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How Circuit Breaker Arc Chutes Work

How Circuit Breaker Arc Chutes Work

(OP)
can someone explain how circuit Breaker Arc Chutes help to extinguish arcs during on and off operations?

RE: How Circuit Breaker Arc Chutes Work

Ever seen a Jacobs Ladder? Youtube has many of them.

That is exactly how Arc Chutes work.

Hot air rises and arcs are the hottest 'air' on earth.

Keith Cress
kcress - http://www.flaminsystems.com

RE: How Circuit Breaker Arc Chutes Work

The functioning depends on what kind of chute and current it is.

For a DC arc, there are blow magnets that force the arc from the contacts into the chutes where they are divided into shorter arcs, which are easier to extinguish. The arcs are prolonged when moving outwards, which decreases V/m and are also cooled by the chute walls. There used to be some agent released from the chute walls, but that is either hearsay or simply not true. The action of this agent was to make life for the arcs harder and, thus, kill them faster.

For an AC arc, the arrangement is similar. But the magnets are usually coils, so that the blowing action is in the same direction, independent on current polarity. There are also consideration regarding short circuit forces and the current path is shaped so that the forces work the "right" way.

Gunnar Englund
www.gke.org
--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

RE: How Circuit Breaker Arc Chutes Work

The arc is formed when contacts separate and as they separate, the arc acts kind of like a capacitor to increase the voltage potential across them, which allows the arc to sustain itself for a dangerous amount of time until the dielectric of the air is enough to extinguish it. The arc chute is a series of plates in the path of that arc that split it up into smaller segments, lowering the energy in each arc segment to where it need less dielectric strength (of air) to extinguish it, or really, to not allow it to sustain itself any longer. The arc chute also serves to cool the thermal energy in the arc. Without arc chutes, the breaker contacts would need to be a lot larger and the heat energy of the arcs would deteriorate it much faster.

It provides no function when closing the breaker, only when opening it.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

RE: How Circuit Breaker Arc Chutes Work

Many but not all arc chutes have an arrangement of parallel metal plates called de-ion plates. These break up the arc and cool the arc, de-ionizing the arc so that it will not re-strike during the next cycle. I have seen arc chutes that only served to contain the arc and let it stretch out until it extinguished itself. I have seen chutes used with and without de-ion plates and I have seen a lot of devices that use the de-ion plates without a chute.
Interrupting an arc with a chute without the help of de-ion plates takes up a lot more space.

Bill
--------------------
"Why not the best?"
Jimmy Carter

RE: How Circuit Breaker Arc Chutes Work

(OP)
Thank you all for the pointers.

RE: How Circuit Breaker Arc Chutes Work

We should invent a kids game related to our industry, Arc Chutes and Jacob's Ladders.


"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

RE: How Circuit Breaker Arc Chutes Work

Actually the configuration of the arcing contacts creates the Jacobs ladder effect, then the chutes take over. Arc chutes use arc runners to draw the arc up into the arc chute where it is broken up and dissipated. There are two basic types of arc chutes, insulated fin and metal fin.

Insulated fin arc chutes use non conductive plates that are used to stretch the path the arc takes to make it longer and therefore making cooling and dissipation of the arc easier. 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”.

MV breakers may use blow out coils and puffers to aid in the process.

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