Online partial discharge diagnostics in medium voltage branched cable networks

Partial discharge (PD) detection and localization in medium voltage (MV) cables connected in branched network configurations, is difficult by using the conventional methods. It is due to interconnected cables of different lengths and impedance which make the interpretation of PD signals quite complex as compared to single cable routes. This paper presents an online technique of PD localization for branched cable network. PD activity emits current pulses propagating away from the discharge location. Polarity of the detected PD pulses with reference to polarity of the supply voltage can determine the direction of arrival of PD pulses. Comparison of the polarity of PD pulses captured at different cable branches identifies the faulty section of the cable network. Evaluation of direction of arrival is based on directionally calibrated installed sensor. In this paper induction sensors are employed for implementation of the proposed technique. Integration of the proposed technique over a wider network can be very useful as an efficient diagnostic tool for improving the reliability of power supply.