The leakage circuit breaker is assembled by the DZ47 series circuit breaker and the leakage protector (usually called the trip unit). The circuit breaker part mainly includes the following components.
1) Overcurrent release (double gold, electromagnetic system);
2) Arc extinguishing device (arc extinguishing system);
3) Contact system;
4) Shell and terminal block;
5) Operating mechanism (handle, lock, jumper, lever).
The realization of the overload protection function of the circuit breaker is based on the principle that the bimetal is oriented and bent regularly as the temperature rises. The bending angle of the normal current (1.13In) is not large, so the thrust is not enough to trip the tripping mechanism. When the overload is reached The current (1.45In) has a large bending angle, and the thrust is sufficient to push the tripping mechanism to disconnect the switch. This is the principle of overload protection.
The short-circuit protection function of the circuit breaker is realized by the instantaneous release (electromagnetic system). The electromagnetic force is proportional to the product of the current and the number of turns. Because the instantaneous release has a small number of coil turns (generally only less than 10 turns), although The instantaneous release is connected in series in the circuit. When the circuit is working normally, due to the small number of turns, the suction force generated by the normal working current is not enough to overcome the reaction force of the spring, so the circuit can work normally, but for the short-circuit current, due to the generated The current is different from the normal working current by several times or even dozens of times or more. The number of turns of the coil has not changed, but the current has increased several times or even dozens of times, so the suction force has also increased several times or even dozens of times, as long as the reaction force Reasonable selection of springs can meet the setting requirements of B-type, C-type and D-type instantaneous releases.