Air circuit breaker: design and principle of operation

To protect electrical equipment and high-voltage power lines, a type of switching device such as an automatic air switch is used. As the name implies, its peculiarity of work is associated with the use of an air gap between the power contacts. Below we will consider the design, principle of operation and purpose of the air machine.

Device

When the load, powerful consumers, is disconnected, an arc arises between the contacts diverging for disconnection, which is not inferior in strength to the rated current. During this phenomenon, plasma is formed, a rise in temperature, as a result of which an uncontrolled self-sustaining arc can form, capable of melt the contacts of the switch and even transfer to the adjacent phase, causing a phase short circuit, which can result in the destruction of an expensive equipment. To avoid such a phenomenon, a device was developed - an arc extinguishing chamber.

The design of the air circuit breaker is illustrated in the diagram below (click on the picture to enlarge):

Operating principle

At the moment of breaking the contacts, an arc occurs. Reaching the lattice of the arc extinguishing chamber, it begins to stretch, and under the influence of heat, the air in chamber, flows out through the lattices, dragging further behind itself the products formed by the plasma, stopping its manifestations physically.

Understanding of the processes occurring in switched circuits, as well as ways to suppress undesirable phenomena, helped to create devices that are sufficiently compact in size and weight, capable of cutting off the current by hundreds ampere. The photo below shows a typical representative of a circuit breaker:

Scope and purpose

Air machines are used for industrial needs, in the energy sector, in the private sector. To date, protective devices of various sizes and dimensions have been developed. From apartment circuit breakers to withdrawable-type power protection and switching equipment, with a built-in parameter controller.

Now let's talk about what machines of this type are used for. The main purpose of air circuit breakers is to protect electrical equipment and power lines from currents short circuit, as well as from excessive power consumption by monitoring the magnitude of the amount of current passing through the contacts machine.

Requirements for modern air circuit breakers:

• unlimited time for passing the rated current;
• multiple disconnection of short-circuit currents;
• short response time;
• resistance to multiple thermodynamic loads;
• the presence of internal protective mechanisms;
• selectivity.

Due to the relative simplicity of their design, they have firmly taken their place in the sun and, moreover, continue to improve in technical terms.

Finally, we recommend watching a video that clearly shows what an air machine consists of:

So we examined the purpose, principle of operation and the device of the automatic air circuit breaker. We hope the information provided was useful and interesting for you!

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