VHF Partial Discharge Detection during After-Laying testing of Power Cables

In this paper the results of after-laying testing of transmission power cable accessories using a non-conventional technique are being presented. The non-conventional system is based on the detection of high frequency signals being emitted by the partial discharge. Therefore, each power cable accessory is equipped with either an internal or external sensor to decouple the partial discharge signals. The partial discharge detection system uses narrow-band detector, in this case a spectrum analyzer. This technique however is very difficult to calibrate due to different factors affecting the frequency response of the measuring setup. This paper also presents a sensitivity check which can be used to validate the sensitivity of the system for a certain required PD level. Examples of on-site sensitivity verification are presented, before the actual PD measurements take place. An example of this system is shown taken from several measurements performed in the field.