How does the molded case circuit breaker work?

Promulgator : TAIXIDate : 2017-05-25Views : 217

The circuit breaker refers to the closing, carrying and breaking current loop normal conditions, and can close, carrying and breaking abnormal circuit conditions within the prescribed period of time (including short-circuit conditions) under current switching device. At present, it has been widely used. So how does a molded case circuit work? What is his working principle?

Molded case circuit breaker is generally composed of a contact system, an arc extinguishing system, operating mechanism, release, shell and other components. When short circuit, high current (typically 10 to 12 times) the magnetic field generated by overcoming reaction spring release, pulling the operating mechanism. The instantaneous tripping switch. When the intelligent low voltage circuit breaker is overloaded, the current increases and the heat gain is increased. The bimetallic plate deforms to a certain extent and pushes the mechanism to move (the greater the current, the shorter the operation time). Now there are electronic type, using mutual inductor to collect each phase current size, and compared with the set value, when the current is abnormal, the microprocessor sends out the signal, causes the electronic release to drive the operating mechanism movement.


The function of MCCB (molded case circuit breaker) is to cut off and switch on the load circuit, and to cut off the fault circuit, so as to prevent the accident from expanding and ensure the safe operation. The high voltage circuit breaker to break 1500V, the current is 1500-2000A arc, these molded case circuit breaker arcs can be stretched to 2m, still continue to burn. Therefore, arc extinction is a problem that must be solved for HV circuit breakers.

The principle of arc blowing arc quenching is the main cooling heat weakened arc free, on the other hand by blowing arc arc elongated reinforced composite and the diffusion of charged particles, while the charged particles dispersed in the arc gap, the insulation strength rapid recovery medium. Low voltage circuit breakers, also known as automatic air switches, can be used to switch on and off load circuits, and can also be used to control motors that do not start frequently. It functions as a switch, over-current relay, voltage collapse relay, thermal relay and electrical leakage protector, part or all of the sum function, is a kind of important protective devices in low voltage distribution network. Isolated circuit breaker has many kinds of protection functions (overload, short circuit, undervoltage protection, etc.), adjustable operation value, high breaking capacity, easy operation, safety and so on, so it is widely used now. Structure and working principle, low voltage circuit breaker consists of operating mechanism, contact, protection device (various release device), arc extinguishing system and so on.