Abstract—Any power transformer protective scheme has to take into account the effect of magnetizing inrush currents. Since during the energisation of the transformer, inrush current results in 10 times full load currents and can cause maloperation of the relays. The ratio of the second harmonic to the fundamental harmonic of the inrush current is greater than that of the fault current. The second harmonic in these situations might be greater than the second harmonic in inrush currents. This paper describes the protection of power transformer from fault condition, i.e., internal faults from inrush currents by using the Wavelet based differential protection scheme. It is shown that the features extracted by the wavelet transform have a more distinctive property than those extracted by the fast Fourier transform due to the good time and frequency localization characteristics of the wavelet transform.

Index Terms—Keywords: Power transformer, Wavelet transform, Detailed coefficient, Fast fourier transforms

Cite: K Ramesh and Y Mallikharjuna Rao, "POWER TRANSFORMER PROTECTION USING WAVELETS," International Journal of Electrical and Electronic Engineering & Telecommunications, Vol. 3, No. 4, pp. 14-21, October 2014.