Principle and practical experiences with a three-phase water monitoring system for XLPE high-voltage cables

Three-phase water monitoring system can check continuously the integrity of high voltage XLPE cables and locate the fault position immediately, if a fault on the cable sheath occurs. The costs of the water monitoring system are only a few percent of the cable cost, but the system can save high costs for repair and avoid unexpected outage of the energy supply. The principle of the three phase water monitoring is shown including the performance of some components of the system. The influence of the different parameters and its measuring uncertainty on the uncertainty of fault location is described in detail. Practical experiences in the outdoor area of the Schering Institute with a real three-phase water monitoring system are presented. The results demonstrate that the developed system is ready for market introduction and operates well under on-site conditions. The reachable uncertainty of ±0.5% is good enough for fault location concerning the uncertainty of a buried cable position