Circuit Breaker Arc Chute

Midwest sometimes is asked to explain what an arc chute does.

Circuit breaker arc chute.

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. In air blast circuit breaker or in breaker where a gas flow is present between the electrical contacts the heat loss of arc plasma occurs due to convection process. The major components of such breakers are. The electric arc is formed between the contacts of a circuit breaker when it interrupts the current flow to load during normal operation.

For excitement read the patent application for an old circuit breaker arc chute if you can stay awake. How do arc chutes extinguish an arc. Circuit breakers use arc chutes to deionize the air and interrupt the flow of short circuit current. Hvdc circuit breakers and hvdc gis at kema labs tests successfully.

Arc chutes can be found inside circuit breakers contactors isolators and other high current interruption devices. We always go for the short version. Medium voltage air circuit breakers found in an industrial environment are usually of the draw out type meaning the breaker is movable and can be separated racked out or connected racked in to the power source using either a manual or electrically operated racking device. Heat loss from an arc in circuit breaker is takes place through conduction convection as well as radiation.

There are two sets of contacts in such breakers named as main contacts and arcing contacts. An arc chute for a circuit breaker characterized by a pair of spaced side walls for an interior arc extinguishing chamber the surfaces of the walls forming the chamber being covered with a coating of an arc resistant ceramic material such as aluminum oxide zirconium oxide chromic oxide magnesium oxide and calcium oxide. The basic characteristics for air magnetic circuit breakers are maximum rationalization and constructional simplicity. The arc chutes for molded case circuit breakers and old power breakers look simple enough but they actually are a complex design and perform extremely important functions.

The air helps quench the arc by pushing it up into the arc chute. Construction of an air circuit breaker arc chute type used for low and medium voltage is shown in the figure. The poles the arc chutes the base frame the operating mechanism. The arc chutes with metal plates provide segmentation of the arc in a number of shorter arcs that burn between a set of parallel plates metal plates are generally made of steel because of its ferromagnetic property that helps to attract the arc and keep it inside the stack.

There are two basic types of arc chutes insulated fin and metal fin. In circuit breaker with plain break arc in oil arc in chutes or narrow slots nearly all the heat loss due to conduction. Arc chutes use arc runners to draw the arc up into the arc chute where it is broken up and dissipated.