Potential distribution on stress grading of inverter-fed rotating machines under DC biased voltage

The erosion of the stress grading system of converter-fed rotating machines may occur by partial discharges and heat generation. There remain unclear issues in the formation of the potential and temperature distributions along the stress grading system of coils. In this paper, the potential distributions on the stress grading system of the model coil bar are measured under the application of 1 kHz square wave voltages of 10 kV in peak to peak value with/without 5 kV DC biased voltage. It turns out that DC bias voltage has little effect on potential distribution on a coil surface