FAULT IDENTIFICATION IN TRANSFORMER WINDING

S.Joshibha Ponmalar, S.Kavitha

Abstract: Transformer fault detection during impulse tests has always been an important topic in power engineering. Transformers connected to overhead lines are often prone to lightning strikes and resulting winding damage. For assessment of their insulation strength against such impulse stresses they are usually subjected to lightning impulse tests after assembly. In the case of a fault inside the winding, the shape of the winding current changes as compared to that of a healthy winding. The pattern of the fault current depends on the type of fault and its location along the length of the winding. This paper investigates Conventional procedures of fault diagnosis involved visual examination of the oscillographic records in time-domain and also applying the Fast Fourier Transform (FFT) algorithm to analyze the transformer ‘fingerprint’ in the frequency-domain. Actually, this method is straight forward technique for interpretation of minor impulse faults in transformers. Also Simulation results obtained for a range of distribution transformer digital models are presented to illustrate the ability of this approach to classify insulation failures during impulse testing. The proposed method has been applied for impulse fault analysis of a analog model of a 12kVA single phase transformer

Keywords: transformer; Impulse test; Fault; FFT

DOI: https://doi.org/10.15623/ijret.2012.0103020