Use of Pulse Propagation Behavior for MV PD Source Localization in Medium Voltage Cables
Partial discharge (PD) is caused in the insulation system such as medium and high voltage cable due to a variety
of defects. Such discharges, if allowed to continue, can degrade the insulation causing its ultimate breakdown. Online PD
(OLPD) measurements are now extensively being used for condition based maintenance programs. The partial discharge
initiates a current pulse which propagates simultaneously in the cable core and the cable earth screen with opposite
polarities. The PD pulses tend to propagate away from the source and their magnitudes become smaller due to attenuation.
Moreover, the high frequency components are attenuated more during propagation in the cable. Thus, PD associated pulses
undergo changes in magnitude and waveform during propagation. Direct and reflected pulses can be used for cable length
measurement and PD source localization. PD propagation studies in cable networks are useful for online PD source
localization purposes. This paper discusses, cable length measurements using direct pulse acquisition in OLPD
measurements. In addition to partial discharge pulse polarity tracing method helps to identify the direction of arrival of
partial discharge pulses. Such polarities as well as peak pulse magnitudes captured by HFCT sensors during the OLPD
measurements are studied in this paper. Lab studies were performed using online PD measurement systems and medium
voltage cable networks, and the results are reported in this paper to point out how PD pulse behaves in single core cable and
how it can help in PD source localization in OLPD method.
Index Terms—Polarity, Tracing, Direct Pulse, Partial Discharge, HFCT, Length.