Whitehead memorial lecture: Challenging defects of high voltage insulation systems

The primary function of a high voltage insulation system is to prevent the flow of electric current between oppositely charged conductors, facilitate heat transportation and provide mechanical support throughout a long service lifetime of more than 30 years. Therefore, high voltage insulation systems typically constitute combinations of different insulators, including interfaces between gases, oils and solids. Such composite systems are difficult to describe in terms of the characteristics of each individual component, and efforts to improve manufacturing and refine the quality of insulating materials are therefore often based on an empirical approach. In this paper, a more fundamental physical approach is taken, aiming to explain how engineering properties such as electrical breakdown, conduction, dielectric loss and endurance are affected by various types of impurities and additives.