부산대학교 도서관

Power transformers play an irreplaceable role in power distribution and transmission networks. Diagnosis of transformer's degradation insulation system is of great importance in order to assess its performance and reliability. This paper discusses about the effect of applying simultaneous electrical discharges of low energy under AC voltage on the characteristics of the impedance and phase of the insulating mineral oil with frequency ranging from 20 Hz to 10 MHz. The impedance and phase are measured with a high precision LCR-meter where the insulation liquid is filled in the test cell with point-plane electrode system and a gap of 2.5 mm. The performed measurements provide a well correlation with the degree of degradation of the mineral oil and hence with its capacity and resistivity when submitted to AC high voltage discharges.