Development of large capacity low-noise gas-insulated transformer

摘要

In order to handle increasing demand for electric power and protection against fires in large cities, larger-capacity and higher voltage SF6 gas-insulated transformers have been developed and are in practical use. They use high pressure gas toenhance cooling and insulating performance. However, they have some drawbacks such as higher noise, heavier tank. We carried out developments to enlarge the ranges of capacity and voltage to which low pressure gas can be applied. Firstly, its interiorstructures and cooling system were designed using thermo-fluid and gas flow analyses. Secondly, electric field stresses in a transformer were kept under control by the adjustment of relative permittivities and position of insulators. Thirdly, a low-noisetype gas blower was developed after careful tests. As a result, 100MVA 154kV SF6 gas-insulated transformer of 65dB class using low pressure SF6 gas (0.24MPa at 20°C) has been developed.