Comparative accelerated ageing test to assess the sealing performance of composite surge arresters and insulators

Good end-seal performance against moisture and/or water ingress contributes significantly to the long-term performance of polymeric housed surge arresters and composite insulators that contain interfaces. A thermal cycling immersion test between -20°C to +85°C in a liquid rather than in air has been used to investigate the comparative behaviour of a wide range of devices. Fast transitions between both temperatures result in considerably higher thermal mechanical stress than most standards recommend. Rapid expansion and retraction of the devices tested formed the basis of this comparative accelerated ageing test. This paper presents some of the comparative results obtained with respectively 5 weeks and 10 weeks thermal cycling testing of a range of 11 kV and 33 kV polymeric surge arresters and 10 weeks thermal cycling of a range of 66 kV suspension composite insulators