Capacitive voltage transformer is an important device to realize the connection between the primary system and the secondary system.It plays an irreplaceable role in the monitoring operation of the power grid.Aiming at a typical abnormality of a 220 kV voltage transformer

this paper uses a joint diagnostic analysis for electrical test and oil test to analyze the cause. The reason is that the voltage transformer′s electromagnetic unit intermediate transformer is connected to the voltage-dividing capacitor connector and the box is grounded to discharge breakdown

which causes a short circuit in the intermediate ground isolation switch.It is finally verified by equipment disassembly.Combined with the abnormal reasons

some suggestions are put forward for the production

manufacture

operation and maintenance of voltage transformer

which can provide reference for the equipment operation and inspection.