Abstract:
The very fast transient overvoltage (VFTO) generated by disconnector operation in gas insulated switchgear (GIS) can cause insulation faults of GIS equipment and electrical equipment connector to it, especially power transformer. In this paper, VFTO at representative position caused by disconnected operation in GIS is calculated and simulated with EMTP, and the characteristic amplitude values of VFTO are analyzed, the VFTO is applied to the transformer windings, and the transient voltage distribution of the transformer windings is analyzed, the potential gradient between the coils and the turns is obtained, the insulation faults of the transformer windings are found, which is in the forward end of the transformer windings.