Easy Measurement of PD transfer impedance using Network Analyzer

IEC60270 requires to measure the transfer impedance Z(f) of the Partial Discharge (PD) measuring system for type, routine and performance tests. ZT(f) is the ratio of the output voltage and input current of the PD measuring system. In many cases this measurement is performed only at few fixed frequencies using a function generator (converted into a current source) and reading the output voltage either from an additional oscilloscope or the PD detector display. Determine the -6dB and-20dB cut off frequencies requested in the IEC 60270 standard may require interpolation between two frequencies. Covering all main filters and coupling impedance combinations is difficult, leading manufacturers to limit the measurement to a single set up. In this paper, a quick and easy method is presented, to…