On radio-frequency based detection of high-frequency circulating bearing current flow

The possibility of bearing damage caused by inverter-induced bearing currents in modern variable-speed drive systems has been well recognised today. Further research is needed to develop appropriate non-destructive methods for detection and monitoring of such currents. A radio-frequency based non-destructive method has been applied to detect discharge bearing currents. The method is understood to work on the energy radiated during the bearing discharge event. Recent research has shown that the method is also to some extent applicable to high-frequency circulating bearing currents. These findings will be presented in this paper. Furthermore, the analysis and understanding of the applicability of the method to detect such currents also contributes to further understanding of the electric characteristics of the bearing, notably the moment the current conduction begins.