Study of MOV operator and motor characteristics to determine torque capability

Motor operated valves (MOVs) 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 MOVs. This paper also deals with a methodology that may be consistently applied to determine the realistic capability (that is, rating) of the motor/operator. As an ongoing resolution to the NRC IEB 89-10 issue of the impact of degraded voltage condition and other environmental conditions on torque capability of the MOVs, the determination of appropriate motor torque capability is essential.