Abstract
The main task of this design is to work out a best design of a chemical plant consumer 10kv step-down. This system has a 10kv power line, than the power would be set to each workshop by a 6kv step-down transformer. At last, the power should be used by each workshop which must be transformer to 220v by step-down transformer first. This design included the line and high-pressure equipment selection, local calculation, short-circuit current calculation, and all sorts of relay protection setting calculation had been instructed detailed. Especially the choice of wiring and transformer, electrical equipment such as circuit breaker, current transformer, voltage transformer etc choice had been instructed detailed. This design fixes protection and conventional protections, also adopts microcomputer protection, through the electric control integrated automation system, it can make the substation attendants or dispatching center within the personnel to grasp the operation situation of substation, directly on the equipment operation, timely, and quickly and fault handling, so it achieves the power supply system, scientific, standardized management, and also can do and other automation system data interchange, give full play to the advantage of the whole system, the comprehensive management information.
Keyword: the calculation of short current, the protection of relay, circuit breaker, PC protection
