Ageing of polymeric insulating materials and insulation system design

This paper presents an overview of the problem of modelling the ageing of polymeric insulating materials used for electrical applications; a relation between ageing and life models; the different approaches brought to phenomenological or chemical-physical life models; the need to search for diagnostic properties and to investigate the prevailing degradation mechanisms as a function of applied stresses and material morphology; and the way design stresses are chosen and reliability evaluations of insulation systems are carried out. © 2002 Society of Chemical Industry.