A FIlter for Optimal Temporal Resolution in Partial Discharge Measurements

In partial discharge measuring instruments, a band-pass filter is always incorporated for noise reduction. Both narrow-band and wide-band filters may be used. Narrowband filters usually give a better output signal-to-noise ratio, but the output pulse width is greater so that a rapid sequence of input pulses may appear as overlapped and distorted waveforms at the output, making it impossible to resolve the individual pulses. The temporal resolution of the measurement system is thus degraded. For broad-band filters, the temporal resolution is better, but the output SNR is worse. Hence there is a trade off between SNR and temporal resolution. In this paper, the problem of optimizing the temporal resolution in the presence of noise is analyzed and a Wiener filter is proposed as the solution. Methods to implement the filter are given and results of computer evaluation studies are presented.