Arc protection device provides fast and safe arc protection for medium and low voltage bus. The double criteria of inverse time arc detection and high-speed over-current detection are used to ensure its safety and fast tripping.

At present, there are two main protection schemes for arc light in switch cabinet, one is to monitor by pressure sensor, the other is to monitor by arc light sensor.

The pressure sensor is used as the arc detection unit. The pressure wave is one of the effects of arc accident in the device. It will appear 10-15ms after the arc occurs. Some pressure sensors can be installed to detect the peak pressure. When the internal pressure reaches the set value, the arc monitoring device sends action command to control the switch action. However, it is not easy to determine the overvoltage value of the arc in the cabinet in advance.

Using optical fiber sensor as arc detection unit, arc phenomenon will produce strong light radiation, so arc in the cabinet can be detected by arc sensor. As a light sensing element, the arc sensor detects the sudden increase of light intensity in the event of arc failure, and transmits the analog light signal to the arc unit or directly to the main control unit. The arc unit converts the light signal into an electrical signal for comparison, filtering, coding and electro-optic conversion. The optical fiber transmits the digital light signal to the arc sensor or the main control unit, and the arc protection system is implemented The detection reaction time of this method is only 7-10 Ms.

Arc protection, as the fast protection of 35kV and 10kV bus and switch cabinet internal fault, is configured according to bus section. Each bus is equipped with a main control unit, several arc light collectors and several arc light sensors. The number of arc light collectors to be configured matches the number of arc light sensors. A main control unit can collect 8 arc lights, that is, it can detect 8 switch cabinets. When there are many switch cabinets in the station, arc light collectors need to be added. One arc light collector is the same as the other The sample can also measure 8-way arc light.