Short circuitise is the most common

Short circuitise is the most common and serious fault in power systems. Short-circuit faults will significantly reduce the system voltage and increase the circuit current. It will not only affect the normal power supply of users, but also damage the stability of the power system, damage electrical equipment. Therefore, in the design and operation of power station substation and even the whole power system, the short-circuit current must be calculated.The short-circuit types of three-phase AC system are mainly three-phase short-circuit, two-phase short-circuit, single-phase short circuit and two-phase short-circuit. A three-phase short circuit is a short circuit between a three-phase conductor in a power distribution system, a two-phase short circuit is a short circuit between any two-phase conductor in a power distribution system, and a single-phase short circuit is a short circuit between any one-phase ground and neutral or midline in a power distribution system. In the above short circuit, the three-phase short circuit is a symmetrical short circuit, and the other short circuit is an asymmetric short circuit. In the power system, the single-phase short-circuit is the most likely, the three-phase short-circuit is the least likely, but in general, the three-phase short-circuit short-circuit current is the most powerful and the most harmful, therefore, the calculation of short-circuit current mainly focuses on the calculation of three-phase short-circuit current.