Symmetric and Asymmetric Wavelet Techniques For Minor Fault Detection in Transformer Windings
Any weakness of insulation in a transformer winding may result in its deformation and hence, in the failure of
the transformer. Comparison of neutral currents is a technique widely used for the detection of fault in the power transformer
winding insulation during impulse test, any shift in the recorded waveforms confirms the existence of fault. In the present
work, a 61MVA, 11.5/230 kV generator transformer has been considered for analysis. Faults have been created in the discs
of the HV windings at specific locations. High voltage impulse is applied to the winding and the neutral currents for the
healthy case and the faulted discs windings have been recorded using digital oscilloscope and these recorded neutral currents
were subjected to analysis after proper processing & neutral current oscillographic methods are used for fault identification
using symmetric & asymmetric mother wavelets by wavelet transform technique.
Index Terms—Power Transformer, Neutral currents, Wavelet transform.