A circuit breaker automatically disrupt the flow of current, if there is any short circuit of over flow of current in circuit. By this, it prevent from being damage the electrical and electronics components and accessories. In that case it is very important part of electrical and electronic circuit. Here I have explained some circuit breaker bellow-

Miniature circuit breaker

  • Rated current not more than 100 A.
  • Trip characteristics normally not adjustable.
  • Thermal or thermal magnetic operation.

Molded Case Circuit Breaker

  • Rated current up to 1000 A. 
  • Trip current may be adjustable.
  • Thermal or thermal magnetic operation.

Air Circuit Breaker

  • Rated current up to 10000 A.
  • Trip characteristics often fully adjustable including configuration trip thresholds and delay.
  • Usually  electrically controlled. 
  • Often used for main power distribution in large industrial plant.

Sulphur Hexafluoride Circuit Breaker

  • It is colorless, odourless non-toxic gas.
  • It has high thermal conductivity  better than that of air and assists in better cooling current carrying part. 
  • Sulphur hexafluoride is strongly electronegative,  which mean the free electrons are  easily removed from discharge by the formation of negative ions.
  • It has a unique property of fast recombination after the source  energising spark is  removed. It has 100 time more  effective as compared to to arc quenching medium. 
  • Its dielectric strength is 2.5 time than that of air and 30% less than that of the dielectric oil. At high pressure  the dielectric strength of the gas increase. 

Vacuum Circuit Breaker

  • Rated current up to 3000 A.
  • These interrupt the arc in a vacuum bottle. 
  • This can also be applied at up to 35,000 V.
  • This circuit breakers tend to have longer life expectancies between overhaul then to  a circuit breaker.

Edited By
Jeion Ahmed
B.Sc. in Electrical & Electronic Engineering (EEE)
Chittagong University of Engineering & Technology (CUET)

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