Study of the ageing process in epdm rubber of commercial electrical insulators by means of an electro-rheological model

R.R. MOCELLINI; J.A. CANO; G.I. ZELADA-LAMBRI; C.L. MATTEO; P.A. SORICHETTI; O.A. LAMBRI

Santiago de Chile

Congreso; SAM/CONAMET 2006; 2006

Electrical insulators of organic type are composed by a rigid nucleus of some type of epoxy resin and for a housing commonly made of EPDM (ethylene-propylene-diene monomer). In the electrical industry, organic insulators with housings made of different kinds of rubber have been employed since more than 20 years in high voltage transmission lines. However, the mechanisms of deterioration of the rubber are still unclear. In fact the progressive deterioration can to produce the unexpected failure of the material. The wide range of mechanical and electrical properties achieved by the polymers cannot be obtained with other type of material. Organic insulators have the advantages of low density, easy handling and good resistance to vandalism. However, environmental agents can damage them. In fact, rain, dust deposition, corona effect and ultraviolet radiation, among others, deteriorate the quality of the polymeric housing employed as watersheds. In the present work we analyse the disentanglement of the crystalline phase in the EPDM by means of the application of an electro-rheological model, recently published. We have performed dynamical mechanical analysis and dielectric relaxation measurements in EPDM samples obtained from commercial insulators. Samples were checked under different conditions of out-door ageing and irradiation with low neutron flux.