A High Bandwidth and Multilevel Counter Circuit for Bearing Current Evaluation

Abstract:
Inverter-induced bearing currents are known to reduce bearing life in electrical machines. Several types of bearing currents can be distinguished, and the different types of bearing currents have different causes, but all these types occur in pulses. In general, the different types also differ in the pulse height. This paper proposes a circuit for live evaluation of bearing currents by counting their occurrence rate as a function of pulse height, while distinguishing between two different current levels. In addition, it is emphasized what needs to be considered when counting bearing current pulses. The occurrence rate and pulse height can be used as indicators for bearing current investigations.