Dutch experience with VLF partial discharge detection

The advantage of the VLF partial discharge detection system is the possibility to characterize the condition of a MV cable including its accessories, new or old. By doing this, cost effective maintenance programs can be setup. This system has been developed by KEMA and has been in operation since 1994. The principle of this system is that weak spots in MV cables produce partial discharges. The consequent inspection of replaced joints and cables has led to component-dependent interpretation `rules´. These rules are based on the discharge magnitude, discharge density and sometimes the cable laying conditions. The information of inspections, including photographs, is stored in a database. With various queries, this database provides adequate information on the behaviour of specific components with respect to partial discharges and the need for replacement. This diagnostic tool is being applied successfully in many countries. This paper describes briefly the background for developing this system and the principle on which it is based. This is followed by the experience that is gained with this system in the Netherlands