Abstract: After the 330MW unit of a power plant was shut down and started up again, it was found that the flow of the EH oil increased from 18L/min to 95L/min (its normal value range is 15L/min to 25L/min); and the current of the motor of EH oil pump was exceeded the limit, and the temperature of the motor was higher. Based on checking analysis, the internal leakage point had been found; and this internal leakage causes the larger flow of the EH oil flow; and the defect was eliminated gradually in unit operation. The flow of EH oil was decreased to 18L/min, and an unplanned outage accident was avoided, and safe and stable operation of the unit was ensured.

Key words: EH oil, flow, servo valve, internal leakage