Transformer fault caused by structure defect of resin impregnated fiberglass bushing

Two faults of 550kV transformer bushing are introduced and the fault phenomenon is discussed. The failure bushing is resin impregnated fiberglass type with compound filled. In order to find the fault cause, the electric field design of bushing is examined by 2D and 3D finite element simulation. The influence of nearby earthing objects on the electric field inside the bushing is studied. Based on the simulation results, it can be concluded that the unreasonable design of the bushing internal shielding pipe is the direct cause of the fault.