What are the accessories of the miniature circuit breaker？

Miniature Circuit Breaker is just a current dependent switch which when tripped will turn itself OFF, interrupting power in case of an overload or short circuit. Various additional functions can be realized when the circuit breaker is used with various accessories such as alerts, shunt trip, under-voltage protection, etc. 

Usually, the Max number of accessories assembled on the circuit breaker is three.

For all these functions, there are specific accessories which turn a single-purpose Miniature Circuit Breaker into a multi-purpose assembly. Commonly used accessories are:

1. Auxiliary Contact
2. Alarm Auxiliary
3. Shunt Tripper
4. Under-voltage / Over-voltage Tripper
5. Busbar
6. Handle Lock-Off Attachment

All of these accessories attach easily to the Miniature Circuit Breaker and provide a great level of functionality for control and automation applications.

What is an auxiliary contact?

Linked with ON, OFF mechanism of main circuit of circuit breaker, mainly used for indication of circuit breaker ON, OFF status. To connect it into control circuit of breaker, through ON and OFF of circuit breaker, the auxiliary contact can take control or interlock to related electrical device.

What is an Alarm Auxiliary?

The Alarm Auxiliary accessory indicates when a Miniature Circuit Breaker or Supplementary Protector is tripped. A trip can be a result of an overload, short-circuit, operation of Shunt-trip accessory, or Undervoltage / Overvoltage module.

Unlike a standard auxiliary, the Alarm Auxiliary will change its contacts state only in case of tripping.

Its contacts can be used in the actuation circuit of audible alarm or visual indication, which will signal the operator about a fault in the system. These contacts can also be used in Digital Input arrangement for use in a SCADA system.

What is a Shunt tripper?

lt is a tripper used for voltage source excitation, its own voltage can be independent from the voltage of main circuit. 

So, shunt tripper is an auxiliary of remote-control tripping, can disconnect circuit by remote, to liaison with fire alarm system. Can also remote control to trip off by Emergency stop button.

What is an Under-voltage / Over-voltage Tripper?

A standalone Miniature Circuit Breaker provides protection only against over-current and short circuit. 

When an Under-voltage / Over-voltage module is used it will trip the miniature circuit breaker or supplementary protector in the event the applied voltage across its coil terminals is out of the specified band.

In short, an under-voltage / over-voltage tripper is useful for protection against voltage dips and swells. Once supply recovers to normal, only then can the breaker be turned ON. This accessory provides a cost-effective and easy way to implement this solution.

What is a Busbar?

In electric power distribution, a busbar (also bus bar) is a metallic strip or bar.

Typically housed inside switchgear, panel boards, and busway enclosures for local high current power distribution. At the same time, it can reduce wiring work and reduce wiring time.

What is a Handle Lock-Off Attachment?

A handle lock-off for MCB prevents the accidental or deliberate switching off of certain electrical circuits.

For example, during panel maintenance when the supply is cut off, a lock-off attachment is placed on the circuit breaker along with a padlock to prevent unauthorized access and an undesired or harmful event.

Conclusion

When the miniature circuit breaker functionality is expanded with the use of accessories, the value of the Miniature Circuit Breaker is increased. Provides multiple uses for electrical equipment and electrical professionals in terms of safety and protection against electrical faults, making application realization easy and cost effective.