Effects of high temperature and pulse voltage on treeing process in silicone rubber

High temperature environment produced in the process of high load, accompanying with pulse voltage generated by switching surges during the switch operation of the converters in the HVDC system, has an important influence on the electrical performance of silicone rubber (SiR) in the cable accessories. The pin-plane electrode system was employed in the test to investigate the treeing characteristics in silicone rubber considering high temperature under repetitive pulse voltage. Results show that when the pulse frequency increases, the tree length and fractal dimension tend to be larger and the main tree morphologies are varied from branch tree to bush tree with application 12 kV pulse amplitude at 30 °C. When the temperature becomes higher, the tree length decreases while the fractal dimension shows a converse tendency. When the temperature is below 90 °C, both branch tree and bush tree are appeared application 9 or 12 kV. However, when the temperature is above 90 °C, the bush tree becomes the lead tree morphology at 200 Hz after 10000 pulse number.