A new PD calibration technique based on the transfer function of stator windings

Partial discharge (PD) calibration for PD detection in electrical machines must be done to obtain accurate and reliable measurement results. However, difficulties in PD calibration exist in that results from different machines cannot be compared on the basis of PD readings and different detectors applied to the same winding will generally produce different values of PD magnitude. This is due to the fact that the propagation of the discharge pulse from the discharge site to the detector is extremely complex owing to a series of factors, including attenuation, reflection, resonance, radiation, impedance mismatch, grounding, etc., which affect the PD test results. This problem is compounded by the variety of detectors in use with variable bandwidth, centre frequency, cut-off frequencies, amplification coefficients and input impedance