An electrical circuit breaker is a switching device which can be operated manually and automatically for controlling and protecting an electrical power system. As the modern power system deals with huge currents, special attention should be given during designing of a circuit breaker to ensure it is able to safely interrupt the arc produced during the closing of a circuit breaker. This was the basic definition of circuit breaker.

Introduction to Circuit Breaker:
The modern power system deals with huge power network and huge numbers of associated electrical equipment. During a short circuit fault or any other type of electrical fault (such as electric cable faults), a high fault current will flow through this equipment as well as the power network itself. This high current may damage the equipment and networks permanently. For saving these pieces of equipment and the power networks, the fault current should be cleared from the system as quickly as possible. Again after the fault is removed, the system must come to its normal working condition as soon as possible for supplying reliable quality power to the receiving ends. In addition to that for proper controlling of the power system, different switching operations are required to be performed. So for timely disconnecting and reconnecting different parts of power system network for protection and control, there must be some special type of switching devices which can be operated safely under huge current carrying condition.

During the interruption of large current, there would be large arcing in between switching contacts, so care should be taken to quench these arcs in circuit breaker in a safe manner. The circuit breaker is the special device which does all the required switching operations during current carrying condition. This was the basic introduction to circuit breaker.

Types of Circuit Breaker:
According to different criteria there are different types of circuit breaker. According to their arc quenching media the circuit breaker can be categorized as:

  • Oil circuit breaker.
  • Air circuit breaker.
  • SF6 circuit breaker.
  • Vacuum circuit breaker.

According to their services the circuit breaker can be categorized as:

  • Outdoor circuit breaker.
  • Indoor breaker.

According to the operating mechanism of circuit breaker they can be categorized as:

  • Spring operated circuit breaker.
  • Pneumatic circuit breaker.
  • Hydraulic circuit breaker.

According to the voltage level of installation types of the circuit breaker are referred to as:

  • High voltage circuit breaker.
  • Medium voltage circuit breaker.
  • Low voltage circuit breaker.