How does a circuit breaker work?

Circuit breakers are used in all household and business electrical systems, and are capable of shutting off the flow of electricity when too much current flows through the electrical system.

A basic electrical circuit is like a closed circuit. Sometimes, there is a fault condition which, if allowed to continue, will create an overvoltage that will damage the device to which the electricity is flowing or otherwise cause a fire or other forms of damage. There are also cases where an overload occurs and the electrical circuit (cables) carries a load or load that is beyond the capacity for which the cables are made. The wires get hot and their insulation melts. When the insulation melts, there is a cut in the insulation or other conductive material touching both sides of the cables, causing electricity to jump from one node of the cable to another. This causes a short circuit, explosion, or fire.

Circuit breakers are designed to break the circuit and shut off the flow of electricity. These circuit breakers are manufactured according to a set current or electricity carrying capacity and when the actual load goes beyond this, the circuit breaker turns off.

The basic circuit breaker is made up of a switch and a movable contact plate that moves when the switch is moved. If the switch switch is in the "on" position, the movable contact plate contacts a stationary contact plate that connects to the electrical circuit system. This means that the electric current is a complete circuit. When the circuit breaker detects a short circuit or an overvoltage, it cuts off the flow of electricity by switching to "off" and disconnecting the movable contact plate from the fixed contact plate, opening the circuit.

One type of circuit breaker uses electromagnetism where the electromagnet is on the circuit breaker. The magnetism increases with the load, but when it exceeds the designated load, the electromagnet increases. At this point, that pull is powerful enough to lower the lever and move the moving contact plate away from the fixed contact plate and breaks the flow of electricity.

A second type is a thermal circuit breaker that uses heat to open the circuit. There is a bimetallic strip made up of two different types of metal with different heating capacities that are welded together. The heat caused by the electricity flowing through the circuit will cause the metal strip to bend but at different speeds. When the electric current exceeds the capacity of the switch, the metal strip bends at such an angle that it would pull the switch lever, disconnecting the movable contact plate from the stationary contact plate and breaking the connection.

The third type of switch uses a combination of thermal and electromagnetism. The electromagnet pulls the lever down in the event of a sudden electrical surge, while the bimetal strip operates when there is a current overload that causes overheating. https://www.singaporeink.net/2020/04/16/ho-ching-says-more-covid-19-cases-got-no-symptoms-and-there-is-one-huge-hidden-cluster-in-migrant-worker-dormitories/