Air Circuit Breaker (ACB) is an electrical device used to provide Overcurrent and short-circuit protection for electric circuits over 630 Amps to 10K Amps. These are usually used in low voltage applications below 450V. We can find these systems in Distribution Panels (below 450V). Here in this article, we will discuss the working of Air Circuit Breaker.
Working Principle
The air circuit breaker working principle is different as compared with other kinds of CBs. We know that the basic function of CB is to stop the restoration of arcing wherever the gap between contacts will resist the recovery voltage of the system.
The air circuit breaker also works the same but in a different way. While interrupting an arc, it makes an arc voltage in place of the voltage supply. This voltage can be defined as the least voltage which is necessary to maintain the arc. The voltage supply can be increased in three different ways by a circuit breaker.
The arc voltage can be enhanced through cooling arc plasma.
Once the temperature of arc plasma and particle motion is reduced, then additional voltage gradient will be necessary to keep the arc. The arc voltage can be increased by splitting the arc into several series
Once the arc path is increased then Arc voltage can also be increased. As soon arc path length is enhanced then the path of resistance will also increase the arc voltage which is used across the arc path thus arc voltage can be increased.
The range of operating voltage is upto 1KV. It includes two sets of contact where the major pair uses the current as well as the contact made with copper. Another pair of contact can be made with carbon. Once the circuit breaker is opened, the first major contact unlocks.
While opening the major contact, the arc contact stays connected. Whenever arc contacts are divided then arcing gets started. The circuit breaker is outdated for average voltage.
Where Are Air Circuit Breakers Used?
Air circuit breakers are mainly in use for controlling power stations and industrial plants. The reason is that they are good at controlling low voltage equipment. Therefore, they can offer protection to industrial plants, capacitors, electrical machines and generators.
These circuit breakers are used in places with a high possibility of fire or explosion hazards in most cases. There are three different types of air circuit breakers. These are the basic break type of air circuit breaker, magnetic blowout type of air circuit breaker and the air chute circuit breaker.
Plain Brake Type
Plain break type of air circuit breaker is the simplest form of a circuit breaker. The device has two horns with the arc circuit breaker extending from one tip-top to the other.
Magnetic Blowout
The magnetic blowout type of air breakers is used in voltages with a capacity of 11KV. It uses the extension of the arc to get magnetic fields provided by the current whenever there is a blowout coil.
Air Chute Air Break Circuit Breaker
This kind of air circuit breaker has the main contacts made of copper and conducts current in closed positions. One notable factor with air chute circuit breakers is the low contact resistance and silver plating. In addition, it has a solid arcing contact, resistant to heat and is made of copper alloy.
How Does Air Circuit Breaker Work
You can operate an air circuit breaker either manually or through an electrical conversion. What happens is that the free tipping of the air circuit breaker locks the main contact in the closed position when the main contact is in a closed state.
The main circuit is connected to the coil of the overcurrent tripper and the thermal element of the thermal tripper. The current air trippers have an aluminum single plate of curtain wall material; with a high aluminum alloy plate. The coil of the device that is the under-voltage trip is connected parallel to the power supply.
The insulated plate is then mounted with left and right-side panels and also with instantaneous overcurrent trip. The upper part of this device is equipped with an arc extinguishing system. The operation mechanism is installed directly on either side or in front and the manual disconnection button.
Installation method
Fixed Type
The unit is directly connected to the panel board and is an economical method installation.
Draw out Type
It consists of two parts the main body of the breaker and the panel board frame.
It is directly connected to the panel board and the main body of the breaker is mounted on the draw out frame.
The main body of the breaker can be separated from the panel board without change in circuit.
Benefits easy checking for its function, easy repairing & charging part and maintenance, easy replacement of breaker itself.
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