TRANSFORMERS FAULT DETECTION USING WAVELET TRANSFORM

In order to analyze a signal, wavelet transform can be applied as well as Fourier transform. Fourier transform and its inverse can transform a signal between the time and frequency domains. Therefore, it is possible to view the signal characteristics either in time or frequency domain, but not the combination of both domains. Differently from the case of Fourier transform, the Wavelet Analysis (WT) provides a varying timefrequency resolution in the time frequency plane. In this paper, a new method for protecting power transformers based on the energy of differential-current signals is introduced. The simulation results show that it is possible to detect different kinds of internal faults using this method. Furthermore, it is possible to distinguish such faults from magnetizing inrush current.