An automated system for measurement of partial discharges in HV generator insulation utilizing a conventional oscilloscope

A computer-aided diagnostic system has been designed and developed for the measurement of partial discharge (PD) activity in high-voltage generator insulation. Through a novel software mapping, a high-bandwidth digitizing oscilloscope can be used as a full-feature discharge detector despite a limited memory. The scheme employs an acquisition system which permits real-time data to be accumulated over a complete 60 Hz cycle by a multi-pass algorithm. The arrangement contrasts with many conventional discharge measurement methods which discard, inevitably, much of the information during high voltage tests. A number of noise reduction, manipulation and analysis routines are presented which permit reconstruction of stored data in order to extract many PD-related characteristics; such as the time and frequency of occurrence, the magnitude, and the polarity of the recorded pulses. Use of the method is illustrated by presenting results using data from an experimental research program. A version of the system is also outlined which is suitable for electrically hostile environments where external interference could contaminate the measurement.