A new approach to the evaluation of organic insulating materials for service in polluted conditions

Considerable work has been done in recent years to develop test methods for estimating the tracking and erosion performance of organic insulating materials, when they are exposed to surface pollution. On the basis of this experience it has been generally agreed that surface discharges can be looked upon as heat sources and their effect on the surface as thermal. The view has been held that knowledge of the chemical structure of organic insulating materials, their thermal decomposition and the characteristics of the decomposition products of the materials is of primary importance in determining the tendency to surface tracking.