stations, recommending spare units at each terminal to improve reliability. It references statistics from prior years to support the recommendation.

NSPML Responses to Bates White Information Requests 1 g) 18 causing failed cable switching sequence operations. 19 ii) This was a planned outage, no root cause report was expected or prepared. These 20 ice accumulation issues were signific...

AI summary The document discusses a planned outage related to ice accumulation on a transmission line, noting that it was investigated by NL Hydro's regulator and third-party analysis. The line was designed with varying return periods based on climatic conditions, and no costs were incurred by NSPML as energy was delivered via a make-up energy agreement.

1 Parties through additional flexibility in the scheduling of the Nova Scotia Block. 2 Conversations to date have revolved around availing of additional Maritime Link capacity 3 in the winter period. 4 5 There are also references in the or...

AI summary The document discusses conversations regarding the use of additional Maritime Link capacity during the winter period, referencing dispatchability of the NS Block, redelivery protections, and reliability expectations compared to the generator it would replace.

Chapter 2 — Looking Forward: Future U.S. Hydropower and PSH Development Pipeline Figure ES-4. Hydropower project development pipeline by project type, region, size, and development stage (as of December 31, 2019) Sources: FERC eLibrary, U....

AI summary As of 2019, the U.S. hydropower development pipeline includes 217 projects totaling 1.49 GW, with significant capacity from retrofitting non-powered dams and existing facilities. 129 projects have federal authorization but no construction has started, highlighting delays in permitting and financing.

AT THE END OF 2019, THE GLOBAL DEVELOPMENT PIPELINE INCLUDED 284 PSH PROJECTS WITH A TOTAL CAPACITY OF 226 GW. Figure ES-9 summarizes the regional distribution of the global PSH pipeline. Thirteen countries were constructing 50 PSH project...

AI summary Global PSH pipeline had 284 projects (226 GW) in 2019, with China leading at 102 GW. North America invested $11.6B in R&U for hydropower/PSH, the oldest fleet globally. 90% of global capital expenditures target new plant development, with Asian regions dominating hydropower/PSH investments.

hem operational is deemed too expensive. Nonfederal public owners (publicly owned utilities, state agencies, municipalities, and cooperatives) added the remaining 28% of new capacity to their plants. The Northwest and Southwest display the...

AI summary The text details new project developments and capacity changes from 2010–2019, emphasizing regional project distribution (Northwest, Southwest), types of installations (conduits, NPDs, NSDs), and specific examples like Smithland NPD and Pueblo Dam NPD. It highlights 583.1 MW in capacity additions, 215.8 MW in downrates, and retirements impacting installed capacity.

1.3 Investment in Refurbishments and Upgrades (2010–2019) Since 2010, at least $7.8 billion have been invested in R&U to the U.S. hydropower and PSH fleets. In 2017–2019, R&U investments have included dozens of projects in the federal flee...

AI summary From 2010–2019, $7.8 billion was invested in R&U for U.S. hydropower and PSH fleets, with 49 projects ongoing by 2019. Investments were uneven across regions, with Midwest plants receiving disproportionate attention due to the Ludington PSH upgrade. Federal fleets accounted for 47% of hydropower R&U investment, while private owners spent more per kilowatt. The Robert Moses Niagara plant's $1.1 billion R&U initiative highlights ongoing large-scale efforts.

2. Looking Forward: Future U.S. Hydropower and PSH Development Pipeline This chapter presents a snapshot of the U.S. hydropower and PSH development pipeline as of the end of 2019. It describes the following pipeline attributes: regional di...

AI summary This chapter provides an overview of the U.S. hydropower and pumped storage hydropower (PSH) development pipeline as of 2019, detailing regional distribution, project types, sizes, developer types, and project development stages.

ess, projects that have obtained a FERC preliminary permit, and projects with an expired preliminary permit but that have submitted a Notice of Intent to file a license or a draft license application. \ \ Pending License includes projects...

AI summary The text categorizes U.S. hydropower projects by license status (pending, issued) and discusses regional distribution, noting that 87% of conduit projects are in the Northwest/Southwest, while 92% of NPD projects are in other regions. Pennsylvania, Kentucky, and Louisiana lead in proposed capacity, with Alaska hosting most NSD projects.

erground powerhouse. The project developers announced they secured equity investment for the project from a Danish investor in July 2019 but, as of July 2020, negotiations for a PPA are still ongoing. Finally, license issuance for Eagle Mo...

AI summary The Eagle Mountain PSH project faces delays due to land access and ongoing PPA negotiations. U.S. PSH pipeline growth accelerated in 2019, with 31% more active projects than the prior year. Figure 11 shows increasing PSH development activity since 2015, driven by new applications and limited license issuances.

3. U.S. Hydropower and PSH in the Global Context This chapter describes the existing global hydropower and PSH fleets and summarizes international trends in hydropower development as well as R&U to the existing fleets. This chapter serves...

AI summary This chapter provides an international context for U.S. hydropower and pumped storage hydropower (PSH) development, detailing global fleets, refurbishment/upgrades (R&U), and trends. It updates previous reports, separates hydropower and PSH metrics, and introduces new sections comparing international permitting and incentives influencing regional investment levels.

3.2.1 Development Pipeline by Region The global development pipeline by the end of 2019 includes 4,545 hydropower projects and 284 PSH projects with total capacities of 414 GW and 226 GW, respectively. Asia accounted for 75% of the combine...

AI summary The global hydropower and PSH development pipeline by 2019 included 4,545 hydropower and 284 PSH projects, with Asia accounting for 75% of potential capacity. China led in construction, while the U.S. and Canada had smaller pipelines with high attrition rates in early stages. East Asia dominated PSH development, with 104 GW in the pipeline.

3.2.2 Global Hydropower and PSH Investment Global hydropower and PSH investment (planned and under construction) amounted to $1.1 trillion at the end of 2019. PSH projects account for 24% of the total. More than 90% of global expenditures...

AI summary Global hydropower and PSH investment reached $1.1 trillion by 2019, with PSH accounting for 24%. Asia dominates expenditures (73% hydropower, 69% PSH), while the U.S. and Canada contribute 4% of global hydropower and at least 20% of PSH investments. Figure 18 (IIR) details regional capital expenditure distribution.

lve replacement of the turbine runners.90 Figure 56. Annual installations of hydropower and PSH turbines in the United States by manufacturer Source: IIR, Existing Hydropower Assets dataset, personal communication with Debbie Mursch (GE Re...

AI summary The text discusses U.S. hydropower and PSH turbine installations, highlighting data on numbers, capacities, and manufacturers. It notes that 33% of installed capacity is PSH, with federal, public, and private fleet distributions. Most installations involve replacements or upgrades rather than new projects, with average capacities varying by facility type.

1.0 Introduction and Summary of Findings - 2 Early in 2020, Newfoundland and Labrador Hydro ("Hydro") commissioned Haldar & Associates Inc. - 3 ("Haldar & Associates") to undertake an "Assessment of Labrador Island Transmission Link (LIL)...

AI summary Newfoundland and Labrador Hydro commissioned an assessment of the Labrador Island Transmission Link's reliability under climatological loads. The assessment evaluated the design against CSA 60826 standards and considered both damage and ultimate limit states, resulting in a baseline reliability of a 1:72 year return period under CSA standards and a 1:160 year return period under ULS analysis.

2.1 EFLA Assessment of As-Designed Structural Capacity of the Labrador-Island Link - 12 In the first stage of the reliability assessment undertaken by Hydro, EFLA Consulting Engineers ("EFLA") - 13 was engaged to complete a comprehensive r...

AI summary EFLA Consulting Engineers assessed the Labrador-Island Link's structural capacity against CSA standards, finding a 1:150 year return period. However, rime icing was excluded as CSA lacks specific requirements. SNC Lavalin's peer review identified discrepancies due to differing ice load inputs and calculation methods based on CSA interpretations.

3.2 Ultimate Limit State Analysis - The return period and failure rates under an ULS was also considered to provide a more complete picture of the considerations necessary with respect to the LIL reliability. The ULS analysis was undertake...

AI summary The ULS analysis of the LIL infrastructure assesses extreme loading scenarios, identifying a 1:160-year return period and 0.48% annual failure rate. Design differences from typical utility practices are noted, with Hydro asserting that mechanical failures are unlikely to cause extended outages due to buffer capacity. Operational protocols and ice removal techniques are highlighted as mitigation strategies.

4.3 Wind Speed-Up Factors - 12 CSA provides limited direction on the use of wind speed-up factors associated with local elevated terrain - 13 for line design. According to the Haldar & Associates Assessment, it is expected this will have a...

AI summary The text discusses the impact of wind speed-up factors on line design, noting that CSA standards provide limited guidance on elevated terrain. Haldar & Associates' assessment found potential 30% higher wind loads at Hawke Hill, though existing structures meet criteria. Original designs used site-specific data and reserve capacity, but some areas lack Hydro's operating experience.

4.4 Combined Wind & Ice - 5 CSA provides direction on load case combinations for wind on ice accumulation. Within these scenarios, - 6 the standard provides a low and high range of factors associated with occurrence. Typically, the decisio...

AI summary The text discusses the application of CSA standards for combined wind and ice loading scenarios, emphasizing the need for site-specific analysis in areas with limited operational experience like Labrador. Haldar & Associates recommends using lower load factors where experience exists but advocates for detailed modeling to validate high-range factors in regions with limited data, to avoid over-conservative designs.

recommendations to determine if adjustments to the as-built design of the LIL are required. 20 Any such adjustments would be considered a change in the design criteria utilized by the original 21 designer and could result in a revised proj...

AI summary The document discusses the need for engineering assessments to validate adjustments to the Labrador-Island Link (LIL) design, emphasizing that baseline reliability measures remain unchanged. Hydro asserts that design modifications should be justified through engineering reviews, while noting that current Haldar & Associates findings do not significantly impact LIL restoration timelines, which depend on incident severity and seasonal conditions.

lastic behaviour) is needed to estimate the collapse probability of coupled structure support-wire support system. This should be pursued for a few critical segments already identified in this report. In addition, the study has also identi...

AI summary The LIL line design exhibits vulnerabilities under ice shedding, failing to meet CSA standards and Hydro's design philosophy. The author disputes CSA's stipulation on UBI classification, emphasizing the need for revised load combination criteria to address unbalanced ice loads in Labrador. Critical segments require reassessment.

Table 2.1 Degree of Severity for BES Disturbances and Local Disturbances (Billinton and Wangdoe, 2006)............................................................................................................................................

AI summary The text provides a list of tables from a technical document discussing reliability, design requirements, and loading scenarios for power systems, referencing standards and studies from various organizations such as CSA, EFLA, and others.

1.1 Impact of Weather Events on Power Delivery Since the commissioning of Hydro's (NLH's) transmission lines in the 60's, much of NLH's system has experienced ice storms and severe ice loadings. The original design wind and ice loads for t...

AI summary The text discusses the historical impact of ice storms on Newfoundland and Labrador Hydro's (NLH) transmission lines, referencing original design standards (CSA C 22.3 No.1) and documented failures since the 1960s. It highlights design load assumptions, ice accumulation issues, and specific failures in regions like the Avalon Peninsula and Buchan's Plain, emphasizing infrastructure vulnerabilities to weather events.

The Maritime link includes: - The transport power to the west coast of Newfoundland - A submarine cable system to the Maritimes The current study is based on a recent EFLA report entitled "Structural Capacity of as-built Design of the LIL...

AI summary The study evaluates the structural capacity of the Labrador Island Transmission Link (LIL) using an EFLA report and Nalcor documents, with data from NLH engineers. The Maritime link is excluded. High-level data review was conducted without validating design assumptions.

to validate the design for an increased return period based on ice and wind loads; however, the clearances due to increased sag and due to swing angles need to be addressed (serviceability criteria)". Mr. Alteen's submission from Newfoundl...

AI summary The text addresses the need to validate design for increased return periods due to ice and wind loads, emphasizing clearances for sag and swing angles. Mr. Alteen's submission highlights reliability concerns for the Labrador Island Transmission Link (LIL) and the Isthmus zone's critical corridor post-Holyrood decommissioning, noting Nalcor's oversight in considering line length in reliability assessments.

1.6 Scope of this Study This study evaluated the overall line reliability of LIL with respect to the likelihood of failure based on a range of climatological loading scenarios. This report includes the inputs and data from the following re...

AI summary This study evaluates the line reliability of the Labrador Island Transmission Link (LIL) under climatological loading scenarios, incorporating structural capacity assessments, rime icing recalibration, and benchmarking against utility operational data. Findings will inform failure likelihood, repair rates, and outage duration calculations.

1.7 EFLA (2020) Report on Strength Assessment of LIL – Summary With respect to first item under the "Scope of the Study", EFLA has submitted a report in April 2020 entitled "Structural Capacity of as-built Design of the LIL following CSA C...

AI summary The EFLA (2020) report found that the Labrador Island Transmission Link (LIL) design did not meet the 500-year return period load effect, instead meeting the CSA 150-year standard in most cases, except specific zones where OPGW and hardware failed. The study excluded rime icing and unbalanced ice loads, recommending an impact study on OPGW loss.

1.8 Deliverables - Baseline LIL reliability (and probability of failure and failure rate) that considers two types of icing exposures and associated climatic hazard exposures - A targeted sensitivity of the following parameters is included...

AI summary The deliverables focus on assessing LIL reliability under icing conditions, sensitivity analyses for terrain, topography, and ice-wind interactions, justification for extreme ice loads, OPGW loading issues, and uncertainty in rime ice modeling. Clearance issues from Section 1.3 are excluded.

Mechanical System Reliability : Reliability of a line is defined as the probability that the line will perform under specified conditions for a specified period, normally defined as the service life. Security : Security is often referred a...

AI summary The text defines reliability as a line's probability of performing under specified conditions and security as its ability to withstand catastrophic failures. Mitigation strategies include designing suspension structures with adequate longitudinal RSL and inserting anti-cascading towers (stop towers) every 20-25 towers to prevent cascade failures.

od of this line was 150 year, complimented by the installation of additional generation support near the load center (Avalon) to support the future load growth increases. Figure 2.3 Typical Optimization Problem Figure 2.4 Flow Chart for Op...

AI summary The text discusses the installation of additional generation support near the Avalon load center to address future load growth increases, emphasizing infrastructure planning and grid modernization efforts to meet evolving energy demands.

2.2 Selection of Optimum Return Period The initial line cost (LCOS) will increase as the reliability increases, and the future failure cost (DCOST) will decrease as line reliability increases. An optimum reliability can be found by balanci...

AI summary The text discusses balancing initial line costs (LCOS) and future failure costs (DCOST) to determine optimal reliability for a HVdc transmission system. It references studies by Haldar and others, emphasizing probabilistic models, risk assessment, and the impact of the Maritime link on risk reduction. The Avalon upgrade study highlights the need for economic justification of reliability improvements, including customer interruption costs.

7,2 10.5 SLS ULS P f 0.7 0.5 0.3 10-1 10-2 1,0-3 1,0- 10.5 10-6 10-7 β -0.5 0.0 0.5 1.3 2.3 3.1 3.7 4.2 4.7 5.2 IEC 60826 3.8 Figure 3.2 Target Reliability Indices and Corresponding Failure Probabilities for Design of Civil Engineering Inf...

AI summary The text presents Figure 3.2, which illustrates target reliability indices and corresponding failure probabilities for the design of civil engineering infrastructures and overhead lines, referencing Gulvanessian, 1990.

Manitoba Hvdro + 500kV HVdc Lines Manitoba Hydro HVDC transmission system consists of three Bipole lines called Bipole I(BP1), Bipole II (BP2), and Bipole III (BP3) respectively. Bipoles I and II were built in the 70's and 80's (?) while B...

AI summary Manitoba Hydro's HVDC transmission system, including Bipole I, II, and III, faces reliability risks from severe weather events. A 1996 microburst caused simultaneous failures of Bipoles I and II, leading to a 2020 MW outage and four-day power restoration. The incident prompted significant R&D investments to mitigate High Intensity Wind (HIW) impacts on transmission infrastructure.

3.6 Review of CSA 60826 (2010) In the CSA standard, the line is considered a system that consists of many major components (subsystems), such as supports, foundations, conductors, insulators, and hardware. Each component can be further bro...

AI summary The CSA 60826 (2010) standard outlines transmission line design, emphasizing system reliability through component strength exceeding weather-related loads, with figures illustrating system hierarchy and connectivity.

4.1 Glaze Ice Loads Freezing precipitation usually occurs when a cold air mass with temperature less than or equal to 0° C is positioned below a layer of warm air through which rain or drizzle is falling. When the liquid droplets pass from...

AI summary The text explains glaze ice formation on conductors and OPGW due to freezing precipitation, detailing supercooled droplet behavior, freezing conditions, and density. It references CSA 60826-10 standards and includes a figure comparing ice thickness values with EFLA 2020 design parameters.

hat are quite close with the icing model and generally predicts slightly higher icing. The exception is the largest value in test span 2009-2 (4.9 kg/m), which is considerably higher in the test span. The final simulated loads are in gener...

AI summary The study on rime icing along the LIL route in Zones 2, 5, and 7 shows simulated icing values generally align with design loads but lower than historical data. The model highlights topographical influence on ice loading and explains low predicted icing due to route selection avoiding critical areas. This is the first reliable quantification of local icing conditions for the LIL.

4.4 Combined Wind and Ice Loads Traditional design for combined ice and wind load requires that the wind speed be applied to ice covered conductor that includes the diameter of the conductor plus the twice of the equivalent ice thickness....

AI summary The section outlines two methods for calculating combined wind and ice loads on conductors: the historical storms method, which uses extreme value analysis from ice accretion models, and the combined load probabilities method, which statistically combines wind and ice occurrence probabilities under independence assumptions.

6.1.3.1 Deterministic Analysis – LIL DESIGN Using NLH Criteria In this section, we compare the analysis results of the two critical towers located in Zones 1 and 3a respectively. These towers are in Labrador and each tower carry five cable...

AI summary This section compares the structural integrity of two critical towers under LIL and NLH design criteria. NLH criteria result in significantly higher use member factors (UF) exceeding 100% for multiple members, with probability of failure (POF) at 1% and 2% respectively. The analysis suggests potential structural risks under specific load combinations, highlighting design concerns for towers in Zones 1 and 3a.

7.3.1 S2-541 Tower (Zone 3a) 1815 1816 1817 1818 1819 1820 1821 1822 1823 1824 1825 1826 1827 1828 1829 1830 1831 1832 1833 1834 1835 1836 1837 1838 1839 1840 1841 1842 1843 1844 1845 1846 1847 Results of the analyses show that the POF is...

AI summary The analysis reveals that S2-541 tower in Zone 3a has a significantly higher Probability of Failure (POF) under combined wind and ice loads compared to baseline scenarios. This increases the overall POF for the Labrador Island Transmission Link (LIL) and highlights the need for revised design standards considering increased reference wind speeds and terrain roughness.

7.4.2 Revision of Avalon Load Based on Lower Failure Rate Value The above load on the Avalon can also be justified based on 1996 Avalon study. During this study, design loads for upgrading and for a short section of a new line on the Avalo...

AI summary The Avalon load revision is based on updated failure rate data from 2004-2023, adjusting the 1996 study's 50-year ice load estimate from 68mm to 48mm. This reflects a 30% reduction due to a revised 11-year failure interval, considering one major icing failure post-2004 upgrades, and accounts for spatial factors observed over 30 years of operational data.

8.2 Design Loads during Bay D'Espoir Power Development in mid 60's Upon review of the pertinent information available during the rural electrification in 60's, two basic load conditions evolved: normal zone, with 25.4 mm radial glaze ice,...

AI summary During the mid-60s Bay D'Espoir Power Development, design loads for Newfoundland and Labrador's bulk electric system included normal and ice zones with specific ice thicknesses (25.4 mm and 38 mm radial glaze ice). Overload factors varied between metal towers (1.33) and wood poles (2.0), with Table 8.1 and figures illustrating the transmission system design.

8.3.1 East Coast Failures (Avalon Peninsula, Haldar 1988, 1996, 2006) The line failures on the Avalon Peninsula occurred in 1970, 1984, 1988, and 1994 (Haldar, 1995). Figure 8.3 depicts the observed glaze ice sample on conductor during the...

AI summary The Avalon Peninsula experienced multiple transmission line failures between 1970 and 1994 due to ice overload, leading to conductor/hardware failures and cascading outages. Design weaknesses and underestimated ice loads (up to 50mm radial glaze ice) were identified, prompting a revision of design standards to 63mm ice thickness. Failures included bridge collapses, tower failures, and significant repair costs, highlighting systemic infrastructure vulnerabilities.

8.3.2 West Coast Failure (TL 228, Haldar 1990) The 230kV line (TL 228) which runs from Buchans to Massey Drive on the west coast of Newfoundland, was commissioned in 1967. Since its commissioning, the line has experienced several major fai...

AI summary The 230kV Buchans-Massey Drive transmission line (TL 228) on Newfoundland faced repeated failures from 1967-1990 due to ice accumulation and wind. Upgrades in 1990-1991, including mid-span towers to shorten spans, resolved the issue. Post-upgrade, no damage has occurred, with ice load models estimating 75mm radial ice as the design threshold.

8.3.3 Northern Peninsula (TL 247 & 248, Hannah et al.) Lines designed and operating at present on the Northern Peninsula have a large dispersion in ice loadings, varying from 0.3 to 4 inches of radial ice. This corresponds to 13.0 to 102mm...

AI summary The Northern Peninsula power lines (TL 247 & 248) exhibit significant ice loading variations (0.3–4 inches radial ice, 1.5–30kg/m load) across 69kV–230kV systems. The Deer Lake–Cat Arm line, designed for 4-inch ice loads (30kg/m), includes a NW-SE segment critical for NE wind-driven freezing precipitation, justifying its higher design standard.

8.4 Benchmarking Outage Data (Before and after Upgrade, Edwards, 2021) The cumulative weather related line outage hours between 1980-1999 were approximately 6700 hours and between 2000-2020, approximately 2765 hours. The high value in the...

AI summary This section compares weather-related and non-weather-related line outage hours in Newfoundland and Labrador (NL) and Canada from 1980–2020. Outage hours decreased significantly after 2000 due to NLH's upgrades, with a notable 2010 spike from a TL208 failure. Data normalization against CEA benchmarks highlights improved system reliability post-2000.

8.5.2 Comparison of Avalon Upgrade Steel Transmission Line and LIL This section compares the structure support system and cable system reliability comparison for the Avalon upgrades and the LIL on the Avalon Peninsula for extreme ice load....

AI summary The section compares the Avalon Upgrade and LIL transmission lines, noting LIL's higher structural reliability under extreme ice loads but lower cable system reliability. Avalon's design prioritized cost control by limiting conductor tension, while LIL's balanced design maintains failure sequence. Historical NLH upgrades post-2001 improved system performance, though LIL still lags behind a Canadian utility's reliability benchmarks.

for determining the LIL POF, following, in principle, CSA 60826-10 DLS criteria. A future follow-up study should consider the following items in revising the LIL POF and these are prioritized here:

AI summary The text outlines a need for revising the Labrador Island Transmission Link (LIL) Performance of Function (POF) criteria, recommending a future study to update the LIL POF following CSA 60826-10 DLS standards. Prioritization of items for revision is emphasized.

NON-CONFIDENTIAL 1 Request IR-20: 2 3 Please refer to Exhibit N-1, Attachment 1, A39 4 a) Please define the length of the "initial period," in a range months, to which the 5 Witness refers. 6 b) Is it the Witness's testimony that the "hurd...

AI summary The response to Request IR-20 defines the 'initial operation period' as 24 to 36 months following commercial in-service and clarifies that the Board's review of the Maritime Link proceeding did not anticipate the extent of delays and operational issues faced by the Labrador Island Transmission Link (LIL).

1 Current Period Overview - 2 Table 3 presents an overview of the current period performance, compared to previous period - 3 performance and most recent Planning Analysis values.

AI summary This section provides an overview of the current period performance, comparing it to previous periods and the most recent Planning Analysis values. It highlights key performance metrics and their alignment with planning projections.

Table 4: EqFOR Overview (%) 1-Jan-2024 to 1-Jan-2025 to Base Planning Analysis Range of Planning Analysis Asset Type Measure 31-Dec-2024 31-Dec-2025 Value Values LIL EqFOR 3.37 0.9616 5 1–10 15 The resource planning model does not differen...

AI summary Table 4 presents an overview of the Equivalent Forced Outage Rate (EqFOR) for the Labrador Island Transmission Link (LIL) from 2024 to 2025, showing a decrease in the EqFOR value from 3.37 to 0.9616, with a base planning analysis value of 5 and a range of 1–10. It notes that the resource planning model does not differentiate between DAFOR and DAUFOP.

1 Hydraulic Unit DAFOR Performance – Regulated Hydro - 2 Detailed results for the current period and the previous period are presented in Table 5 and Chart 1. - 3 These results are compared to Hydro's near-term and resource planning analys...

AI summary The document presents detailed results comparing the current and previous periods' hydraulic unit DAFOR performance to Hydro's near-term and resource planning analysis values for forced outage rates, as used in the 2024 Resource Plan and the November 2025 Near-Term Report. Units exceeding established values are discussed.

3 Hydraulic Unit DAFOR Performance – Muskrat Falls - 4 Detailed results for the current period and the previous period are presented in Table 6 and Chart 2. - 5 These results are compared to Hydro's near-term and resource planning analysis...

AI summary This section presents detailed results for the current and previous periods regarding the hydraulic unit DAFOR performance at Muskrat Falls. The results are compared to Hydro's near-term and resource planning analysis values for forced outage rates, as used in the 2024 Resource Plan and the November 2025 Near-Term Report. Overall, plant performance has improved, though individual units not meeting established values are discussed.

Page 13 Chart 4: GT DAUFOP: Hardwoods/Stephenville Units - 1 The DAUFOP for the Happy Valley GT was 10.57% for the current period, as shown in Table 9 and Chart - 2 5. This is above the near-term and resource planning analysis value of 4.6...

AI summary The DAUFOP for the Happy Valley GT was 10.57% in the current period, which is above the near-term and resource planning analysis value of 4.65%, indicating a decline in performance compared to the previous period. This has prompted a discussion in Section 7.1.

Introduction - The Muskrat Falls Assets, made up of the Labrador-Island Link ("LIL"), which includes the Soldiers Pond - Synchronous Condensers ("SCs"), the Labrador Transmission Assets and the Muskrat Falls Hydroelectric - Generating Faci...

AI summary The Muskrat Falls Assets, including the Labrador-Island Link and hydroelectric facilities, face early operational challenges due to manufacturing defects and equipment failures following a 'bathtub-shaped curve.' Newfoundland and Labrador Hydro addresses these issues through maintenance, capital projects, and engineering studies to improve long-term asset reliability.

Soldiers Pond Synchronous Condensers - Hydro continues to address the remaining items that were noted in punch list reports submitted with - the commissioning certificate and outstanding warranty claims.

AI summary The document indicates that Hydro is addressing remaining items from punch list reports and outstanding warranty claims related to the Soldiers Pond Synchronous Condensers project, as noted in commissioning certificate submissions.

Cable Switching - As reported in Hydro's final 2024–2025 Winter Readiness Report, 3 new equipment was successfully - installed to mitigate cable switching transients at the LIL Transition Compounds in mid-October 2024. - Since that time, H...

AI summary Hydro installed new equipment to mitigate cable switching transients at LIL Transition Compounds in 2024 but identified an icing issue with disconnects. General Electric developed an improved ice guard design, with installation planned for early 2026. Hydro has implemented temporary operating procedures to ensure winter reliability.

Quarterly Report on Asset Performance in Support of Resource Adequacy for the Twelve Months Ended December 31, 2025, Appendix B - 2025, with the assemblies to be purchased and installed as required through a capital project. 9 - Additional...

AI summary The report details infrastructure upgrades including a 2025 capital project for conductor assemblies, 2024 OPGW suspension clamp procurement installed in 2025, and enhanced testing protocols. Hydro emphasizes emergency preparedness and reliability measures through its Emergency Response Plan and material stockpiling to prevent service disruptions.

Top Plate Design - In December 2022, there were two incidents impacting two adjacent structures of the LIL where the - connection of the top plate of the OPGW suspension detached from the tower, falling onto the cross - arm. Analysis was c...

AI summary The text details incidents in December 2022 involving top plate detachment on the Labrador-Island Link (LIL), leading to an analysis identifying 63 towers (A3/A4) requiring reinforcement. By 2024, 61 towers were repaired, with remaining work planned for 2026-2028. Other tower types (A2, B1, B2) may require future repairs if deformation occurs, with designs completed in Q3 2025.

Ice Monitoring - In response to icing experienced on the LIL, Hydro has undertaken capital projects for the installation of - a real-time weather station, as well as the installation of on-line ice and galloping monitoring - equipment. In-...

AI summary Hydro has implemented capital projects to install real-time weather stations and ice monitoring equipment on the Labrador-Island Link (LIL) in 2025, with plans for a second station in central Labrador by late 2026 to address icing issues.

4.5 Engineering Studies and Reports - Since the commissioning of LIL in April 2023, Hydro has gained valuable insight into LIL operations. Using - Hydro's operating experience and recommendations from its investigations, supplemented by th...

AI summary Hydro has identified three potential reinforcements to the Labrador-Island Link (LIL) post-commissioning in 2023 to enhance reliability, address failure modes, and mitigate risks. Engineering assessments, including ice load reviews, mid-span structures, and electrode conductor relocations, have been completed, with cost estimates evaluated through Q4 2025. Findings are summarized in Attachment 1.

4.7 Restoration Plans and Operational Strategy - In addition to engineering studies to inform potential reinforcements to mitigate the risk of component - failures and outages, Hydro is currently in the process of contracting a consultant...

AI summary Hydro is updating restoration plans with a consultant to address geographic and weather challenges, evaluate alternative restoration approaches, and analyze time and cost-benefit factors for improving restoration efficiency and effectiveness.

1.0 Introduction - The Labrador-Island Link ("LIL") is an important transmission line for the provincial energy grid due to its - power carrying capacity that is used to deliver a large portion of the winter peak energy and demand to - the...

AI summary The Labrador-Island Link (LIL) is critical to Nova Scotia's energy grid, with past failures attributed to icing and unbalanced loading. Newfoundland and Labrador Hydro conducted investigations, leading to a 2026–2028 capital project to reinforce the line, including tower modifications, damping systems, and electrode conductor relocations to enhance reliability.

2.0 Background - Line L3501/2 is the 350 kV High Voltage direct current ("HVdc") overland transmission line portion of the - LIL, traversing approximately 1,100 km through three major meteorological loading zones, referred to as - average,...

AI summary The document describes the 350 kV HVdc transmission line (L3501/2) as part of the Labrador-Island Link (LIL), detailing its route, structure, and design considerations, including meteorological loading zones and tower types.

Table 1: Tower Types Tower Type Structure Type Insulator Assembly Type Deflection Angle Limit (degree) A1, A2, A3, A4 Guyed Suspension 0–1 B1 Guyed Suspension 0–3 B2 Self-Support Suspension 0–3 C1, C2 Self-Support Dead-End 0–30 D1, D2 Self...

AI summary Table 1 outlines different tower types used in power infrastructure, including their structure type, insulator assembly type, and deflection angle limits. This information is relevant to infrastructure planning and grid modernization.

3.0 Investigation Overview Issues with components of the LIL during ice events over the past five years have primarily caused damage to the electrode crossarms, OPGW tower peaks, and the electrode conductor. Investigations determined that...

AI summary The document discusses issues with the Labrador-Island Link (LIL) caused by ice events over the past five years, leading to damage on electrode crossarms and OPGW tower peaks. The root causes included overloading from ice accumulation and unbalanced ice loads, with some failures attributed to galloping. A capital project is planned for 2026 to address these issues.

Number of Date Location Number of Damaged EL Crossarms Locations of Damaged EL Conductor Number of Damaged OPGW Peaks Number of Damaged OPGW Top Plates Approximate Radial Equivalent Ice Thickness (mm)4 Approximate Weight of Ice on EL Condu...

AI summary The table presents data on the number of damaged electrical infrastructure components, including crossarms, conductor, and OPGW peaks and top plates, across different locations and dates, along with ice thickness and weight measurements. This data is relevant to understanding the impact of ice loading on power infrastructure.

- 2 December 2022, which caused damage to two OPGW top plates on two A3 towers. During this event, - 3 the top plate connections failed and caused deformation and damage to the top plate and the hanger - 4 bracket on two A3 towers. While t...

AI summary An icing event on 2 December 2022 caused damage to OPGW top plates on two A3 towers due to a design error. The ice load was below the design specifications, but the connection capacity was insufficient. Reinforcement work was completed in 2024, and recommendations from investigation reports are summarized in Appendix A.

Table 3: Investigation Reports Report Title Document Number Failure Investigation Report – TL3501/2 Tower and Conductor Damage Icing Event January 2021 in Labrador7 ILK-EG-ED-6200-TL-H15-0001-01 L3501/2 Failure Investigation – OPGW Tower P...

AI summary This section lists several failure investigation reports related to icing events and structural failures on the Labrador-Island Link (LIL) transmission line, along with their document numbers. It also mentions a capital project related to LIL engineering studies scheduled for 2024–2025.

8 Damping system - 9 In 2024, an engineering consultant was engaged to provide an updated damper technical specification - 10 based on past issues. A damper supplier was also engaged to determine the quantity and type of - 11 dampers to pr...

AI summary In 2024, an engineering consultant and damper supplier were engaged to address past issues with a damping system. Vibration equipment was installed but faced weather-related failures, prompting new installations in 2025. A 2026 recommendation for a new damping system is anticipated, supported by asset performance reports from Newfoundland and Labrador Hydro.

Optimizing Clamp Designs - Three alternative suspension clamps were installed on the electrode conductor at 10 structures in 2024, - and will be inspected annually for performance. These alternative clamp designs are intended to reduce - s...

AI summary The document outlines the installation of alternative suspension clamps on electrode conductors and OPGW assemblies to reduce stress from oscillations and ice loading. An ice study informed updated design loads, leading to tower reinforcement plans. Redesigned clamps and modified tower structures aim to improve system reliability and mitigate overloading risks.

5.0 LIL Strengthening Capital Project (2026–2028)

AI summary Section 5.0 outlines the LIL Strengthening Capital Project (2026–2028), aimed at enhancing the Labrador-Island Link's reliability, capacity, and resilience. The project involves infrastructure upgrades to ensure grid stability and support growing energy demands in the region.

5.1 Evaluation of Alternatives - For the LIL Strengthening Capital Project proposal, four alternatives were evaluated to address issues - with the OPGW peak, the electrode crossarm and the electrode conductor: - Installation of mid-span st...

AI summary The LIL Strengthening Capital Project evaluated four alternatives to address technical issues with the OPGW peak, electrode crossarm, and electrode conductor. These included mid-span structures, re-designing the electrode assembly, reinforcing OPGW peaks, and relocating the electrode conductor to wood poles. Appendices provide detailed reports and cost estimates for these alternatives.

5.1.1 Mid-Span Structures - This alternative would include the installation of mid-span structures to reduce the ice loads on the - towers. Analysis determined that the reduction in loading on both the electrode crossarm and OPGW - peaks i...

AI summary The installation of mid-span structures to reduce ice loads on towers was evaluated but found insufficient to address overstress from increased ice and unbalanced loads, rendering the alternative technically infeasible.

5.1.2 Remove Electrode Line Conductor from Towers and Install on Wood Poles - This alternative would remove the EL from towers and install on a wood pole line. In addition to - reducing the ice loads on the towers, there are several other...

AI summary This alternative proposes moving the electrode line from towers to wood poles, reducing ice loads and facilitating repairs. However, it requires a new right-of-way, incurs higher costs (~$101,562 per tower), and may face challenges with obstacles like waterbodies. The wood pole line has shorter spans and may not handle elevation changes effectively.

5.1.3 Re-design EL Assembly - This alternative would include the installation of a newly designed electrode assembly on the electrode - crossarm. Two options were designed under the 2024-2025 project: one that can be installed on the - exi...

AI summary The alternative proposes redesigning electrode assemblies to reduce longitudinal loads and address conductor forces under unbalanced ice loads. Two options are available: one for existing crossarms ($10,000/structure) and a reinforced version ($29,000/structure). However, neither fully addresses high unbalanced ice loads or OPGW peak loads.

5.1.4 Reinforcement and Re-design of OPGW Peaks and EL Crossarms - This alternative would include replacing the existing electrode crossarms and OPGW peak with new - reinforced sections and adding reinforcing members to the existing cage....

AI summary This section discusses reinforcing OPGW peaks and EL crossarms with new reinforced sections and additional members to address ice and unbalanced ice loads. The alternative is low-cost per structure ($36,000 for both components, $29,000 for crossarms alone) but does not resolve electrode conductor failures. Installation can occur during monopole outages.

5.2 Recommended Alternative - The recommended alternative is the Reinforcement and Re-design of OPGW Peaks and EL Crossarms - with Re-design of the EL Assembly for most sections, with two exceptions. The combination of these - alternatives...

AI summary The recommended alternative involves reinforcing and redesigning OPGW peaks and EL crossarms, with exceptions in sections of southern Labrador due to higher icing and absence of electrode conductor. Installing new sections is deemed more cost-effective than reinforcing existing ones. Exceptions include removing EL conductor from towers in specific areas and redesigning only OPGW peaks where electrode conductor is absent.

5.3 Scope of Work - The project scope includes procurement and installation work on a total of 309 Type A1 towers, as - follows: - Replacement of OPGW peaks, EL crossarms, and EL assemblies for 186 towers: - o 18 A1 towers from structure 1...

AI summary The project involves replacing OPGW components and reinforcing towers across specific line sections, prioritizing areas with past failures. Material procurement includes reinforcement for ice load risks, with repairs deemed non-urgent due to no outage risk. Selection criteria prioritize sections with multiple past events.

5.5 Project Schedule - The construction schedule for the 2026-2028 project is shown in Table 4. Procurement of all material - will occur in year 1, and installation work will take place over a three-year period based on priority. Similar c...

AI summary The 2026-2028 project's construction schedule is outlined, with material procurement scheduled for year 1 and installation spanning three years based on priority. Similar characteristics such as loading zones, tower types, icing, and elevation are noted.

Table 4: Project Schedule Activity Date Procurement: Materials ordered. Year 1 Top Plate Reinforcement: 2 A4 towers, structure 1831 and 1821 Year 1 Replacement of OPGW Peaks, and Removal of EL Conductor and Installation on Wood Poles: 18 A...

AI summary Table 4 outlines a project schedule for various activities related to infrastructure upgrades, including procurement, tower reinforcement, and replacement of OPGW peaks and EL conductors across multiple years.

Summary of all Failure Investigation Recommendations Document Number Report Title Recommendation Status Comments Monitor ice by line patrol Addressed Lines are monitored regularly during the winter by helicopter line patrol. Additional hel...

AI summary The document outlines recommendations from a failure investigation related to icing events and line damage in Labrador. Key actions include monitoring ice through helicopter patrols, installing real-time ice monitoring systems, and implementing procedures for mechanical ice management. The LIL Strengthening Capital Project is ongoing, and engineering consultants have been engaged to improve damper specifications.

1.0 INTRODUCTION NL Hydro has experienced several performance issues for the Labrador-Island Transmission Link, +/- 350 kV HVDC. Performance issues include the following: - · Electrode conductor failure - Electrode cross-arm structural fai...

AI summary NL Hydro's Labrador-Island Transmission Link (LIL) faces technical issues including electrode conductor failures and tower buckling. The memo proposes mid-span structures to reduce tower loading and address weight span imbalances, enhancing transmission line performance.

2.0 STUDIED TOWER LOCATIONS Six tower locations were inspected for potential candidates for mid-span structure additions. Locations were chosen to have unique characteristics that may represent a good sample space for potential highly load...

AI summary Six tower locations were inspected for potential mid-span structure additions. The locations were selected for their unique characteristics and represent a diverse sample of potentially highly loaded tower positions. The tower names are based on PLS-CADD models provided by NL Hydro on January 15, 2025.

3.1 $4-502 (2469) Tower position S4-502 (2469) was chosen due to the presence of a significant ahead/back weight span imbalance with a ratio of approximately 1.63 for the 'Max ice' weather case. Weight span imbalances amplify unbalanced ic...

AI summary Tower position S4-502 (2469) was selected due to a 1.63 ahead/back weight span imbalance under 'Max ice' conditions, which exacerbates longitudinal loads. Using the A1 tower in this configuration increases span lengths, leading to localized high loading and prior peak failures (L3501/2 Failure Investigation).

3.1.3 Discussion The introduction of a mid-span tower between S4-501 (2468) and S4-502 (2469) provides significant reduction to the wind and weight spans for icing cases however does not address all structural overstresses in the peak memb...

AI summary Adding a mid-span tower between S4-501 and S4-502 reduces icing-related stresses but fails to resolve all structural overstresses, requiring reinforcement of S4-502. However, reinforcing S4-502 alone is more economical than installing the mid-span tower due to high construction costs in a wet low-lying area.

3.2 $4-576 (2543) Tower position S4-576 (2543) was chosen due to long weight spans on both sides of the tower, as shown in Table 4. To avoid weight spans imbalance, it was decided to add two mid-span structures; one in the back span (BS) a...

AI summary Tower position S4-576 (2543) was selected due to long weight spans on both sides, necessitating mid-span structures to balance loads. Long spans create high vertical loads during ice events, leading to local peak failures despite no electrodes being present.

3.3.3 Discussion As shown in Table 7, adding one mid-span structure decreases the peak braces and legs overstresses, however, members reinforcement would still be required. The addition of the mid-span structure in this scenario of the lin...

AI summary The analysis in Table 7 indicates that adding a mid-span structure reduces peak overstresses but creates imbalances in adjacent structures. Reinforcing the existing tower avoids overstresses, making it a more practical solution than adding mid-span structures in this downhill scenario.

3.4 S1-318 (319) Tower position S1-318 (319) was chosen due to the long wind spans as well as weight spans on both sides of the tower with electrode wires strung. This tower configuration induces high transverse loads during wind events an...

AI summary The tower configuration S1-318 (319) requires two mid-span structures (AS and BS) due to long wind and weight spans causing high transverse and vertical loads. The current A1 configuration has overstressed components like diagonals, legs, and cross arms.

3.4.1 Wind and Weight Span Overstresses are observed in the peak, electrode cross-arms, and the cage above the pole compression chord connection, therefore the OPGW and electrode loads are most relevant. The OPGW and electrode wind & weigh...

AI summary The analysis identifies overstressing in OPGW and electrode components due to wind and weight spans. Existing and modified span lengths are compared, showing significant reductions when mid-span structures are added. The OPGW wind/weight spans are presented as representative of electrode spans, with visual comparisons in Figure 5.

3.4.3 Discussion Adding one or two mid-span structures will reduce tower S1-318 (319) overstresses. Reinforcing of overstressed members will still be required. This makes the mid-span structure addition not an economical solution in this s...

AI summary Adding mid-span structures to reduce overstressing in tower S1-318 (319) is deemed uneconomical as reinforcement of overstressed members remains necessary. The analysis concludes that existing tower reinforcement is a more viable solution than adding mid-span structures in this scenario.

3.5 S1-370 (371) Tower S1-370 (371) has electrode wires strung, with a weight span imbalance ratio of approximately 2.4 for the 'Max ice' weather case. These conditions increase longitudinal loads during an ice event. A possible solution t...

AI summary Tower S1-370 (371) exhibits a weight span imbalance ratio of 2.4 during 'Max ice' conditions, increasing longitudinal loads. A proposed mid-span structure aims to address the imbalance, but terrain challenges may hinder visibility and cause uplift risks.

3.5.3 Discussion Adding one mid-span structure will reduce tower S1-370 (371) overstresses, but does not eliminate all of them. Reinforcing of overstressed members will still be required. Due to the topography at the new mid-span structure...

AI summary The analysis evaluates structural reinforcement options for tower S1-370 (371). Adding a mid-span structure reduces but does not eliminate overstresses, while reinforcing the existing tower is deemed more feasible due to topographic constraints and reliability considerations.

3.6.1 Wind and Weight Span Similar to tower S1-318 (319), the OPGW and electrode wind & weight spans were found to be similar so only the OPGW is presented.

AI summary The document discusses the similarity between the OPGW and electrode wind & weight spans, referencing tower S1-318 (319), and notes that only the OPGW is presented due to their similarity.

3.6.3 Discussion As shown in Table 13, adding a mid-span structure will slightly improve weight imbalance, but it won't be enough to avoid overstresses. This is due to the land topography at this section (towers running uphill), which intr...

AI summary The analysis concludes that adding a mid-span structure will only marginally improve weight imbalance caused by uphill terrain, making tower reinforcement a more practical solution to avoid overstress.

3.7.1 Tower S4-576 (2543) Reinforced Model Overstresses As shown in Table 5, the reinforced model shows overstresses with a ratio of 100.2%. This scenario is encountered if no mid-span structures are added and only reinforcing of the exist...

AI summary The reinforced model of Tower S4-576 (2543) shows overstresses of 100.2% due to discrepancies between envelope load cases and as-built load cases from PLS CADD. This occurs when no mid-span structures are added and only tower A1 is reinforced, leading to increased axial forces in member GW217.

4.0 CONCLUSIONS The introduction of mid-span structures can effectively reduce the wind and weight spans and therefore the applied loads. The weight span imbalance may be improved to reduce longitudinal loads. For the structures studied, t...

AI summary The analysis concludes that reinforcing A1 structures is more economical than adding mid-span structures, though both approaches have limitations. Mid-span structures reduce loads but cannot fully address overstresses, while reinforcing A1 structures may still require case-by-case inspections due to load discrepancies.

LIL Engineering Study – A1 Electrode Suspension Assembly Tetra Tech REV. No. ISSUE DATE PREPARED BY REVIEWED BY APPROVED BY DESCRIPTION OF REVISION 00 June 10, 2025 Julien Dupas Tarek Ghazal Greg Sheppard Issued for use -

AI summary This document outlines the engineering study for the A1 Electrode Suspension Assembly as part of the Labrador-Island Link project. It includes a table with revision details, such as the revision number, issue date, and responsible personnel.

3.0 PERMISSIBLE LENGTH INCREASE The length that the electrode suspension insulator string can be increased is dependent on the required electrical clearances, minimum separations to pole conductors, and existing tower geometry. The main in...

AI summary The permissible increase in electrode suspension insulator string length depends on electrical clearances, conductor separations, and tower geometry. Key inputs include specific design drawings and PLS-CADD models from NL Hydro, focusing on damaged A1 tower ranges. The analysis uses 239 A1 tower positions as a representative sample.

3.3 TRANSVERSE SWING UNDER MAXIMUM WIND SWING The transverse swing angle on the tower type A1 electrical clearance drawing ILK-JY-SD-6200-TL-D99-0012-01-A3 is listed as 70°. The distribution of as-built transverse swing angles under maximu...

AI summary The transverse swing angle for tower type A1 is 70°, but improvement options require reducing it to 67° or 66° to maintain electrical clearance. Conductor weights, specifically the MPS HDW-100-SS model, are recommended to mitigate exceedances.

3.4 VERTICAL AND HORIZONTAL SEPARATIONS TO POLE CONDUCTORS Tower type A1 design requirements drawing ILK-SN-CD-6200-TL-DD-0112-01-C4 outlines the required separation between the electrode and the poles. The limitations are as follows: - Ho...

AI summary The text outlines design requirements for vertical and horizontal separations between electrode and pole conductors, referencing specific drawings and calculations. It highlights that existing designs exceed minimum vertical separation due to shorter-than-anticipated pole insulator strings, but warns that lengthening electrode insulators or increasing horizontal offsets could violate these limits. The analysis emphasizes the need to study galloping ellipse clearance to assess acceptability of potential encroachments.

3.7 OPTION 2 PERMISSIBLE INCREASE The tower type A1 reinforcement scope showed significant overusages in most of the electrode cross-arm members that are not easily addressed with reinforcement. For this reason, it is more economical to de...

AI summary Option 2 for tower reinforcement prioritizes cross-arm replacement over reinforcement due to overusage in electrode cross-arm members. The permissible increase is 325 mm, governed by maximum wind swing cases, with potential for an additional 50 mm if the climbing bolt is removed, as confirmed by NL Hydro.

4.0 LONGITUDINAL ARTICULATION ANGLE One of the field observations from existing conditions is contact of the bottom insulator unit and the electrode conductor under longitudinal loading cases. Based on the geometry from the electrode insul...

AI summary The document discusses the permissible longitudinal articulation angle for insulator units under load, noting a maximum of 50° before contact. Design requirements specify 33°, within the permissible range, but a failure case showed 60°, leading to proposed hardware modifications to increase articulation beyond 70°, confirmed by SLACAN.

6.0 OPTION 2 DESIGN The second design option is to further increase the insulator length and address structural shortcomings in the insulator attachment to the cross-arm as described in the Failure Investigation Report. The hardware change...

AI summary Option 2 Design addresses structural and insulator attachment issues by increasing insulator length, replacing hardware with U-bolts and socket ball extensions, and modifying cross-arm configurations. Changes aim to reduce load moments, improve electrical clearance, and comply with 350 kV HVdc technical specifications.

Appendix D LIL Engineering Study – Calculations for OPGW Peak Reinforcement

AI summary Appendix D references an engineering study focused on calculations for OPGW (Optical Ground Wire) peak reinforcement as part of the Labrador-Island Link (LIL) project. The content includes visual aids but lacks detailed textual analysis or discussion of specific methodologies or findings.

2.1 GEOMETERY As seen in Figure 1 below, the grey members are the existing members, while the green members represent additional steel sections to be added for reinforcement. As shown in the figure, the suggested reinforcement includes add...

AI summary The text describes structural reinforcement measures for towers, including adding bent plates, back-to-back angles, and stiffeners. Existing members are shown in grey, while new steel sections are highlighted in green. Specific modifications are outlined for towers A4, B1, A2, and B2, with references to figures illustrating the design changes.

LIL Engineering Study - Calculations for OPGW Reinforcement Newfoundland and Labrador Hydro Figure 2: OPGW Peak Model for Towers A4 and B1 - a) Isometric View - b) Plan View

AI summary The LIL Engineering Study details calculations for OPGW (Optical Ground Wire) reinforcement, including visual representations of the OPGW Peak Model for Towers A4 and B1. The study is conducted by Newfoundland and Labrador Hydro.

Purpose The purpose of this report is to summarize costs for two options to reduce electrode conductor failures. Option 1 is to remove the existing electrode lines from the transmission towers and place them on nearby wood pole lines. Opti...

AI summary This report evaluates two options to reduce electrode conductor failures: relocating lines to wood pole lines (Option 1) or installing midspan structures to reduce infrastructure loads (Option 2). Sections 3.1 and 3.2 provide detailed cost analyses for each approach.

Table 1: Previous Construction Data Cost Estimate Item Unit Price #Units Cost Mobilization LS Refer to Section 3.1.1 Demobilization LS Refer to Section 3.1.1 Tree Clearing $0.00 Snow Clearing $0.00 Excavation Class A (Rock) $980.00 180 $23...

AI summary Table 1 presents a cost estimate for construction activities, including mobilization, excavation, pole installation, and framing. It also includes inflation factors and a total cost estimate of approximately $873,379.68 per kilometer plus $560,000. Section 3.2 discusses Option 2, which involves midspan structures installation.

Original construction costs were utilized to evaluate the cost of installing midspan structures along the existing 350 kV HVdc line in Southern Labrador. The material costs of installing type A1 towers in Southern Labrador is summarized in...

AI summary The original construction costs for installing midspan structures along the existing 350 kV HVdc line in Southern Labrador were evaluated, with material costs for type A1 towers summarized in tables.

Conclusion In conclusion the preliminary data suggests that out of these two options the most cost effective approach would be to install a dedicated wood pole electrode line near the existing transmission line in identified high risk zone...

AI summary The preliminary data suggests installing a dedicated wood pole electrode line near existing transmission lines in high-risk zones is the most cost-effective solution, with estimated costs of $313,379.68/km plus $560,000. Further analysis of assumptions, PLS-CADD options, and constructability implications is recommended.

er types (A1, A2, A3, A4, B1, B2, C1, C2, D1, D2, and E1) were designed to meet the loading requirements, which consist of a specified wind load, ice load, and combination of both applied to the line. There have been a number of failures t...

AI summary Transmission line failures in central Labrador (2021, 2022) caused damage to electrode crossarms and conductors due to unbalanced ice loads exceeding design specifications (50 mm radial glaze ice). Events involved ice thicknesses of 54-72 mm, with damage attributed to ice shedding on A1-type towers.

2. Sections for Consideration Due to the cost of building a wood pole line from Muskrat Falls to the start of the existing wood pole electrode line at structure 1229 (approximately 376 km), the removal of the electrode line from L3501/2 wi...

AI summary The document discusses the removal of 85 km of electrode line (L3501/2) due to high costs and factors like past failures, high icing, elevation changes, and galloping risks. Six sections are recommended for removal, with Figure 2 summarizing the criteria.

3. Analysis The failure investigations of damage to the towers and conductors in past events determined the root cause was overloading due to unbalanced ice loads. To determine the benefits of removing the electrode conductor from the towe...

AI summary The analysis examines power line failures caused by unbalanced ice loads, comparing scenarios with and without electrode conductors. Removing electrodes significantly reduces structural failures under balanced ice loads (60-70 mm), though failures increase beyond 70 mm. Results highlight infrastructure reliability concerns under extreme ice conditions.

Under unbalanced ice load (UBL) with 80 m of ice: - structures with the electrode: - 95% of structures failed for all load cases, - · structures without the electrode: - on the OPGW (g) the percentage of structure failure for 70/100% unbal...

AI summary Structures with electrodes show significantly higher failure rates under unbalanced ice loads compared to those without electrodes. For 80 mm ice, 95% of structures with electrodes failed, while failures without electrodes ranged from 21% to 33%. Removing electrodes reduces failure risks, particularly under balanced and unbalanced ice conditions.

4. Summary, Conclusions, and Recommendations There have been a number of failures on the L3501/2 transmission line due to ice events over the past 4 years. The electrode crossarms and the electrode conductor are two components that are oft...

AI summary Over the past four years, the L3501/2 transmission line has experienced failures due to ice events, primarily caused by unbalanced ice loads. Removing the electrode conductor from towers and running it parallel on a wood pole line could reduce damage. Analysis shows significant benefits, especially for ice loads of 70 mm, with some sections showing greater improvements under higher ice loads.

1.2 Operations During the third quarter of 2024, the LIL experienced five pole trip events. On July 28, 2024, two under frequency load shedding events occurred which resulted in customer outages to Labrador East and the Island, due to an e...

AI summary The LIL experienced multiple pole trip events in Q3 2024, including a July 28 incident caused by a ground fault during maintenance at Muskrat Falls Terminal Station, leading to outages for 5,500 and 126,269 customers. Pole compensation mitigated further impacts, and Hydro will report on winter readiness by October 10, 2024. LIL's capacity is limited to 450 MW under normal operations.

NSPML Responses to Consumer Advocate Information Requests 1 month that resulted in excessive icing). Additional details to support the request for relief 4 5 (e) The outages noted are not related to underperformance of the LIL. The referen...

AI summary NSPML responds to consumer advocate information requests regarding the performance of the Labrador Link (LIL), clarifying that outages were not due to LIL underperformance and that the LIL has operated reliably since commissioning in April 2023. NSPML also notes that NLH's load is significantly lower than forecasted, impacting energy delivery considerations.

PARTIALLY CONFIDENTIAL 1 • NLH continues to operate Holyrood in the winter period which was not forecasted 2 in 2013. 3 • Although the generation capacity at Muskrat Falls is 824 MW, as the facility is 4 primarily run of river (with minima...

AI summary The text discusses planned outages at the Labrador Island Link (LIL) in July 2023, aimed at improving the reliability of the LIL through software updates and system testing. The outage was coordinated with system operators and scheduled during the summer to minimize impact on customers.

NSPML Responses to Consumer Advocate Information Requests 1 2 3 4 5 accordance with the 30-day outage coordination period previously established by the system operators for outages affecting the delivery of the NS Block, including planned...

AI summary NSPML explains that a July planned outage was consistent with Good Utility Practice and not related to asset commissioning. The outage was necessary for software updates to enhance asset reliability and was coordinated with system operators. The outage was also compared to similar outages at Maritime Link post-commissioning.

NSPML Responses to Industrial Group Information Requests 1 Request IR-05: 1 ii) The planned outage dates were: 2 September 17 - September 26: LIL Bipole outage 3 September 3 - September 26: LIL Pole 1 outage 4 September 17 - October 8: LIL...

AI summary The text outlines planned maintenance outages for the Labrador Island Link and Maritime Link, scheduled for the Fall of 2024 and 2025. The outages are due to coordination needs, hydrology factors, and the need to prepare for winter demand. These outages are part of annual maintenance and may vary in duration.

1 Planned Outages: Start Date and Time End Date and Time Duration [h] Cause Identified Date 6-18-23 16:00 6-26-23 23:00 199 Non-critical punch list, SCADA & electrol line fault indicator 01-May-23 130 Preparation for final software update,...

AI summary The table outlines multiple planned outages with dates, durations, and causes, including software updates, maintenance, and repairs. Notably, the March 2024 transmission repair was the only outage with less than 30 days' notice, highlighting potential reliability concerns and regulatory considerations.

8 ML P1 ML P2 LIL P1 LIL P2 LIL BP 2023 September 11 to September 14 to September 3 to September 17 to September 17 to September 14, 2023 September 17, 2023 September 26, 2023 October 8, 2023 September 26, 2023 2024 September 23 to Septemb...

AI summary The document outlines the planned construction periods for various power line projects in Nova Scotia, including ML P1, ML P2, LIL P1, LIL P2, and LIL BP, spanning from 2023 to 2026 with specific start and end dates for each year.

NON-CONFIDENTIAL 1 Request IR-08: 2 3 Reference: N-01 Application, page 19, lines 10-11. 4 The Application states that more than 370 software updates have been completed at the 5 Maritime Link since commissioning in 2018. Of those 370 soft...

AI summary Request IR-08 asks NSPML to confirm how many of 370 Maritime Link software updates required multi-day outages. NSPML responds that no updates caused such outages. The exchange focuses on operational impacts of software updates on grid reliability.

- 9 a) Please explain why the section of line at issue is designed for a maximum of 50 mm of radial 10 glaze ice and a combined wind and ice load of only 25 mm of radial glaze ice with 60 km/h 11 wind, given the climatic conditions prevale...

AI summary The document requests explanations regarding the design criteria for a power line section, specifically its ice and wind load capacity, and whether these were consistent with standards. It also inquires about past icing incidents, the duration and causes of a recent outage, and the impact of the icing event on energy deliveries. Engineering reports and corrective actions are requested.

third party in connection with the March–April 2024 29 icing event, including any findings comparing actual weather conditions to design criteria and 30 any recommendations for design upgrades. 1 2 3 A. a) Line L3501/2 is the 350 kV HVdc o...

AI summary The third party inquired about the March–April 2024 icing event's impact on the 350 kV HVdc transmission line L3501/2, including design criteria comparisons and upgrade recommendations. The line spans 1,100 km through three meteorological zones, with 19 loading zones and 11 tower types. Damage occurred to specific towers during the incident.

ds and utility experience. Structure numbers that sustained damage 10 during the April 2024 incident are str. 1218–1228 and 1232, located on the south coast of Labrador in an average loading zone.1 11 12 The main root cause of the damage t...

AI summary Structural damage to power line L3501/2 occurred due to ice loads exceeding design specifications (100–125 mm radial ice) and potential galloping-induced cyclic loading. The incident, located on Labrador's south coast, prompted a 2024–2025 capital project to implement mitigation measures, with CSA 22.3 No. 60826 referenced for load standards.

sup>1 While the design loads for this section of line are slightly below the combined load case specified by CSA 22.3 No. 60826, the final as-built line will meet the CSA 50 year combined loads. scope items2 1 , while others required addit...

AI summary The document discusses reinforcement measures for a section of line to meet CSA 50-year combined load requirements, including capital project recommendations for 2026–2028. It also references customer outages caused by extreme icing on Hydro's transmission and distribution lines between 2020 and 2026, with specific details on the Line L3501/2 structures affected in the April 2024 incident.

Table 1: Outages Due to Extreme Icing (2020-2026) Date Location Description 2021- 11-25 Labrador East On November 25, 2021, at approximately 03:10 hours (AST), Hydro experienced an unplanned outage to customers in Labrador East. At the tim...

AI summary The text discusses two unplanned outages in Labrador East and Cartwright caused by extreme icing conditions, highlighting the impact of weather on infrastructure. It also references capital projects aimed at improving resilience through ice monitoring and reinforced designs.

1 and securing the OPGW to allow for tower repairs. Repair work which allowed the LIL to 2 return to monopole operation began on April 10, 2024. All repair work, which included 3 replacement of tower steel and electrode conductor, was comp...

AI summary The text discusses repair work on the Lower Island Link (LIL) involving the securing of the OPGW to allow for tower repairs. The repair work, which included replacement of tower steel and electrode conductor, was completed by April 19, 2024, and resulted in a reduction of 26,513 MWh in Base NS Block deliveries.

Appendix A: Summary of all Failure Investigation Recommendations Appendix B: LIL Engineering Study – Mid-Span Structure Addition Report Appendix C: LIL Engineering Study – A1 Electrode Suspension Assembly Appendix D: LIL Engineering Study...

AI summary The document includes appendices summarizing failure investigation recommendations and engineering studies related to the Lower Island Link (LIL), including mid-span structure additions, electrode suspension assemblies, OPGW peak reinforcement calculations, wood pole and mid-span cost estimates, and analysis of removing an electrode conductor.

1.0 Introduction - The Labrador-Island Link ("LIL") is an important transmission line for the provincial energy grid due to its - power carrying capacity that is used to deliver a large portion of the winter peak energy and demand to - the...

AI summary The Labrador-Island Link (LIL) transmission line has experienced ten failures over five years due to icing-related overloading. Investigations identified root causes and led to a 2026–2028 capital project to strengthen the line through infrastructure upgrades, including ice monitoring, tower modifications, and electrode conductor reconfiguration to enhance reliability and reduce failure risks.

3.0 Investigation Overview Issues with components of the LIL during ice events over the past five years have primarily caused damage to the electrode crossarms, OPGW tower peaks, and the electrode conductor. Investigations determined that...

AI summary The document discusses issues with components of the Lower Island Link (LIL) caused by ice events over the past five years, primarily affecting electrode crossarms, OPGW tower peaks, and the electrode conductor. Root causes include overloading from ice accumulation and unbalanced ice loads, with some failures attributed to galloping. A capital project is planned for 2026 to address these issues.

Number of Date Location Number of Damaged EL Crossarms Locations of Damaged EL Conductor Number of Damaged OPGW Peaks Number of Damaged OPGW Top Plates Approximate Radial Equivalent Ice Thickness (mm)4 Approximate Weight of Ice on EL Condu...

AI summary The document presents a table detailing the number of damaged electrical crossarms, conductor locations, and optical ground wire (OPGW) peaks and top plates in various regions of Labrador and Newfoundland between January 2021 and January 2025, along with approximate ice thickness and weight on conductors.

- 2 December 2022, which caused damage to two OPGW top plates on two A3 towers. During this event, - 3 the top plate connections failed and caused deformation and damage to the top plate and the hanger - 4 bracket on two A3 towers. While t...

AI summary An icing event on 2 December 2022 caused damage to OPGW top plates on two A3 towers due to a design error in the connection capacity of the top plate and hanger bracket. The ice load was below the design specifications, but the failure occurred because the connection was insufficient for the vertical design load. Reinforcement work on 61 critical A3 towers was completed in 2024.

Table 3: Investigation Reports Report Title Document Number Failure Investigation Report – TL3501/2 Tower and Conductor Damage Icing Event January 2021 in Labrador7 ILK-EG-ED-6200-TL-H15-0001-01 L3501/2 Failure Investigation – OPGW Tower P...

AI summary The text presents a list of failure investigation reports related to various infrastructure incidents, including icing events and structural failures, along with their corresponding document numbers. It also mentions an engineering study capital project for the Lower Island Link (LIL) from 2024 to 2025.

5 Ice Monitoring - 6 A total of three sensors were installed on structures 514 (central Labrador), 1224 (southern Labrador) - 7 and 2597 (central Newfoundland) in 2025 to monitor ice load and galloping.

AI summary Three sensors were installed in 2025 on structures located in central Labrador, southern Labrador, and central Newfoundland to monitor ice load and galloping. This initiative aims to enhance infrastructure monitoring and safety in these regions.

Optimizing Clamp Designs - Three alternative suspension clamps were installed on the electrode conductor at 10 structures in 2024, - and will be inspected annually for performance. These alternative clamp designs are intended to reduce - s...

AI summary The document discusses the installation and evaluation of alternative suspension clamps on electrode conductors to reduce stresses from oscillations and unbalanced icing. Redesigned clamps and tower reinforcements based on ice load studies are proposed to enhance system reliability and address overloading risks.

5.0 LIL Strengthening Capital Project (2026–2028) - 5.1 Evaluation of Alternatives - For the LIL Strengthening Capital Project proposal, four alternatives were evaluated to address issues - with the OPGW peak, the electrode crossarm and th...

AI summary The LIL Strengthening Capital Project (2026–2028) evaluates four alternatives to address OPGW peak, electrode crossarm, and conductor issues: mid-span structures, wood pole relocation, electrode assembly redesign, and reinforcement. Appendices B–F provide technical reports and cost estimates for implementation.

5.1.1 Mid-Span Structures - This alternative would include the installation of mid-span structures to reduce the ice loads on the - towers. Analysis determined that the reduction in loading on both the electrode crossarm and OPGW - peaks i...

AI summary The installation of mid-span structures to reduce ice loads on towers was evaluated but found technically infeasible, as it does not sufficiently address overstress caused by increased ice and unbalanced ice loads on electrode crossarms and OPGW peaks.

5.1.2 Remove Electrode Line Conductor from Towers and Install on Wood Poles - This alternative would remove the EL from towers and install on a wood pole line. In addition to - reducing the ice loads on the towers, there are several other...

AI summary The alternative proposes removing the electrode line conductor from towers to wood poles, reducing ice loads and facilitating repairs, but requires a new right-of-way and does not address OPGW issues. Estimated costs are around $101,562 per tower.

5.1.4 Reinforcement and Re-design of OPGW Peaks and EL Crossarms - This alternative would include replacing the existing electrode crossarms and OPGW peak with new - reinforced sections and adding reinforcing members to the existing cage....

AI summary This section discusses reinforcing OPGW peaks and EL crossarms with new reinforced sections and additional members to address ice load issues from past events. The reinforcement can be installed during monopole outages at a relatively low cost per structure, though it does not resolve electrode conductor failures. Estimated costs are $36,000 per structure for both components and $29,000 for only the crossarm.

5.2 Recommended Alternative - The recommended alternative is the Reinforcement and Re-design of OPGW Peaks and EL Crossarms - with Re-design of the EL Assembly for most sections, with two exceptions. The combination of these - alternatives...

AI summary The recommended alternative involves reinforcing and redesigning OPGW peaks and EL crossarms, with exceptions in specific sections due to higher icing and existing infrastructure. This approach is deemed more cost-effective than alternatives like mid-span structures or removing conductor.

5.3 Scope of Work - The project scope includes procurement and installation work on a total of 309 Type A1 towers, as - follows: - Replacement of OPGW peaks, EL crossarms, and EL assemblies for 186 towers: - o 18 A1 towers from structure 1...

AI summary The project scope involves replacing OPGW peaks, EL crossarms, and assemblies on 309 Type A1 towers across multiple sections, prioritizing areas with past failures. Material procurement for reinforcement and installation on specific towers is included, with repairs deemed non-urgent but necessary for structural integrity under maximum ice loads.

5.5 Project Schedule - The construction schedule for the 2026-2028 project is shown in [Table 4.](#page-52-1) Procurement of all material - will occur in year 1, and installation work will take place over a three-year period based on prior...

AI summary The project schedule for the 2026-2028 project outlines that material procurement will occur in year 1, with installation work spanning three years based on priority. Similar characteristics such as loading zones, tower types, icing, and elevation are noted.

Table 4: Project Schedule Activity Date Procurement: Materials ordered. Year 1 Top Plate Reinforcement: 2 A4 towers, structure 1831 and 1821 Year 1 Replacement of OPGW Peaks, and Removal of EL Conductor and Installation on Wood Poles: 18 A...

AI summary Table 4 outlines a project schedule detailing various activities and their corresponding years, including procurement, reinforcement, and replacement of infrastructure components such as towers, OPGW peaks, and EL conductors. The schedule spans multiple years and involves various structures and components.

Summary of all Failure Investigation Recommendations Document Number Report Title Recommendation Status Comments Monitor ice by line patrol Addressed • Lines are monitored regularly during the winter by helicopter line patrol. Additional h...

AI summary The summary outlines recommendations from a failure investigation report related to line damage caused by icing events. Measures include monitoring ice through helicopter patrols, installing real-time ice sensors, and implementing mechanical ice removal procedures. Tower modifications and vibration equipment installation are ongoing to improve line resilience.

LIL Engineering Study – Mid-Span Structure Addition Report Newfoundland and Labrador Hydro Report No. ILK-TT-CD-6200-TL-H15-0003-01 TT Document Number 705-2579500100-REP-G0002-00 May 23, 2025

AI summary This document is a report on the LIL Engineering Study focusing on the addition of a mid-span structure. It is authored by Newfoundland and Labrador Hydro and dated May 23, 2025. The report likely addresses infrastructure planning and grid modernization related to the Labrador-Island Link (LIL) project.

3.1 S4-502 (2469) Tower position S4-502 (2469) was chosen due to the presence of a significant ahead/back weight span imbalance Weight span imbalances amplify unbalanced icing cases longitudinal loads relative to towers in a balanced ahead...

AI summary The tower position S4-502 (2469) was selected due to a weight span imbalance, leading to increased longitudinal loads. The absence of an electrode and increased span lengths with the A1 tower configuration have caused peak loading issues, with prior failures documented in the referenced failure investigation report.

3.1.3 Discussion The introduction of a mid-span tower between S4-501 (2468) and S4-502 (2469) provides significant reduction to the wind and weight spans for icing cases however does not address all structural overstresses in the peak memb...

AI summary Introducing a mid-span tower between S4-501 and S4-502 reduces wind/weight spans for icing but does not fully resolve structural overstresses. Reinforcing S4-502 alone is deemed more economical than adding a mid-span tower with partial reinforcement.

3.2 $4-576 (2543) Tower position S4-576 (2543) was chosen due to long weight spans on both sides of the tower, as shown in Table 4. To avoid weight spans imbalance, it was decided to add two mid-span structures; one in the back span (BS) a...

AI summary Tower position S4-576 (2543) was selected due to long weight spans on both sides, necessitating mid-span structures to balance loads. Long spans create high vertical loads during ice events, leading to local peak failures despite no electrodes being present on the tower.

3.2.3 Discussion As shown in Table 5, adding one mid-span structure only does not address the peak members overstresses. This is due to the unbalanced weight spans that were introduced when only one mid- span structure was added (i.e., imb...

AI summary The analysis reveals that adding one or two mid-span structures fails to fully resolve overstresses in tower configurations due to unbalanced weight spans. Reinforcement remains necessary for certain towers, while adding multiple towers is deemed impractical. This highlights challenges in structural design for power line infrastructure.

3.3 S4-598 (2565) Tower S4-598 (2565) has no electrodes strung, and it was chosen due to its location on a downhill with increasing stationing, which causes high longitudinal loads due to the weight span imbalance with a ratio of approxima...

AI summary Tower S4-598 (2565) lacks electrodes and was selected due to its downhill location, causing high longitudinal loads from weight span imbalance (ratio ~2.4 in 'Max ice' weather). Similar issues were observed in towers S4-502 (2469) and S4-576 (2543) during unbalanced ice weather cases.

3.3.3 Discussion As shown in Table 7, adding one mid-span structure decreases the peak braces and legs overstresses, however, members reinforcement would still be required. The addition of the mid-span structure in this scenario of the lin...

AI summary Adding a mid-span structure to a downhill power line reduces some overstresses but creates new imbalances on adjacent structures, making it impractical. Reinforcing existing towers avoids overstresses, suggesting alternative solutions may be more viable in this scenario.

3.4 S1-318 (319) Tower position S1-318 (319) was chosen due to the long wind spans as well as weight spans on both sides of the tower with electrode wires strung. This tower configuration induces high transverse loads during wind events an...

AI summary The tower configuration at S1-318 (319) was selected due to long wind spans and weight spans on both sides with electrode wires. This setup causes high transverse loads during wind events and vertical loads during ice events. Adding one mid-span structure would create imbalance, so two (AS and BS) were added to address overstressing in the current tower A1 configuration.

3.4.3 Discussion Adding one or two mid-span structures will reduce tower S1-318 (319) overstresses. Reinforcing of overstressed members will still be required. This makes the mid-span structure addition not an economical solution in this s...

AI summary The discussion evaluates structural reinforcement options for tower S1-318/319, concluding that adding mid-span structures is uneconomical due to remaining reinforcement needs. Existing tower reinforcement is deemed a more viable solution.

3.5 S1-370 (371) Tower S1-370 (371) has electrode wires strung, with a weight span imbalance ratio of approximately 2.4 for the 'Max ice' weather case. These conditions increase longitudinal loads during an ice event. A possible solution t...

AI summary Tower S1-370 (371) has a weight span imbalance ratio of 2.4 under 'Max ice' conditions, increasing longitudinal loads. A proposed mid-span structure may address this, but terrain challenges could cause visibility issues and uplift risks.

3.5.3 Discussion Adding one mid-span structure will reduce tower S1-370 (371) overstresses, but does not eliminate all of them. Reinforcing of overstressed members will still be required. Due to the topography at the new mid-span structure...

AI summary The discussion evaluates structural reinforcement options for tower S1-370 (371). Adding a mid-span structure reduces but does not eliminate overstresses, requiring further reinforcement. Reinforcing the existing tower is deemed more feasible due to topographic constraints at the proposed mid-span location.

3.6.3 Discussion As shown in Table 13, adding a mid-span structure will slightly improve weight imbalance, but it won't be enough to avoid overstresses. This is due to the land topography at this section (towers running uphill), which intr...

AI summary Reinforcing existing towers is proposed as a practical solution to address weight imbalance caused by uphill terrain, as adding a mid-span structure only slightly improves the imbalance without resolving overstress issues.

4 l and discation Envelope forces (IAN) As built faress (Ishl) D:ff- Table 14: Load Cases Comparis son for $4-576 (2543) (A As built VS Envelope Lo bads) LCA/Set name Load direction Envelope forces (kN) As built forces (kN) Difference (kN)...

AI summary This section discusses the comparison of envelope forces and as-built forces for a specific tower model, highlighting differences in vertical, transverse, and longitudinal directions, and notes that the reinforced model overstresses.

Appendix C LIL Engineering Study – A1 Electrode Suspension Assembly

AI summary Appendix C contains an engineering study titled 'LIL Engineering Study – A1 Electrode Suspension Assembly,' accompanied by two images. The content focuses on technical details of the Labrador-Island Link (LIL) infrastructure, though no textual analysis or discussion is provided beyond the title and image references.

LIL Engineering Study – A1 Electrode Suspension Assembly Newfoundland and Labrador Hydro Report No. ILK-TT-CD-6200-TL-H15-0001-01 TT Document Number 705-2579500100-REP-G0001-00 June 10, 2025

AI summary A technical report from Newfoundland and Labrador Hydro (NLH) on the A1 Electrode Suspension Assembly for the Labrador-Island Link (LIL) engineering study, dated June 10, 2025. The document provides detailed analysis of the electrode suspension assembly as part of the LIL project's infrastructure planning.

1.0 INTRODUCTION NL Hydro has experienced several performance issues with the electrodes that are mounted on the same towers as the pole conductors (tower type A1) for the Labrador-Island Transmission Link, +/- 350 kV HVDC. Electrode perfo...

AI summary NL Hydro reports performance issues with electrodes on the Labrador-Island Transmission Link's HVDC towers, including conductor failure and structural failures. A technical memo proposes two improvement strategies: one low-cost, minimal-effort solution for critical issues, and a more comprehensive approach requiring additional field work.

2.0 WORK COMPLETED TO DATE Extensive study of the performance issues has previously been completed by NL Hydro and the root cause of most of the issues is that the line has experienced weather loading events that exceeded the initial desig...

AI summary The line L3501/2 experienced performance issues due to weather loading events exceeding initial design assumptions, primarily caused by electrode suspension longitudinal loading during icing events. Reports from 2021 and 2024 detail the damage and root causes, including unbalanced ice accumulation and shedding.

3.0 PERMISSIBLE LENGTH INCREASE The length that the electrode suspension insulator string can be increased is dependent on the required electrical clearances, minimum separations to pole conductors, and existing tower geometry. The main in...

AI summary The permissible length increase for electrode suspension insulator strings depends on electrical clearances, conductor separations, and tower geometry. Key inputs include drawings ILK-JY-SD-6200-TL-D99-0012-01-A3 and ILK-SN-CD-6200-TL-DD-0112-01-C4. Inspections of NL Hydro's PLS-CADD models focus on damaged tower ranges (e.g., 244-340, 342-388) to assess as-built conditions for 239 A1 towers.

3.2 ELECTRODE CONDUCTOR DROP The electrode conductor drop on the tower type A1 electrical clearance drawing ILK-JY-SD-6200-TL-D99-0012-01-A3 is listed as 270 mm. This value is dependent on the vertical departure angle and describes decreas...

AI summary The electrode conductor drop on tower type A1 is 270 mm, determined by vertical departure angles affecting electrical clearance. However, as-built data in Figure 2 adjusts this to 200 mm, considering maximum vertical departure angles of 14°, with 15° cases neglected due to limited transverse swing angles from heavy weight spans.

3.3 TRANSVERSE SWING UNDER MAXIMUM WIND SWING The transverse swing angle on the tower type A1 electrical clearance drawing ILK-JY-SD-6200-TL-D99-0012-01-A3 is listed as 70°. The distribution of as-built transverse swing angles under maximu...

AI summary The document discusses transverse swing angles under maximum wind conditions for tower type A1, noting a 70° angle on the clearance drawing. Two improvement options reduce this to 67° and 66°, with conductor weights (MPS HDW-100-SS) proposed to address exceeding limits. The solution involves strategic placement of weights to maintain electrical clearance.

3.4 VERTICAL AND HORIZONTAL SEPARATIONS TO POLE CONDUCTORS Tower type A1 design requirements drawing ILK-SN-CD-6200-TL-DD-0112-01-C4 outlines the required separation between the electrode and the poles. The limitations are as follows: - Ho...

AI summary The document discusses design requirements for vertical and horizontal separations between electrode and pole conductors, noting that existing designs exceed minimum vertical separation. Calculations show that modifying electrode insulator length or increasing horizontal offsets could violate these clearances, necessitating a study on galloping ellipse clearance to ensure safety.

3.6 OPTION 1 PERMISSIBLE INCREASE The permissible increase for option 1 was determined to be 295 mm governed by the maximum wind swing case with electrical clearance to the cage, see Figure 5. Note that the EDT (0°C, 0 Pa) limit at 11° tra...

AI summary The permissible increase for Option 1 is 295 mm, determined by the maximum wind swing case with electrical clearance to the cage. The MAXIMUM WIND SWING (-20°C, 788 Pa) limit at 67° covers required clearances, while reduced wind swing limits are omitted. Additional insulator length improves electrode shielding angles.

3.7 OPTION 2 PERMISSIBLE INCREASE The tower type A1 reinforcement scope showed significant overusages in most of the electrode cross-arm members that are not easily addressed with reinforcement. For this reason, it is more economical to de...

AI summary Option 2 involves replacing cross-arms instead of reinforcing due to overusage, allowing a 325 mm permissible increase governed by wind swing cases. Additional length may be added if the climbing bolt is removed, confirmed by NL Hydro. Structural improvements and insulation adjustments are discussed.

4.0 LONGITUDINAL ARTICULATION ANGLE One of the field observations from existing conditions is contact of the bottom insulator unit and the electrode conductor under longitudinal loading cases. Based on the geometry from the electrode insul...

AI summary The document discusses the permissible longitudinal articulation angle for insulator hardware, noting that existing designs meet safety limits (33° required, 50° permissible). Proposed modifications increase the angle beyond 70°, confirmed by SLACAN. A failure investigation report (2021) shows a 60° swing angle in a damaged tower.

5.0 OPTION 1 DESIGN The design solution for option 1 to meet the permissible insulator length increase of 295 mm is to add a socket ball extension SLACAN catalogue no. 63149 between the bottom insulator and the socket tongue, see Figure 8....

AI summary The design for Option 1 involves adding a socket ball extension (SLACAN catalogue no. 63149) to increase insulator length by 292 mm, complying with the permissible 295 mm increase. This requires replacing the arcing horn to maintain spark gap geometry, with design details in Appendix C.

6.0 OPTION 2 DESIGN The second design option is to further increase the insulator length and address structural shortcomings in the insulator attachment to the cross-arm as described in the Failure Investigation Report. The hardware change...

AI summary Option 2 design involves increasing insulator length, replacing hardware (shackle with U-bolt, adding socket ball extension and insulator unit), and modifying cross-arm structure to address failure risks. Changes include reducing longitudinal load moment arm, adjusting plan eccentricity, and using welded plate assemblies to mitigate block shear failure. Electrical clearance requirements and fabrication simplifications are also addressed.

APPENDIX C: NEW HARDWARE DRAWINGS

AI summary Appendix C presents new hardware drawings, likely related to power infrastructure projects. The content includes visual references (e.g., Figure 1 on page 102) but lacks textual details on specific components, compliance standards, or regulatory implications.

LIL Engineering Study Calculations for OPGW Reinforcement Newfoundland and Labrador Hydro

AI summary The document presents engineering study calculations for OPGW reinforcement as part of the Labrador-Island Link (LIL) project by Newfoundland and Labrador Hydro (NLH). It focuses on infrastructure planning and transmission planning for power line reinforcement.

Purpose The purpose of this report is to summarize costs for two options to reduce electrode conductor failures. Option 1 is to remove the existing electrode lines from the transmission towers and place them on nearby wood pole lines. Opti...

AI summary The report outlines two infrastructure options to mitigate electrode conductor failures: relocating lines to wood pole lines (Option 1) or installing midspan structures to reduce spans (Option 2). It references Sections 3.1 and 3.2 for detailed analysis of each approach.

3.1 Option 1: Wood Pole Line Installation Two methods were utilized to develop a per km cost estimate for reinstatement of the electrode lines onto new wood pole line. The first method was to review a previous estimate for emergency work s...

AI summary The analysis evaluates two methods for estimating per km costs of reinstating electrode lines on new wood pole lines. The first method involves reviewing a prior April 2024 emergency work estimate from Locke's Electrical, with findings detailed in Section 3.1.1.

Table 1: Previous Construction Data Cost Estimate Item Unit Price #Units Cost Mobilization LS Refer to Section 3.1.1 Demobilization LS Refer to Section 3.1.1 Tree Clearing $0.00 Snow Clearing $0.00 Excavation Class A (Rock) $980.00 180 $23...

AI summary Table 1 provides a detailed breakdown of construction costs for various items related to infrastructure projects, including mobilization, excavation, pole installation, and framing. The table also includes estimated inflation factors and total costs, with a note that the total cost includes additional amounts per kilometer and a fixed sum.

Original construction costs were utilized to evaluate the cost of installing midspan structures along the existing 350 kV HVdc line in Southern Labrador. The material costs of installing type A1 towers in Southern Labrador is summarized in...

AI summary The original construction costs for installing midspan structures along the 350 kV HVdc line in Southern Labrador were evaluated, with material costs for type A1 towers summarized in tables.

4.2 Option 2: Midspan Structures Installation The cost of installing new midspan structures is approximately $328,662.00 per tower + $315,000.00 + $700,000.00 . Assumptions were made in the development of this estimate which can be reviewe...

AI summary The installation of midspan structures for the Labrador-Island Link (LIL) is estimated at $328,662 per tower, with assumptions including a 2x inflation factor and A1 structure type. Potential outages during construction could incur $500,000/day costs, requiring further investigation to assess feasibility and financial impacts.

Conclusion In conclusion the preliminary data suggests that out of these two options the most cost effective approach would be to install a dedicated wood pole electrode line near the existing transmission line in identified high risk zone...

AI summary The conclusion recommends installing a dedicated wood pole electrode line near existing transmission lines in high-risk zones as the most cost-effective solution, with costs estimated at $313,379.68/km + $560,000. Further analysis of assumptions, PLS-CADD models, and constructability factors is advised.

e ice at a density of 0.9 g/cm 3 (20.6 to 21.6 kg/m), and the damage likely occurred due to unbalanced ice loads from ice shedding. There were no other components damaged in this icing event. In March 2024 there was an icing event in south...

AI summary Multiple icing events between 2024 and 2025 caused damage to electrode crossarms and conductors in Labrador. Ice shedding led to unbalanced ice loads, resulting in failures at various locations. The damage was documented in Table 1, with a total of 30 electrode crossarms and 56 conductor locations affected.

2. Sections for Consideration Due to the cost of building a wood pole line from Muskrat Falls to the start of the existing wood pole electrode line at structure 1229 (approximately 376 km), the removal of the electrode line from L3501/2 wi...

AI summary The document outlines the consideration of removing sections of the electrode line (L3501/2) due to high costs and factors like past failures, high icing, elevation, and galloping risks. Six sections totaling 85 km are recommended for removal based on these criteria.

3. Analysis The failure investigations of damage to the towers and conductors in past events determined the root cause was overloading due to unbalanced ice loads. To determine the benefits of removing the electrode conductor from the towe...

AI summary The analysis evaluates structural failure risks in power line towers under balanced and unbalanced ice load scenarios with and without electrode conductors. Removing electrodes significantly reduces failure rates (e.g., 5-80% failures with electrodes vs. 0% without for 60-70 mm ice loads). Over 70 mm balanced ice causes near-total failures regardless of electrode presence, highlighting critical infrastructure vulnerabilities.

Under unbalanced ice load (UBL) with 70 mm of ice: - structures with the electrode: - o the percentage of structure failure range between 77% to 91% for all load cases, - structures without the electrode - o on the OPGW (G) the percentage...

AI summary Under 70 mm unbalanced ice load (UBL), structures with the electrode show 77-91% failure rates, while those without the electrode have 68-86% failures on OPGW (G). No failures are reported on EL1, EL2, P1, and P2. This highlights structural vulnerability under UBL conditions.

Under unbalanced ice load (UBL) with 80 m of ice: - structures with the electrode: - o 95% of structures failed for all load cases, - structures without the electrode: - o on the OPGW (g) the percentage of structure failure for 70/100% unb...

AI summary Structures with electrodes exhibit significantly higher failure rates under unbalanced ice loads (UBL) compared to those without electrodes. For 80 mm UBL, 95% of structures with electrodes failed, while failures on OPGW and other components were 82% and 32-36% respectively. Removing electrodes reduces failures, particularly under balanced and unbalanced ice loads, indicating a safety benefit.

Background - The Labrador-Island Link ("LIL") is an important transmission line for the provincial energy grid due to its - power carrying capacity that is used to deliver a large portion of the winter peak energy and demand to - the Islan...

AI summary The Labrador-Island Link (LIL) is a critical 350 kV HVdc transmission line that delivers winter peak energy to the Island Interconnected System. It traverses three major meteorological zones and includes 19 loading zones with 11 tower types designed to handle wind, ice, and combined loads.

5.3 Restoration Summary - Crews and equipment mobilized to site on April 3rd with work beginning on April 4th . The work began - with cleanup of the failed electrode conductor and securing the OPGW to allow for tower repairs. The - contrac...

AI summary Crews mobilized on April 3rd, with work starting on the 4th to clean a failed electrode conductor and secure OPGW for tower repairs. Contractor repairs began on April 10th, involving steel and conductor replacement, completed by April 19th.

Analysis of Loads Causing Failures - A complete as-built model of L3501/2 includes the existing terrain, as-built tower locations and heights, - with complete finite element tower models. PLS-CADD is a transmission line design program that...

AI summary The analysis uses PLS-CADD software to model L3501/2 transmission line towers under various loading conditions. Tower failure is defined as exceeding 100% maximum utilization, calculated as force applied divided by damage limit capacity. The document emphasizes structural performance evaluation under extreme loads.

Table 4: Comparison of Field Damage and Modeling Results for Ice Loading Field Damage Modeling 9 90 mm Modeling 100 mm Crossarm EL Crossarm EL Crossarm Dan nage OPGW Tower Damage OPGW Damage OPGW Tower EL1 EL2 Peak (% Utilization) Tower Pe...

AI summary Table 4 compares field damage observations with modeling results for ice loading on various structures, including towers and crossarms, under different ice thickness scenarios (9 mm and 100 mm). The data includes utilization percentages and damage indicators for specific poles and electrodes.

Recommendations - Recommendations for consideration to prevent future failures and better understand the issue with the - line include the following: - Monitoring of ice conditions along the line; - Strengthening of the tower to withstand...

AI summary The recommendations focus on preventing transmission line failures by monitoring ice conditions, strengthening towers against unbalanced ice loads, modifying line designs to reduce tower stress, evaluating alternative suspension assemblies, and using radiography to assess conductor issues. Monitoring methods include patrols, test spans, and ice load equipment to inform future upgrades.

Executive summary Wayland Engineering Ltd. was asked by Newfoundland and Labrador Hydro (NL Hydro) to conduct an investigation for two electrical conductors (EL-1 and EL-2) removed from suspension Tower #1225. The conductors routed electri...

AI summary Wayland Engineering Ltd. investigated failures in conductors EL-1 and EL-2 at Tower #1225, attributing the ductile limit load fracture to ice accumulation and wind forces. Steel core migration and wind-induced galloping were identified as contributing factors, with radiographic imaging recommended for future inspections.

Table of contents Executive summary ii Table of contents iii List of figures iv List of tables viii 1 BACKGROUND 1 2 PRELIMINARY EXAMINATION 4 2.1 Preliminary Examination of Failed Conductor EL-1 4 2.2 Preliminary Examination of Failed Con...

AI summary The document outlines a technical examination of failed conductors EL-1 and EL-2, analyzing their dimensional, mechanical, and metallurgical properties. It includes evaluations of intact conductors for comparison, aiming to determine causes of failure and recommend actions. The study is part of a regulatory proceeding under the Nova Scotia Utility and Review Board (NSUARB).

2.1 Preliminary Examination of Failed Conductor EL-1 Figure 2-1 and Figure 2-2 show two views of the single section of failed conductor EL-1 provided by NL Hydro as received for analysis. The section consisted of an approximately 60 cm lon...

AI summary The analysis of failed conductor EL-1 revealed severe bird-caging at one end, fractured aluminum strands with exposed steel core at the other, and migration of the steel core toward the lower part of the wire clamp. These findings indicate structural failure likely due to mechanical stress or corrosion.

cal external circumferential surface of conductor EL-2 as installed in the field. The image shows the fracture ends of the wire strands observed on the upper circumferential surface of the conductor. Figure 2-16: Photograph of the lower ve...

AI summary The text describes the preliminary examination of failed conductor EL-2, including visual analysis of fracture ends, aluminum strand fusing, and fracture morphology observed during disassembly. Figures illustrate technical failure characteristics of the conductor's external and internal surfaces.

4.2 Metallurgical Characterization of Failed Conductor EL-2 Samples from several of the outer aluminum wire strands, which included the fracture surface associated with the strand failure were removed from conductor EL-2. The samples were...

AI summary This section discusses the metallurgical analysis of failed conductor EL-2, focusing on the fracture surfaces and fusing between strands. SEM and EDS analyses revealed ductile fracture mechanisms and the presence of zinc from steel reinforcing strands, which contributed to the failure.

6 CONCLUSIONS AND RECOMMENDATIONS The conclusions and recommendations inferred by the investigation for the failed sections of conductor EL-1 and EL-2 from suspension Tower #1225 include: - The physical, chemical and metallurgical evidence...

AI summary The failure of conductors EL-1 and EL-2 at Tower #1225 was attributed to ductile limit load fracture caused by ice accumulation and wind forces, with steel core migration exacerbating the issue. Radiographic imaging is recommended for detecting such failures. NL Hydro is advised to investigate this method with radiography experts.

Appendix A - Interconnection Facilities, Network Upgrades, and Distribution Upgrades Appendix B – Milestones Appendix C – Interconnection Details Appendix D – Security Arrangements Details Appendix E – Commercial Operation Date Appendix F...

AI summary The document outlines various appendices related to interconnection facilities, network upgrades, distribution upgrades, milestones, security arrangements, commercial operation dates, notice addresses, interconnection requirements for wind generating plants, and operating assumptions for generating facilities.

uirements of law to which Transmission Provider would be subject in the engineering, procurement or construction of Transmission Provider's Interconnection Facilities and Stand Alone Network Upgrades;

AI summary The text references legal requirements governing the engineering, procurement, and construction of interconnection facilities and standalone network upgrades by the Transmission Provider, emphasizing compliance with applicable laws during these processes.

- 5.13 Lands of Other Property Owners. If any part of Transmission Provider or Transmission Owner's Interconnection Facilities and/or Network Upgrades is to be installed on property owned by persons other than Interconnection Customer or T...

AI summary The text outlines procedures for installing transmission facilities on third-party land, obtaining permits, and early construction of base case facilities. It mandates cooperation between parties, use of eminent domain where applicable, and adherence to regulatory requirements for interconnection.

nts, if applicable, and the appropriate measures under such agreements, shall be executed and implemented prior to the placement of the Large Generating Facility in the other Balancing Authority Area.

AI summary The text outlines a procedural requirement for executing and implementing measures under relevant agreements before placing a Large Generating Facility in another Balancing Authority Area, emphasizing coordination between entities involved in the process.

Interconnection Facilities, Network Upgrades and Distribution Upgrades Interconnection Facilities: 1. [insert Interconnection Customer'sInterconnection Facilities]: (a) (b) [insert Transmission Provider'sInterconnection Facilities]: 2. Net...

AI summary The text outlines sections related to interconnection facilities, network upgrades, and distribution upgrades, with placeholders for specific details. It references Appendix B to the Large Generator Interconnection Agreement (LGIA).

Security Arrangements Details Infrastructure security of Transmission System equipment and operations and control hardware and software is essential to ensure day-to-day Transmission System reliability and operational security. FERC will e...

AI summary FERC requires Transmission Providers and market participants to comply with infrastructure security recommendations from the President's Critical Infrastructure Protection Board and future best practices from the electric reliability authority, ensuring physical, operational, and cybersecurity standards for public utilities.

Preface Submarine power cables have always been the unknown cousins of the submarine telecom cables. Telecom cables encircle the globe through all oceans in an enormous mesh, and have attracted public attention since the first Channel cabl...

AI summary The preface highlights the historical underappreciation of submarine power cables compared to telecom cables, emphasizing their technological evolution, increased economic viability, and expanding applications over the past two decades due to advancements in manufacturing and installation.

Table 2.1 Specific resistivity and its temperature coefficient Copper Aluminium mm2/m R20: Specific electric resistivity @20◦C, α: Thermal coefficient of the specific electric resistivity @20◦C, 1/K 0,01786 0,00392 0,02874 0,0042 conductor...

AI summary Table 2.1 provides specific resistivity and temperature coefficients for copper and aluminum conductors. The IEC 60228 standard is referenced for conductor resistance values, which consider the influence of strand lay length.

2.3.1 Lead Sheath Wheatstone and Cooke suggested lead sheaths for telegraph cables already in 1845. Lead extrusion was known since 1797, but it took the relentless efforts of some known and countless unknown cable engineers to arrive at th...

AI summary The text discusses the historical development and technical aspects of lead sheaths used in submarine cables. It highlights the evolution from early manufacturing methods to modern extrusion techniques, the importance of lead alloys for durability, and the challenges posed by mechanical and environmental stress on lead sheaths.

3.1.1.2 A Pair of Buried Cables For two identical equally-loaded HVDC cables laid in the same depth, T 4 can be calculated as: Fig. 3.2 Symbols used for the calculation of T 4 3.1 Thermal Design $$T_4 = \frac{\rho_T}{2\pi} \left( \ln\left(...

AI summary This section discusses the thermal design of HVDC cables, focusing on the calculation of thermal resistance (T4) for a pair of equally loaded cables buried at the same depth. It provides equations and a figure to determine T4 based on soil thermal resistivity, burial depth, and cable spacing. The ampacity of the cables is calculated using these values and a maximum allowable temperature difference.

3.1.3.6 Conditions Changing with Time Seafloor conditions, which have been charted by survey operations, may alter during the cable's lifetime. While water temperature hopefully increases only slowly with the climate change, other paramete...

AI summary Submarine cable design must account for dynamic seafloor conditions, including bathymetric shifts from tides/storms, thermal changes from human activities, and marine growth causing insulation and overheating risks. These factors necessitate robust infrastructure planning to mitigate long-term operational risks.

3.2.1 Tensional Forces During Laying When the cable is being laid from a cable ship there are at least four components that contribute to the tensional forces at the laying wheel: - Static weight of the cable between the laying ship and th...

AI summary The text details tensional forces during underwater cable laying, identifying four contributing factors: static cable weight, residual bottom tension, catenary line weight, and dynamic forces. It provides formulas for calculating tension (Ts = w·D and T = √(T0² + w²s²)) and explains the catenary line's role in bottom tension and cable positioning.

3.3.7 Availability and Reliability The choice of the insulation wall thickness is as much an asset management task as it is an engineering task. Considering the Weibull plots of the cable insulation material, the cable designer will chose...

AI summary The text discusses the engineering and asset management considerations for submarine cable insulation thickness, balancing reliability against costs. It highlights the use of Weibull plots to determine insulation thickness, the trade-off between thicker insulation (reducing breakdown risk) and increased material costs, and operational rules to mitigate failure risks through temperature and voltage control.

tween the stiff joint casing and the flexible armoring of the submarine cable, bend restrictors in the shape of conical rubber sleeves enclose the cable at the exit of the steel casing (cf. Fig. 4.3). Rigid joints cannot be transported thr...

AI summary Rigid joints for submarine cables face challenges in transportation and installation due to stiffness and larger diameter, requiring complex crane arrangements. While they offer mechanical protection, flexible joints are preferred for simplicity. Rigid joints are used in 3C cables but lack pre-fab options for MI d.c. cables, making on-site assembly necessary.

4.1 Submarine Cable Joints 115 – In many projects the submarine cable is 3C while the land cable system consists of three single-core cables. The transition joint is usually erected in the shoreline The design and installation of beach joi...

AI summary The text discusses challenges in designing and installing submarine cable joints, emphasizing the need for dry environments, cofferdams, and platforms to manage beach joints for HVDC systems. Tidal currents and environmental considerations are highlighted as critical factors affecting installation processes.

pots, allowing for the negligence of ridges and outcrops in-between [3]. Between the spotted and charted soundings, there may exist natural ridges, outcrops, shipwrecks, and other disturbing features. A very useful source for desktop-studi...

AI summary Accurate bathymetric data is critical for designing underwater cables and selecting appropriate laying vessels. Sonar-based systems like multi-beam echo-sounders (MBES) provide high-resolution seabed mapping, while unit conversion errors (e.g., fathoms vs. feet) can lead to costly mistakes. NOAA's charts are a key resource, though depth units may vary.

6.3 Sub-bottom Profiling If the submarine cable is to be protected, the knowledge of the seafloor bathymetry is not enough. Especially for cable burying it is necessary to know what is hidden below the sea bottom. The character, hardness,...

AI summary Sub-bottom profiling is critical for submarine cable protection, as it reveals sub-seafloor layers affecting burial methods and thermal parameters. Inadequate profiling can lead to unexpected obstacles, such as encountering bedrock or hidden pipes, causing costly operational changes. Comprehensive profiling ensures accurate planning and avoids risks during cable installation.

6.4 Visual Inspection In complicated waters a survey performed from the sea surface may be too insensitive to reveal all underwater features. In order to achieve a complete picture on the subsea conditions before cable laying, manned subma...

AI summary Visual inspection methods for underwater cable laying include ROVs/AUVs for detailed seabed assessments and site visits to evaluate soil conditions and logistics. Data collection from interviews and DTS complements these efforts to inform installation technology choices and hazard mitigation.

6.5 Soil Sampling Sometimes, the sub-bottom profiling has no sufficient resolution to provide data for a burial assessment survey [8]. Soil sampling can deliver additional data from selected locations to support decisions on burial tools....

AI summary Soil sampling is critical for burial assessments, thermal resistivity analysis, contamination detection, and cost-effective cable design. It provides tangible data on seafloor hardness, thermal properties, and potential chemical contamination, influencing burial methods and conductor cross-section optimization.

-core cables with single wire armoring are good candidates for the use of fixed tankes. Medium-voltage three-phase submarine cable can also be loaded in a similar technique in oblong holds in vessels. Cable drums . For many submarine cable...

AI summary The text discusses cable laying vessel operations, emphasizing positioning accuracy, anchoring systems using anchor handling tugs (AHTs), and cable drum installation methods for submarine cables. It highlights challenges in maintaining precise cable corridor alignment and the use of specialized vessels for short-length projects.

designing the installation, one of the machines is defined as the "master". This machine defines the laying speed and all other machines, including the vessel propulsion, must follow the master speed. If the cable would be let down to the...

AI summary The text details technical considerations for submarine power cable installation, emphasizing the need for a master machine to control laying speed, maintaining a stable catenary line to avoid damage, monitoring parameters like bottom tension, and using ROVs for critical sections. Proper tension and catenary management are crucial to prevent cable looping, snaking, and residual tension issues.

7.1.5 Landing of Submarine Cables The landing of submarine power cables sometimes requires the most engineering, the most equipment and often the most time of all efforts of the cable project. The majority of all submarine cable projects h...

AI summary The landing of submarine power cables is a complex engineering process requiring careful planning and execution. Methods vary based on shore conditions, equipment capabilities, and regulatory requirements. Examples like the NorNed cable project demonstrate successful open trench landings even in sensitive areas like dikes.

ines during jointing, plus 100–150 m depending on the length of the cable guides onboard. It can be prudent to have an extra length to provide cable for a second try if the first joint must be redone. Another similar set-up is to have the...

AI summary The text details technical procedures for after-installation joints in transmission lines, including configurations for jointing cables on a vessel, stability requirements, and considerations for cable handling and jointing shack setups.

7.1.7 Weather Weather is the cable crew's worst enemy. Countless are the hours during which an armada of cable laying vessels and working boats has been rolling idly in waves and wind for hours, days, or even weeks until useful weather app...

AI summary Weather significantly disrupts cable laying operations, causing costly delays and operational challenges. The unpredictability of wave and wind patterns complicates planning, as safe laying depends on statistical wave movements rather than direct wind or wave measurements. 'Waiting on weather' is highlighted as a major operational inefficiency.

7.1.7.1 Winds Wind generates waves. The wind distribution can be very different for different places and is subject to strong seasonal variations, which may create weather windows of different length for the cable laying. The wind speed is...

AI summary The section discusses wind's role in generating waves and its impact on cable laying operations, noting seasonal variations and weather windows. Wind speed measurements are described using the Beaufort scale and other units, with Table 7.1 correlating wind conditions to sea-state characteristics.

7.1.7.4 Other Impacts of Wind and Waves Vessel movements can introduce adverse effects on cable laying beyond the tensional force on the cable: Crew work ability . Many seamen suffer from seasickness. In heavy weather, 10– 30% of the crew...

AI summary Vessel movements during cable laying pose risks due to crew sickness in heavy weather, dangers from unsecured cables and equipment, and potential loss of vessel position. These factors can lead to safety hazards, operational delays, and legal consequences for prioritizing cost over crew safety.

7.1.8 Organisation In 1964, a report on a submarine cable laying operation declared: "Captain and crew of the boats shall be cooperative with the cable laying work and, if possible, having experience in cable handling" [11]. The insight be...

AI summary The text outlines the organizational structure and coordination required for submarine cable installation projects, emphasizing the roles of various stakeholders, the importance of clear responsibilities, and the benefits of coordination meetings to ensure project success.

7.2 Protection of Submarine Power Cables Submarine cables are precious assets and need to be protected from external hazards. The 1986 Cigré study [14] presents a comprehensive compilation of submarine cable faults and protection methods....

AI summary Submarine power cables require protection from external hazards through four steps: route selection, cable armoring, seafloor protection (e.g., burial), and post-installation monitoring. Proper protection enhances system reliability and reduces repair/maintenance costs, as highlighted by the 1986 Cigré study.

7.2.1 Selection of a Suitable Cable Route After a desktop study a provisional cable route can be selected. As far as possible, hazardous areas should be avoided, such as: - Shipping lanes, anchorages, harbour entrances - Fishing grounds -...

AI summary The selection of a submarine cable route requires avoiding hazardous areas like shipping lanes, fishing grounds, and unstable shorelines. Key considerations include minimizing interference with maritime traffic, preventing damage from fishing activities, and accounting for environmental and future development impacts on cable integrity.

7.2.3.1 Trenching The most common protection method today is trenching, i.e. the burial of the cable under the seafloor. There is a variety of different trenching methods, and new equipment is being developed as the amount of submarine inf...

AI summary Trenching, specifically ploughing, is a common method for burying submarine cables under the seafloor. The process involves cutting a slit with a ploughshare, guiding the cable into the trench, and facing risks in rocky soils. Ploughing is economical for soft to medium soils but requires careful management in deeper waters and rocky conditions.

7.2.3.2 Jetting Methods Another group of burial equipment relies on water jetting action. A sword carrying a row of water nozzles is pushed down into the seafloor (Fig. 7.25). The high-pressure Fig. 7.25 Cable jetting device. The sword car...

AI summary The text describes water jetting methods used in submarine cable burial, involving swords with nozzles, sledge carriers, and ROVs. High-pressure water fluidizes the seafloor, allowing cables to sink into slurry, which later re-solidifies. ROVs offer advanced systems with propulsion, pumps, and monitoring equipment, though they require complex auxiliary support.

7.2.3.5 Other Protection Methods There are also pre-laying trenching methods using dredging or excavating. The cable trench is prepared before the laying vessel brings the cable. The necessary furrow in the seafloor can be prepared by diff...

AI summary The section outlines trenching methods for submarine cables, including dredging, mechanical disintegration, and artificial covers (cast iron, concrete, rock dumping). Challenges like rocky terrain and burial depth requirements are discussed, along with specific cases such as the 1967 SACOI HVDC cable and unconfirmed methods in Istanbul.

7.2.4 After-Installation Protection Even after the successful and completed installation of submarine power cables, the protection can be maintained and improved by active measures. Unfortunately, the after-installation protection measures...

AI summary The text emphasizes the importance of post-installation protection for submarine power cables, highlighting human activity as a primary cause of damage. It recommends measures like signage, information dissemination to maritime authorities, collaboration with fishermen, vessel monitoring systems (VMS/AIS), and patrols to prevent cable damage and ensure safety.

8.1.1 Causes of Damages Fishing gear and anchor damages are accused for most of submarine cable failures, both for telecom cables and power cables. Figure 8.1 shows the cause of damages to telecom cables in the Atlantic [1]. The distributi...

AI summary The text identifies fishing gear and anchor damage as primary causes of submarine cable failures, noting differences in risk between shallow coastal waters and harbor areas. It highlights that power cables face less risk from fish bite compared to slim telecom cables, with examples like dynamite fishing in the Philippines.

used with weights up to 30 t for the largest ships. The anchors of "Queen Mary 2" weigh 23 t. Different anchor shapes have different efficiency and behave different in their contact to the sea bottom. The risk of anchor damages of a given...

AI summary The text discusses assessing anchor damage risks to cables using statistical methods, analyzing ship traffic data, and an empirical formula linking ship deadweight to anchor mass. It references anchor damage examples and distribution models for cable routes.

8.2 Repair The repair of submarine cables is one of the most demanding tasks of submarine cable engineering. Not only must the fault be found and identified in water depths often inaccessible to divers, also the damaged cable must be made...

AI summary Submarine cable repair is complex, requiring specialized methods like external sealing cassettes and submersible workshops. Challenges include inaccessible depths, surface retrieval, and adverse conditions. Preparation with 'red alert' plans is emphasized for effective repairs.

8.2.1 Spare Cable Almost every repair job requires that the cable would be lifted on board the repair vessel. In most cases, the cable lays on the sea floor on a straight line and must be cut before lifting the ends. For the repair, a spar...

AI summary Spare submarine power cables are critical for repairs, requiring lengths covering double water depth, catenary lines, and safety margins. Procurement delays and high costs necessitate stockpiling. Operators maintain spare cables, often produced alongside original cables, and prioritize experienced management to avoid shortages during repairs.

8.2.2 Repair Vessel The repair vessel may differ very much from the laying vessel, as there are different needs for load capacity and deck arrangements. A load capacity of a few hundred tons can be enough to carry the spare cable and all h...

AI summary The repair vessel differs from laying vessels in load capacity, deck arrangements, and specialized equipment needs. It requires open decks, jointing houses, cable handling systems, and may use ROVs for complex repairs. Repair setups vary based on cable type (e.g., 600 MW HVDC vs. 11 kV) and environmental conditions.

8.3.2 Bridge Measurements Another useful fault location principle is based on resistance measurements in the conductor from one cable end to the fault. Using variations of resistance bridges, many different bridge measurement schemes are k...

AI summary This section discusses bridge measurement techniques for fault location in cables, including the Murray scheme and Wheatstone bridge applications. It explains how resistance measurements can pinpoint faults with high accuracy, using formulas and historical context dating back to the 1880s. Modern equipment simplifies these measurements, though adjustments for conductor resistance variations are necessary.

9.1.5 Cable Terminations The proximity of many submarine power cable terminations to the sea may cause severe salt layer deposits on the insulators calling for a regular cleaning schedule. Some cleaning can be done under energized lines. S...

AI summary Proximity of submarine power cable terminations to the sea leads to salt deposits on insulators, requiring regular cleaning and hydrophobicity testing. Corrosion, especially galvanic corrosion, must be monitored in terminations near shore or marine platforms.

9.2.2 Failure Statistics for Large HVDC Cable Projects The failure rate calculated from the data given in Table 9.2 is 0.264 failures/year/100 cable kilometres for mechanical faults and 0.0143 failures/year/100 cable kilometres for other f...

AI summary The failure rate for large HVDC cable projects is 0.264 mechanical failures/year/100 km and 0.0143 other failures/year/100 km. The 1964–1988 Kontiskan 1 project significantly contributed to these rates, with its many mechanical failures. Poor engineering and unsuitable installation methods are identified as primary causes of cable failures.

11.3 The Pilot I had overseen the design, testing, and part of production of this powerful submarine cable. Now I was on board one of the largest cable ships of the world with more than 6000 t capacity, to watch the installation. After yea...

AI summary The narrative describes the installation of a submarine cable, highlighting the role of the 'pilot' (cable laying chief) and an anecdote about a past incident where four 230 kV cables broke due to a telephone cable ship's error. The pilot, who was involved in both events, ensured the current cable's smooth installation.

NSPML Responses to NSEB Information Requests 1 Request IR-11: 2 3 Regarding the performance of the Labrador Island Link: 4 a) Has testing to establish that the LIL can operate at full capacity of 900MW been 5 completed? If so, when? 6 b) W...

AI summary NSPML responds to NSEB's information request about the Labrador Island Link (LIL) testing. The final 900 MW test was completed on March 26, 2026, after delays due to system conditions and coordination. The LIL is confirmed to operate at full capacity with no impact on operations.

NON-CONFIDENTIAL 1 commissioning relate to the performance of the LIL should provide comfort that the Newfoundland 2 & Labrador System Operator, Canada's Independent Engineer and many others involved in the 3 commissioning of the LIL were...

AI summary The text discusses the commissioning process of the Labrador Island Link (LIL), highlighting the need for a July 2023 outage to address software issues discovered after its April 2023 commissioning. The software update introduced functionality problems, leading to a rollback to the previous working version.

NON-CONFIDENTIAL 1 non-critical punch list items on a $15+ billion mega project, is indicative of failure to follow good 2 utility practice. Date Filed: April 21, 2026 NSPML (NSEB) IR-13 Page 3 of 3

AI summary The text criticizes NSPML's management of a $15+ billion mega project, citing non-critical punch list items as evidence of poor utility practice. The filing date is April 21, 2026, and references NSPML (NSEB) IR-13 Page 3 of 3.

10 Response IR-18: 11 12 a) NSPML's expectation for LIL availability would have been in line with their publications 13 referenced in PUB-NLH-212, which NSPML understands forecast a Bipole Forced Outage 14 Rate for the LIL of 0.0114 percen...

AI summary NSPML initially expected LIL availability based on a 0.0114% Bipole Forced Outage Rate from PUB-NLH-212. Post-commissioning, NLH found this rate impractical due to the LIL's complexity, leading to a system-wide reliability assessment. Daymark Energy Advisors was engaged to evaluate HVdc outage rates for accurate reliability planning.

Reference to Annex C indicates that: - The area surrounding the Churchill River is considered to have a loading condition of medium loading B; - The area traversed by the proposed HVdc line from Muskrat Falls to the Strait of Belle Isle is...

AI summary The document outlines loading conditions for HVdc line routes in Newfoundland and Labrador, specifying medium, heavy, and severe loading zones, with corresponding radial ice thicknesses from Table 30 (12.5mm for medium/heavy, 19mm for severe). These conditions inform infrastructure planning for power transmission.

Section 10 of C22.3 No. 1‐06 states: The reliability‐based method should be used for supply lines greater than 70 kV phase‐to‐phase, in areas where significant amounts of meteorological data are readily available. This method may also be u...

AI summary Section 10 of C22.3 No. 1-06 mandates the use of reliability-based methods for high-voltage (70 kV+) supply lines in regions with abundant meteorological data. It also permits application for lines designed with specific climatic loads, relying on prior experience or calibration with historically reliable lines.

NLH Line Design At this point it is worth describing how each of the above noted standards has impacted transmission line design within the Island Interconnected System. The 230 kV transmission lines on the Avalon Peninsula are used to dis...

AI summary The document discusses the evolution of 230 kV transmission line design on the Avalon Peninsula, highlighting historical ice storm failures due to inadequate design standards (1:10 return period) and subsequent upgrades to a 1:50 return period (60–75 mm radial ice) to improve reliability. Reinforcements between 1998–2002 addressed extreme ice events (up to 150 mm) and aligned with CSA C22.3 standards.

IMPACT OF THE LABRADOR – ISLAND HVdc LINK ON ISLAND SYSTEM RELIABILITY The Labrador – Island HVdc Link has the following nominal ratings: - ±320 kV operating voltage (bipole); - 2 x 450 MW, 1406 A per pole; - 900 MW at Muskrat Falls; - 92....

AI summary The Labrador-Island HVdc Link's impact on the Island Interconnected System's reliability is analyzed, including its modeling as a generator with a forced outage rate, the need for 50 MW combustion turbines to maintain LOLH below 2.8 hours/year, and sufficient generating capacity until 2036. Transmission planning criteria ensure reliable integration.

Forced outages to the HVdc overhead transmission line is of more concern in the context of the Labrador – Island HVdc Link given the length, environmental conditions and mean time to repair. The CIGRE statistics do not provide long term av...

AI summary Forced outages on the Labrador – Island HVdc Link are of greater concern due to its length, environmental conditions, and repair times. CIGRE statistics do not provide long-term average forced outage rates for similar systems, and no direct comparisons exist for the Labrador – Island HVdc Link.

s that the HVdc line is intact but the converter station cannot function as there is insufficient ac system transmission strength and capacity to operate the station or transmit power to load centers. With the typical service or economic l...

AI summary The HVdc line's design load considers a 1:50 year return period, implying a 50-year service life for steel transmission structures. The converter station at Soldiers Pond requires at least one 230 kV transmission line to ensure stable operation, but insufficient AC system capacity could prevent the station from functioning.

Table 2-2: Converter Unavailability Item Performance Indicator Spare Transformer No Yes Yes Spare Smoothing Reactor No No Yes Terminal Unavailability 3.04% 0.94% 0.21% Hours/ Year 266 82.5 18.6 Based on the above information, it is recomme...

AI summary The table presents converter unavailability statistics, including spare transformer and smoothing reactor availability. It recommends providing spare units at each terminal to improve reliability, citing performance indicators from 2007 and 2008 for converter stations with spare units.

RELIABILITY & AVAILABILITY ASSESSMENT OF THE HVDC ISLAND LINK Nalcor Doc. No.: ILK-SN-CD-8000-EL-SY-0004-01 B1 Date Page SLI Doc.: No. 505573-480A-47ER-0017 00 10-Apr-2012 7 Table 2-3: Converter Reliability (Average 2007-2008) Outage FOR (...

AI summary The document discusses the reliability and availability assessment of the HVDC Island Link, focusing on converter reliability based on historical data from 2007-2008. It notes that while future improvements may reduce failure rates, historical data is used for conservative analysis. The Soldiers Pond converter is near St. John's, while the Muskrat Falls converter is more remote, potentially affecting repair times.

Table 4-1: Converter Reliability (Average 2007-2008) Outage FOR (%) FU(hrs/yr) F/yr Repair Time (hrs) Pole 0.265 24 1.64 13.8 Bipole 0.00025 0.02 0.24 0.13 Objective 2: To develop R&A performance indices for the HVdc transmission line from...

AI summary This section presents a table detailing converter reliability metrics for the HVDC transmission system from 2007 to 2008, including outage rates and repair times. It also outlines an objective to develop R&A performance indices for the HVDC transmission line from Muskrat Falls to Soldiers Pond.

4.2 Recommendations At each converter station, a spare converter transformer of each type (single phase) and a spare smoothing reactor should be provided. This will significantly improve the availability of the converters. Other critical c...

AI summary The text recommends providing spare components at converter stations to improve converter availability and reliability, with specific mention of converter transformers and smoothing reactors. Other long-lead-time components should also be considered for on-site spares based on reliability targets.

NSPML Responses to Small Business Advocate Information Requests 1 Request IR-01: 9 the LIL is designed to resist, without damage, a climatic event of severity seen once 10 every 50 years. NL Hydro has stated that while the LIL was designed...

AI summary NSPML agrees that the LIL is designed to withstand a 50-year climatic event but acknowledges that climate change and microclimates may pose new risks. NSPML has discussed these issues with NLH and is considering longer-term solutions to ensure reliability. The responsibility for funding these solutions is under review, and NSPML is concerned about potential intergenerational subsidization.

Table 2. Calculation of undelivered and makeup volumes of Base Block (2021-2025) (MWh)[37](#page-12-1) 1 Month/Year Contract Net Undelivered Net Undelivered Volume Delivered Undelivered Makeup (Month) (Cumulative) Aug-21 45,923 6,131 39,79...

AI summary Table 2 presents the calculation of undelivered and makeup volumes for the Base Block from 2021 to 2025, detailing monthly and cumulative figures. The data includes net undelivered volumes, makeup volumes, and delivered volumes for each month.

11 - 13 Q. For the four months in which deliveries were below threshold, did NSPML claim - 14 that the deficiencies were explained by "good utility practice" and/or "exceptional - 15 circumstances?" 48 NSPML Application, page 10 lines 12 t...

AI summary NSPML claims that deficiencies in NS Block volumes during four months were due to 'good utility practice' and 'exceptional circumstances,' specifically citing a planned LIL outage in July 2023 and other factors related to the LIL's performance, not Muskrat Falls or the Maritime Link.

dates designed to remedy non-critical software punch list items," verification of "several Supervisory Control and Data - Acquisition (SCADA) points to enable greater LIL visibility and control at the NSPML Application, page 17 line 25 to...

AI summary The text discusses software punch list items and SCADA points related to the Labrador Island Link (LIL), including the impact of bipole and monopole outages on transfer capability and NSPML's explanation of delivery performance relative to contract values.

](#page-29-1) Distinguishing between "severe harsh conditions" known at the time of - design and approval and weather events that are incrementally more "extreme" or "severe" is not - straightforward. - Q. Do you agree that weather could b...

AI summary The text discusses whether weather can be classified as an 'exceptional circumstance' under regulatory thresholds and confirms the March 2024-April 2024 LIL outage was caused by an icing event. NSPML cites force majeure clauses in power purchase agreements and references a 2020 study by Haldar commissioned by NLH on LIL's structural reliability.

did not achieve 90% delivery in five of the six months following the "Compliance Period."[18](#page-5-18) - Over half of this amount appears to be related to work necessary to complete the full commissioning of the LIL at 900 MW. The large...

AI summary NSPML's evidence includes details of outages related to the LIL project's commissioning and maintenance, such as a converter station update (July 29–September 14, 2024) and planned maintenance periods. These outages contributed to a Holdback, with 57 days of outages (9% of the period) tied to commissioning and 23 days (4%) to annual maintenance.

SUMMARY OF PROFESSIONAL EXPERIENCE - 2023– Present Vice President, Grid Strategies, LLC . Provides research, technical assistance, and expert testimony on electric- and gas-utility planning, economics, and regulation. Reviews electric util...

AI summary The individual has extensive experience in utility regulation, energy efficiency, and renewable energy, including roles at Grid Strategies, Southern Alliance for Clean Energy, and Resource Insight. They have provided expert testimony, designed programs, and evaluated resource planning and procurement strategies for regulated and competitive markets.

- "Cleaner Energy for Southern Company: Finding a Low Cost Path to Clean Power Plan Compliance," Southern Alliance for Clean Energy, July 2015. - "Analysis of Solar Capacity Equivalent Values for Duke Energy Carolinas and Duke Energy Progr...

AI summary The text lists reports by Southern Alliance for Clean Energy (SACE) and collaborators on energy efficiency, solar capacity, and decarbonization in the Southeastern U.S., including a 2021 review of Nova Scotia Power's Integrated Resource Plan (IRP) for the Nova Scotia Consumer Advocate. Topics include renewable energy, procurement practices, and emissions reduction.

EXPERT TESTIMONY - 2008 South Carolina PSC Docket No. 2007-358-E, surrebuttal testimony on behalf of Environmental Defense, the South Carolina Coastal Conservation League, Southern Alliance for Clean Energy and the Southern Environmental L...

AI summary Expert testimony from 2008–2010 details advocacy for energy efficiency cost recovery mechanisms (shareholder incentives, lost revenue adjustments) and evaluation of integrated resource plans by SACE, Environmental Defense, and allied organizations in South Carolina, North Carolina, and Georgia regulatory proceedings.

Response IR-2: - (a) - (i) Confirmed. - (ii) The Maritime Link had returned to full 500 MW transfer capability on September 15, 2023, two days before the start of the LIL bipole annual planned outage identified by NSPML in response to NSPM...

AI summary Response IR-2 confirms the Maritime Link's full 500 MW capacity was restored before the LIL bipole outage. Data shows no flow exceeded 225 MW during monopole operation, indicating unused headroom. Overlapping outages could have optimized capacity, but timing was not aligned. This addresses infrastructure planning and grid reliability considerations.

Request IR-4: 2 Reference: N-7, Evidence of Bates White, p. 33, lines 7-18. All parties agree that the LIL traverses a route that is subject to severely harsh winter weather conditions, and thus high wind and ice events are not exceptional...

AI summary All parties agree that the LIL route experiences severe winter weather, leading to high wind and ice events. Concerns have been raised about the LIL's design adequacy, as highlighted by the Haldar report and acknowledged by NLH.

3 Q35. HOW DO YOU RESPOND TO THE ARGUMENT THAT THE LIL OPERATES IN 4 A HARSH ENVIRONMENT AND THEREFORE SUCH EVENTS SHOULD NOT 5 BE CONSIDERED EXCEPTIONAL? 6 A35. I do not agree with that reasoning. The fact that a transmission facility ope...

AI summary The response argues that while the Labrador Isthmus Link (LIL) operates in a harsh environment, this does not make severe weather events ordinary. The LIL is designed with engineering standards and planning criteria, but extraordinary events can still occur, leading to damage that is not expected under normal operations.

ess its ROE? Refer to the Application, Attachment 1, p. 25 of 36, paragraph A34 at lines 6-14, which states, in response to a question about whether the LIL was designed for the Newfoundland Climate: Yes. The original basis of design for t...

AI summary The text discusses the design and climate risks of the Lower Churchill Project's LIL, including its 50-year return period design and the impact of changing microclimates. It raises questions about NSPML's agreement with NLH on risks, discussions between the parties, responsibility for long-term solutions, and potential changes to agreements to avoid intergenerational subsidization.

- 27 (i) the planned outage timeline as originally scheduled, 28 compared to the actual outage start and end dates, or 29 identify if unplanned; 1 (ii) the cause of each outage and whether within the control of 2 NSPML, NLH, or external; 3...

AI summary The text outlines a request for information regarding planned and unplanned outages, including their timelines, causes, affected assets, and impacts on delivery reliability and holdback funds. It also asks for outage schedule forecasts for the years 2023 to 2026.

- 26 Reference: N-01 Application, page 19, lines 10-11. - 27 The Application states that more than 370 software updates have been completed at the Maritime - 28 Link since commissioning in 2018. Of those 370 software updates, please confir...

AI summary The Application references a request for information regarding software updates at the Maritime Link, specifically asking how many of the 370 completed updates required multi-day bipole outages and requesting a list of those events.

2 Request IR-9: 3 Reference: N-01 Application, pages 21-22; and Footnote 26. 11 wind and ice load of 25 mm of radial glaze ice with 60 km/h wind. - 4 Preamble: The Application states that April 2024 fell short of the 90% threshold due to 5...

AI summary The document raises questions about the design criteria of a transmission line, specifically why it is rated for lower ice and wind loads than the conditions experienced during an outage in April 2024, and whether similar issues have occurred elsewhere. It also seeks clarification on the duration of the outage.

ion line over which it has no operational control.") Is the Witnesses' position conditioned on whether the planned outage is prudent or otherwise consistent with Good Utility Practice? Please explain. - Request IR-9: Please refer to Exhibi...

AI summary The text includes requests asking witnesses to explain their positions on planned outages, verify statements about maintenance and system enhancements, and confirm if they reviewed specific assets like Muskrat Falls or the Maritime Link.

ly 2023 “Outage,” please provide: 1. Explanation of the referenced “software.” 2. Explanation of the “software update” and why the update was needed. 3. If the LIL had been able to operate at 900 MW as designed, would the software update h...

AI summary The document requests detailed information regarding the September 2023 outage on the Labrador Island Link (LIL), including the software involved, the reasons for the software update, identified deficiencies, corrections, and the impact of the outage on Nova Scotia ratepayers. It also asks about maintenance activities, outage timing, and independent diligence conducted by NSPML.

e outage. 6. Did NSPML conduct any independent diligence regarding this outage? If so, please provide the results of that diligence. 7. Did this outage impose costs on Nova Scotia ratepayers? Please provide NSPML’s best estimate of those c...

AI summary The text contains a series of questions directed at NSPML regarding an outage that occurred in March 2024, including inquiries about the technical causes, root cause analysis, performance of components during an icing event, design flaws, and the financial impact on Nova Scotia ratepayers.

1. Please refer to Exhibit N-1, Attachment 1, page 10, lines 7-9 2. Please describe the Witness’s efforts to independently verify that the planned outages “were conducted for necessary maintenance and system enhancements.” 3. Please provid...

AI summary The text contains a series of questions directed at a witness regarding the verification of planned outages, maintenance activities, and supporting documentation for various infrastructure projects, including the Labrador Island Link (LIL) and Muskrat Falls Generating Station. The questions focus on the witness's independent verification efforts and the documents used to support their claims.

pers, and analyses that the Witness relied upon to independently assess the details and necessity of the July 2023 outage. 14. Please describe the Witness’s efforts to independently verify the details and necessity of the September 2023 ou...

AI summary The text consists of a series of questions directed at a witness regarding their verification of outages in 2023 and 2024, as well as their reliance on documents and analyses, and their understanding of the Labrador Island Link (LIL) and its design standards.

o have been conducted at a different point in time. What is established, however, 14 is that the work conducted was important and consistent with good utility practice in 15 maintaining the asset. 16 17 Further, questions raised regarding...

AI summary The text argues that all down-time experienced by the Labrador-Iceland Link (LIL) was consistent with good utility practice or exceptional circumstances. It clarifies that the LIL design was not flawed based on information available at the time and that reliability improvements have been implemented. The text also emphasizes that the test for removing the Holdback is based on actual delivery performance, not future reliability concerns.

April 2024 NSPML seeks relief for April 2024 deliveries on the grounds of "exceptional circumstances," arising from the forced LIL bipole outage caused by significant ice accumulation in late March that continued into April 2024. Ice accum...

AI summary NSPML is requesting relief for April 2024 deliveries due to an ice accumulation event on the LIL, which caused a forced outage. However, the Industrial Group argues that the event does not qualify as 'exceptional circumstances' because the LIL had known design vulnerabilities and prior icing events, indicating that the issue was foreseeable and not truly exceptional.

Date Filed: July 23, 2026 Page 17 of 44 1 energy to Nova Scotia. Customers during this period were not impacted and planned 25 follows: 26 27 1. The Report did not conclude the LIL was improperly designed; 28 2. The Report did not recommen...

AI summary The document discusses the Labrador Island Link (LIL) and its design in response to the March/April 2024 icing event. It clarifies that the LIL was designed according to engineering standards at the time and that no improper conclusions were drawn about its design. The report did not recommend immediate system-wide modifications, and further long-term monitoring is suggested.

In response to Industrial Group IR-9, NSPML has produced the LIL Strengthening Overview Report of NL Hydro which confirms that in total, there have been ten failure events on L3501/2 over the past five years; each was a localized issue aff...

AI summary The document discusses the structural failures of the LIL transmission line due to ice loading, referencing prior events and the Haldar Report, which identified known design vulnerabilities. The Industrial Group supports Bates White's conclusion that the 2024 outage was not excused by exceptional circumstances. NSPML disagrees with the Inspector General's position on the need for prior remediation.

Haldar Recommended to go Slow and Collect Actual Geographic Specific Data The Haldar Report indicates that under its more extreme value assessment only 2% of towers are potentially in need of reinforcement in anticipation of potential stor...

AI summary The Haldar Report suggests only 2% of towers may need reinforcement due to potential storms, but recommends collecting more geographic data before proceeding. NLH has addressed 10 failure events on L3501/2, with seven caused by ice accumulation. Reinforcement projects are planned for 2026-2028 to improve reliability and reduce failure risks.

13 Pre-2024 Weather Events Affecting the LIL 14 As the above ground portion of the LIL was constructed over eight years ago, it is not 15 surprising that there have been some weather impacts. As noted in NSPML's 16 submissions (including C...

AI summary The text discusses weather events affecting the Labrador Island Link (LIL) prior to 2024, noting that while there have been weather impacts, none resulted in complete transmission tower failures. The March/April 2024 event was more extreme than previous ones, but the damage was not classified as structural failure before this event.

1 NLH Response to Reliability Reports 2 NLH has not ignored reliability management for the LIL. In the first quote above from 3 the February 4, 2022 letter it is clear that NLH is taking a well-reasoned approach to 4 collect data and focus...

AI summary NLH is addressing reliability management for the Labrador Island Link (LIL) by collecting data, developing a capital plan, and making short-term improvements. The Haldar Report supports NLH's approach, emphasizing the need for long-term data collection before making modifications to infrastructure based on wind and ice loading data.