November 3, 2000

S&C’s Power Systems Services Meets Aggressive Schedule for Critical Maintenance of Substation Circuit Breakers.

A large midwestern utility needed to perform maintenance on over 300 medium-voltage, metal-clad air and vacuum circuit breakers and a similar number of reactors in eight different substations across their service territory. The units consisted of 1950’s- and 1960’s-vintage G.E. MagneBlast; 1960’s Allis-Chalmers MC & FC, 1960’s I-T-E 15HK, 1970’s Westinghouse DH & DHP, and 1980’s Square D VAD circuit breakers.

The work had to be completed in less than three months.

S&C’s Power Systems Services Division met this challenge by staffing the project with a dedicated project manager, five lead technicians, and a sub-contracted group of union electricians divided into five crews. The work began after an initial project meeting — and only two weeks after the initial request to S&C.

S&C crews worked on the circuit breakers by removing front covers, arc chutes, and barriers, and then completed the following general tasks on each circuit breaker:

• Thorough visual and mechanical inspection of the circuit-breaker operating mechanism, racking mechanism, pole-units, primary- and secondary-contact assemblies, ground shoes, arc chutes, puffers, and wiring.
• Thorough cleaning and lubrication of all mechanisms, stab-on assemblies, and conductors.
• Thorough mechanical exercising of the circuit breaker as well as electrical operation via the circuit-breaker test stations.
• Electrical testing, including insulation resistance, contact resistance, continuity of control circuits, and over-potential (vacuum circuit breakers only).
• Completion of an extensive circuit-breaker maintenance report for each unit.
• Update of the utility maintenance database information, including work order numbers, asset numbers, and asset disposition.

S&C also obtained parts through the utility inventory system — or via outside suppliers — and performed minor repairs as needed. Larger repairs were deferred to a later date if safe to do so.

The bottom line: The critical breaker maintenance work was finished in time to meet the utility’s requirements and allowed utility crews to perform other much-needed tasks on the system.

Contact your local S&C Representative or Power Systems Services at 773-338-1000 to learn more about how S&C can help you stay ahead of the maintenance curve and maintain the equipment reliability electric consumers demand today.