Characterization Method for the Swelling Effect of an Insulating Washing Agent on Silicone Rubber in Power Systems

Insulating washing is a valid method to recover the electrical performance of silicone rubber composite insulators under accumulation contamination; however, its swelling effect may deteriorate the electrical and mechanical properties after live washing. The swelling effect of the insulating washing agent on the electrical and mechanical properties of silicone rubber and its mechanism were investigated by macroscopic and microscopic characterization methods. The results showed that the swelling degree of silicone rubber increased as the immersing time increased and the increasing trend gradually slowed down. The degradation in mechanical properties is much greater than that in electrical properties, and the tensile strength at break dropped greatly by 16.3% at 20 min of immersing. Physical defects such as holes and cracks were observed by scanning electron microscopy. The main and side chains were partially broken, and the inorganic flame retardant Al(OH)₃ was decreased by Fourier transform infrared spectroscopy. The damage to the microstructure caused by the swelling effect under the action of the washing agent is the main reason for the decrease in the mechanical properties of silicone rubber.