Power-Factor Testing of Transformer Insulation

This paper points out a method for analyzing the results obtained from dissipation-factor tests of transformer insulation. Experimental data, obtained both from transformer tests, extending over the past three years, and from tests of sample insulation, indicate a definite relation between resistance and capacitance, with varying conditions of temperature and moisture. This relation furnishes an additional means for determining the condition of insulation when considered with other accepted methods. The physical arrangement of the transformer windings, and the type of test equipment used, affect the tests and should be considered when interpreting results.