Motor-Operated Valve (MOV) Actuator Motor and Gearbox Testing (NUREG/CR-6478, INEL-96/0219)

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Publication Information

Manuscript Completed: February 1997
Date Published: July 1997

Prepared by:
K. DeWall, J.C. Watkins, D. Bramwell

Idaho National Engineering Laboratory
Managed by the U.S. Department of Energy

Lockheed Idaho Technologies Company
Idaho Falls, ID 83415

G. H. Weidenhamer, NRC Project Managers

Prepared for:
Division of Engineering Technology
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

NRC Job Code A6857

Availability Notice


This report documents the results of valve research sponsored by the U.S. Nuclear Regulatory Commission (NRC) and conducted at the Idaho National Engi­neering and Environmental Laboratory (INEEL). The research provides technical bases to the NRC in support of their effort regarding motor-operated valves (MOVs) in nuclear power plants. Specifically, the research measured the capabili­ties of typical valve actuators during operation at simulated design basis loads and operating conditions. Using a test stand that simulates the stem load profiles a valve actuator would experience when closing a valve against flow and pressure, we tested five typical electric motors (four ac motors and one de motor) and three gear­boxes at conditions a motor might experience in a power plant, including such off­normal conditions as operation at high temperature and reduced voltage. We also monitored the efficiency of the actuator gearbox. The testing produced the follow­ing results:

  • All five motors operated at or above their rated starting torque during tests at normal voltages and temperatures.

  • For all five motors (de as well as ac), actual motor torque losses due to volt­age degradation were greater than the losses calculated by methods typically used for predicting motor torque at degraded voltage conditions.

  • Startup torques in locked rotor tests compared well with stall torques in dynamometer-type tests.

  • For three of the ac motors, the actual motor torque losses due to elevated operating temperatures were equal to or lower than losses calculated by the typical predictive method; for the de motor, the actual losses were signifi­cantly greater than the predictions.

  • For all three actuator gearboxes, the actual running efficiencies determined from testing were lower than the running efficiencies published by the manufacturer. In most instances, the actual pullout efficiencies were lower than the published pullout efficiencies.

  • Operation of the gearbox at elevated temperature did not affect the operating efficiency.

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