Effect of relative humidity on surface discharge characteristics of polymeric material under AC stress

Polymers are widely used as insulation material because of their good insulation, physical and chemical properties. Nevertheless, electrification and degradation process due to partial discharge such as surface discharge usually occur and affects the life time of the insulation. The surface discharge can occur due to presence of high voltage stress which can lead to permanent insulation failure after many years if appropriate actions are not taken. One of the factors which cause this phenomenon is humidity. This paper investigates the effect of air relative humidity (RH) on surface discharge characteristics of polymeric material using IEC (b) electrode configuration. Result shows that the sample with higher RH revealed less surface discharge compared to other samples with lower RH. However, the sample with higher RH experiences more surface degradation compared to other samples with lower RH.