PEA Space Charge Performance of HTV Silicone Rubber in the Process of Water Permeation

As the material for sheds and sheaths of composite insulators, long-term performance is a key property of high temperature vulcanized (HTV) silicone rubber. However, after subjected to the operating environment, water permeation from the air can diffuse into the silicone rubber and harm both electrical and mechanical properties of the silicone rubber. In this paper, pulsed electro-acoustic (PEA) space charge measurement is employed to study the performance degradation of HTV silicone rubber caused by water permeation. HTV silicone rubber samples are immersed into deionized water for different durations, followed by PEA space charge measurement. In the PEA tests, more space charges are injected into immersed samples than samples before water immersion, which means that after the water permeation process, traps will form because of the movement of water molecules. As the immersion time goes longer, the changes in the space charge distribution become more obvious.