The circuit breaker is generally composed of contact system, arc extinguishing system, operating mechanism, tripping device, shell, etc. When the short circuit, the large current (typically 10 to 12 times times) generated by the magnetic field to overcome the counter-force spring, the release of the operating mechanism pull the action, switching instantaneous tripping.
When overloaded, the current becomes larger, the calorific value intensifies, the bimetal plate deforms to a certain extent to promote the mechanism action (the larger the current, the shorter the action time).
Electronic type, using a transformer to collect the current size of each phase, compared with the set value, when the current is abnormal when the microprocessor sends a signal, so that the electronic tripping device to drive operating mechanism action. The function of the circuit breaker is to cut off and turn on the load circuit, and cut off the fault circuit, prevent the accident to enlarge and ensure safe operation. The high-voltage circuit breaker to open 1500V, the current is 1500-2000a arc, these arc can be elongated to 2m still continue to burn not extinguished.
So the arc extinguishing is a problem that must be solved by HV circuit breaker.
The principle of arc-blowing is that the cooling arc weakens the heat free, and on the other hand, the composite and diffusion of charged particles is strengthened by the arc-blowing, and the charged particles in the arc gap are blown away, and the dielectric strength is quickly restored. Low-voltage circuit breakers, also known as automatic air switches, can be used to connect and break load circuits, or to control motors that do not start frequently. Its function is equivalent to the knife switch, over current relay, voltage loss relays, thermal relays and electric leakage protector and other electrical parts or all of the total function, is a low-voltage distribution network An important protection of electrical appliances.