Experiences with continuous condition monitoring of in-service MV cable connections

A new technology for assessing the condition of MV cable connections is described. The technique measures partial discharges (PDs) from joints and cables on-line, i.e. while the cable connection remains in-service. The system (called PD-OL) is able to locate the origin(s) of PDs from a complete cable connection by using only two inductive sensors, each at one cable termination. These sensors can often be installed while the cable remains in-service. Data is measured continuously and measurement results are collected in a centralized Control Center, in which the results are analyzed and interpreted. Results from this are made visible on a secured web-site for the network owners. The first field experiences from ca. 100 installed systems show some very interesting phenomena, not seen before. Furthermore, various (verified) weak spots have already been detected before leading to an outage. With that various outages have already been prevented.