DIFFUSION BEHAVIOUR OF LUBRICANTS IN POLYMERIC INSULATION MATERIALS

Abstract

The diffusion of lubricants in insulation materials, which is the core parameter of the electrical and

mechanical long-term behaviour of solid insulation interfaces, is studied. In this paper the focus is put

on pluggable and non-pluggable slip-on cable accessories. Therefore, four different greases, based

either on silicone or PTFE as well as a silicone oil, are under investigation on material samples. Grease

generally consists of a stabilizer and an oily phase. The diffusion of grease depends both on the solid

insulation material and on the grease itself. The highest diffusion can be measured by the combination

of a silicone grease and silicone rubber. However, for silicone rubber there are low and no diffusion

lubricants available. The diffusion in EPDM, EP and XLPE is commonly much lower. In EP and XLPE,

no type-dependency of the grease can be observed. With the knowledge of the diffusion behaviour, the

desired interface properties can be achieved for the whole lifespan of the high voltage equipment.