The circuit breaker is generally composed of contact system, arc extinguishing system, operating mechanism, decoupler, housing, etc.
When a short circuit occurs, the magnetic field generated by the high current (generally 10 to 12 times) overcomes the counterforce spring and the decoupler pulls the operating mechanism into action, tripping the switch in an instant. When the power is overloaded, the current becomes larger, the heat generation intensifies, and the bimetal is deformed to a certain degree to push the mechanism into action (the larger the current, the shorter the action time).
There are electronic types, using mutual transformers to collect the size of the current of each phase, compared with the set value, when the current is abnormal, the microprocessor sends a signal to make the electronic decoupling drive the operating mechanism action.
The role 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 to open 1500V, the current is 1500-2000A arc, these arcs can be stretched to 2m still continue to burn without extinguishing. Therefore, arc extinguishing is a high-voltage circuit breakers must solve the problem.
The principle of blowing arc extinguishing is mainly to cool the arc to weaken the heat free, on the other hand, the arc is stretched by blowing arc to strengthen the composite and diffusion of charged particles, while the charged particles in the arc gap blown away, quickly restore the dielectric strength of insulation.
