Electrical Treeing Characteristics in Epoxy under Electro-magnetic Coupled Field

Abstract

Abstract Epoxy resin is a kind of material used as electrical insulation in superconducting magnetic devices. The dielectric properties of the epoxy resin directly affect the safety and stable operation of the whole magnet. While operating, the epoxy resin faces the challenges of complex electric field and strong magnetic field. Researches on the effects of harmonic superimposed dc voltage and magnetic field on the electrical treeing behaviour in epoxy resin were carried out. Experimental results show that low-order harmonics are more likely to lead to the extension of electrical tree branches, which mainly results from the higher energy generated by partial discharge under low-order harmonic voltages. Meanwhile, the addition of dc voltage can result in more sever partial discharge because of the asymmetric charge accumulation, and eventually accelerates the degradation process. Zeeman effects were taken into account while considering the effect of magnetic field. More shallow traps are generated under strong magnetic field, thus charges are more easily to migrate under the action of magnetic field and gain enough energy to break the molecular chain. Besides, Lorenz force leads charges to hit the molecular chain more frequently. The above results in the more serious damage in epoxy resin under electro-magnetic coupled field.