N-2CI C0044172 REFILE - Redacted
29 passages
DESCRIPTION: This project is for the investigation, custom hardware development, testing, and installation of a new vibration dampening solution for the L-7005 transmission line across the Canso Strait. The new vibration mitigation system...
AI summary This project involves the installation of a new vibration dampening solution on the L-7005 transmission line across the Canso Strait. Fatigue-related failures were identified in the existing dampers during a 2021 inspection, caused by Aeolian vibration and galloping due to low-to-moderate wind speeds and ice accumulation, exceeding original design assumptions.
1.0 SCOPE AND PURPOSE The L7005 230kV Canso Crossing constructed in 2017 has experienced conductor damage due to extreme weather induced vibration and galloping. The location of the crossing is subjected to severe weather, winter storms, c...
AI summary The L7005 230kV Canso Crossing has experienced conductor damage due to extreme weather conditions, including vibration and galloping. The document outlines the challenges, engineering studies, expert engagement, and planned mitigation measures for this unique crossing.
8.0 DAMPERS & AFS In addition to repairing any conductor damages, the mitigation measure for aeolian vibration and galloping consists of PLP special dampers and Air Flow Spoilers (Refer Appendix F). L8004 Canso strait crossing which is loc...
AI summary The document discusses the installation of PLP special dampers and Air Flow Spoilers (AFS) to mitigate aeolian vibration and galloping on power lines. It references the successful implementation on L8004 Canso Strait Crossing and outlines testing requirements for the new dampers. NSPI has engaged Kinectrics Inc. to conduct damper tests and provide a detailed report. Placement guidelines for dampers and AFS are also outlined, including updated charts and distribution requirements.
1. INTRODUCTION The 345 kV crossing of the Canso Strait is the second crossing span and was built in 2017. Figure 1 shows the plan of the crossing including the new towers. Initial operation is at 230 kV, but the line was designed for ulti...
AI summary This interim report discusses the 345 kV power line crossing the Canso Strait, which was constructed in 2017. The line is currently operating at 230 kV but was designed for 345 kV. Severe damage to the main conductor has occurred due to wind-induced vibrations, and the report proposes short-term and long-term corrective measures.
3. DAMPING DESIGN The design of damping system for the crossing spans was contracted to the A. Salvi & C., Milano, Italy, and that company developed a six-damper scheme for each end of each of the main and back spans. (Canso-Strait 345kV p...
AI summary The damping design for the Canso Strait 345kV project involved a six-damper scheme developed by A. Salvi & C. and tested using ESANEM software and indoor testing. However, Professor Giorgio Diana raised concerns about the scheme's effectiveness under conditions with significant ice accumulation, noting limitations of current technology to handle thick ice layers.
REDACTED CI C0044172 Attachment 1 Page 25 of 247 REDACTED (CONFIDENTIAL INFORMATION REMOVED) Canso Strait 230 kV Crossing Assessment lay ratio, breaking load, stress-strain and dc resistance test. The creep test on the full conductor was c...
AI summary The document discusses the Canso Strait 230 kV Crossing Assessment, including tests such as lay ratio, breaking load, stress-strain, and dc resistance, with the creep test conducted at the Shanghai Electric Cable Research Institute.
5. ALTERNATIVE DAMPING SCHEMES FOR AEOLIAN VIBRATION. There are power lines crossing large bodies of water in several countries, many exposed to both channeled winds and accretion of ice or wet snow. Serious vibration problems have been wi...
AI summary The document discusses alternative damping schemes for aeolian vibration on power lines, focusing on the use of 'festoon dampers' and the concerns raised about the SALVI damping scheme in the Canso Strait 230 kV Crossing project. Issues with the tension clamp design and past failures are highlighted, with ZTT proposing an alternative using dampers and damping wire loops.
6.1 Interphase Spacers The summarizing statement in the State-of-the-Art report published by CIGRE in 2007 is: "No control method can guarantee it will prevent galloping under all conditions". (CIGRE Technical Brochure No. 322 "State of th...
AI summary The document discusses interphase spacers tested by Hydro Quebec for reducing conductor galloping in heavy icing locations. The CIGRE report from 2007 notes that no control method can completely prevent galloping, but spacers can reduce its effects. The tests involved four spacers in each of three full-sized test spans, and the findings are applicable to the Canso crossing spans.
6.2 Detuning Pendulums Detuning pendulums are weights attached to the conductor, either single or bundle, at a prescribed arm length to impose a torsional rotation on the conductor that is different from the normal wind driven torsional mo...
AI summary Detuning pendulums are weights used on overhead conductors to reduce galloping by altering torsional motion, preventing resonance with vertical oscillation. They are effective for normal span lengths but lack data for extreme spans.
6.3 Air flow spoilers Air flow spoilers are a wrap of PVC rod designed to modify the flow of the wind around the conductor to break up coordinated eddies from vortex shedding, in a similar fashion to strakes of a vertical chimney. They are...
AI summary Air flow spoilers are PVC rods used to modify wind flow around conductors, reducing galloping caused by vortex shedding. They were effective in field trials up to 25 mm ice or wet snow coverage and were used on the first crossing span to address severe galloping.
INSIGHTS FROM THE FIRST CROSSING SPAN The following is based on discussions with Balraj Bilju of NSPI and a paper from the Havard Engineering archives entitled: "Experience at the Strait of Canso Crossing in Nova Scotia", by Robert Whapham...
AI summary The first crossing span, completed by Nova Scotia Power Company in 1983, experienced significant conductor motion and flashovers due to insufficient self-damping properties of the conductor, despite its high strength and design for 230 kV and 345 kV. The conductor was strung at 40% of rated tensile strength to reduce tower height, but it failed to control low-frequency oscillations such as conductor galloping.
REDACTED CI C0044172 Attachment 1 Page 37 of 247 REDACTED (CONFIDENTIAL INFORMATION REMOVED) Canso Strait 230 kV Crossing Assessment Air flow spoiler coverage should be more than that of the first crossing to compensate for the lack of imp...
AI summary The document discusses the assessment of the Canso Strait 230 kV Crossing, emphasizing the need for increased air flow spoiler coverage to compensate for reduced impact damping in the new conductor.
NEW SALVI DAMPING SCHEME Salvi have offered another damping solution based on Stockbridge dampers, including some with low frequency capabilities, but this still falls short of damping conductor motions in the really low frequency range, s...
AI summary The document discusses a new damping scheme proposed by Salvi for conductor motion control on the Canso Strait 230 kV line. It highlights concerns about the effectiveness of current dampers, especially under thick ice layers and galloping conditions, and notes issues with damper clamping during inspections. Alternative solutions such as air flow spoilers and monitoring systems are suggested.
g, in addition to Salvi's dampers, before the winter closes in. Strakes used on tall chimneys have a well stablished record of effectiveness for control of that particular type of wind driven motion. I have participated in application of t...
AI summary The document discusses the use of airflow spoilers on transmission lines, referencing past applications such as the Canso Strait crossing. It mentions studies and papers on the effectiveness of spoilers in reducing conductor oscillations and references a paper by Robert Whapham from 1987.
Wind tunnel study inconclusive
AI summary The wind tunnel study conducted to assess the impact of AFS on power line structures was found to be inconclusive, leaving uncertainties about their effectiveness and safety.
9. LONG TERM RECOMMENDATIONS - ❖ Install long term damping scheme if tests are successful - ❖ anticipate and repair further damage from 2021 install interphase spacers - ❖ Change suspension clamps to better supports, maybe AGS or long sadd...
AI summary The long-term recommendations include installing a damping scheme if tests are successful, anticipating and repairing damage from 2021 interphase spacers, and replacing suspension clamps with better supports such as AGS or long saddle clamps.
REDACTED CI C0044172 Attachment 1 Page 50 of 247 APPENDIX 1 DOCUMENT LIST 0001_2_V6.pdf Strait of Canso crossing rock _ 2017-02-20 anchor details Hatch H349324-00000-35-197-0001- 345 kV transmission line Drawing of 171 m suspension 60 mm o...
AI summary The document lists technical drawings and design requirements for a 345 kV transmission line crossing the Strait of Canso, including details on suspension towers, braced portal lattice dead end towers, and lighting and marking layouts. The documents are from various dates and include information on ice and wind loadings.
REDACTED CI C0044172 Attachment 1 Page 86 of 247 REDACTED (CONFIDENTIAL INFORMATION REMOVED) REDACTED CI C0044172 Attachment 1 Page 87 of 247 Canso Strait 345 kV Crossing 2023 Assessment
AI summary The document refers to the Canso Strait 345 kV Crossing 2023 Assessment, which appears to be a technical evaluation related to a high-voltage power line crossing. The page number and image reference suggest this is part of a larger regulatory proceeding.
DRAFT INTERIM REPORT ON MAY 16, 2024, DRONE-BASED SURVEY OF NOVA SCOTIA POWER'S L7005 345 kV CANSO STRAIT CROSSING by David G. Havard Ph.D., P.Eng. President, Havard Engineering Inc. 3142 Lindenlea Drive Mississauga, Ontario, Canada, L5C 2...
AI summary This draft interim report, authored by David G. Havard Ph.D., P.Eng., details a drone-based survey conducted on May 16, 2024, of Nova Scotia Power's L7005 345 kV Canso Strait Crossing. The survey is part of an assessment of the infrastructure.
2. Video inspection February 1 and 2, 2024 (The following comments were made after review of the drone-based videos) Viewing conditions at the time were far from optimum. Snow was falling on the second day and the conductor was out of focu...
AI summary The video inspection of the Canso Strait 345 kV Crossing conducted in February 2024 was hindered by poor visibility and out-of-focus images, making it difficult to assess conductor conditions. The most exposed span (3A-4A) showed potential surface markings from conductor impacts, but details were unclear. Recommendations include re-inspection in clear weather with better imaging techniques and detailed labeling of photos.
Island looking east, showing\nundamaged suspension insulator string and dampers on conductors, including the failed PLP damper on bottom conductor of the west During the 2022-2023 winter considerable damage occurred on the span across the...
AI summary This document describes damage observed on the Canso Strait 345 kV Crossing during a May 2024 drone inspection. It highlights issues with the suspension structure on Cape Breton Island, including failed dampers, conductor damage, and repairs using preformed rods. The damage occurred during the 2022-2023 winter and has not worsened in the following winter.
5. Photos around the Suspension Structure on the Nova Scotia Mainland: May 26 2024 Figure 9 Suspension structure on Nova Scotia Mainland looking east along the Canso Strait. Detail from Photo No. DJI_20240116032428_0047_w.jpg Figure 10 Sus...
AI summary The document provides photos and descriptions of a suspension structure on the Nova Scotia mainland, focusing on damage and repairs to conductors caused by wind-induced damage. It mentions the use of Salvi and PLP dampers and highlights areas requiring further protection.
7. Main span over the Canso strait A serious omission in the recent drone-based survey is recording of the condition of the main span across the Strait beyond the immediate vicinity of the towers. It should be noted that in the earlier, to...
AI summary The drone-based survey of the main span over the Canso strait failed to record the condition of the span beyond the immediate vicinity of the towers. A previous inspection in May 2022 identified a loosened Salvi damper that may have caused damage to the conductors. The document highlights concerns about conductor galloping and its potential to cause service interruptions.
REPORT FOR NS POWER CONDUCTOR DAMAGE CANSO STRAIT CROSSING
AI summary This document is a report regarding conductor damage at the Canso Strait Crossing for Nova Scotia Power. It provides details on the incident, its impact, and potential implications for the power grid.
Str 731, NE Foundation The majority of nuts on one plate needed to be torqued. Plate located on angled steel support which points towards the SE corner of the str. Picture attached. Approx a third of the remaining bolts also moved. It shou...
AI summary The text describes a foundation issue at Str 731, NE, with nuts needing torque and signs of wear. It includes images and references to Nova Scotia Power Inc. tower inspections at Canso Crossing.
Scope This document presents the proposed vibration damper placement for the replacement of the existing damping system on the Canso crossing. NOTES: 1. On spans with armour rods installed near the suspension clamp for conductor repair, th...
AI summary The document outlines the proposed placement of vibration dampers for the replacement of the existing damping system on the Canso crossing. Adjustments are required for spans with armour rods installed near suspension clamps, and damper spacing must follow the guidelines provided.
Modelling and Analysis of Canso Crossing Lattice Towers 7005 - 315kV Double Circuit - Towers 730-731 Assessment with new dampers Prepared by: Cedrik Levesque, P.Eng. Engineer, Energy Lines and Substations Structural Engineering ENS #: 1160...
AI summary This document outlines an assessment of lattice towers 730-731 on the 315kV double circuit line of the Canso Crossing, including the evaluation of new dampers. The assessment was prepared by Cedrik Levesque and verified by Mario Robichaud.
REDACTED CI C0044172 Attachment 1 Page 212 of 247 Modelling and Analysis of Canso Crossing Lattice Towers 7005 – 315kV Double Circuit – Towers 730-731 Assessment with new dampers CIMA+ file number: Z0017482 September 3 rd , 2024 – Revision...
AI summary This document discusses the modelling and analysis of lattice towers 7005 – 315kV double circuit – towers 730-731 at Canso Crossing with the assessment of new dampers. The CIMA+ file number is Z0017482, and the revision is A, dated September 3rd, 2024.
1.1 Background L7005 is a double circuit 315 kV transmission line owned and operated by Nova Scotia Power Inc. Spanning the Strait of Canso the section from structures 729 to 732 covers approximately 3 km, with a central span of around 150...
AI summary The document discusses the L7005 transmission line owned by Nova Scotia Power Inc., focusing on the need for a capacity assessment of towers 730 and 731 due to increased vertical loads from recent hardware modifications.