Abstract
Performance of materials and their compatibility determine the size of the electrical insulation in power equipment. For this reason dielectric properties of electrical insulation materials are needed for low temperature power applications. In this work we report the dielectric properties of four polymers: polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polyvinyl butyral resin (PVB), and polyimide (PI--Kapton\textregistered). The dielectric measurements are performed with an electrical impedance analyzer in the frequency domain. The impedances are recorded in a cryocooler in the temperature range from 45K to 350K. The dielectric breakdown characteristics of the polymers are measured in a liquid nitrogen bath at atmospheric pressure. It is observed that PI and \pmma\ dissolved in toluene have the lowest dielectric losses for temperatures lower than $100\ \kelvin$. \Blx\ and PI have the smallest spread in their breakdown strength data.