In-situ Repair Saves 9 Days of Repair Times

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In-situ Repair Saves 9 Days of Repair Times

Westinghouse Electric Company LLC is a US based nuclear power company. It offers nuclear products and services to utilities internationally, including nuclear fuel, service and maintenance, instrumentation, control and design of nuclear power plants.

The silver on three slip rings on a 480 Volt, 28 Amp Westinghouse WWG-0600 Wind Turbine Generator was worn away due to the graphite contacts. Fortunately, Westinghouse contacted the experts at SIFCO ASC and the slip rings were repaired in-situ, approximately 100 feet above ground, with the portable SIFCO Process® of selective (brush) plating.

The three slip ring areas were 18” in diameter, 1/4” wide and approximately 1/4” deep. These OEM, copper-based slip rings were molded together with epoxy to isolate them. The molded slip ring assembly was originally tank electroplated with 0.0015” silver. Premature failure occurred as graphite contacts eroded the silver. The contacts caused the silver to be “ground” into a dust, which when combined with the light lube coating created an abrasive paste that completely wore through the silver and into the copper substrate.

A thickness of 0.030” of copper was brush plated to resize the worn diameters. The grooves were then dressed back with a standard file and sandpaper until plan dimensions were achieved. After dressing the plated copper deposit, 0.003” thick layer of silver was then brush plated for improved conductivity.

While removing and reinstalling the entire assembly after repairing it on the bench was estimated to be a 10- to 14-day, $100,000 job; brush plating provided a viable, cost effective alternative completing the repair in approximately 40 hours with less than $1,000 in material costs.

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