Detailed explanation of the working principle of the circuit breaker

When the system fails, the protection of the faulty component and the failure of the circuit breaker fails to trip, the protection of the faulty component acts on the adjacent circuit breaker of the substation to trip, and the channel can be used to make the remote related circuit breaker simultaneously. The wiring of the trip is called breaker failure protection.

Generally, after the phase-phase component of the phase-separated phase is operated, two sets of starting contacts are output, and when the line, the mother-link or the segmented circuit breaker fails, the fail-safe protection is started in series with the external action protection contact.

The role of the circuit breaker

Circuit breakers are mainly used in motors with frequent breaking loads and large-capacity transformers and substations. The circuit breaker has the function of breaking the accident load and cooperates with various relay protection to protect the electrical equipment or the line.

The circuit breaker is generally used in low-voltage lighting, the power part can play the role of automatically cutting off the circuit; the circuit breaker has many functions such as overload and short-circuit protection, but the load at the lower end is problematic and needs to be repaired. The role of the circuit breaker is not enough.

There is now a circuit breaker with isolation function that combines the functions of a common circuit breaker and an isolating switch. The circuit breaker with isolation function can also isolate the switch. In fact, the isolating switch can not be operated with load, but the circuit breaker has short circuit, overload protection, under voltage protection and so on.

Detailed explanation of the working principle of the circuit breaker

Basic: The simplest circuit protection device is a fuse. The fuse is just a very thin wire, plus a protective sleeve and then connected to the circuit. After the circuit is closed, all current must flow through the fuse—the current at the fuse is the same as the current at the other points on the same circuit. This fuse is designed to allow it to blow when the temperature reaches a certain level. Burning the fuse can create an open circuit, preventing excessive current from damaging the wiring of the house. The problem with the fuse is that it only works once. Whenever the fuse is blown, it must be replaced with a new one. The circuit breaker can function the same as the fuse, but can be used repeatedly. As long as the current reaches a dangerous level, it can immediately create an open circuit.

The basic working principle: the live wire in the circuit is connected to both ends of the switch. When the switch is placed in the on state, current flows from the bottom terminal, sequentially through the electromagnet, the moving contactor, the static contactor, and finally flows out from the top terminal. The current can magnetize the electromagnet. The magnetic force generated by the electromagnet is enhanced with the increase of the current, and if the current is decreased, the magnetic force is also weakened. When the current jumps to a dangerous level, the electromagnet generates a large enough magnetic force to pull a metal rod that is connected to the switch linkage. This causes the moving contactor to tilt and leave the static contactor, which in turn cuts off the circuit. The current is also interrupted. The bimetal strip design is based on the same principle, the difference being that there is no need to energize the electromagnet, but the metal strip is bent at high current, which in turn activates the linkage. Some circuit breakers also rely on filling explosives to displace the switch. When the current exceeds a certain level, the explosive material is ignited, and then the piston is opened to open the switch.

Enhanced: More advanced circuit breakers eliminate simple electrical equipment and use electronic devices (semiconductor equipment) to monitor current levels. Ground Fault Circuit Interrupter (GFCI) is a new type of circuit breaker. This type of circuit breaker not only prevents damage to the wiring of the house, but also protects people from electric shock.

Enhanced working principle: GFCI constantly monitors the current on the neutral and live wires in the circuit. When everything is ok, the current on both lines should be identical. Once the line of fire is directly grounded (for example, if someone accidentally touches the line of fire), the current on the line will suddenly increase sharply, while the zero line will not. GFCI will immediately cut off the circuit after detecting this condition to prevent electric shock and casualties. Since GFCI can take action without waiting for the current to rise to dangerous levels, its response speed is much faster than conventional circuit breakers.