Characteristic Parameters for Electrical Bearing Damage

This paper focuses on different parameters to describe the sensitivity of a powertrain, consisting of a two-level voltage source inverter and an AC motor, to an electrical bearing damage due to bearing currents. This damage is mainly caused by fluting of the bearing raceways. Two characteristic parameters for electrical bearing damage have been introduced: apparent bearing current density $\hat{J}_{b}$, apparent bearing power $\hat{S}_{b}$ and the related electrical bearing wear which are compared and discussed. Both have in common the electrical bearing current amplitude. This current is measurable via modifications at the bearing shields. Long-term tests with different apparent bearing current densities lead to a probabilistic prediction of critical values, above which bearing damage may occur due to fluting.