Breakdown characteristics of HTV silicone rubber under multiple stress conditions at high altitude

The special working environment of composite insulator for transmission line at high altitude area is discussed in this study. The accelerated aging method combining ultraviolet (UV) radiation and large temperature difference method is used to investigate the relationship between physical and chemical properties and breakdown characteristics of aged high Temperature Vulcanized (HTV) silicone rubber materials. The hydrophobicity of the silicone rubber, the tensile strength and the elongation at break have decreased after aging. The breakdown voltage of the material under the action of AC voltage shows a downward trend with the prolongation of aging time, but the inception voltage of the discharge remains stable. The holes and cracks on the surface of the HTV silicone rubber after aging treatment are increased. As the aging time increases, the radius and number of holes increases, which results in the decrease of surface flatness. This is also the main reason for the breakdown voltage of HTV silicone rubber samples. Under the harsh running environment of silicone rubber composite insulator at high altitude, multi-factor aging accelerates the breakdown development speed of HTV silicone rubber material, which is the direct reason for the deterioration of silicone rubber performance. Adequate attention should be paid to the project in practice.