Failure analysis & diagnostics of power transformer using dielectric dissipation factor

The quality of power transformer insulation system is evaluated on a routine basis by measurement of the dielectric dissipation factor and capacitance of the insulation system. The use of dielectric dissipation factor measurements at the end of the production cycle not only assures that the quality of the transformer meets the specified levels but also provides insight into the subtleties of the manufacturing process. This tool is used for many years for diagnosing the health of electrical apparatus. It is a routine test conducted at site to know the dryness of insulation in transformers. This paper highlights our experience on the measurement of dissipation factor using GST & Guard mode techniques of earthing systems other than dryness of insulation in transformers. All our experiences are presented in this paper.