The working principle of miniature circuit breaker and installation precautions

Miniature circuit breaker is a kind of terminal protection electrical appliance, and it is the most widely used in building electrical terminal power distribution device. It is used for single-phase and three-phase short-circuit, overload, overvoltage protection under 125A, including single-pole 1P, two-pole 2P, three-pole 3P, and four-pole 4P. Today we will understand the working principle of the miniature circuit breaker and the matters needing attention in installation.

working principle:

The miniature circuit breaker is composed of operating mechanism, contacts, protection devices (various trip units), arc extinguishing system, etc. The main contact is 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 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. When the circuit is short-circuited or severely overloaded, the armature of the overcurrent release pulls in, causing the free tripping mechanism to operate, and the main contact disconnects the main circuit. When the circuit is overloaded, the heating element of the thermal trip unit will bend the bimetal and push the free trip mechanism to move. When the circuit is under-voltage, the armature of the under-voltage release is released. The free trip mechanism is also activated.

Install:

The installation of the circuit breaker needs to meet the requirements of the GB13955-92 standard and instructions.
The installation of the circuit breaker should fully consider the power supply line, power supply mode, power supply voltage and system grounding type.
The rated voltage, rated current, short-circuit breaking capacity, and breaking time of the circuit breaker should meet the requirements of the protected power supply line and electrical equipment.
The installation and wiring of the circuit breaker should be correct. The wiring of the residual current protector in the single-phase, three-phase three-wire, and three-phase four-wire power supply systems of different system grounding forms is different, so full attention should be paid.
The above is a brief description of the miniature circuit breaker. You still need to pay attention to safety during the installation process, especially when no one is watching over.