For the use of four pole circuit breaker, take CM1 as an example:

The four pole MCCB is divided into four types: A, B, C and D.

Type a-N pole is not equipped with over-current release, and N-pole is always on and is not combined with other three poles.

Type B - N-pole is not equipped with over-current release, and N-pole is combined and separated with other three poles.

Type C - N-pole is equipped with over-current release, and N-pole is combined with other three poles.

Type D - N pole is equipped with over-current release, and N-pole is always on and is not combined with other three poles. Here are two questions to note:

1 in the case of using four pole MCCB, it is necessary to indicate which one of the products is selected, because it is the same as four pole, but whether there is an over-current release installed on the n-line, its function and purpose are different. The over-current release is installed on line n, which can be used in the line with single-phase load of three-phase and four wire distribution, or in the non-linear load generating a large number of harmonics, such as gas discharge lamp, thyristor dimming and speed regulating line, or other occasions with special requirements. MCCB with n-wire without over current release can be selected for general equipment circuit.

2 in fact, although the two types A and D are called four pole circuit breakers, their N-poles are always connected and are not combined and separated with other three poles. Therefore, such MCCB is commonly known as "false four pole", which is not essentially different from the three pole MCCB. The only useful thing is that in the complete cabinet, the line may be more convenient to enter and exit. Therefore, this type of MCCB can only be used in three pole situations. If the choice is wrong, it will not only play a protective role, but also have to have a big problem. This is the most disordered problem in design and use at present, which should be paid attention to.