In this paper

the field operating overvoltage test results of 126 kV single break vacuum circuit breaker are introduced. First

determine the application and design of the circuit breaker overvoltage test scheme; Then

testing and comparing the operating overvoltage of vacuum circuit breaker and SF

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circuit breaker switching transformer; Finally

testing the operating overvoltage of vacuum circuit breaker switching no-load line. The research showed that

the VCB and SF

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circuit breaker had similar operating overvoltage

there was no operating overvoltage when switching the no-load transformer

and the overvoltage multiple is1.46 p.u. when switching the on-load transformer. The VCB’s overvoltage when switching the transformer are1.34 p.u. and 1.25 p.u. respectively.