Study On The Short Circuit Current And Equipment Inspection In Power Supply And Distribution Of Building

In the design and operation of the power system, the primary task is to ensure the safety and stability of the system. As we know, the power accidents often will bring serious harm. But, most of them are caused by short circuit fault. So the prevention and control of short circuit fault is very important. The related departments of power supply design should deal with the short circuit current in scientific computing, and accord to the short-circuit current data of the electric power system for rational planning to ensure the electric power system safe, reliable and stable.In the paper, focusing on the three-phase short-circuit current calculation analysis and its application as the research subject, this article’s research content including the following several aspects:(1)Comb the basic concepts of the short-circuit in the electric power system:With the clue of the short-circuit, firstly we analyze the types of short circuit. short-circuit current, periodical component short-circuit current, aperiodical component short-circuit current, peak short-circuit current and so on are discussed explicitly.And the roles of these physical quantities in engineering design of the electric power system are analyzed in detail. Secondly we introduce the common causes of short-circuit fault in the electric power system to provide the basis for the prevention and elimination of short circuit fault. And then focused on the three effects: short circuit current caused by the thermal effect, force effect, magnetic effect, there is a comprehensive analysis of the harm of short-circuit fault. Finally through the short-circuit current calculation in deep analysis of two common methods: the ohm value method and the per-unit value method in IEC standard in order to provides a reliable basis for the related designers to design electric power system, and select wires and electrical equipment much more scientifically and rationally.(2)Study the application of short-circuit current calculation about the selection in practical engineering: In practical engineering, the first priority is to ensure the safe and stable operation of the whole system. When the local short circuit or even the central short disintegration, occurs in the power system, that will lead to the paralysis of the entire system and the lack of system security. Therefore, short circuit current check and calculation is veryimportant for the whole system, electrical equipment, wire and relay protection device of the entire capital all need to short circuit current check, in order to ensure timely removal of short circuit. Not only the system can quickly return to the safe and stable running state, but also the equipment can be recycled.(3)The analysis of a practical engineering case: this is the theory application part of the subject. According to theory formula of the subject before, it is to calibrate the selected equipment with short-circuit current, including high voltage circuit breaker, current transformer, high voltage cable, low voltage bus bar in this project, in order to estimate whether the project selected wires and electrical equipment can meet the mounting point of prospective short-circuit fault of electrical technical requirements, in order to ensure the safety and stability of the system.The purpose of this study is to analysis the short circuit current in detail with a view to provide a theoretical basis for selecting electrical equipment, tuning relay protection device, analyzing the power accidents, etc. These theoretical basis should be applied reasonably as far as possible to reduce the occurrence of short circuit fault for people to create a safe, stable electrical environment.