1p, 2p, 3P and 4P refer to the number of poles of the miniature circuit breaker, which represents how many lines can be broken. The miniature circuit breaker is mainly the breaking line (L). Secondly, there are 1p + N and 3P + n. n is the zero line. When the miniature circuit breaker breaks the fire line, it also cuts off the zero line.

微型断路器能够分断火线，主要是断路器设置了脱扣装置。假设有一个4P、20A的微型断路器和一个3P+N、20A的微型断路器，零线电流25A，那种微型断路器会自动跳闸？

The miniature circuit breaker can disconnect the live wire, mainly because the circuit breaker is equipped with a tripping device. Suppose there is a 4P, 20A miniature circuit breaker and a 3P + N, 20A miniature circuit breaker with a zero line current of 25A, which miniature circuit breaker will trip automatically?

前面提到了微型断路器的核心装置，脱扣装置，此装置具有热磁脱扣功能。

The core device of the miniature circuit breaker, tripping device, has the function of thermal magnetic tripping.

脱扣器采用的是磁线圈，当电流足够大时产生的磁场力克服反力弹簧吸合衔铁打击牵引杆从而带动机构动作切断电路。

The release adopts a magnetic coil. When the current is large enough, the magnetic field force generated overcomes the reaction spring to attract the armature to strike the traction rod, so as to drive the mechanism to act and cut off the circuit.

例如，短路、过载都会引起电路中有很大的电流。短路不比多说，火零相碰即为短路，意思说电回路中没有负载，只有导线和电源了，由于电源内阻和导线的线电阻是非常小的，在电压不变的情况，突然整个电回路电阻变得很小，就有很大很大的电流产生，称之为短路。过载一般是指用电设备的超负荷工作，工作电流超过了规定的额定电流。

For example, short circuit and overload will cause a large current in the circuit. Short circuit is no more than short circuit. Fire zero collision is short circuit, which means that there is no load in the electrical circuit, only the conductor and power supply. Because the internal resistance of the power supply and the line resistance of the conductor are very small, when the voltage remains unchanged, suddenly the resistance of the whole electrical circuit becomes very small, there is a large current, which is called short circuit. Overload generally refers to the overload operation of electrical equipment, and the working current exceeds the specified rated current.

微型断路器接火线，必须要经过脱扣器，否则起不到短路、过载保护。例如这个问题，假设有一个4P/20A的微型断路器和一个3P+N/20A的微型断路器，零线电流25A，那种微型断路器会自动跳闸？

The grounding wire of the miniature circuit breaker must pass through the release, otherwise it will not have short circuit and overload protection. For example, in this problem, suppose there is a 4P / 20A miniature circuit breaker and a 3P + n / 20A miniature circuit breaker with a zero line current of 25A, which kind of miniature circuit breaker will trip automatically?

根据上述可知，肯定是4P、20A的微型断路器跳闸，3P+N、20A断路器不会跳闸，除非把N线接到了P上面，本应接N的通道接了火线，才可能跳闸。

According to the above, it is certain that the miniature circuit breakers of 4P and 20A trip, and the circuit breakers of 3p + N and 20A will not trip. Unless the N line is connected to P and the channel that should be connected to n is connected to the live line, it can trip.