Fault Diagnosis and Treatment of a Newly Put into Operation 220kV Transformer

In view of the abnormal problem of the insulating oil chromatography data of a newly put into operation 220kV transformer, two methods of insulating oil chromatography test and high-voltage electrical test were used to analyze the fault, and the main transformer fault was located at the position of the bushing joint lead position, determine the main transformer for installation process quality problems to produce magnetic flux leakage, leading to thermal cracking occur insulating oil overheating. According to the inspection results of the disassembly of the transformer returned to the factory, it was determined that the cause of the fault was the wrong assembly of the medium voltage B-phase first-end terminal and the bushing, resulting in local overheating, which confirmed the accuracy of the theoretical and experimental analysis, and effectively avoided the transformer failure caused by the expansion of the transformer. It also provides analysis and handling experience for fault diagnosis and defect handling after abnormal chromatography data of transformer insulating oil.