The release is a component of the low voltage circuit breaker used to accept the signal. If the line is not normal or by the operator or relay protection device to send a signal, Circuit Breakers the release will be based on the signal through the transmission components to contact the switch off the switch off the circuit. Low-voltage circuit breakers are generally over-current release, thermal release, Circuit Breakers loss of voltage release, shunt release, and several several.
When the low-voltage circuit breaker is put into operation, the operating handle has closed the main contact, and the free trip mechanism locks the main contact in the closed position, and the various releases are in the running state.
1. Electromagnetic release
The electromagnetic trip unit is connected in series with the protected circuit. Line through the normal current, the electromagnetic force generated by the electromagnetic force is less than the reaction force of the spring, the armature can not be sucked by the electromagnet, the circuit breaker normal operation. When the short circuit fault occurs in the line, the current exceeds the normal current several times, Circuit Breakers the electromagnetic force generated by the electromagnet is greater than the reaction force of the spring force, the armature by the electromagnet suction through the drive mechanism to promote the free release mechanism to release the main contact. The main contact in the sub-gate under the action of the separation circuit to play a short circuit protection.
The thermal release is connected in series with the protected circuit. When the line through the normal current, the heating element heating so that bimetal bending to a certain extent (just contact with the transmission) and to achieve a dynamic equilibrium state, bimetallic no longer continue to bend. Circuit Breakers If there is an overload phenomenon, the current in the line increases, the bimetallic will continue to bend, push the free trip mechanism through the transmission mechanism to release the main contact, the main contact under the action of the sub-gate spring, cut off the circuit to play overload protection The role of.
Loss of voltage release in parallel to the circuit breaker power measurement, can play the role of undervoltage and zero pressure protection. When the power supply voltage is normal, Circuit Breakers the operating handle is pulled, the normally open auxiliary contact of the circuit breaker is closed, the electromagnet is energized, the armature is sucked by the electromagnet, Circuit Breakers and the free tripping mechanism can lock the main contact in the closing position and the circuit breaker is put into operation The When the power side of the power outage or power supply voltage is too low, the electromagnetic force generated by the electromagnetic force is not enough to overcome the reaction of the spring force, the armature is pulled up, through the drive mechanism to promote the free trip mechanism to open the circuit breaker, And zero pressure protection.
When the power supply voltage is 75% ~ 105% of the rated voltage, the voltage relief device ensures that the circuit breaker is closed. When the supply voltage is less than 40% of the rated voltage, Circuit Breakers the depressor release ensures that the circuit breaker is disconnected. It is also possible to use a normally closed button in series in the solenoid loop of the voltage relief release.