What is Arc Chute?
Arc chute is consisting of metallic or nonmetallic fins positioned in the equal air gap. It is used to quenching the arc being produced during circuit is opening. During high current breaking, the arcs are prolonged when moving outwards, arc chute decreases the voltage to distance (V/m) ratio. And the temperature can be reduced by the chute surface.
Working Principle of Arc Chute
Do you know? how does arc form?
Just take an example, an Air circuit breaker carries 1500 Amps at 690V. As you know the distance between the male and female contact for the air circuit breaker is 20mm. Consider Male contact is connected at the input side and female contact is connected at the output side.
Suddenly a short circuit occurred between two lines at anywhere in the output side, and due to this, the short current flow rises to 12000kA.
What happens Now?
The relay associated with the circuit breaker sends the opening command to the breaker, hence breaker opens the circuit at 12000kA of current flowing.
When opening the circuit, the high current tries to reach the source. Therefore, the current (charges) ionizes the air surrounded by the breaker contact. It will be achieved too.
Therefore, ionize air conduct electricity. Finally, the conduction of electric charges through gas produces plasma, it glows with very high temperate and it moves outside.
While moving outside, the fin placed in the arc chute divides the arc into several parts. Hence the conduction will be broken. Finally, the arc will get extinguished. Look at the picture the MCB is quenching the arc.
Metallic and Non-metallic arc chute:
For small rating we use a non-metallic type which will be placed very nearer to the contacts, the best example is Siemens 3TF 47 contactors.
But for high current rating application, we should use metallic fins made up of ferromagnetic material and it will be placed little away from the contacts.
Metal fin arc chutes utilize magnetic fields to aid in breaking up the arc into several smaller arcs so that the heat can be dissipated easier; these arc chutes are sometimes referred to as “splitters”.
The best example for metallic arc chute is Siemens 3 WT circuit breaker.
Also so current interrupting devices come along with the metal chutes.
