MCB development mode of analysis

Mainly in the low voltage circuit breakers for power distribution network used to distribute power and protect power lines and equipment against overcurrent (including overload and short circuit) and other hazards. Once the power supply is ideal for a distribution network in over-current fault occurs at the department promptly tripped circuit mcb circuit breakerbreaker removal failure. And neither the hazard further expanded, does not cause the other in series with the supply line circuit breaker tripped for no reason, and affect supply.

Residential Distribution Protection of the fifties and sixties was originally mostly simple knife switch and fuse (ceramic plug-RC1) combination. Short circuit occurs, the whole house was dark, replace the fuse inconvenient. The late sixties to the seventies China has successively developed DZ5, DZ12, DZ15 series molded case circuit breaker poles. The late seventiesbreaker Beijing Switch Factory introduction of German technology and the transfer of domestic manufacturers S060 series miniature circuit breakers, but for various reasons are not large-scale promotion. Eighties, the late, Tianjin Merlin Gerin C45N and produced many domestic manufacturers produce miniature circuit breaker DZ47 series of large-scale production, so I breakers for overcurrent protection for countries rose to a new level.

Entering the new century, people's material life has been further improved, power distribution systems in residential areas of application for automation and high reliability have become increasingly demanding. However, in real circuit protection application process often lead to the same level fault current circuit breaker tripped while even the phenomenon of grade trip. To ensure the reliability of the power distribution system and to reduce its impact in the event of failure to just within the scope of the fault point, we should increase its performance in addition, also be connected in series for ways to improve the distribution network, lower circuit breaker protection coordination between the selective way.

Selective protection of low voltage circuit breaker is actually two or more between the over-current protective devices with an overcurrent. It simply is the next level of protection within the scope of protection of electrical short-circuit, over-current fault should be the protection of electrical action, does not operate on a protective device, and when the protection of electrical tripping, the only action on a protection meter of electrical To sub-ranges and have to prioritize requirements.

According to GB14048.2-2008 "Low-voltage switchgear and control equipment - Part 2: Circuit Breaker" provisions of the standard, can be divided into the following two categories:

Full Optional: the two series overcurrent protective device, the load side of the protective device to implement protection without causing the other overcurrent protective devices selective protection.

Local Optional: the two series overcurrent protective device, the load side of the protective device over a given current value and do not result in the less protected in the other overcurrent protective devices selective protection.