Performance evaluation of a new digital partial discharge recording and analysis system

We describe the design and performance evaluation of a new digital partial discharge (PD) recording system capable of real-time recording of PD pulse trains for later off-line computerized stochastic analysis. The new recording system consists of a custom two-channel PD digitizer coupled to a new 16-bit parallel digital interface installed in a personal computer. The digitizer is under software control with the resulting data being stored in binary files on the computer´s hard disk. Since post-test analysis software run on the computer provides the needed stochastic analysis of the data files, the new system offers a unique capability to perform stochastic analysis on non-stationary PD data such as found in aging studies. By way of illustration, measurements were made of the time-varying stochastic behavior of ac-generated PDs in point-to-dielectric gaps in air where the insulation material was cast epoxy with aluminum oxide filler, extending the work reported previously. Sample analysis results are presented, demonstrating that the new system provides analysis results comparable with the results achieved by the existing NIST analog PD stochastic analysis system. Sample stochastic analysis results are presented demonstrating the additional insights possible with the new system