Giant Magneto-Resistive (GMR) Sensors for Non-Contacting Partial Discharge Detection

Partial discharge (PD) detection is a standardized technique to qualify the insulation condition in power equipment. The main purpose of the paper is to evaluate the performance of an extra high-sensitivity adapted giant magneto-resistive (xMR) sensor for non-contacting PD detection. Firstly, compensation and signal conditioning circuits of the sensor are designed. Frequency response and time-domain response to fast calibrator pulses of the sensor with the implemented circuit are measured. Besides, PD experiments based on corona and surface models are carried out and compared with measurements using a high-frequency current transformer (HFCT). The results show that the xMR system can measure the magnetic fields produced by the PDs at distances up to 50 cm. The correlation between the HFCT and xMR signals is proportional under different voltages, showing that PDs can be effectively detected and evaluated by this method. PDs in a cross-linked polyethylene (XLPE) cable with an artificial discharging defect are successfully measured, demonstrating the sensitivity and performance of the xMR system.