Discussion on Countermeasures against Faults of HV Bus Voltage Transformer in a Substation

In combination with examples of disposing voltage transformer(VT) accidents in a large power grid in recent years,the paper starts with structure and principle of secondary circuit of bus voltage transformer and analyzes and discusses on countermeasures against faults of HV bus voltage transformer in a substation.It is believed that in the separate operation of double bus,paralleled operation of secondary side of VT is prohibited.Furthermore,principles for accident proposal and improvements on protection configuration,namely,on the condition that there is tripping of secondary air break switch of bus voltage transformer,the primary and secondary air break switch should be immediately switched on if it is allowed by field regulations.If the fault point is not effectively isolated,routine "switching on and then off" bus switching of bus is strictly prohibited;improvement of functions of relaying protection devices etc.