An improved detection technique for measurement and analysis of partial discharges

The measurement of partial discharges may be achieved using very different detection techniques. In classical systems, based on band pass filtering, there is a lack of very important information: the value of the applied voltage which induce the discharge and the time instant in which it occurs. A different approach is based on separation of the partial discharge signal from the main frequency by a notch filter. This particular instrumentation devoted to the measurement of partial discharge, is able to detect, measure and store in a large size memory the apparent charge of every single pulse, the corresponding value of the applied voltage and the time instant in which it occurs. It is so possible to track the real-time evolution of partial discharge. This paper presents both a theoretical analysis and an experimental evaluation which validate the results obtained from such a system. The practical difficulty in achieving an integrator for very sharp pulses in the nanosecond range, minimizing error and noise typical of real systems is shown. The interest of such an approach to the problem is confirmed by experimental results.