Zhejiang Jinji Electric Co.

The main contact of the low-voltage circuit breaker is either manually operated or electrically closed. After the main contact is closed, the free trip mechanism locks the main contact in the closing position. The coil of the overcurrent tripper and the thermal element of the thermal tripper are connected in series with the main circuit, and the coil of the undervoltage tripper and the power supply are connected in parallel.

When the circuit is short-circuited or seriously overloaded, the armature of the overcurrent tripper is engaged, so that the free tripping mechanism acts, and the main contact disconnects the main circuit.

When the circuit is overloaded, the heat of the thermal element of the thermal tripper bends the bimetal sheet, which pushes the free trip mechanism to act, and the main contact disconnects the main circuit.

When the circuit is under-voltage, the armature of the under-voltage tripper is released, which also makes the free tripping mechanism act, and the main contact disconnects the main circuit.

When the shunt trip button is pressed, the armature of the shunt tripper engages to make the free tripping mechanism act, and the main contact disconnects the main circuit.