Study on AC and lightning impulse breakdown characteristics of nano SiO2 modified mineral oil for power transformer applications

Abstract

Electrical energy is the prime source of life for day to day activities. In order to meet the periodically increasing electric power demand, electrical utilities are developing ultra high voltage power transmission lines. In India, power transmission at 400 kV AC is now upgraded to 765 kV AC system. Very soon electrical utilities are planning to run the power transmission system at 1200 kV ultra high voltage level. The major benefits of electric power transmission at ultra-high voltages are, increase in voltage newlinereduces the current carrying limit of conductors and hence sizes of the conductors are reduced. This also leads to decrease in losses which results in improved efficiency. Since the current flow in transmission line is reduced it results in less voltage drop and hence it improves voltage regulation. However, as the power transmission is going to be upgraded to ultra high voltage level, naturally there is a need to concentrate more on the design of proper insulation structure for high voltage transformers. Power newlinetransformers are an expensive and key component of electric power transmission and distribution system. The performance, life and stability of the transformer depend upon the proper selection of the insulation system and therefore insulation is the most critical part of the transformer. The most commonly used transformer insulations inside the transformer are oil, pressboard and paper. newline newline