Modelling of PDIV evolution over time under multiple ageing factors for insulation of inverter-fed electrical machines

The presented study falls within the scope of research on multi-factor tests and lifetime prediction of insulation systems for electrical machines. It is an attempt to find an indicator of state or remaining life of an insulation system for inverter fed electric motors. Samples of twisted pairs are subjected to high temperature and inverter voltage over long periods of time. Partial Discharge Inception Voltage (PDIV) is measured over the course of their life. The article contains the description of the experimental test bench, method of PDIV measurement and a method of analysis and modeling of the obtained PDIV evolution over time. Changes of PDIV over time are observed. The found evolution of PDIV is modeled with Inverse Power Model with a prediction error of a few percent.