Accelerated Ageing Test of Non-Ceramic Insulation

The paper presents the evaluation on accelerated ageing of non-ceramic insulation used at outdoor substations. The insulation was evaluated inside a salt fog chamber by applying cycles of salt fog, clean fog, drying, UV radiation and constant voltage. The insulation of two polymeric housed surge arresters and two polymeric bushings was evaluated. An arrester and a bushing were polluted with kaolin during all the evaluation. The insulation was subjected to over 5000 hours of ageing. Every 2500 hours, the insulation performance was evaluated by the leakage current, corona and electric field techniques. During the evaluation, evidence of tracking, erosion or puncture was observed on the insulation. These results show that this accelerated ageing test can be considered as a useful design test, in order to demonstrate deficiencies of bushing and surge arrester material and design.