The use of fault-recorder data for diagnosing timing and other related faults in electricity transmission networks

This paper describes a model-based diagnostic system for diagnosing faults in Electrical Transmission Systems (Timely's off-line system). This diagnos tic system uses data available from digital fault recorders which are colle cted after a network event (such as a short circuit) has occurred. The data are used to detect incipient faults in network equipment by comparing thei r operation against that predicted by extended finite state automaton known as Augmented Reactive Models (ARM), Thus Timely's off-line system combines signal processing and model based di agnostic techniques to provide a practical model-based system that aids the analysis of the performance of protective equipment after a network event has occurred. In particular its use of data derived directly from fault rec order files (such as voltage and impedance magnitudes) means that the syste m can diagnose much more subtle faults (e.g. timing related faults).