In this paper

YJV22-8.7/10-3 × 240 mm

2

XLPE cable is used to make a needle defect partial discharge model. The pulsed current method is used to study the partial discharge characteristics of the needle defects at 50 ℃

70 ℃ and 90 ℃. It is shown by the result that

in case of increase of temperature

the partial discharge initial voltage of the needle defect discharge model shows downward trend. The insulation cross-section of the cable at the defect place shows electrical trees near the needle tip. Increase of temperature leads to intensification of free radical reaction

which triggers the initial voltage of the electrical trees

reduce. The morphology of the PRPD pattern of needle defect at three kinds of temperatures is basically identical

with broad discharge phase distribution and remarkable polarity effect. Both cumulative discharge amount and discharge repetition rate increase with the rise of ambient temperature. The discharge strength is increased due to such two aspects of factors as acceleration of thermal motion velocity of charged particle and the increase of initial electron due to high temperature. The experimental result will help the operators adjust timely the parameters of the PD monitoring system in accordance with different operating loads of the power system

thereby reducing the risk of false alarms of the system.