Statistical model of electrostatic discharge hazard in bearings of induction motor fed by inverter

In this paper, a statistical approach has been applied to determine the influence of inverter drive parameters on the rate and the amplitude of flashover currents in bearings of AC motors. The main cause of bearing currents is a charge accumulated on the shaft as a result of temporarily electric asymmetry at the output of the inverter in a presence of parasitic capacitive couplings inside the motor. The proposed statistical method could be the basis for comparative analyses of bearing damage hazard in a various drive configurations.