What is an Arc Chute? Definition and Working Principle

Arc chute is made from an arranged set of metal plates. These metal plates are insulated from each other and arranged in parallel. This insulation provides safety, division, and cooling to extinguish an electric arc. This is also known as arc divider or arc splitter. Arc chute can be found in high current interruption devices such as circuit breaker, contactor, and insulator. 

Everytime a circuit breaker operates by interrupting high current, there will be an electric arc generated. An electric arc is the discharge of an electric current through gas or air. Conduction of electrical charge through the plasma generating gas, which glows. The electric arc generates heat which can melt the breaker contacts and even damage the circuit breaker itself. To avoid that, the arc must be extinguished safely and effectively. This part serves for this purpose.

what is an arc chute

What is an Electric Arc

An electric arc is also known as arc discharge. This arc is produced from electrical breakdown and produces electrical discharge with the gas as its medium. When the electric discharge is moving through nonconductive material such as air, it produces plasma with a visible light characteristic. This visible light can be seen easily with naked eye.

Electric arc relies on thermionic emission of electrons from the electrodes supporting the arc. An electric arc is formed from electric discharge of highest current density. Its maximum current depends on the external circuit, not by the arc.

What is an Arc Chute

When we are searching about this we will find that:

An arc chute is the set of insulating barriers inside a circuit breaker to confine and prevent the arc from damaging other parts.

This is built from nonmetallic or metallic fins with air gaps in between. These fins will suppress the arc which is generated when we open the circuit. When the high current circuit is breaking, the big arc is produced and needs to be suppressed.

Arc Chute Working Principle

Electric arc forms between the contacts when the circuit breaker interrupts the flow of current to the load during normal operation. In the event of a short circuit, the arc that is formed will be more intensive than a normal arc. The metal plate in the arc channel is made of ferromagnetic material. Therefore the arc that is formed is attracted towards the plate and moves towards the arc channel through the arc runner by itself.

When faults occur such as short-circuit and overload, the circuit breaker will immediately interrupt the electric current only by moving apart the contacts. This is when an electric arc occurs, when the circuit breaker is separating the contacts from each other. The arc has a high temperature and produces a lot of heat. This heat can damage the circuit breaker and even melt it. In order to eliminate this damage, arc chute is necessary.

As it reaches this place, the structure of the arc chute widens the arc further and splits it into small segments. This increases the length of the arc. Hence it cools down and eventually gets extinguished.

what is an arc chute
Figure 1

Observe the working principle below:

  1. When the arc is generated, it will move towards the metal plates used for arc chute. These plates are made from ferromagnetic material.
  2. The arc inside it is scattered and divided into small parts.
  3. This will cause the arc length to become longer to cool it down.
  4. After a period the arc will extinguish.

From the Figure.(1) above we can see that:

  1. When the arc chute in a circuit breaker is operating, it will attract the arc into position 1 and move to position 2, and then position 3.
  2. From this movement, the arc widens each time it moves.
  3. After moving to the last point (position 3), the arc scatters into small sizes.

And this is how arc chute works.

Frequently Asked Questions

Why Are arc chutes used?

As it reaches the arc chute, the structure of the arc chute widens the arc further and splits it into small segments. This increases the length of the arc. Hence it cools down and eventually gets extinguished.

What is the function of arc chute in MCB?

The arc runner and arc chute limit and dissipate the arc energy during the interruption of an overload or short circuit event. During an overload or short circuit event, the contacts of the breaker separate and an electrical arc is formed between the contacts through air.

What Are arc chutes made of?

Arc chute is made from an arranged set of metal plates. These metal plates are insulated from each other and arranged in parallel.

What Are arc chutes what are their primary functions?

These fins will suppress the arc which is generated when we open the circuit. When the high current circuit is breaking, the big arc is produced and needs to be suppressed.

What is arc chute definition?

An arc chute is the set of insulating barriers inside a circuit breaker to confine and prevent the arc from damaging other parts.

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