Highly Thermally Conductive Insulation for High Power Synchronous Machines

Silicone impregnated fiberglass insulation has long been used as stator coil electrical insulation for low voltage, direct current, traction motors.  Silicone based insulation is particularly suited for this application because its thermo-oxidative stability ensures excellent long term resistance to arc tracking and dielectric breakdown.  Next generation, high speed, synchronous, alternating current, rotating machines provide an insulating challenge for traditional silicone impregnated fiberglass and epoxy mica stator coil insulation systems.  High frequency voltage supply for these rotating machines is required to produce high rotational speed and to deliver greater power output.  The downside of increased frequency is greater loss, which ultimately leads to higher operational temperatures that can cause machinery damage.  This paper investigates functional electrical insulation integrity of highly thermally conductive silicone impregnated fiberglass insulation through short term accelerated aging tests.  This insulation system offers three times the thermal conductivity of traditional insulation, which facilitates rapid heat transfer and provides a design element for reducing rotating machine operational temperature.