Short circuit is the most common an

Short circuit is the most common and serious fault in power system. Short circuit fault will greatly reduce the system voltage and increase the loop current. It will not only affect the normal power supply of users, but also destroy the stability of the power system and damage electrical equipment. Therefore, in the design and operation of the power station substation and the entire power system, the short-circuit current must be calculated. The short-circuit types of three-phase AC systems mainly include three-phase short circuit, two-phase short circuit, single-phase short circuit and two-phase ground short circuit. Three-phase short circuit refers to the short circuit between the three-phase conductors in the power supply and distribution system; two-phase short circuit refers to the short circuit between any two-phase conductors in the power distribution system; single-phase short circuit refers to any one phase in the power supply and distribution system Short circuit between ground and neutral or neutral. Among the above short circuits, three-phase short circuits are symmetric short circuits, and other short circuits are asymmetric short circuits. In the power system, the possibility of single-phase short-circuit is the largest, and the possibility of three-phase short-circuit is the smallest, but in general, the short-circuit current of the three-phase short-circuit is the largest and the hazard is the most serious. The calculation of current.