Overview of an automatic distribution fault location system using power quality monitors

In 2008, United Illuminating Company (UI) began a pilot project to use power quality monitors to locate faults on distribution feeders supplied by 13.8 kV systems. Fault measurements captured by the meters are downloaded automatically, integrated into a relational database, and processed for reactance calculations. The reactance calculations are combined with detailed distribution circuit models and geographic information system data to build estimated fault location tables and web-based map displays. The systems are integrated on the company intranet and used in real-time by numerous groups within UI including power quality engineers, control room operators, field operations, and distribution planning. The algorithm used for waveform processing can distinguish between single-phase faults, multi-phase faults, subcycle faults, and feeder energizing magnetizing inrush. This paper will present an overview of some of the parameters and practices for finding faults at UI.