New partial discharge detection method for live power cable systems

A novel partial discharge detector, the REDI (resonance-type high-frequency partial discharge) sensor, is developed for picking up the high-frequency components of partial discharge (PD) current pulses from live cable systems. This sensor was applied to initial AC breakdown tests of practical joints of XLPE (cross-linked polyethylene) insulated cables, and PD could be clearly observed in all cases (the minimum apparent charge was 5 pC with 275 kV cables). The phase characteristics of PD against the applied voltage changed just before the breakdown. >