The innovative inductive calibration technique for partial discharge detection apparatus

The recently devised inductive calibration technique (ICT) for partial-discharge detection offers several advantages over the conventional direct and indirect calibration methods. These include negligible loading of the test circuit, better reproduction of the true partial discharge pulse frequency spectrum and isolation from the applied AC test voltage (i.e. the ICT can be performed in the presence of high voltage). The key specifications for the ICT include an applied charge range of approximately 0.1 to >10 pC, calibration pulse risetime of approximately 3 ns, adjustable pulse repetition rate and negligible loading impedance (i.e. 0.02 Omega in parallel with 4 mu H). The design, implementation and usage of the ICT are described. Calibration plots that were determined for a typical partial discharge detection system via the ICT and direct calibration method are compared.<>