Tracking resistance behaviour of the blends of silicone and EPDM polymeric insulators

The insulators made from polymeric materials offer numerous advantages in out-door insulation systems due to their good dielectric properties, light weight, better pollution performance, low cost, quicker processing etc. However, they can be degraded by environmental stress like heat, moisture, contaminants and this could lead to tracking and surface discharges which ultimately cause flashover of the insulator. Tracking, which is mainly due to heat of electrical discharges across dry bands or in the presence of wet contaminant layer on the insulator surface, remains to be the most serious problem. Inorganic fillers are incorporated into the polymeric materials such as silicone rubber and ethylene propylene diene monomer EPDM to minimize the effects of tracking. The widely used fillers are silica and alumina trihydrate. Having this in view, in the present work, the behaviour of the tracking resistance of the blend of silicone and EPDM is discussed. The performance of insulators are identified by many means and it has been noticed earlier that the failure of out-door insulation structure is due to tracking. Hence in this present work, careful experimental studies were carried out based on IEC 587. It is well known that the material performance depends on the characteristics of the insulating material (ingredients). To obtain a complete database, studies were carried out with different percentage of silica fillers viz. 10%, 20% 30%, 40% & 50% in the polymeric combination which consists of silicone and EPDM in 50:50 weight percentage compositions