Relation of insulation resistance and deteriorated ratio of reference voltage of oil-immersed surge arrester elements enclosed in pole transformers

About ten years have passed since oil immersed surge arrester elements enclosed in 6.6 kV pole transformers were first used. At present, technical developments are being demanded to judge the soundness of these oil immersed surge arrester elements by a simple method, allowing one to judge easily whether these elements can be used or not onsite. The authors empirically investigated the correlation between the insulation resistance and the deteriorated ratio of the reference voltage of these oil-immersed surge arrester elements. It was found that the deterioration of the oil-immersed surge arrester elements can be detected by measuring the insulation resistance.