Working principle of molded case circuit breaker

The main contact of low-voltage circuit breaker is manually operated or electrically closed. After the main contact is closed, the free tripping mechanism locks the main contact at the closing position. The coil of the over-current release and the thermal element of the thermal release are connected in series with the main circuit, and the coil of the undervoltage release is connected in parallel with the power supply< Br>In case of short circuit or serious overload in the circuit, the armature of the overcurrent release will be pulled in to make the free tripping mechanism act, and the main contact will disconnect the main circuit< Br>When the circuit is overloaded, the heating of the thermal element of the thermal release makes the bimetallic sheet bend, pushes the free tripping mechanism to act, and the main contact disconnects the main circuit< Br>When the circuit is undervoltage, the armature of the undervoltage release will also make the free release mechanism act, and the main contact will disconnect the main circuit< Br>When the shunt release button is pressed, the armature of the shunt release is pulled in to make the free tripping mechanism act, and the main contact disconnects the main circuit< br>