Against the example of main transformer damage caused by circuit breaker flashover in power plant

this paper analyzes the influence of transient overvoltage of generator excitation circuit on generator terminal voltage at the moment of field circuit breaker disconnection

and analyzes the coordination relationship between the total time limit of fault flashover protection and fault protection and the dynamic stability capability of transformer. It is considered that the coordination of flashover protection and failure protection of circuit breaker specified in the current standard can not effectively protect the main transformer. According to the analysis results

this paper proposes to shorten the time limit of circuit breaker flashover and failure protection for existing devices

or change the outlet mode of circuit breaker flashover protection

so that it can directly act on all adjacent circuit breakers of fault circuit breaker or all circuit breakers of the bus.