Behaviour of multilayer PET polymer film insulation in high electric fields

Experimental results of breakdown voltage, tanδ and the parameters of partial discharges for multilayer polyfilm insulation are presented. It is shown that the breakdown voltage of multilayer film insulation may be increased approximately by 70% compared with single-layer insulation of the same thickness due to the correct choice of the films´ thickness. It is established that this increase in the breakdown voltage is associated with the increase of the ignition voltage of critical partial discharges.