What are Air Circuit Breakers?

An Air Circuit breaker is a type of circuit breaker in which Air is used as an insulating medium.

An Air Circuit Breaker (ACB) is designed to protect electrical circuits and equipment from short circuits. It is a key component in power distribution systems and is commonly used in various industrial, commercial, and residential applications.

ACBs use air as the medium for arc interruption. When the contacts open, an arc is formed, and the surrounding air helps extinguish the arc, preventing damage to the equipment.

Types Of Air circuit breaker

Air Break C.B
Air Blast C.B

Air Break C.B

An Air break is a type of air circuit breaker in which Air is filled as an insulating medium to Distinguish the Arc. The operating mechanism of this breaker consists of pre-charge springs.

when connections are disjointed, the arc is produced between the contacts and the surrounding air is also ionized due to high temperature. Different methods exist to Distinguish the arc, increase the arc length, cool down the arc and disperse the arc.

Air Circuit Breaker (Types , Advantages and Disadvantages ) - Electronicsinfos

The air circuit breaker is used for low and medium voltages. There are different applications of Air break circuit breakers i.e. AC circuit breakers, industrial switchgear, auxiliary switches gear, generating stations etc. The Arc Distinguish process is different in DC as compared to the AC system.

In this method, we use air blow to transfer the arc to the arc runner side and cool down the resulting arc. There are two possibilities for voltages if

Arc voltage is greater than the supply voltage the arc is distinguished due to zero arc current.
If the arc voltage is less than the supply voltage the arc is not distinguished due to high arc current.

The construction of an air break CB is simple. The main principle of an Air break circuit breaker is a high resistance interruption system.

The principle is defined as minimizing the arc using cooling, lengthening and splitting the arc.

The Air break CB is used as DC and AC circuits up to 12 kV. This type of Circuit breaker is normally used indoors. There are different parts of Air break CB is

Main contacts
Arching Contacts
Arc rising in the direction of arrow
Arc getting split
Arc splitter plates
Current carrying terminals
Arc runners

Air Blast C.B

Airblast is a type of Air circuit breaker in which High air pressure is Filled. Air Blast circuit breakers are used for different purposes. The voltage range of the Airblast breaker is between 11kv to 1100kv.

This circuit breaker has different properties: mechanically strong, fast switching, Auto reclosure, simple assembly, unit type multi-break, etc.

Air Circuit Breaker (Types , Advantages and Disadvantages ) - Electronicsinfos

We used an Air Receiver to maintain the air pressure in the compressor plant. This circuit breaker is useful for repeated switching work. for example, in railways, arc furnaces etc.

This circuit breaker is also used in interconnected lines where fast switching is important. The pressure range in the air blast C.B. is between 18 to 20 kg/cm2.To maintain the pressure we need a compressed air plant in which air is gathered in the air reservoir.

The different parts of the Air Blast circuit breaker are

Tank Air Reservoir
Hollow insulator assembly
double arc extinction Chamber
pneumatic Operating mechanism
operating rod
pneumatic valve
connection for current
arching horns optional
Resistance switching unit

The main principle of the Air Circuit breaker is high interruption resistance so we provide insulation through the gasses for example nitrogen and carbon dioxide etc. There are different types of air blast circuit breakers W.r.t Direction of airflow including

Types of Airblast C.B

Axial-Blast Air Breaker
Cross Blast Air Breaker
Radial Blast Breaker

Axial-Blast Air Breaker

An axial-blast air circuit breaker is a type of air blast C.B. in which air is entered in the direction of the arc to distinguish the arc.

The fixed and moving contacts are connected in normal conditions with the help of a spring. The Air reservoir is attached to the Air valve in the air chamber.

This valve is normally in close condition when faults occur the value opens with the help of a tripping impulse. The difference between the contacts is 1.75cm. this low distance does not provide enough insulation clearance.

Cross Blast Air Breaker

The Direction of Air is at 90 degrees Concerning the arc they cross each other that's why this breaker is called cross blast air breaker.

when moving contacts are separated the arc is produced in the fixed and moving contacts.

The Arc enters through the chute that consists of arc splitters. The plates of arc splitters depend on the capacity of the beaker. The splitter is used to increase the arc length.

Radial Blast Breaker

A Radial Blast is an air blast circuit breaker in which blast air is entered radially into contact space. Those circuit breakers with a Double air system are also called radial air blast systems. The arc time is low in this type of breaker.

Advantages Of Air circuit breaker

This circuit breaker is safe from Fire.
The equipment size is small because of the low final contact gap.
The arching time is low due to the fast recovery of dielectric strength.
This is suitable for Repeated Switching operations.
The Efficiency of the breaker At all currents is the same.
The Arc medium is free from decomposition.
The Air is naturally available.
The switching operation is fast.
The Circuit breaker needs a low level of maintenance.
To obtain the high breaking capacity we connect in series.
The operation is reliable
An air circuit breaker is a low weight.
The construction of contacts is simple.

Disadvantages Of Air circuit breaker

The Compressed air system is complex
The cost is high
This CB needs skilled labour to operate.
This is sensitive due to the increase in the recovery voltages.
The dielectric strength is low for Air.
Air leakage is possible in the compressor.
The current chopping is brutal.
This system needs an auxiliary high-pressure system.

Applications of air circuit breaker

ACBs are used for main power distribution to protect and control the power supply.
They safeguard equipment like transformers, generators, and capacitors.
ACBs control power station auxiliaries and industrial plants.
CBs are preferred in environments with a fire or explosion risk, as they do not use oil like older oil circuit breakers.
ACBs can be found in distribution panels to protect circuits over 800 Amps to 10K Amps.

Conclusions

In conclusion, air circuit breakers are reliable, and environmentally friendly devices used for electrical protection in a wide range of applications.

Their ability to handle high fault currents, ease of maintenance, and rapid arc extinction make them a preferred choice for many electrical systems.