An arc chamber for low-voltage circuit breakers, whose particularity consists of the fact that it comprises: multiple substantially U-shaped metallic plates; an enclosure made of insulating material which is substantially shaped like a parallelepiped and comprises two side walls, a bottom wall, a top wall and a rear wall, the side walls having, on the inside, multiple mutually opposite slots for the insertion of the metal plates, the bottom and top walls each having at least one opening and the enclosure being open at the front.
It is known that molded case power circuit breakers are normally used in industrial low-voltage electrical systems, i.e., systems operating at up to approximately 1000 Volt. Said circuit breakers are usually provided with a system which ensures the nominal current required for the various users, the connection and disconnections of the load, protection against any abnormal conditions, such as overloading and short-circuit, by automatically opening the circuit, and the disconnection of the protected circuit by opening the moving contacts with respect to the fixed contacts (galvanic separation) in order to achieve full isolation of the load with respect to the electric power source.
The critical function of interrupting the current(whether nominal, overload or short-circuit current) is provided by the circuit breaker in a specific portion of said circuit breaker which is constituted by the so-called deionizing arc chamber. As a consequence of the opening movement, the voltage between the contacts causes the dielectric discharge of the air, leading to the forming of the electric arc in the chamber. The arc is propelled by electromagnetic and fluid-dynamics effects inside a series of metal plates arranged in the chamber, which are meant to extinguish said arc by cooling. During arc forming, the energy released by Joule effect is very high and causes thermal and mechanical stresses inside the plate containment region.
