By introducing the tripping process of 300 MW unit in a thermal power plant and the checking and analyzing process of its causes

it is pointed out that the main reason for the tripping event is the mistransmission of the MFT relay operating signal caused by the communication fault of the DCS loop.At the same time

through the analysis of the communication transmission mode adopted by the MFT relay operating signal and the hidden trouble existing in the logic design of communication signal’s quality inspection

the paper puts forward the preventive measures in the aspects of account management

logic design and emergency plan

so as to prevent the repeated occurrence of similar accidents and provide reference for the units with similar problems.