Analysis and Treatment in More Than One Grounding Points on the Clamping Piece of Power Transformer

The iron core of the transformer in normal operation should be grounded at one point, but due to the design, manufacturing, transportation and installation, the iron core and clamping piece touch each other or touch the grounding part directly. So there is a circulation current in the iron core grounding wire during the operation of the transformer. This situation often occurs in the substations. A multi-point grounding fault of a 500kV transformer clamping piece is analyzed in this article. Firstly, the poor ground insulation of the clamping piece during the pre-test of the transformer is described. Then the abnormal grounding current of the clamp after it is put into operation is analyzed. Finally, the defect is found through the power failure inspection and corresponding measures are taken to successfully eliminate the fault.