The arc extinguishing methods of circuit breakers mainly include the following four types, among which the working principle of magnetic blowout arc extinguishing is as follows:
I. Common Arc Extinguishing Methods
1. Mechanical Arc Extinguishing: The arc is rapidly lengthened by a limiting device (such as a contact spring), and then cooled and extinguished using the arc's own energy. This is commonly used in switching devices.
2. Magnetic Blowout Arc Extinguishing: A magnetic blowout coil connected in series with the contacts generates a magnetic field. The electromagnetic force lengthens the arc and blows it into a solid medium (such as a metal sheet) inside the arc extinguishing chamber, where the arc is rapidly extinguished through cooling and the action of the medium.
3. Narrow-slit (longitudinal-slit) arc extinguishing: Under the influence of a magnetic field, the electric arc is divided into multiple segments, which enter the narrow slits of the arc extinguishing chamber. The narrow slits allow the arc to fully contact the solid medium, accelerating cooling and extinguishing. This method is commonly found in AC contactors.
4. Gas/liquid arc extinguishing:
- Oil circuit breaker: Utilizes the gas and pressure generated by oil decomposition to cool the arc, and elongates the arc by blowing it laterally or longitudinally through nozzles.
- SF₆ circuit breaker: Creates a high-pressure airflow by compressing gas through a compressor chamber or self-energizing structure, combined with the insulating properties of SF₆ gas, to rapidly extinguish the arc.
Working Principle of Magnetic Blowout Arc Extinguishing
1. Magnetic Field Generation: When the circuit breaker trips, the series-connected magnetic blowout coils are energized, generating a magnetic field. This magnetic field acts on the arc, causing the charged particles in the arc to accelerate under the influence of electromagnetic force.
2. Arc Elongation and Cooling: The electromagnetic force generated by the magnetic field elongates the arc, allowing it to enter the solid medium (such as a metal sheet or slit) within the arc extinguishing chamber. The arc collides with gas molecules in the medium, rapidly cooling and lowering its temperature, eventually extinguishing the arc.
3. Structural Advantages: Magnetic blowout arc extinguishing requires no additional energy source, relying solely on the magnetic field and contact structure. It is suitable for medium and low voltage circuit breakers and effectively reduces contact erosion.
12kV vacuum interrupter for vacuum circuit breaker is a critical component of high voltage power switches in 12kV systems. Its primary function is to utilize the excellent insulating properties of the vacuum within the tube to quickly extinguish the arc and suppress the current once the medium to high voltage circuit is interrupted. This process helps prevent accidents and unexpected incidents. The vacuum interrupter is mainly used in power transmission and distribution control systems.
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