Partial discharge (PD) may occur in a transformer winding due to ageing processes, operational over stressing or defects introduced during manufacture. The presence of PD does not necessarily indicate imminent failure of the transformer but it will lead to serious degradation and ageing mechanisms which can be considered as a precursor of transformer failure. A necessary step is required in ord...

Inrush currents in transformers are non-sinusoidal, high magnitude currents generated due to flux saturation in the core during energization. For protection purpose, in this paper an efficient method for detection of inrush current in distribution transformer based on wavelet transform is presented. Using this method inrush current can be discriminated from the other switching transients such a...

The success of health monitoring and condition assessment of power transformers based on winding current signature analysis lies on proper extraction of features. The extraction of features in turn depends on appropriate signal processing methods. Fourier based signal analysis provides only frequency information and also suitable only for stationary signals. In this paper we present a combined ...

Insulation used in transformer is mostly oil pressboard insulation. Insulation failure is one of the major causes of catastrophic failure of transformers. It is established that partial discharges (PD) cause insulation degradation and premature failure of insulation. Online monitoring of PDs can reduce the risk of catastrophic failure of transformers. There are different techniques of partial d...

This paper proposes a restricted earth fault protection based on the wavelet transform (REFW) for detecting ground faults close to transformer neutral point (turn-to-ground faults) and supporting conventional phase differential protection, which presents limitations in this kind of faults. The proposed REFW uses only high-frequency components instead phasor estimation, speeding up detection tur...

This paper presents the characterization of transients resulting from faults in transformers using discrete wavelet transform (DWT). This characterization will aid in the development of an automatic detection method for internal incipient faults in the transformers. The detection method can provide information to predict failures ahead of time so that the necessary corrective actions are taken ...