Performance Evaluation of Radio Frequency Based EDM Bearing Current Detection Method

The possibility of a bearing damage caused by inverter-induced bearing currents in modern frequency converter driven systems is well recognised today. A non-intrusive method to detect and monitor the frequency of occurrence of these currents has been developed by authors. This technique makes it possible to analyze the appearance of inverter-induced bearing currents in a variable speed drive system, and to estimate the risk they might cause to the bearings. The proposed method is based on the measurement of the radio frequency signal emitted by the discharge and transmitted by the machine. The method has been shown to be able to detect electrical discharges in the bearings of induction machines. Currently, the rate of the discharges (discharge activity) is used as a measure. In this paper the proposed electrical discharge detection method is further studied. This study aims to the utilization of this non-intrusive measurement method in field conditions in industry.