There are commonalities between all circuit breakers but many functions will vary
depending on the voltage class, current rating, and type of circuit breaker. The main function of all circuit breakers is to detect a fault, whether in the device itself (common in small and low voltage breakers) or otherwise. Once a fault is detected the breaker must disrupt the charge by separating the contacts. The contacts in a circuit breaker are typically separated using a spring or compressed air. Another common way to separate the contacts is through the use of the extra current itself, in higher voltage breakers this is commonly done with thermal expansion or a magnetic field. When the contacts are separated the electrical current can create an arch that will heat the contacts considerably. For this reason, it is important that the contact is made with a highly conductive metal capable of withstanding the heat when the contacts are separated, typically copper or silver. The heat generated in the arch must also be contained and cooled in order for the contacts to once again be able to conduct the current necessary for a working breaker. The following are some of the ways in which cooling takes place:
Division into partial arcs
Intensive cooling (in jet chambers)
Lengthening or deflecting the arc
Connecting capacitors in parallel with contacts in DC circuits.
Its no doubt that circuit breakers are a feat of engineering and very helpful in our
everyday lives. Although you might have never given it any thought, these devices are both
sophisticated and pretty cool.