Arc light is a common point hazard in power plant. The protection scheme set in medium and low voltage bus bar has very small protection effect on arc light hazard. Therefore, in order to avoid the damage caused by arc light to operation and maintenance personnel and electrical equipment, it is necessary to take advantage of the harm brought by arc protection device.

The generation of arc light is mainly due to the high voltage between the two electrodes, the positive and negative ions in the surrounding air form a high-speed rotating power plant under the influence of the voltage, and in the process of moving, they constantly collide with other molecules to produce new ions, and these ions increase, coupled with the increase of temperature, will produce an arc, which is essentially a kind of discharge The voltage requirement is not very high. As long as the voltage between the two electrodes can exceed the insulation strength of the surrounding air, arc discharge will occur. This discharge will directly affect the operation of electrical equipment around the arc. Moreover, the temperature rises sharply during the occurrence of arc light, which will have a great impact on the electrical equipment. The gas generated during the discharge will cause severe vibration of the switchgear equipment, In the process of vibration, the fixed components on the switchgear will fall off, and the insulation resistance will directly lose its function, and even may cause the switch cabinet explosion, which will directly threaten the personal safety of the operation and maintenance personnel in the power station.

There are four bus bars in the power system of a power plant in Sichuan Province. The incoming line of each bus is one circuit. The side fault of the bus is mainly caused by the over-current protection of the incoming line. When there is no arc protection, the fault on the bus can not be eliminated in time, which will cause irreversible damage to the bus and electrical equipment. In view of this, the electric arc protection system is installed in the power plant.

For the power plant, the bus is the power supply hub of the whole plant power supply system and power consumption system. Once the bus fault occurs, all the components connected to the bus will be affected, and at the same time, it will transfer to another group of bus, which will also cause damage to the other group of bus, which will lead to the occurrence of forced power failure, affect the stability of the whole power system and give power plant operation Therefore, it is necessary to strengthen the protection of bus bar, and the impact of arc light on bus is also great. The corresponding arc light protection of power plant equipment is needed to protect the bus bar and reduce the damage caused by arc light.