Ageing of thermally and electrically stressed mineral oil impregnated presspaper insulation systems

Experimental data of a long term test for accelerated ageing of mineral oil impregnated presspaper insulation systems are presented. Devices under test were thermally or combined thermally and electrically stressed. After a defined ageing period, the insulation systems were analysed to determine the influences of the different stresses on ageing of presspaper and mineral oil. For the evaluation of the ageing progress dielectric, chemical and physical methods of analysis were used.