Effects of gamma-ray irradiation on discharge characteristics of organic insulating materials

Organic insulating materials have been widely used as insulators for electrical elements in various environmental conditions. These investigations are further enhanced due to the increasing of organic insulating materials being used in radiation environment of space and nuclear power facilities. This paper describes the effects of gamma-rays irradiation on the discharge characteristics of organic insulating materials. The samples of modified polyphenylene oxide, polybutylene, epoxy resin and polybutylene terephthalate which were irradiated in air up to 100 kGy and 1 MGy with a dose rate of 10 kGy/h using a 60Co gamma source. The experiment was carried out on the sample surface by applied a dc impulse voltage between a plate and needle electrode. The solution droplet was placed on the plate of sample in contact with the needle electrode. The total dose effects on the discharge quantity, contact angles and extending length of droplet have been studied. As the total doses are increased, the tendency of discharge quantity decreased with modified polyphenylene oxide, polybutylene and epoxy resin, on the other hand the discharge quantity increases with polybutylene terephthalate. The author found that the effects of gamma-rays irradiation on surface discharging quantity are due to radiation-induced degradation and cross-linking of organic insulating materials. (author)