There are three types of air circuit breaker tripping methods: thermal, electromagnetic and double tripping.
When the line is generally overloaded, the overload current can not make the electromagnetic release action, but can cause the heat element to generate a certain amount of heat, causing the bimetal to be bent upwards by heating, pushing the lever to disengage the hook from the lock, and the main touch The head is broken and the power is turned off. When the line is short-circuited or severely overloaded, the short-circuit current exceeds the instantaneous trip setting current value, and the electromagnetic tripper generates a sufficient suction force to attract the armature to the impact lever, causing the hook to rotate upwardly around the shaft seat and disengage the lock. The lock buckles the three main contacts under the action of the reaction force spring to cut off the power.
The trip mechanism of the switch is a set of linkage devices. When the main contact is closed by the operating mechanism, it is locked by the lock hook in the closed position. If a fault occurs in the circuit, the relevant trip unit will act to disengage the lock hook in the trip mechanism, so that the main contact is quickly broken by the release spring. According to the different protection effects, the trip unit can be divided into an overcurrent release and a voltage loss release.