With the continuous development of modern science and technology, new technology new materials continue to emerge, the circuit breaker production process and various materials continue to improve the performance of circuit breaker has been greatly improved, in addition to the international well-known brands, such as ABB, Schneider, some domestic companies are not far behind, by developing or the introduction of foreign advanced technology, and to digest and absorb, also launched a mature product to the market.

Such products have zero flying arc, high broken, large capacity, the direction of entry and exit can be interchangeable, intelligent and quadrupole, internal annex modular structure, installation blocks, miniaturization and other characteristics. To achieve selective protection function and a variety of auxiliary functions required by motor circuit protector, and with the communication interface, the low-voltage distribution system automation and networking possible; reduce the dynamic and thermal stability of low-voltage power distribution equipment requirements; narrow distribution equipment volume; greatly improves the reliability of the power supply system and equipment operation.

However, at present in some electrical design, reasonable selection of motor circuit protector and unsatisfactory, often ignore the selected manufacturers of MCCB specifications, models, accessories and other electrical parameters, especially the electrical parameters of some new understanding of MCCB through, marked incomplete, application categories, applications and uses are not considered week. The MCCB is not appropriate to set factory orders difficult, the protection of selective variation, sensitivity, rationality does not meet the design requirements, not only the motor circuit protector did not make the best use, but the cause of the waste, reduce the reliability of power distribution system, the influence of industrial production and people's life. For this reason, this article talks about some views on the correct selection of MCCB in combination with the commonly used parameters and national standards about MCCB.