Diagnosis of winding fault in three-winding transformer using lightning impulse voltage

Abstract

Diagnosis of winding fault is very important for maintaining transformers. The traditional lightning voltage test relies on the experience of the testers and is generally used to detect partial discharge faults in the winding. In this study, the waveshape parameters of lightning impulse voltage is 1.2/50μs±20%, and the amplitude is 4kV. The overvoltage response of three-winding transformer faults was researched using lightning impulse voltage. A test platform with a capacity of 400kVA, a rated voltage of 10kV/0.4kV, a frequency of 50Hz, and a YNyn0 transformer with a reduced scale ratio was used. The winding voltage was measured under normal and fault conditions. The transfer function was calculated for the short circuit of single-phase winding and winding deformation on the high-voltage side. Moreover, the statistical indicators of the frequency response of the transfer function was analyzed so we could diagnose the fault of the three-winding transformer.