Aging Characteristics of Silicone Rubber Composite Insulators Based on Space Charge Behavior

Silicone rubber composite insulators are widely used in high-voltage transmission lines, but they face serious aging problems during long-term operation. In this paper, the unaged and aged silicone rubber composite insulator samples are taken as the research object. The space charge detection is carried out in the range from 0.6 to 30 kV/mm, and the aging characteristics of this insulating material are analyzed by charge density, accumulation rate and maximum electric field distortion rate. The results show that the charge accumulation threshold field decreases after aging. For both unaged and aged samples, the rate of charge accumulation is divided into three stages, from slow accumulation to fast accumulation, and finally back to slow change. At the first inflection point of charge accumulation rate, the corresponding field intensity reduces significantly in the aged sample. Besides, the maximum electric field distortion rate of the aging sample increases at each tested electric field. And the position of the maximum distortion point migrates from the middle of the sample to the lower surface.