Protective function of circuit breaker

Circuit breaker refers to a switching device that can close, carry and break current under normal circuit conditions and can close, carry and break current under abnormal circuit conditions within a specified time. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The division of high and low voltage is relatively fuzzy. Generally, those above 3kV are called high-voltage electrical appliances.

Circuit breakers 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 experience serious overload, short circuit, or undervoltage faults. Its function is equivalent to a fuse switch Combination with overheating and underheating relays, etc. Moreover, it is generally not necessary to change parts after breaking the fault current. At present, it has been widely used.

Wiring method of circuit breaker:

1. Wiring mode behind the board:

The biggest feature of the wiring behind the board is that the circuit breaker can be replaced or repaired without rewiring, just disconnect the front-level power supply. Due to the special structure, the product has been equipped with special mounting plates and mounting screws and wiring screws according to the design requirements when leaving the factory.

Special attention should be paid to the fact that the contact reliability of the large-capacity circuit breaker will directly affect the normal use of the circuit breaker. Therefore, attention must be paid to the installation and the installation must be carried out in strict accordance with the requirements of the manufacturer.

2. Plug-in wiring:

On the mounting board of the complete set of equipment, first install a circuit breaker mounting seat, 6 plugs on the mounting seat, and 6 sockets on the circuit breaker connection board. There are connecting plates on the surface of the mounting base or bolts behind the mounting base, and the mounting base is pre-connected with power cords and load lines. When in use, insert the circuit breaker directly into the mounting base. If the circuit breaker is broken, just pull out the broken one and replace it with a good one.

Its replacement time is shorter than the front and back wiring of the board, and it is convenient. A certain amount of manpower is required for plugging and unplugging. Therefore, for China's plug-in products, the frame current is limited to a maximum of 400A. This saves maintenance and replacement time. When installing the plug-in circuit breaker, check whether the plug of the circuit breaker is tightly pressed, and securely fasten the circuit breaker to reduce contact resistance and improve reliability.

3. Drawer type wiring:

The in and out drawer of the circuit breaker is rotated clockwise or counterclockwise by the rocker. The plug-in structure is adopted in the main circuit and the secondary circuit, and the isolator necessary for the fixed type is omitted, so that one machine can be used for two purposes.

It improves the economy of use, and at the same time brings great convenience to operation and maintenance, and increases safety and reliability. In particular, the main circuit contact holder of the drawer seat can be used in common with the NT type fuse circuit breaker contact holder.