Circuit breakers consist internally of two parts, a thermal protection and a magnetic protection: Thermal protection: Protects against circuit overloads, the current passes through a bimetallic switch which, when heated, expands and hits the mechanism of the device to open the contact and disconnect it. Magnetic protection: It is in charge of protecting the circuit against short circuits, it consists of an electromagnet, it works in such a way that when a very high current circulates it generates a magnetic force, thus attracting a piece that opens the contact of the device.