Circuit breaker
What is a circuit breaker? It refers to the switching device that can turn on, carry and break the current under normal circuit conditions and turn on, carry and break the current under abnormal circuit conditions within the specified time. The circuit breaker is divided into high-voltage circuit breaker and low-voltage circuit breaker according to its scope of use. The high and low voltage boundaries are relatively vague, and the ones above 3kV are generally called high-voltage electrical appliances. The circuit breaker can be used to distribute electric energy, start asynchronous motors infrequently, protect power lines and motors, etc., and automatically cut off the circuit when they have serious overload, short circuit, undervoltage and other faults. Its function is equivalent to the combination of fuse switch and over/under heat relay. In addition, it is generally not necessary to change parts after breaking the fault current. At present, it has been widely used. Power distribution is an extremely important link in the generation, transmission and use of electricity. The power distribution system includes transformers and various high and low voltage electrical equipment, and the low-voltage circuit breaker is a widely used electrical appliance. Working principle of the circuit breaker: when there is a short circuit, the magnetic field generated by the large current (generally 10 to 12 times) overcomes the reaction spring, the release pulls the operating mechanism to act, and the switch trips instantaneously. When the overload occurs, the current becomes larger, the heat generation intensifies, and the bimetallic sheet deforms to a certain extent to push the mechanism to act (the greater the current, the shorter the action time). The function of the circuit breaker is to cut off and connect the load circuit and cut off the fault circuit to prevent the accident from expanding and ensure safe operation. The high-voltage circuit breaker needs to break 1500V and 1500-2000A arcs, which can be stretched to 2m and still burn. Therefore, arc extinguishing is a problem that must be solved for high-voltage circuit breakers. Classification of circuit breakers: according to the number of poles: single pole, two pole, three pole and four pole; According to the installation mode, it can be divided into plug-in type, fixed type and drawer type. The circuit breaker structure is composed of auxiliary contact, alarm contact, shunt release, undervoltage release, electric operating mechanism, rotating operating handle, extended handle, handle locking device and other parts.