Contact Us+8613505873345

Search

The working principle of molded case circuit breaker

Jan 19, 2019

The main contact of the low voltage circuit breaker is manually operated or electrically operated. After the main contact is closed, the free tripping mechanism locks the main contact in the closing position. The coil of the over-current tripping device and the thermal element of the thermal tripping device are connected in series with the main circuit, and the coil of the under-voltage tripping device is connected in parallel with the power supply.

When the circuit short circuit or serious overload occurs, the armature of the over-current tripping device is absorbed to make the free tripping mechanism operate and the main contact is disconnected from the main circuit.

When the circuit is overloaded, the thermal element of the thermal tripping device heats up and makes the bimetallic sheet bend, pushing the free tripping mechanism to move, and the main contact disconnects the main circuit.

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

When the shunt tripping button is pressed, the shunt tripping armature is absorbed to make the free tripping mechanism operate and the main contact disconnects the main circuit.