Study of effects of standard and non-standard impulse waves on power transformer

This paper aims to highlight the observations made on surge performance of a power transformer. The impulse test on power transformers simulates the conditions that exist in service when a transformer is subjected to an incoming high voltage surge due to lightning or other disturbances on the associated transmission line. A simulated non-linear transformer model helps to analyze the surge response under varying impulse waveforms accurately and so surge modeling of the transformer using MATLAB SIMULINK has been done. For a range of applied waves (both standard and non-standard) and different winding connections, comparison of the insulation characteristics under non-standard lightning impulse voltage waveforms which represent actual surge waveforms encountered in the field and the characteristics under the standard lightning impulse waveform quantitatively can be made. An investigation on the transformer behavior when subjected to standard and non standard impulse waves is done in this paper. The maximum voltage to ground and maximum voltage across the coils along with the time of their occurrences against different coils for 0% tapping and 10% tapping respectively is recorded and analyzed.