Small circuit breaker introduction and small circuit breaker production trade exporters recommended

Small Circuit Breaker is one of the most widely used terminal protection appliances in building electrical terminal distribution devices.
Should be like the selection of moulded case Circuit Breakers and frame circuit breakers, calculate the maximum short circuit capacity before selection.
The design and use of Mini Circuit Breaker is for 50~60Hz AC power grid, such as for direct current circuit, should be based on the manufacturer provided by the magnetic trip action current and power frequency change coefficient to convert; When the ambient temperature is greater than or less than the calibrated temperature value, the rated current value of the circuit breaker must be adjusted according to the temperature and current carrying capacity correction curve provided by the manufacturer.
The short-circuit current of the low-voltage distribution line is related to the cross section of the power supply line, the way of laying the wire, the distance between the short-circuit point and the power supply, the capacity of the distribution transformer, the percentage of impedance and other electrical parameters.
General industrial and civil building distribution transformers low-voltage side voltage is mostly 0.23/0.4kV, transformer capacity is mostly 1600kVA and below, the low-voltage side line short-circuit current increases with the increase of distribution capacity. The short circuit current at the low voltage feeder end is different for different capacity configurations. Generally speaking, for residential buildings, small shopping malls and public buildings, due to the low-voltage power grid power supply by the local power supply enterprises, the cable or overhead wire cross-section of the power supply line is smaller, and the distance between the electrical equipment and the power supply is far away, the small circuit breaker with 4.5kA and above breaking capacity can be selected.
For users who have a special supply or a 10kV transformer station, often because the cable section of the power supply line is thicker and the power supply distance is short, a small circuit breaker with a rated breaking capacity of 6kA and above should be selected. For similar occasions such as the transformer distribution station (the lighting and power supply used in the station are directly from the low-voltage total bus) and the large-capacity workshop transformer distribution station (for the workshop electrical equipment), the power supply distance is short, you must choose a small circuit breaker with a breaking capacity of 10kA and above, and pay special attention to the specific selection: the rated breaking capacity of the small circuit breaker is in the upper terminal into the line and under Measured when the terminal is out of line.
In the project, if the lower terminal into the line and the upper terminal out of the line are required under special circumstances, due to the reason of arc-extinguishing when the fault current is broken, the miniature circuit breaker must be used in reduced capacity, that is, the rated breaking capacity must be converted according to the relevant capacity reduction coefficient provided by the manufacturer. The protection characteristics of mini circuit breaker according to IEC898 are divided into A, B, C, D four characteristics for users to choose :A feature is generally used for the use of fast, no delay trip, that is, for the lower peak current value (usually 2 to 3 times the rated current In), to limit the allowed through the short circuit current value and the total breaking time, the use of this feature can make a small break The device replaces the fuse as the overcurrent protection of electronic components and the protection of the mutual inductance measurement circuit; The B feature is used in applications where fast tripping is required and the peak current is not very large.
Compared with the A characteristic, the peak current allowed by the B characteristic is less than 3In, which is generally used for the protection of resistive loads such as incandescent lamps and electric heaters and residential lines; Characteristic C is suitable for most of the electrical circuit, it allows the load through the high short-term peak current and the small circuit breaker does not operate, characteristic C allows the peak current <5In, used for fluorescent lamp, high voltage gas discharge lamp, power distribution system line protection; The D feature is suitable for very high peak current (<10In) circuit breaker equipment, can be used for AC rated voltage and frequency of the control transformer and local lighting transformer primary line and solenoid valve protection.