Smreap arc protection device is a new type of arc protection system with wide practicability and high reliability. The arc protection system adopts the double criterion principle of arc detection and over-current detection, which has the characteristics of fast action speed and high reliability.

The auxiliary / distribution medium voltage switch cabinet is the power supply hub of the auxiliary machine / power supply system of the whole plant. In case of internal fault, whether the fault can be removed quickly is very important for the safe operation of the whole plant / power distribution system. However, according to the current protection scheme, there are several problems as follows:

① the medium voltage bus is not equipped with any special protection, but is considered by the relevant backup protection of the incoming switch;

② the protection of incoming switch and outgoing switch shall cooperate with each other: the delay level difference of general quick break protection shall be at least 300ms, or even 500ms;

③ the coordination level difference of over-current protection is up to 1-2 seconds.

Therefore, any fault on the medium voltage bus of the auxiliary / distribution system shall be removed at least in time delay. In other words, the existing auxiliary medium voltage bus can cut off the fault protection in the first time is still a blank. However, as long as we pay a little attention, it is not difficult to find that many electrical equipment, whether upstream or downstream of the medium voltage switch bus, are not equipped with fast protection. In contrast, we are afraid that it is difficult to have sufficient reasons to explain that the safety and reliability of medium voltage bus should be slackened. In view of the important position of medium voltage bus, the delay removal of any fault is a situation we are extremely reluctant to see. Because of all kinds of faults in the switch cabinet, the arc generated by the short-circuit current and a large number of high temperature make the gas in the cabinet expand rapidly, which can reach the peak in a very short time, seriously endangering the safety of people and equipment.

The importance of arc light protection device lies in:

1. Reduce or reduce the harm of electric arc to human body.

2. Reduce or reduce the damage to equipment caused by arc short circuit fault.

3. Avoid the dynamic stability damage caused by the short-distance bus fault of the transformer, and extend the service life of the transformer.

4. Shorten the removal time of arc light fault to avoid serious loss caused by affecting the DC system in the station.

5. Reduce the shutdown time of equipment caused by arc light fault, and restore power supply faster.