Experimental investigation on the DC breakdown of silicone Polymer composites employable to 500kV HVDC insulator

HVDC technology has been widely used for the bulk power transmission due to its advantages over the conventional HVAC such as higher efficiency with larger current carrying capability and lower electrical losses for long-distance transmission. In this regards, many research institutes have put their intensive efforts to commercialize relevant components in order to realize better HVDC transmission system. One of the critical components for HVDC transmission systems is HVDC polymer insulators which shows rather severe requirements compared to HVAC ones. It has been perceived uneasy to achieve relevant insulation properties with proper design of power apparatus under HVDC. Especially, there is few research works presented concerning the insulation properties of insulator which is a fundamental power component in HVDC system. In this work, dielectric insulation characteristics of various silicone composites have been experimentally investigated under DC stress, of which the results could supply essential base for developing HVDC polymer insulator. For this purpose, polymer composite samples have been prepared in different ways by mixing silicone and ATH respectively and then have been under DC stress to evaluate breakdown characteristics. For the comparison both in DC and AC environment, withstand voltage test and surface discharge test under AC were also performed.