Presented at the IEEE Switchgear Committee, Calgary, Alberta, October 13-15, 2008

Lambert, Frank

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Scholarly Materials And Research @ Georgia Tech

Accelerated Weathering of Overhead Loadbreak Switch InterruptersNEETRACFrank C. LambertGeorgia Tech / NEETRACHigh Voltage Switch SubcommitteeCalgary, AlbertaOctober 15, 20082NEETRAC Members 2008 - 20091. 3M2. ABB3. ACA Conductor Accessories4. Ameren Services5. American Electric Power6. Baltimore Gas & Electric7. Borealis Compounds LLC8. Con Edison9. Cooper Power Systems10. Dominion Virginia Power11. Dow Chemical Company12. Duke Energy13. Entergy14. Exelon15. Florida Power & Light16. First Energy17. GRESCO Utility Supply 18. Hubbell19. NRECA20. NSTAR21. PacifiCorp22. Prysmian Cables & Systems 23. Public Service Electric & Gas24. South Carolina Electric & Gas25. Southern California Edison26. Southern Company27. Southern States28. Southwire29. Thomas and Betts30. TVA31. tyco / Raychem32. Zenergy Power3Introduction• NEETRAC completed a scoping study to identify field problems with distribution loadbreak switch interrupters in 2005.• Utilities reported problems with “stuck”interrupters or failures when opening.• 17 loadbreak interrupters were removed from field service and returned to NEETRAC for evaluation.• Many of the problems with these units appeared to be caused by UV deterioration and corrosion. 4Field EvaluationReturned from Field Service:Alabama Power Company5Field EvaluationReturned from Field Service:Alabama Power Company6Field EvaluationInterruption ChamberRubber Tip was Torn and Seal LostOperatingLeverReturned from Field Service:Dominion7Accelerated Weathering of OH Loadbreak Interrupters• Based upon a review of the units returned from the field, a project was initiated to investigate the affects of both UV deterioration and corrosion on new interrupters.• Six different loadbreak interrupters from five manufacturers were exposed to both UV / condensation and salt-fog accelerated weathering at NEETRAC.• Benchmark tests were performed during the aging process to measure dc contact resistance and mechanical force required for operation.8Accelerated Weathering of OH Loadbreak Interrupters• Both new and aged interrupters were then subjected to the full load current interruption tests according to Section 9.1 of IEEE C37.34 at a high power laboratory.• Failures from the full load current interruption tests were examined to assess the impact of the weathering on performance.9Samples TestedS&C Electric CompanyOmni-Rupter17 kV, 900 A147442R1-Z3-S115S&C Electric CompanyAlduti-Rupter17 kV, 600 A137512R7-S10210Samples TestedBridgesVector25 kV, 900APN963XF-41ASA. B. ChanceAutomation Ready29 kV, 900 AAR114MSLP11Samples TestedCooper Power SystemsM-Force25.8 kV, 900 AM2A41SC3ATInertia25 kV, 600 ATRS26STSHX112512UV / Condensation AgingUV / condensation aging according to ASTM D4329-05 and ASTM G154-06 using UVA-340 lamps. 13UV / Condensation Aging• 2,000 hours total aging was required to produce results similar to those observed on field aged units (includes UV & condensation periods).• The following aging cycle was used:– 8 hours of UV at 60 ± 3 °C – 0.25 h water spray (no light), temperature not  controlled– 3.75 h condensation at 50 ± 3 °C• Rotation of samples approximately every 333 hours, horizontally across the rack.• Distilled water was used for the chamber. 14Salt-fog Aging• Performed on one sample of each design after 2,000 hours of UV / condensation aging. • 1,000 hour salt-fog aging test according to ASTM B117-07.• A continuous fog of 5% salt solution was used.15Benchmark Tests• dc contact resistance (closed position)• Mechanical performance – torque, force, etc. (both opening and closing)• Performed on the samples four times: –new –after 1,000 hours of UV aging –after 2,000 hours of UV aging –after 1,000 hours of salt-fog aging • Sample designations:–UV is UV / Condensation aging only–UVS is UV / Condensation and Salt-fog aging16Benchmark Test Results0.0600.0310.039H-UV-6139815000.0290.0190.068H-UVS-50.0180.0810.054H-UV-40.0080.0070.006G-UV-6open0.2060.0110.0200.009G-UVS-5Could not close interrupter internally after it was operated post salt-fog.0.0100.0180.007G-UV-40.0060.0280.004F-UV-60.0980.0120.0780.0150.063F-UVS-50.0140.0340.006F-UV-40.2830.2860.176E-UV-61.4805.5600.2350.2300.485E-UVS-50.1820.3790.297E-UV-4125450.0180.0030.0140.004D-UVS-60.0320.0070.009D-UV-5Interrupter was rusted shut when removed from salt-fog. After interrupter was forced open, internal contacts never opened.0.0050.0060.003D-UV-40.1340.0680.2180.3390.067A-UVS-60.3850.1580.085A-UV-50.8300.1150.061A-UV-4Post Salt-Fog Aging After OperationPost Salt-Fog Aging  Before OperationPost 2,000 hr UV AgingPost 1,000 hr UV AgingInitialCommentsdc Contact Resistance in OhmsSample Number17Benchmark Test Results7.81.08.20.68.40.9E-UV-68.22.07.90.97.50.47.60.9E-UVS-57.80.48.10.67.80.6E-UV-426+24+19.420.122.219.921.023.0D-UVS-621.821.919.023.020.023.7D-UV-519.220.721.022.918.025.0D-UV-49.913.910.310.010.89.88.89.6A-UVS-610.710.510.212.49.911.4A-UV-510.511.09.810.08.29.8A-UV-4Closed to Open ContactsOpen to Closed ContactsClosed to Open ContactsOpen to Closed ContactsClosed to Open ContactsOpen to Closed ContactsClosed to Open ContactsOpen to Closed ContactsSample NumberPost 1,000 hr Salt-Fog AgingPost 2,000 hr UV AgingPost 1,000 hr UV AgingInitialForce Measurements in lbsSample D-UVS-6 had to be lubricated with rust buster and forced open in order to record the post salt-fog aging measurements.18Benchmark Test Results15.40.216.11.219.02.7H-UV-612.64.014.90.515.10.917.05.7H-UVS-516.10.415.00.915.03.8H-UV-412.00.411.40.511.90.4G-UV-610.22.012.30.612.60.912.00.4G-UVS-511.10.113.10.812.90.3G-UV-49.815.110.618.79.815.3F-UV-616.214.29.314.510.216.09.815.0F-UVS-511.015.210.014.59.813.9F-UV-4Closed to Open ContactsOpen to Closed ContactsClosed to Open ContactsOpen to Closed ContactsClosed to Open ContactsOpen to Closed ContactsClosed to Open ContactsOpen to Closed ContactsSample NumberPost 1,000 hr Salt-Fog AgingPost 2,000 hr UV AgingPost 1,000 hr UV AgingInitialForce Measurements in lbs19Load Current Interruption Tests• Performed at Powertech Labs – October 2007• IEEE Std 1247™ 2005, Clause 8.3.2.1, Load-switching tests20Load Current Interruption TestsTest plan for each manufacturer’s switch:1. Perform 10 load break switching operations at 100% load with new (un-aged) interrupters (as required by IEEE Std 1247™).  A five minute “cool down” period was provided between each switching operation.2. If the unit passed IEEE Std 1247™ requirements, replace interrupters with new (un-aged) interrupters and perform three additional load break switching operations under wet conditions.  Prior to each operation, each interrupter was thoroughly wetted with water using a spray bottle with 100 ± 15 Ω-m water. A five minute “cool down” period was provided between each switching operation.21Load Current Interruption Tests3. Replace interrupters with the aged units (two UV aged only and one UV + salt-fog).  During setup / calibration, locate the pole that opens first and install the UV + salt-fog interrupter at that location.  Perform 10 load break switching operations at 100% load. If an interrupter fails, substitute a new interrupter to try to complete the series to gain as much data as possible from the tests.  A five minute “cool down” period was provided between each switching operation.4. If the unit passed the requirements in (3), perform three additional load break switching operations under wet conditions.  Prior to each operation, each interrupter was thoroughly wetted. A five minute “cool down” period was provided between each switching operation.22Load Current Interruption Test Results*6004G3103*510H310310A*42 *4310E3 *3338F*2*2*27 *1DAged Wet(3)Aged(10)New Wet(3)New(10)ManufacturerNumber of Successful InterruptionsNotes:  *1 – Switch was removed from field service.  Interrupters were not new.*2 – New and aged interrupters’ mounting brackets were different. Aged units could not be tested.*3 – Only the aged F-UV-6 interrupter completed the three wet tests.*4 – Interrupters pickup hooks were not replaced after the tests on new interrupters.  These worn hooks may have contributed to the failure of the aged interrupters.*5 – Wet tests were performed on the original new interrupters (13 total operations on same units). *6 – Wet tests were not performed on the aged interrupters due to previous failures.23Benchmark Test Observations• dc contact resistance measurements did indicate problems with samples D-UVS-6, G-UVS-5, and H-UVS-5 after the salt-fog aging.• Force measurements also indicated problems with D-UVS-6 after the salt-fog aging.24Interruption Test Observations• Wet tests did not affect results of the load current interruption tests.• Three of the interrupters were definitely affectedby the accelerated weathering tests.–D-UVS-6 seized up due to corrosion.–F-UV-4 and F-UVS-5 failed after only three successful interruptions.–H-UVS-5 experienced corrosion of a riveted connection that vaporized during testing, but none-the-less passed as the connection arced over.25Interruption Test Observations• Two of the interrupters may have been affectedby the accelerated weathering tests.–Manufacturer E interrupter tests terminated early due to pickup clip failure.–Manufacturer G failed interruption tests (new units also failed).• One interrupter was definitely not affected by the accelerated weathering tests.–Manufacturer A interrupter passed all of the tests.26Recommendations for IEEE C37.34• Add requirements for accelerated UV / Condensation aging prior to interrupting tests in Section 9 for usual service conditions. • Add requirements for accelerated UV / Condensation aging and salt-fog aging prior to interrupting tests in Section 9 for unusual service conditions involving contaminated environments. 27Contact InfoFrank C. LambertGeorgia Tech / NEETRAC404-675-1855frank.lambert@neetrac.gatech.edu

Accelerated Weathering of Overhead Loadbreak Switch Interrupters

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Accelerated Weathering of Overhead Loadbreak Switch Interrupters

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