How To Choose A, B, C, And D Types of Miniature Circuit Breakers?(3)

3. Differences and applications of miniature circuit breakers

A. For miniature circuit breakers, 1P+N, 1P, 2P are generally used as the on-off control of single-phase electrical appliances

(1) Difference:

1P single-pole circuit breaker: with thermal trip function, can only control the live wire (phase wire), the horizontal number is 18 mm.

1P+N single-pole+N circuit breaker: control the live wire and neutral wire at the same time, but only the live wire has thermal tripping function; the horizontal number is also 18 mm.

2P single-phase 2-level circuit breaker: control the live wire and neutral wire at the same time, and both have thermal tripping function, the horizontal number is 2*18 mm=36 mm.

(2) Application:

* In order to reduce costs, 1P can be used. However, the upper-level circuit breaker must have the function of leakage tripping. In order to prevent accidents caused by the disorder of live and neutral lines, the upper-level power supply must be cut off.

* To avoid 1 problem during maintenance, 1P+N can be used.

* Reason for using 2P: For the same 18mm module circuit breaker case, there is a difference between 1P and 1P+N inside. The former "ultimate breaking capacity" in a short-circuit accident state is higher than the latter, after all, space is an important factor affecting the breaking capacity. Therefore, it is better to use 2P (higher cost) for power circuits that are more important, frequently overhauled and operated, and prone to failures.

* The premise of using 1P is that the lighting distribution box must have the function of leakage tripping, and at least the incoming line (or the upper level of the outgoing line) must use a residual current circuit breaker.

* It is perfectly fine to use 1P+N for ordinary socket circuits, but if you want to add leakage current, it will not work, because 1P+N circuit breakers cannot be assembled with leakage protection accessories and other electrical accessories.