Effect of secondary insulation on breakdown using polymer nano-composites

This paper focuses on testing the motor insulation with a secondary insulation made up of polymer nano-composites in addition to the primary one. Twisted pair samples are used to investigate the motor winding behaviour. Modified polyester is the primary insulation here. The primary insulation is subjected to direct testing and the breakdown voltage is determined. Then a secondary insulation layer of nano-composites is coated over the modified polyester layer. The secondary insulation is made in two fold. Primarily epoxy resin is used as secondary insulation and then epoxy resin with filler is used. The secondary insulation was thus made with fillers like Alumina (Al2O3) and Titania (TiO2) of various concentrations added to base epoxy. The direct and withstand tests were performed with these samples coated with secondary insulation. A comparison made between the experiments conducted with primary and secondary insulation shows that the sample with secondary insulation coating was observed to have higher insulation strength compared to the sample with primary insulation. Also the premature insulation failure, caused by the switching frequency produced by power electronic converters have been discussed with respect to primary insulation.