Low voltage air circuit breaker is also called the automatic air switch or air switch, belong to the switch electrical appliances, is used when circuit overload, short circuit and under-voltage fault breaking the circuit automatically when the electric appliances, also can be used as not frequent start motor or open circuit, low voltage air circuit breaker has universal type circuit breaker, molded case circuit breaker, mini circuit breakers, leakage circuit breaker, etc.
First, the structure of low-voltage circuit breaker:
1, main contact (1 in the figure below), connect or disconnect the main circuit.When manual or electric closing, the main contact is closed, when the circuit short circuit, overload, undervoltage of the main contact is disconnected.
2. Free trip mechanism:
The function of the free trip mechanism (2 in the figure below) is to lock the main contact on the closing position after the main contact is closed, and unlock the trip when the protection mechanism moves.
Arc extinguishing system: when the main contact is disconnected, the iron grating in the fire extinguishing room will induce strong magnetism.The arc is drawn into the grid and burned in sections to protect the contacts from damage.
4, tripping device:
(1), over current trip (3 in the picture below), (2) thermal trip (5 in the picture below), (3) under voltage trip (6 in the picture below), (4) separation trip (4 in the picture below).
5, operating mechanism, used for opening and closing operation.
Two, the principle of low-voltage circuit breaker:
The schematic diagram of the low-voltage circuit breaker is shown below
1. After manual or electric closing, the free tripping mechanism locks the main contact on the closing position, and the main circuit is connected.
2. The coil of the overcurrent release and the thermal element of the overcurrent release are connected in series with the load. When the circuit is short-circuited or seriously overloaded, the armature of the overcurrent release is closed to promote the action of the free release mechanism.
3. When the circuit is overloaded, the thermal element of the thermal release device heats up, bending the bimetal sheet, jacking up the free release mechanism and disconnecting the main contact.
4. In the figure above, the coil of the under voltage trip is connected in parallel between L1 and L2. When the power supply voltage is under voltage, the coil attraction of the under voltage trip is insufficient, and the armature is pulled by the spring to push the free trip mechanism to move.
5. Shunt tripper is used for remote control. The coil is powered off during normal operation.
