Evaluation of a calibration technique in measuring partial discharges inside mineral oils with a high-frequency current transformer (HFCT) sensor: A case study

Abstract

Partial discharge is one of the main reasons for insulation degradation in high-voltage apparatuses. Partial discharge is an ineluctable phenomenon that happens when a high electrical field is adjacent to an insulator. High-frequency current transformers are widely used for detecting partial discharge current in high-voltage equipment. Determination of the apparent charge in pico coulombs is essential for having a common understanding of results and verifying that the measuring system can obtain specified partial discharge magnitude correctly. To this end, a high-frequency current transformer sensor and a partial discharge calibrator have been prepared to measure the current of the partial discharge (PD) pulses inside mineral oil. The constructed PD calibrator has been evaluated. The high-frequency current transformer (HFCT) sensor has been simulated using a mathematical model-based AC analysis and has been characterized and then calibrated using a calibration technique to measure the apparent charge of the PD pulses. Experimental results show the effectiveness of the HFCT sensor and the proposed calibration method.