Dielectric frequency response measurement as a tool for troubleshooting insulation power factor problems

Abstract

This paper presents a new method of evaluating the dielectric frequency response (DFR) test for troubleshooting and identifying the cause of high or unusual insulation power factor test results. The method involves preparing a dielectric frequency response signature (DFRS) from the DFR test on a transformer. The signature of the measured response is then compared with a modeled response of a transformer with a "normal" insulation structure and a library of signatures of known defects. Based on this comparison, it is possible to diagnose power factor defects in the insulation structure of the transformer under test.