Simulation of Power Transformer Winding Sections Provided with Metal Oxide Surge Absorber Blocks Using Full and Chopped Impulse Voltage Waves

Very fast transient voltage behavior of power transformer winding sections can be improved by providing suitable metal oxide surge absorber (MOA) blocks across sections of the windings. Computer simulations have been carried out to investigate surge voltage performance of these type of windings for appearance of 1.2/50 microseconds wave shape, full and chopped impulse voltages at line terminal. Transformer windings with α (Square root of ratio of total ground capacitance to total series capacitance of the winding) values in range of 6 to 18 have been analyzed. Results of studies carried out to identify presence of faults in winding section due to appearance of full and chapped impulse voltage waves with MOA blocks provided across all winding sections are reported in this paper.