Diagnóstico del devanado terciario de un autotransformador de subestación

Diagnosis of the tertiary winding of a substation autotransformer

Abstract

This article presents the results of the Frequency Sweep Response Analysis as a diagnostic method for the tertiary winding of an autotransformer that, for some time, has been presenting hot spots in the screws that join the casing or bell with the base of the tank. This phenomenon was monitored with the help of infrared images that confirmed abnormal heating. The SFRA method was applied to this equipment to confirm or rule out the possible causes of the defect. The open-circuit and short-circuit admittance configurations were used. Comparisons of the transfer response functions were made between phases of the same tertiary winding and the Chinese Standard DL/T 911-2004 was applied for the analysis of the results. It was found that there is an obvious deformation in this winding and that the excessive heating of the screws is not caused by this deformation.