At present, in our market, air circuit breakers 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, accessories add more abundant protection functions and control modes to the circuit breaker, so that it can be applied and protected. The way of operation and installation is 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 improper selection, it can not only play a protective role, but will cause great economic losses. This paper will analyze the function and application of the internal accessories of air circuit breaker, and bring you the function and application of the external accessories later.

Function and application of internal accessories for air circuit breakers:

1. Auxiliary contacts: contacts mechanically linked with the main circuit breaking mechanism of air circuit breaker for indicating the breaking/closing state of the circuit breaker.

The auxiliary contacts are connected in the control circuit of the air circuit breaker, and the related electrical appliances are controlled or interlocked by the switch's closing. Conventional air circuit breakers are equipped with six pairs of contacts (three normally open and three normally closed), and DW45 series has eight pairs of contacts (four normally open and four normally closed).

2. Alarm contact: alarm contact for ACB circuit breaker.

When the alarm contacts are released only after the air circuit breaker is released, and when the load of the circuit breaker appears overload short circuit or undervoltage and other faults and freely trips, the alarm contacts are transferred from the original normally open position to the closed position, and the indicators, bells or buzzers in the auxiliary circuit are connected to show or remind the breaker of failure.

3. Shunt release: release for voltage source excitation.

The shunt release is an attachment for remote operation. When the supply voltage is between 70% and 110% of the rated voltage, the circuit breaker can be reliably broken. Distribution tripper is a short-term working system, the coil power-on time can not exceed 1 s, otherwise the coil will be burned.

4. Undervoltage tripper: When the terminal voltage drops to a certain set value, it is used for delayed or non-delayed disconnection of ACB circuit breaker.

Undervoltage trippers are used for delayed or non-delayed disconnection of universal circuit breakers when the power supply voltage falls to 35%-70% of the rated operating voltage. When the power supply voltage is equal to or greater than the rated working voltage of 85% undervoltage tripper, the reliable closure of circuit breaker can be guaranteed under thermal conditions; when the power supply voltage is equal to or lower than the rated working voltage of the tripper, the undervoltage tripper should prevent the closure of the circuit breaker. When in use, the undervoltage tripper coil is connected to the power supply side of the circuit breaker. After the undervoltage tripper is electrified, the circuit breaker can close, otherwise the circuit breaker can not close.