What is circuit breaker?


Circuit breakers it's switching device which designed to control the currents movement. It can be used to turn on / off as well as for carrying currents in certain conditions. Such device protects whole system from short circuit.


  1. Working principle of circuit breaker
  2. Circuit breaker design
  3. Types of trip mechanisms

Working principle of circuit breaker

Structural features and the operation principle of the circuit breakers are determined by their application and purpose. Such devices has a huge number of different types. Circuit switches are classified by:

  • type of current in the network;
  • design;
  • number of poles in circuit;
  • current limiting;
  • installation type;
  • availability of free contacts.

Such devices are also made with different degrees of protection and drive types. Switching is performed in manual and automatic modes by using drives.

At rated current more than 1000A, a manual drive is used. Such function ensures the fastest possible switching.

Electromotive and electromagnetic drives are supplied directly from power source.

Turning of the device on the limiting short-circuit current is interrupted at 85-110% of nominal value of the supply voltage. This allows turning off circuit in time and avoiding further damage to other system elements. In the case of an overload and short circuit, device triggering also occurs when the handle is holding in turn-on position.

Circuit breaker design

New models of circuit breakers are releasing every day. However, overall design is more or less the same and consists of following basic parts:

  1. Arc suppression systems.
  2. Tripping mechanisms.
  3. Contact systems.
  4. Control mechanisms.

Device contact system consists of fixed and moving groups of contacts. Some are coupling to the body, while others models with hinge are located on the half-axis of control mechanisms.

Arc suppression devices are mounted at device poles and used to extinguish the electric arc. They are represented by special chambers equipped with a deionic lattice of steel plates.

Actuator mechanisms have a hinge structure. They most often have three or four links. They ensure disengagement of contact system by automatic or manual control.

Solenoid releases, which are electromagnets with an anchor. They are designed for automatic switching in case of short circuit.

Types of trip mechanisms

Trip elements are one of the most important parts of the device. They managing and controlling voltage parameter of the electrical circuit.

With the help of releasers, it is possible to turn off machine on distance. There are several types of such devices:

  • semiconductor;
  • combined;
  • thermal;
  • electromagnetic

Each type approaches its own specific conditions.

On our website, you can find the most popular circuit breakers created by ABB or Schneider Electric.

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