Study of the behaviour of partial discharges for proactive diagnostics in medium voltage cables

The use of power cables is increasing worldwide. Aging and insulation degradation reduce the in-service lifetime of a power cable. Effective partial discharge (PD) analysis can quantify the stage of the insulation damage. This paper presents a study on the PD behavior prior to possible breakdown of a medium voltage (MV) cable. An artificial defect was introduced into the insulation of the cable sample. Electrical stress is applied across the sample and increased until the breakdown occurred. PD activity is monitored and time-domain analysis is performed to study the behavior of PD characteristics. During increased electric stress, the pattern of the PD characteristics such as pulse amplitude and pulse repetition rate is studied. The analysis of PD inception to breakdown stages provide valuable information to identify the breakdown vicinity. Timely information of the ongoing insulation degradation can help to avoid the sudden failure of the power cables.