Temperature Coefficient of Resistivity of Polythene and Oil-impregnated Paper

Abstract

THE distribution of d.c. electric stress in insulation is controlled by the resistivities of the dielectrics involved. In turn, the resistivity at any point is a function of the temperature at that point. Thus in order to compute the electric stress under d.c. conditions, a knowledge of the variation of the resistivity of the dielectric with temperature after long periods of electrification is necessary. Some data on the properties of polythene have been given by Fowler and Farmer¹ and by Ramsey² ; but the agreement is poor, and in general the published information is scant. Accordingly, it has been necessary to make some measurements on polythene and oil-impregnated paper in connexion with a high-voltage d.c. cable project.