Experimental characterization of the maximum turnto-turn voltage for inorganic high temperature motor

Ceramic-insulated wires have very good thermal characteristics. With an adapted motor design, such inorganic wires could be used for building new electric motors able to work at very high internal temperatures, up to 500°C, which opens interesting perspectives for very high power density electric motors. After explaining the advantages of high internal temperatures, electrical characteristics of inorganic coils are compared to conventional enameled wires associated with a polymer impregnation. For classical organic wire, the Partial Discharge Inception Voltage (PDIV) is an important parameter; for ceramic wires, physical phenomena are very different and this concept is not still completely defined. However, the tests performed on ceramic-coated wires show that fast current pulses appears for voltages over a threshold measured for temperatures up to 500°C. This threshold voltage is an interesting indicator for inorganic coil designs: the turn-to-turn voltage must remain below this threshold at any point of the coil.