Effect of insulation systems on the moisture resistance of encapsulated motors

Water in the liquid or vapor state affects electrical insulation in two ways. The first is that the water will be distributed through a volume of solid insulation by absorption and the second is that the water forms a film on the surface of insulating materials. The encapsulated insulation system attempts to eliminate the effect of the second or film on the surface. An encapsulated system is defined for the purpose of this paper as one in which a thickness of material one or more orders of magnitude greater than a varnish film. The encapsulated motor attempts by means of a heavy coating completely covering the windings to shield them from the environment.