Principle And Method Of Arc Extinguishing Of Circuit Breaker

Arc extinguishing is one of the important applications of circuit breaker, because the arc will not only damage the equipment line, but also affect the personal safety. Thus what is necessary to extinguinate arc, in general, there are four commonly used methods of extinguishing arc, including mechanical extinguishing arc, magnetic blowing out arc, etc. In this paper, I explain the common methods of extinguishing arc and some common circuit breaker extinguishing principle.
First of all, the commonly used arc extinguishing methods are discussed, which mainly include the following four kinds:
1, mechanical arc extinction: through the limit device will be rapidly elongated arc. This method is often used in switching appliances.
2. Magnetic blowing out arc: Under the action of the magnetic field produced by the magnetic blowing coil in series with the contact, the arc is stretched by the action of the electromagnetic force, and is blown into the arc extinguishing cover composed of solid media, and the solid media contact, the arc is cooled and extinguished.
3, narrow seam (longitudinal seam) arc extinguishing method: under the action of the magnetic field electric power formed by the arc, the arc can be elongated and enter the narrow (longitudinal) seam of the arc extinguishing cover, several longitudinal joints can be divided into several sections and contact with the solid medium, the arc will be quickly extinguished. This structure is mostly used in AC contactors.
4. Grid arc extinction method: when the contact is separated, the arc generated under the action of electric power is pushed into a group of metal grid pieces and is divided into several segments. Each piece of the metal grid pieces insulated with each other is equivalent to an electrode, so there are many Yin and Yang extreme voltage drop. For AC arc, near the cathode, there will be a 150V ~ 250V dielectric strength when the arc passes zero, so that the arc can not continue to be maintained and extinguished. Because grid arc extinguishing effect is much stronger than DC, so AC electric appliances often use grid arc extinguishing.
These methods are mainly aimed at some low-voltage circuit breakers. To understand the reasons for these methods, it is necessary to clarify the principle of circuit breaker arc-extinguishing. The following are discussed for some commonly used circuit breakers.
The arc-extinguishing principle of vacuum breaker
At the breaking moment of the vacuum circuit breaker, due to the existence of capacitance between the two contacts, the insulation between the contacts will be broken down and vacuum arc will be generated. Due to the shape and structure of the contact, the vacuum arc column spreads rapidly to the vacuum area outside the arc column body. When the broken current is close to zero, the temperature and pressure of the arc between contacts drop sharply, so that the arc can not be maintained and extinguished. Within a few μs after the arc is extinguished, the pressure tolerance level of the vacuum gap between the two contacts quickly recovers. At the same time, the contacts also reach a certain distance, can withstand high recovery voltage. Therefore, the general current after zero crossing, will not occur arc reignition and be broken. That's how it kills the arc.
The arc extinguishing principle of high - pressure drop - melt breaker
As we all know, in the case of high voltage and large current, switch in order to extinguisher often use more complex methods and structure, and the high voltage drop type fuse but only need a very simple hose can be smoothly and very good arc extinguisher, the main reason is: first, the high voltage drop fuse current is not very big. The resulting arc is not very large. Second, it uses air to extinguish the arc. Kind of the same principle as the circuit breaker. It's just a different structure.