Diagnosis and Analysis of Metal Expander Punching Defect of Oil-immersed Current Transformer

In this paper, a 220 kV oil-immersed upright current transformer metal expander punching defect is studied. Through the routine test, diagnostic test and disintegration inspection of the current transformer, it is determined that the insulation paper of the intermediate screen is not completely dry, resulting in low-energy discharge during operation, resulting in a large amount of gas and metal expander punching. Finally, relevant measures and suggestions are put forward to prevent the occurrence of this defect.