Analysis of master fuel trip of boiler arising from start-up of feed-water pump

The boiler MFT (master fuel trip) protection was actuated during start up of feed water pump A of Unit 1 and 2 in Huaneng Shantou Power Plant. The possible causes of the failure are analyzed and tested. It comes to the conclusion that the failure was caused by the automatic switching off of the coal feeder contactor resulting from excessively low control voltage. On this basis, improvements on the circuit and corresponding precautions are presented.