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

Abstract

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.

One-Dimensional Model for the Nonlinear Resistive Electric Field Control in Medium-Voltage Rotating Electrical Machines

“…The difference between the model and FEA estimated data for the FGM5, FGM6 and FGM13 is caused by the assumptions in the analytical model that neglect the field independent conductivity term 0 and the capacitive current term 0 SGT f(t)/ t in Equation (11) during AC supply (f = 50 Hz) are 821 and 819 kV/m, as it can be seen in Figure 5a. The data in Figure 6 for FGM5 shows Jres/Jcap 5.4; the resistive current term dominates over the capacitive current in the SGT.…”

“…in [7]. The available measured data on the resistive nonlinear properties of FGMs for medium voltage rotating electrical machines are depicted in Figure 3 [1, [7][8][9][10][11][12][13][14][15][16][17]. The data was reproduced from respective references at temperatures close to 80 C for comparative purposes.…”

“…The data was reproduced from respective references at temperatures close to 80 C for comparative purposes. Table 1 shows the dielectric properties of materials in Figure 3, which are estimated with Equation (11). The measured relative permittivity SGT of nonlinear resistive FGMs is in the range from 6 to 20 [7,8,[13][14][15][16].…”