Dielectric Properties of the Composite Insulator Mica Epoxy-Novolac

Abstract

As electric insulators of the copper conductors in the electric generators of alternative current or in electric motors of high tension, there are used with priority the composite crosslinked mica-epoxy. Pre-impregnated band with solvent was introduced, the impregnation being performed with phenolic-novolac resin. The studied material got superior dielectric properties at function temperatures corresponding to the insulation class F(155C). Its main components are: mica paper (53%), glass cloth (13%) and the basic epoxy phenolic-novolac resin. The complex permittivity and conductivity were determined with the Time Domain Spectrometer (TDS); the apparatus allows the determination of the electric values in the domain of frequencies: very large domain of frequencies. The temperature varied in the domain 23-190C with the help of an oven. The purpose of this article is to report the dielectric properties of mica-epoxy-novolac composite insulator, for which very few data have so far been published.