Pattern classification of internal incipient faults during impulse tests using continuous wavelet analysis

In the case of a fault occurrence, the pattern of the fault currents obtained by the standard impulse tests contains a typical signature of the nature and the location of the insulation failure involved. This paper presents a new approach to classify the pattern of the arc discharge location as one of the important types of internal incipient faults in transformer windings. The continuous wavelet transform (CWT) has been used to calculate the most predominant frequency of each fault and its time of occurrence. The data obtained from the field tests of a 66 kV/25 MVA interleaved transformer winding and the computer simulations have been used for the classification.