Improved motors for utility applications

The reliability and performance of powerhouse motors was evaluated and design and operational characteristics which, through advanced development, offer the potential of increased reliability, performance, and efficiency were identified. A data base of utility motor applications, operating factors, failures, causes of failures, and impacts of failures on the operation of the generating station was developed. A survey of 132 generating units was conducted and data on 4800 low and medium voltage motors with ratings greater than 100 hp was obtained. Results are presented relating motor failures to units, utilities, manufacturers, and applications. A separate survey was undertaken with the goal of documenting utility industry experience in using vacuum devices to switch motors in generating station auxiliaries systems. Eleven utilities were identified as having installations involving vacuum switching devices at 12 generating stations representing 122 motors.