Circuit short-circuit causes and short-circuit types - News - Global IC Trade Starts Here.

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The normal production of the various sectors of the national economy and the normal life of the people require the power supply system to operate continuously, safely and reliably. However, due to various reasons, the system will often fail, causing the normal operating state to be destroyed.
A short circuit is a common serious fault in the system. The so-called short circuit is a short circuit between various types of abnormal phase and phase or phase and ground in the system. There are many reasons for the system to have a short circuit, mainly:
(1) Damage to electrical equipment and components. For example, the insulation part of the equipment is naturally aging or the equipment itself is defective, and the short circuit is broken during normal operation; and the equipment defects caused by improper design, installation and maintenance eventually develop into a short circuit.
(2) Natural reasons. Such as: the weather is bad, due to high wind, low temperature wire icing caused the overhead line to break the line; due to direct lightning or lightning induction, equipment over voltage, insulation is broken down.
(3) Man-made accidents. Such as: the staff violates the operating procedures with load pull, causing phase arc short circuit; violation of the electrical safety work regulations with grounding knife gate closing, causing gold shaving short circuit, human error neglecting the wrong line caused by short circuit or poor management caused by small animals Into a live device to form a short circuit accident and so on.
In a three-phase system, short-circuit faults that may occur are: three-phase short-circuit (K(3)), two-phase short-circuit (K(2)), single-phase short-circuit (K(1)), and two-phase short-circuit (K) (1.1)).
The various types of short circuits are shown in Figure 5-1.

The three-phase short circuit is a symmetrical short circuit, and the others are all asymmetric short circuits.
Judging from the opportunity of various short-circuit faults, the actual operation of the system shows that the single-phase short-circuit is the most frequent, the two-phase short-circuit is the second, and the three-phase short-circuit has the least chance. However, the general system has taken measures, and the single-phase short-circuit current value does not exceed the three-phase short-circuit current. The two-phase short-circuit current value is usually also smaller than the three-phase short-circuit current value. Therefore, the consequences of three-phase short circuit are generally the most serious, and should be given enough attention to give sufficient research. At the same time, we can also find that when the analytical calculation of various asymmetric short circuits adopts the symmetrical component method, it will be attributed to the symmetrical short circuit calculation. Therefore, the symmetrical three-phase short-circuit study is also the tomb of asymmetric short-circuit calculation.