About the relevance of using Paschen's criterion for partial discharges inception voltage (PDIV) estimation when designing the electrical insulation system of inverter fed motors

In the literature, the Paschen's criterion is widely used to determine partial discharges (PD) inception in the electrical insulation systems (EIS) of machines. This criterion has been established for 2 metallic plane electrodes facing each other in a uniform electric field. The objective of this communication is to determine whether Paschen's criterion may still be used in a configuration of enameled round wires in non-uniform field. For that purpose, PD risk between 2 parallel enameled round wires at atmospheric pressure has been studied, from both measurements and simulation points of view. Different experiments with different samples geometry, fully measured by a digital microscope, has been compared to simulation using Paschen's criterion. This work aims to bring out a more complete criterion on PD detection, in the case of enameled round wires, in order to use it as a reference in a software under development. This software will help designers to take into account the PD phenomena in the design stage of the EIS of a low voltage rotating machine fed by an inverter.