Low viscosity epoxy impregnants for motors and generators

Recent developments in liquid epoxy resins have made available compounds capable of impregnating and insulating wire wound equipment. These compounds have demonstrated good thermal stability in the cured condition, and when properly applied, are fulfilling the qualities of a good impregnating compound. The epoxy impregnating resins discussed in this paper are complete liquid systems before they are cured, which classifies them as “Solvent-less” varnish systems. The absence of solvents or volatiles from the impregnating systems for motors and generators has its advantages in the following: 1. Flammability hazards are minimized. 2. Shrinkage accompanying solvent evaporation is eliminated. 3. Multiple impregnating operations are no longer necessary. 4. Voids in the windings are minimized.