Frequency and field roles in water absorption in composite dielectrics

Consisting of more than one material and having internal interfaces, composite insulators are susceptible to water ingress. It has been shown previously that the absorption of water is increased in the presence of an electric field. This paper presents results of more recent work done on this subject. It was found that the frequency of the applied field had a definite influence on water ingress and also that the quantity of absorbed water depended on the type of the interfacing material used in the composite dielectric. To study this aspect a number of experiments were performed using specimens of different composite dielectrics.