ABB micro circuit breaker consists of operating mechanism, contact, protection device (various release device), arc extinguishing system and so on. The main contact is operated by hand or by electric closing. After the main contact is closed, the free tripping mechanism locks the main contact at the closing position. The coil of the over-current release and the thermal element of the heat release are connected in series with the main circuit, and the coil of the undervoltage release is connected in parallel with the power supply. When the circuit is short circuited or seriously overloaded, the armature of the over-current release device is pulled in, so that the free tripping mechanism is operated, and the main contact is disconnected from the main circuit. When the circuit is overloaded, the heat element of the heat release device is heated to bend the bimetallic plate, and the mechanism of the free tripping mechanism is driven. When the circuit is under voltage, the armature of the undervoltage release is released. The free tripping mechanism is also operated.

　　ABB miniature circuit breaker, referred to as MCB (Micro Circuit Breaker), is the most widely used terminal protection device in building electrical terminal power distribution equipment. For 125A below the single-phase, three-phase short-circuit, overload, over-voltage protection, including unipolar 1P, diode 2P, three pole 3P, quadrupole 4P and other four kinds.

　　⑴ 断路器与断路器的配合应考虑上级断路器的瞬时脱扣器动作值，应大于下级断路器出线端处最大预期短路电流，若由于两级断路器处短路时回路元件阻抗值差别小，使之短路电流值差别不大，则上级断路器可选择带短延时的脱扣器。

　　⑵ 限流断路器在短路电流大于或等于其瞬时脱扣器整定值时，将会在数毫秒内脱扣，故下级保护电器不宜用断路器实现选择性保护要求。

　　⑶ 具有短延时的断路器，当其时限整定在最大延时时，其通断能力下降，因此，在选择性保护回路中，考虑选择断路器的短延时通断能力应满足要求。

　　⑷ 还应考虑上级断路器的短路延时可返回特性与下级断路器的动作特性时间曲线不应相交，短延时特性曲线与瞬时特性曲线间不应相交。

　　⑸ 断路器与熔断器配合使用时应考虑上下级的配合，应将断路器的安秒特性曲线与熔断器安秒特性曲线比较，以使在发生短路电流的情况下，具有保护选择性。

　　⑹ 断路器作配电线路的保护时，宜选用带长延时动作过流脱扣器的断路器，当线路末端发生单相接地短路时，短路电流不小于断路器瞬时或短延时过流脱扣器整定电流的1.5 倍。

　　SH200-B 系列微型断路器

　　型号 极数 额定电流 (A)

　　SH201-B6 1 6

　　SH201-B10 1 10

　　SH201-B13 1 13

　　SH201-B16 1 16

　　SH201-B20 1 20

　　SH201-B25 1 25

　　SH201-B32 1 32

　　SH201-B40 1 40

　　SH201-B50 1 50

　　SH201-B63 1 63

　　SH201-B6NA 1+NA 6

　　SH201-B10NA 1+NA 10

　　SH201-B13NA 1+NA 13

　　SH201-B16NA 1+NA 16

　　SH201-B20NA 1+NA 20

　　SH201-B25NA 1+NA 25

　　SH201-B32NA 1+NA 32

　　SH201-B40NA 1+NA 40

　　SH201-B50NA 1+NA 50

　　SH201-B63NA 1+NA 63

　　SH202-B6 2 6

　　SH202-B10 2 10

　　SH202-B13 2 13

　　SH202-B16 2 16

　　SH202-B20 2 20

　　SH202-B25 2 25

　　SH202-B32 2 32

　　SH202-B40 2 40

　　SH202-B50 2 50

　　SH202-B63 2 63

　　SH203-B6 3 6

　　SH203-B10 3 10

　　SH203-B13 3 13

　　SH203-B16 3 16

　　SH203-B20 3 20

　　SH203-B25 3 25

　　SH203-B32 3 32

　　SH203-B40 3 40

　　SH203-B50 3 50

　　SH203-B63 3 63

　　SH203-B6NA 3+NA 6

　　SH203-B10NA 3+NA 10

　　SH203-B13NA 3+NA 13

　　SH203-B16NA 3+NA 16

　　SH203-B20NA 3+NA 20

　　SH203-B25NA 3+NA 25

　　SH203-B32NA 3+NA 32

　　SH203-B40NA 3+NA 40

　　SH203-B50NA 3+NA 50

　　SH203-B63NA 3+NA 63

　　SH204-B6 4 6

　　SH204-B10 4 10

　　SH204-B13 4 13

　　SH204-B16 4 16

　　SH204-B20 4 20

　　SH204-B25 4 25

　　SH204-B32 4 32

　　SH204-B40 4 40

　　SH204-B50 4 50

　　SH204-B63 4 63