Comparison of conducted and irradiated PD acquisition systems

In Type I insulating systems the presence of partial discharge (PD) leads to the fast degradation of the insulating system dielectric characteristics. This could result in the short-medium term, to a total breakdown discharge provoking the failure of the system. A predictive diagnostic system is advisable to prevent the failure of the motor. This kind of diagnostic system should be non-invasive and economically feasible. For these reasons different types of antenna sensors have been employed and evaluated. The captured irradiated partial discharge signals are then processed with different filters and amplifiers. This study has been conducted on suitable twisted pairs specimens subjected to PWM-like waveforms typical of electronic variable speed drive supplies. A comparison between measuring sytems based on the detection of conducted or irradiated PD signals have been performed. The peculiarities and potentiality of both systems have been assessed and evidenced.