Study on Different Partial Discharge Testing Methods Qualifying Insulation Materials for Automotive Applications

In order to avoid electrical aging within the insulation system of an electric traction motor, the insulation has to be partial discharge (PD) free. Based on ICE standard, the ramp to ramp testing, where two conductors are positioned to each other, is the usual way of testing PD. It is well known, that PD is highly sensitive to environmental factors such as temperature and pressure. Besides these known parameters, this paper will discuss the influence of the test specimen and the testing setup on the results. In order to figure out the differences in the testing setup, a detailed comparison on the setup as well as on the results will be given. The testing setups under investigation are the ramp to ramp testing, testing of the insulation within a steel spheres bath and as a third testing setup testing of the insulation within a salt bath. The sensitivity of the insulation material to the testing setup is also demonstrated taking into account different insulation materials such as PAI, PPS and PEEK on a HairPin Conductor. Based on the results, the conclusion gives a suggestion to the most suitable testing method to qualify insulation materials for automotive applications.