During a power outage test on a 220 kV transformer

it is found that the data and waveform of the test items such as dielectric loss

capacitance and short-circuit impedance are abnormal. Through the comprehensive diagnosis and analysis of oil chromatography test

dielectric loss and capacitance test

short-circuit impedance test and so on

it is preliminarily determined that there may be deformation in the windings of the medium voltage side and low voltage side of the transformer. After returning to the factory for inspection

the correctness of the theoretical analysis is verified. It is suggested that routine tests and other routine operation and maintenance of transformers should be carried out regularly.