Mastering Partial Discharge

Partial Discharge (PD) can be easily understood as discharge within or close to an isolating material. In the long term, this degrades the isolation material and can lead to the risk of fire. New concepts operating bare electronics in low pressure, modern and fast semiconductor technology (e.g. SiC) for Power Electronic applications have driven the necessity of dealing with PD. The strongest driver, nevertheless, has been the More Electric Aircraft (MEA) and even the All Electric Aircraft at the horizon. The increase of electrical power comes with higher voltages, thus the drastically increased probability of PD. Mastering PD means understanding PD, being able to test for PD and adapting to new standards.

Approximately ten years ago, Liebherr started the work on PD. To have a quick start, we involved many renown research institutes as the Laplace Institute, IRT Saint Exupéry (both institutes are in Toulouse), Manchester University and the University of Bologna.

The results are the improved design of motor windings and wound components in general, the handling of transients in electrical systems, and the testing for PD even in a noisy environment like the PWM operation of inverters, of which the latter is a novelty! A Liebherr working group follows and coordinates all PD activities from the very beginning.

Furthermore, two PhD works on PD have been accomplished. Standardization work is the next step. Our customers appreciate our knowledge of PD and the ability to safely design power electronics and motors.