Automatic fault location for underground distribution network

This paper describes an automatic fault location technique for permanent faults in Underground Low Voltage Distribution Networks (ULVDNs). The system pre-processes Time Domain Reflectometry (TDR) signals to eliminate reflections due to tee-offs, and to locate 3-phase open or short circuit faults. The system also uses adaptive filtering to analyse the TDR signals to locate single and phase-to-phase faults. The procedure not only minimises the interpretation skill required from a user of a typical TDR based fault location instrument, but also differentiates between singlephase tees and faults. The performance of the new method was evaluated relative to current practice, using field data that were obtained from real ULVDNs.