STUDY OF MOV OPERATOR AND MOTOR CHARACTERISTICS TO DETERMINE TORQUE CAPABILITY

Motor operated valves (MOV's) used in the nuclear generating stations require the high torque capability of a motor when demanded during an accident scenario, This paper specifically deals with the behavior and classification of motors used in ac MOV's, This paper also deals with a methodology that may be consistently applied to determine the reali stic capability (that is, rating) of the motor/operator, As an ongoing resolution to the NRC IEB 89-10 issue of the impact of degraded volta ge condition and other environmental conditions on torque capability o f the MOV's, the determination of appropriate motor torque capability is essential.