An experimental approach for investigating low-level interturn winding faults in power transformers

Abstract

Interturn faults are one of the most prevalent and potentially destructive electrical faults in power transformers. In spite of an extensive interturn fault detection literature, the issue still constitutes an open problem. The difficulty is mainly caused by lacking of enough information on the characteristic signatures associated with interturn faults which were not clearly brought out by the previous studies. This contribution is aimed at obtaining a better understanding of the physical behavior of the power transformers in the presence of interturn faults as well as extracting several features which would be useful to specify the transformers interturn faults. The approach keeps at disposal a 100 kVA distribution transformer on which interturn faults were imposed and an experimental setup consisting of an instrumentation system and suitable transducers which enables monitoring selected characteristics of the transformer. The paper examines the faulted transformer performance under various fault and transformer operating conditions. Unique characteristic fault-signatures derived from the experiments will provide an important basis for developing more reliable and sensitive methods to detect interturn faults on the transformer windings well before such faults lead to a catastrophic failure with serious damage to the windings.