Types of Circuit Breakers:
What is Circuit Breaker?
A circuit breaker is an automatically operated electrical switch designed to protect an electrical circuit from damage caused by excess current from an overload or short circuit or in no-load condition.
Basic About Circuit Breaker:
Circuit breakers are made in varying sizes, from small devices that protect low-current circuits or individual household appliances, to large switchgear designed to protect high voltage circuits feeding an entire city.
The generic function of a circuit breaker, RCD, or a fuse, as an automatic means of removing power from a faulty system, is often abbreviated as OCPD. Many classifications of circuit breakers can be made, based on their features such as voltage class, construction type, interrupting type, and structural features.
Classification:
Firstly we classify the circuit breakers according to the voltage levels they can operate on. So there are three most used types of circuit breakers in this category.
1. Low voltage circuit breaker.
2. Medium voltage circuit breaker.
3. High voltage circuit breaker.
Low voltage circuit breaker:
Low-voltage breaker types are common in domestic, commercial, and industrial applications, and include MCB, Miniature circuit breaker, rated current not more than 100 Amp. Trip characteristics are normally not adjustable. Thermal or thermal-magnetic operation. Breakers illustrated above are in this category.
Medium-voltage circuit breakers rated between 1 and 72 kV may be assembled into metal-enclosed switchgear lineups for indoor use or maybe individual components installed outdoors in a substation. Air-break circuit breakers replaced oil-filled units for indoor applications, but are now being replaced by vacuum circuit breakers up to about 40.5 kV.
Electrical power transmission networks are protected and controlled by high-voltage breakers. The definition of high voltage varies but in power transmission work is usually thought to be 72.5 kV or higher. High-voltage breakers are nearly always solenoid-operated, with current sensing protective relays operated through current transformers. In substations the protective relay scheme can be complex, protecting equipment and buses from various types of overload or ground or earth fault.
High-voltage breakers are broadly classified by the medium used to extinguish the arc:
There are four types in this category.
1. Air circuit breaker.
2. Oil circuit breaker.
3.SF6 circuit breaker.
4. Vacuum circuit breaker.
Air Circuit Breaker:
Air Circuit Breaker is an electrical device used to provide Overcurrent and short-circuit protection for electric circuits over 800 Amps to 10K Amps. These are usually used in low voltage applications below 450V. Air brake circuit breaker the arc is initiated and extinguished in substantially static air in which the arc moves.
Oil Circuit Breaker:
The oil circuit breaker is such type of circuit breaker which used oil as a dielectric or insulating medium for arc extinction. In an oil circuit breaker, the contacts of the breaker are made to separate within an insulating oil.
SF6 circuit breaker:
SF6 gas has excellent dielectric, arc quenching, chemical, and other physical properties which have proved its superiority over other arc quenching mediums such as oil or air.
Vacuum Circuit Breaker:
A vacuum circuit breaker is a kind of circuit breaker where the arc quenching takes place in a vacuum medium. The operation of switching on and closing current carrying contacts and interrelated arc interruption takes place in a vacuum chamber in the breaker which is called a vacuum interrupter.
