Influence of High Resistance Grounding of the Transformer Core on Winding Capacitance and Dielectric Loss Test

Abstract

In this paper, based on the abnormal capacitance and dielectric loss data in the routine test of the transformer, combining with the test principle and the transformer structure design, an equivalent RC circuit model is established, and the influence of the high-resistance grounding of the transformer is deeply studied. Capacitance and dielectric loss measurements of winding is described in detail. The reasons for the abnormal capacitance and dielectric loss data are deeply explained. Studies have shown that when the iron core is grounded with high resistance, the measured capacitance and dielectric loss data of each winding will become abnormal. With the increase of the grounding resistance value, the measured capacitance value decreases slightly, and the dielectric loss data increases sharply; secondly, the influence of the high resistance grounding of iron on the measured capacitance and dielectric loss data of each winding is also closely related to the real capacitance of the measured winding itself. The larger the real capacitance of the measured winding, the greater the impact of the high resistance grounding of the iron core.