Air circuit breaker, also known as frame circuit breaker, is a mechanical switching device that can switch on, load and break the current under normal circuit conditions, and can also switch on and load a certain time and break current under specified abnormal circuit conditions.

At present, in our market, air circuit breaker are mainly divided into DW15, DW16, DW17 (ME), DW45 and other series, the products are composed of ontology and accessories. ACB circuit breaker itself does not have any accessories, but it can effectively divide and close the circuit, automatically cut off the line to protect the load when the circuit or equipment overload, short circuit and other accidents occur; and as the derivation and supplement of the function of circuit breaker, the accessories add more abundant protection functions and control modes to the circuit breaker, making its application, protection, operation and installation more abundant. Circuit breaker accessories have become an integral part of circuit breakers. But the more accessories, the better. Users need to use the accessories rationally according to the actual control and protection lines to avoid unnecessary waste. At the same time, when selecting the type, they need to distinguish the voltage level, AC or DC, the logarithm of auxiliary contacts and so on. If improperly chosen, it will not only play a protective role, but also cause great economic losses.

Intelligent air circuit breaker is suitable for 50Hz AC, 380V, 660V rated voltage and 200A-6300A rated current distribution network. It is mainly used to distribute electric energy and protect lines and power supply equipment from overload, undervoltage, short circuit, single-phase grounding and other faults. The circuit breaker has a variety of intelligent protection functions, which can achieve selective protection, accurate action and avoid unnecessary. Power failure, improve the reliability of power supply. Universal circuit breaker is used to distribute electric energy and protect the overload, undervoltage, short circuit of power line and power equipment. Under normal conditions, it can be used as the infrequent conversion of line. Circuit breakers below 1250A can be used to protect motor from overload and short circuit in the network with 50Hz AC voltage 380V. Under normal conditions, it can also be used as an infrequent starting of motor.

The ACB circuit breaker refusing to interrupt may have the following kinds of faults and solutions.

1. Button failure
Button mechanical failure or poor contact of conductor contacts will make the tripping circuit impassable, resulting in no electricity of the shunting trip coil, the armature can not be sucked, and the circuit breaker can not be broken.

2. Breakdown of Excitation Releaser
Open circuit or short circuit of shunt trip coil and obstacle of armature engagement all affect trip of circuit breaker. Therefore, it is necessary to inspect the shunt tripper regularly, remove the obstacles affecting the armature suction, and replace the coils with open or short circuit in time to ensure that the circuit breaker can be quickly broken when the circuit needs to be disconnected.

3. Failure of free release mechanism
The contact surface between the tripping half-axis and the tripping half-axis of the free tripping mechanism is too large (usually 2~3mm2), which will make the circuit breaker refuse to break. Therefore, the adjusting screw is used to make the tripping half-axis rotate at a certain angle to meet the requirements of the contact surface of 2~3mm2, and low temperature extreme pressure grease is applied on the contact surface to reduce friction and facilitate the tripping.