Abstract
The design of the main tasks is a electrical plant distribution system design’ current protection. The high voltage 10 kV line was into the mill of the substation. The power was supplied to the workshop, which was transformed to 10 kV through the main transformer and transformed it into 380V. After the basis for the design of the data analysis, found that all workshop equipment are three class load, only a small part of the two class load. Through calculating and looking up a lot of relevant information, finally, the main transformers of 1000 kVA was chose. The line of main transformer to workshop is the single-bus line. According to the computation electric current, chooses each equipment, check and setting calculation through the short-circuit current and the voltage loss .and completion the relay protection system and the setting calculation, finally finish the design, working out the power supply diagram.
Keywords：power supply system、load calculation、short-circuit currents calculation method、current protection
