Abstract
The design of 35 KV substation system including Steel foundry, Iron foundry, electricity Assembly shop, Model room, Forge shop and so on, the factory has production machinery of high concentration, electricity demand of the equipment is great, the request of power supply is high .Power interruption will cause decline in production and product quality, leading to great economic losses. To avoid accidents and ensure the smooth progress of production, we must adopt a series of technical measures and corresponding management system to ensure the security of electricity supply,such as against receiving an electric shock, overload, over-current protection and anti-radar. Through the analysis of the firsthand information, the computation of entire factory load, choosing the corresponding main transformer number and the capacity, thus determining its concrete power supply system. Then carrying on the corresponding short circuit computation and the choice and verification of high pressure unit and the verification again to its primary election's system, and carrying on the choice and the verification of the high-tension line, finally set the explanation of the relay protection establishment simply. according to the elementary knowledge of the textbook and the substation system operational aspect in our country and as well as the standard of various transformers, switch cabinets, lines, we can carry on the concrete quota choice of electric appliance equipment, finally we can obtain concrete power supply diagram of the factory’s total dropping and changing voltage substation.