1, Different types: MCCB is molded case circuit breaker, while MCB is Miniature Circuit Breaker
2, Different installation location: MCCB is installed in the middle of the line, while MCB is used in the load end;
3, Different breaking ability: mccb's breaking ability is better than MCB's breaking ability
4, Different size: mccb's volume is bigger than MCB's volume. A circuit breaker is a switching device that can close, load and break the current under normal loop conditions and can close, load and break the current under abnormal loop conditions within a specified time. Circuit breakers are divided into high-voltage circuit breakers and low-voltage circuit breakers according to their scope of use. The boundary between high and low voltage is blurred. Circuit breakers can be used to distribute electrical energy, start asynchronous motors infrequently, protect power lines and motors, etc. , and automatically cut off circuits when they have serious overloads or short-circuits or under-voltages, etc. , its function is equivalent to the combination of fuse-type switch and overheat relay. And generally do not need to change parts after breaking the fault current. At present, it has been widely used.
5, Different load should choose different types of circuit breakers the most common load distribution lines, motors and household and similar household (lighting, household appliances, etc.) three categories. Accordingly, there are distribution protection type, motor protection type and household and similar household protection type circuit breakers. The protective properties and characteristics of these three types of circuit breakers are different. For distribution circuit breakers, there are Class A and Class B: Class A is non-selective, class B is selective. The so-called selective type refers to the circuit breaker with overload long delay, short-circuit short delay and short-circuit instantaneous three-section protection characteristics. Most of the DW15 series, DW17(ME) series, AH series and DW40, DW45 series of universal (also called frame type) circuit breakers are B-type, however, DZ5, DZ15, DZ20, TO, TG, CM1, TM30 and HSM1 series and some specifications of Universal DW15, DW17 only have two-stage protection of overload long-delay and short-circuit instantaneous, they are non-selective class A circuit breakers. Selective protection, as shown in Figure 1. When the f-point is short-circuited, only the QF2 circuit breaker near the f-point acts, while the QF1 circuit breaker in the upper position does not, this is known as selective protection (keeping power on the QF3 and QF4 branches that are not malfunctioning because QF1 does not act) . If QF2 and QF1 are Class A circuit breakers, a short circuit will occur at F point. When the short circuit current reaches a certain value, QF1 and QF2 will act at the same time, and the circuit of QF1 circuit breaker and its branches will all be out of power, it's not selective protection. The reason for selective protection is that QF1 is a class B circuit breaker with short-circuit short-delay performance. When f-point is short-circuit, short-circuit current flows through QF2 branch and QF1 circuit, qF2 instantaneous action release action .
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