Performance of Corona Resistant Insulation for Aerospace

Impulse voltage waveforms from power converters enhance the voltage stress on the turn insulation system of rotating machines. When the voltage stress exceeds a critical level, partial discharges can be incepted leading to premature failure of the machine insulation. Besides using thicker insulation, hybrid organic/inorganic insulation (Corona Resistant, CR) can be used. CR systems have proved to be successful to extend the lifetime of industrial drives. For aerospace applications as the More Electrical Aircraft, one should consider the challenging conditions posed by operation at reduced pressures. It has already been proven that the energetic content of Partial Discharges (PD) is greatly influenced by the reduction of pressure. However, the reliability of CR insulation systems in conditions representative of those experienced by systems used in the MEA have not been investigated so far. Therefore, electrical life tests at constant voltage and different pressures were performed on both non-CR and CR Grade 2 enameled wires. The results obtained show that CR insulation systems are not able to ensure the reliable operation of electrical drives used in aerospace application.