Effect of nanocomposite on insulation characteristics for epoxy/enamel composite insulation systems

Nanocomposite insulation materials have attracted a lot of attention as innovative insulation materials. They are particularly known as having excellent resistance to partial discharges. Many previous studies have focused on characteristics of nanocomposite insulation materials such as epoxy resin, enameled wires and so on. However, electric power equipment using a single insulation material are less common than electric power equipment using composite insulation systems. Therefore, it is important to obtain the insulation properties of composite insulation systems. Therefore, this paper discusses the lifetimes of epoxy/enamel composite insulation systems using nanocomposite materials against partial discharge. Experimental results show that epoxy/enamel composite insulation systems with nanocomposite enameled wires have longer average lifetimes than conventional systems under ac partial discharges. They also show that epoxy/enamel composite insulation systems with nanocomposite enameled wires and epoxy resin have longer average lifetimes than conventional systems under ac partial discharges. On the other hand, the minimum lifetime of nanocomposite systems is mostly shorter than that of conventional ones. The increase of resin viscosity due to nano-filler dispersion affects the decrease of their minimum lifetime. However, with reducing nano filler rate, the minimum lifetime of nanocomposite systems is also longer than that of conventional systems. Thus, for composite insulation systems, it is shown that not only the material characteristics but also manufacturability becomes important.