NEWS & KNOWLEDGE

A Circuit Breaker is a switching device that can close, pass and break current under normal loop conditions, and can close, pass and break current under abnormal loop conditions within a specified time. Circuit breakers are classified into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The distinction between high voltage and low voltage is relatively fuzzy. Generally, those above 3kV are called high-voltage electrical appliances.

Circuit breakers can be used to distribute electrical energy, start asynchronous motors infrequently, protect power lines and motors, etc., and automatically cut off the circuit in the event of severe overload, short circuit and undervoltage faults. Its function is equivalent to a fuse switch with overheating and overheating relays. In addition, after disconnecting the fault current, there is usually no need to replace parts.

In the generation, transmission and use of electricity, power distribution is a very important link. The power distribution system includes transformers and various high-voltage and low-voltage electrical equipment. Low-voltage circuit breakers are widely used electrical appliances.

The circuit breaker usually consists of a contact system, an arc extinguishing system, an operating mechanism, a trip unit and a housing. When a short circuit occurs, the magnetic field generated by a large current (usually 10 to 12 times) overcomes the reaction force spring, the trip unit pulls the operating mechanism, and the switch instantly trips. When overloaded, the current becomes larger, the heating increases, and the bimetal deforms to a certain extent to push the mechanical device to move (the larger the current, the shorter the action time).

The function of the circuit breaker is to cut off and connect the load circuit, as well as cut off the fault circuit, to prevent the expansion of the accident and ensure safe operation. The high-voltage circuit breaker needs to disconnect the 1500V, current 1500-2000A arc, these arcs can extend to 2m, and continue to burn without being extinguished. Therefore, arc extinguishing is a problem that must be solved by high-voltage circuit breakers.

The principle of arc blowing and arc extinguishing is mainly to cool the arc to reduce thermal decomposition. On the other hand, by blowing the arc to lengthen the arc to enhance the recombination and diffusion of charged particles, while blowing away the charged particles in the arc gap to quickly restore the dielectric strength of the medium.

Low-voltage circuit breakers are also called automatic air switches, which can be used to connect and disconnect load circuits, and can also be used to control motors that start infrequently. Its function is equivalent to the sum of some or all electrical appliances such as knife switch, overcurrent relay, voltage loss relay, thermal relay and leakage protector. It is an important protective electrical appliance in the low-voltage power distribution network

- Mar 18, 2021-