Effects of RLC Parameters of a Measuring Circuit on the Frequency Spectrum of Partial Discharges

With the availability of modern acquisition systems it has been possible to measure partial discharge (PD) pulses with enough bandwidth as to record its pulse shape. This new approach has made possible to compute new parameters that were not possible with the tradition narrow band measurements guided by the standard IEC60270. However, broader bandwidth also means more chances to measure noise and disturbances. The measuring circuit plays a main role because it may be the cause of resonances that distort the shape of the PD pulses. This paper presents a test set-up design that contributes to control the RLC parameters of the detection circuit and thus reduce the distortions such as oscillations of the PD pulses. The RLC parameters are estimated by means of a simple but novel procedure where a fast pulse from a calibrator is induced in the detection circuit leading to an easy detection of resonance frequencies.