Common Faults and Solutions in the Process of Electric Valve Commissioning of EPR Nuclear Power Unit

There are 926 electric valves in an evolutionary power reactor (EPR) nuclear power plant in China. During the commissioning of electric valves, six common faults were found in the electric actuators, namely, deviation between the torque value and the designed value, frequent triggering of the open torque microswitch, reversal, lack of jumper in the control loop, unreasonable selection of gear ratio in the reduction gear, and leakage of lubricating grease in the motor gearbox. This paper addresses these six common faults by providing detailed descriptions of the fault phenomena and analyses of the fault causes, and then proposes corresponding fault-solving methods, including torque calibration of the electric actuator, adding a bypass for the open torque microswitch, adjusting the phase sequence of the cables, adding a jumper, replacing the gear with the appropriate number of teeth in the reduction gear, and replacing the seal ring. The solution to these six common faults not only improves the reliability of the electric valve operation, but also provides experience for the subsequent design and commissioning of nuclear power unit electric valves.