The characteristics and selection principle of circuit breaker

Miniature circuit breaker, miniature circuit breaker is also called, advanced structure, reliable performance, high breaking capacity, compact appearance and other characteristics, is suitable for AC 50/60Hz rated voltage 230/400V, rated current to 63A overload and short-circuit protection circuit used in normal circumstances can not frequent operation into line with. The miniature circuit breakers are mainly used in various places such as industry, commerce, high rise and civil residence. Here is a brief introduction to the characteristics of small circuit breakers and the principles of selection.

(a) characteristics

1), rated short circuit breaking capacity, some of the rated current level can reach more than 10KA.

2), dual wiring function, can be easily connected to the standard bus and soft wire.

3), with finger touch protection combined type of terminal, higher security.

4), with the energy storage type mechanism operation, the contact point is closed quickly, which overcomes the adverse effect caused by the speed of the manual operation handle, and improves the service life of the product.

5), a variety of accessories to choose from, and modular, flexible combination, user installation is very convenient.

6), the shell and parts of the function of the use of foreign imports of high flame retardant, high temperature resistance, impact resistant plastic.

7), the limiting factor is high, performance price ratio.

(two) the load current must be less than or equal to the rated current in the range of the rated current when the circuit breaker is selected.

Usually divided into C type and D type, type, C type for distribution, type D for power. In order to avoid the motor at the start of the circuit breaker overload break, so the electric motor and the like to choose D type. A lot of electrical appliances in the power of the moment, due to the internal capacitance, the instantaneous current will be relatively large. So in the choice of open space, must pay attention not only in accordance with the current stability after the election, to choose a higher level model in the choice of when.

Breaker is a protective device, its function is short circuit protection and short-circuit protection is the most important parameter is the ability of the short circuit current. If a short circuit accident occurs, the circuit breaker will act in an instant. But the circuit breaker segment ability is less than the short circuit current, the arc is unable to extinguish. Therefore, in the choice of circuit breaker, to calculate the expected short circuit current, to ensure that the circuit breaker segment capacity than the expected short circuit current.