Thermal conductivity improvements for electric motors

The varnishes used to process or impregnate electric motor stator coils usually are solvent thinned; and therefore, the volume filled is reduced as the solvent evaporates, during processing, allowing air to fill the space in the slots. Stagnant air will trap heat in the slot and produce a hot spot. Resins that are 100% solid will fill the slots better, but the present dip and bake/spin or vacuum pressure impregnation processes allow for the resin to drain from the slots, which allows air to trap and hold heat. If one could completely fill the slots, one could increase the thermal conductivity of the material filling the slot. This paper describes the trickle process, which is such a process, and has been used to fill slots without loss of resin because of fast reaction rates