The main function of switch cabinet is to open and close, control and protect electrical equipment in the process of power generation, transmission, distribution and power conversion. The components in the switch cabinet are mainly composed of circuit breaker, disconnector, load switch, operating mechanism, transformer and various protection devices.

      The positions that may produce arc light in the switch cabinet include: aging of bus insulator in electrical equipment, mechanical wear of circuit breaker and disconnector, flashover of insulating sleeve of transformer inlet and outlet line; misoperation of operators during maintenance, tools left behind and damage of small animals; external factors such as dust, humidity, temperature, corrosion, etc., may lead to the connection between bus and bus Transformer, switch cabinet and other important equipment produce phase to phase or other short circuit faults, which lead to the generation of arc.

       Arc light is easy to be generated in the bus room and circuit breaker room of the switch cabinet. Therefore, it is necessary to actively take protective measures to timely detect the arc light generated by the fault inside the switch cabinet, and quickly eliminate the arc.

       The arc protection device is used to quickly remove the arc short circuit fault, which fundamentally limits the development of the fault arc and eliminates the harm of its various effects on equipment and personnel. If the arc protection can remove the fault within the arc withstand time of the switch cabinet, the damage of the switch equipment caused by the arc light will be limited to a large extent.

       From another point of view, the arc protection system limits the damage of the switchgear, that is, it blocks the possibility of fault development, so as to avoid the main transformer from being damaged by short-circuit current for a long time, and can also prevent the arc from spreading to the station DC system and developing into system fault.

       Arc protection is an urgent need to take effective measures to limit the burning of switch equipment caused by arc short-circuit fault and the damage of transformer due to short-circuit current impact.