It can not only contact and break the circuit, but also protect the short circuit, serious overload and undervoltage of the circuit or electrical equipment, and can also be used for motors that are not started frequently.
Extended data
major function
Under normal circumstances, the armature of the overcurrent release is released; In case of serious overload or short circuit fault, the coil connected in series with the main circuit will generate strong electromagnetic attraction, which will attract the armature downwards and push the unlocking hook to disconnect the main contact. The working principle of undervoltage release is just the opposite. When the voltage is normal, electromagnetic attraction attracts the armature and the main contact is closed.
Once the voltage drops seriously or the power is cut off, the armature is released and the main contact is disconnected. When the power supply voltage returns to normal, it must be switched on again to work, thus realizing voltage loss protection.
The tripping mechanism of the switch is a set of connecting rod devices. When the main contact is closed by the operating mechanism, it is locked in the closed position by the locking hook. If there is a fault in the circuit, the related trip will release the lock hook in the trip mechanism, so the main contact will be quickly disconnected under the action of the trip spring.
Baidu encyclopedia-air switch