The Revolution of a Motor Program

摘要

The expectations of a motor within a nuclear station are quite different than in other industries. An annual failure rate of 3 or 4 motors, out of several hundred, is not acceptable. Until recently, it has been difficult to invest funds into maintaining motors that have been operating perfectly well. But the youngest of Duke Power's nuclear stations has been in operation for at least 10 years. And recent failures have not only resulted in lost revenue, but have also resulted in a loss of confidence by our regulators. As a result, Duke Power Nuclear Station's Motor Program has been revitalized. This revitalization began by a Duke Power Corporate Team coming together in 1995 to determine appropriate inspections and testing to perform on large motors (motors rated greater than 575 Volts and 200 hp). This new philosophy of inspections and testing was carried out for the majority of large motors installed at Catawba Nuclear Station, Unit 1, during the summer 1996 Unit 1 refueling outage. However, because of several failures that summer, we quickly found that the development of our Motor Maintenance Program was not going to be an evolution, but rather a revolution. McGuire Nuclear Station experienced two on-line failures of reactor coolant pump motors, forcing two unscheduled outages. And after a failure of a small 25 hp motor forced a Catawba unit to shutdown, nothing, in the way of program development, could come too soon. Engineering became heavily involved with investigating the cause of these failures to improve the maintenance program. Small motors were quickly added to the Motor Program at Catawba Nuclear Station. An on-line testing program was developed to obtain thermography and current data. Recent problems with spare motors in the warehouse caused us to examine how spare motors were transported, stored, and maintained. To gain consistency between each of the three nuclear stations, a multi-site motor project was sponsored by Engineering Management to expedite program development. The program created at Catawba Nuclear Station, as well as lessons learned, were used to develop the Nuclear Motor Program. Benchmarking was performed with other utilities to see what the industry, as a whole, was doing with their motors. A list of critical motors to include in the Motor Program was assembled for McGuire and Oconee Nuclear Stations. Standard procedures for testing were developed for inspections and testing of induction motors and dc motors. Procedures were developed to address preparing motors for storage and transportation. Repair strategies for small motors were developed. Lubrication issues were also addressed. Preventive Maintenance Templates were created to identify maintenance activities required for each type of motor. All of these program enhancements are still in the process of being implemented at the three nuclear stations.