Fault analysis of servomotor on static test

XU Guangcheng, ZHU Shuanjun

(Hangzhou Steam Turbine Company Limited, Hangzhou 310022, China)

Abstract: Aiming at the large difference of outlet air pressure between two boiler draft fans of a power plant in the east of Zhejiang which are under the same valve setpoint, resulting in that the two boiler draft fans can not be parallel operation, through the practical observation, it was found that the deviation of the stroke was a big problem in the process of the servomotor of the steam turbine. After carrying out the related inspection and analysis of feedback board, pilot valve , slide-piston, sealing ring and connection piece of the servomotor, then related improvement plans were proposed. Aiming at these schemes. The static test method was used to measure and compare the stroke values of the steam turbines servomotor, and to analyse the corresponding measured data. The results indicate that the main reason for the deviation of the stroke during the operation of the turbine is the use of the unqualified sealing ring which can cause the trace oil leakage. After the loading operation, the effectiveness of the solution is confirmed.

Key words: servomotor; sealing ring; pilot valve