Electrostatic Analysis of SF6 Gas Insulated Distribution Transformer

Abstract

In recent years, environmental awareness has been a great concern, and even governments have sometimes been under pressure to comply with bilateral agreements. Mineral oil is one of the most harmful pollutants if it infiltrates the soil. Of course, it provides a good insulation material in (distribution/power) transformers, but it presents some disadvantages such as low firing value, additional insulation costs, requirement for an extinguishing apparatus, long clearance distance, being non-edible, and extensive soil spill cleanup, among others. Explosion is another danger for oil-insulated transformers. For this reason, gas-insulated transformers have nowadays been put into specifications. SF6 GITs present more reliable working conditions due to the inherited specs of SF6 because it has non-flammable insulation and explosion-proof design. Therefore, the proposed transformer design is mostly suitable for security risk environments such as submarines, mines and nuclear power plants. Apart from these advantages, the new SF6 GIT design is compact in design and lighter than the oil-type one. In this study, electrostatic analysis of a three phase SF6 gas-insulated transformer (GIT) with 50 kVA rating, 34.5/0.4 kV, 50 Hz was conducted by using finite element method. Electric potential and electric field distributions inside the transformer were investigated.