Impact of low pressure aerospace environment on machine winding insulation

The concept of More Electric Aircraft is chiefly concerned with the replacement of heavy non-electrical systems with electrical systems. For the aerospace industry to move forward to the More Electric Aircraft and its partner concepts such as More Electric Engine, structures of the electrical, hydraulic, pneumatic and mechanical power transmission systems on board need to be modified and optimized. Therefore, the insulation system used in the full range of electrical components is going to face more challenging working conditions which include higher voltage, extreme temperatures and pressures, etc. One important feature of the working environment for aircraft insulation system is the pressure range can vary from approximately 10,000 Pa to 400,000 Pa. Given the importance to deliver a long insulation life, the impact of this pressure variation on the electrical degradation of insulation must be understood. This paper describes the tests that have been carried out to examine the impact of voltage and pressure on the partial discharge behaviour of different types of machine winding insulations.