Time domain analysis of a 12 coil section and 18 coil section transformer model winding subjected to a variety of surge voltages

The response of transformer windings due to the impact of high voltage surges has evoked the attention of insulation engineers for almost a century. The reason is simple: These fast rising voltages give rise to non-uniform voltage stress distribution along the coil sections and can endanger the insulation of high voltage power transformer windings. Hence an in depth knowledge of this is necessary for insulation engineers to design the winding insulation and also protective devices to be used to ensure that insulation failure does not take place when such fast rising voltages appear at the terminals of high voltage power transformers. In this paper, time domain analysis on model winding of a high voltage power transformer with 12-coil sections and 18-coil sections is being carried out to investigate its dynamic behaviour under a variety of fast rising impulse voltages. Simulation results of both the 12-coil sections and 18-coil sections of model winding impressed with full impulse, time-step and chopped impulse surge voltages with α=10 and 20 have been presented.