A New Technique for Detecting Partial Discharge of Micro Electrical Tree Defect

Electrical tree (ET) defect is the main cause of XLPE cable and accessories breakdown. For micro electrical tree defects, the partial discharge (PD) detection method has the disadvantages of high PD initial voltage and low sensitivity, and the detection effect is poor at low voltage. In this paper, X-ray is used to excite the PDs of micro electrical tree defect to realize the purpose of detecting defect under low applied voltage. Firstly, XLPE sample was made in the laboratory to produce micro ET defect, and an X-ray excited experiment platform was built. The experimental results show that X-ray can reduce the partial discharge initial voltage (PDIV), X-ray can reduce the PDIV from an average of 6.3 kV to 5.5 kV, which is reduced by 12.6%. X-ray can also increase the discharge repetition rate at the same time, taking 6.8 kV as an example, under X-ray irradiation the discharge repetition rate becomes 2.3 times of the natural state. The research results will provide a new idea for detecting micro electrical tree defects of XLPE cable and accessories.