Abstract: In the emergency tripping system of the 200MW steam turbine manufactured by the Dongfang Turbine, the more mature highpressure tripping module and lowpressure tripping module were adopted. However, in commissioning process of the unit No.2 of the Zhengzhou Zhengdong New District Heat and Power Corporation Limited, at the start, the turbine could not latched repeatedly; and after latched, the system was unable to keep the latchon state. The fault was analyzed and researched in depth, and the problem was solved finally.

Key words: latch, emergency trip slide valve, oil drainage port