TYPES OF CIRCUIT BREAKER AND ITS RATING

DIFFERENT TYPES OF CIRCUIT BREAKER AND ITS RATING:

Different type of circuit breaker is given below:

1. Air circuit breaker (ACB)
2. Air blast circuit breaker (ABCB)
3. Water circuit breaker (WCB)
4. Oil circuit breaker (OCB)
5. Vacuum circuit breaker (VCB)
6. Sulfur hexafluoride (SF6) breaker 

We can read the basic principal and working of circuit breaker on clicking this link.

1.Air circuit breaker (acb): In this type of circuit breaker the arc quenching medium is air.

Air circuit breaker

Operation: In this type of circuit breaker, when the circuit breaker operate means contact of circuit breaker separate.Then arc produced between contact.Due to the movable contact of circuit breaker, it increases the arc length.Thus arc suppressed between contact in the presence of arc.

→The mechanical life = 5 lac operation

Rating of air circuit breaker: This type of circuit breaker used in both AC and DC.This is used for low voltage (up to 6.6 KV).

Features: The features of air circuit breaker is given below:

• The installation of air circuit breaker is economical and easy.
• The design of circuit breaker is very simple.
• The operation of circuit breaker is easy.
• The maintenance cost is less.

Drawbacks: The drawbacks of air circuit breaker is given below:

• It is mainly designed for low voltage.
• It is used in closed place.

2.Air blast circuit breaker (abcb): In this type of circuit breaker the arc quenching medium is fast blow compressed air between the contacts.

Air blast circuit breaker

Operation: In this type of circuit breaker, when the circuit breaker operate means contact of circuit breaker separate.Then arc produced between contact.Due to fast blow of compressed air between contacts, it suppress the arc between contact.The air blow between contact may be axial, radial or cross blast according to the construction of circuit breaker.The compressed area is collected in a tank and its pressure range is 85 to 175 kg/cm square.

→The mechanical life = 5 lac operation

Rating of air blast circuit breaker: This circuit breaker used in the voltage range of 6.6 KV to 400 KV.

Features: The features of air circuit breaker is given below:

• The operating speed is high.
• It reduces the risk of fire.
• The extinguishing of arc easily take place.
• The maintenance cost is less as compared to oil circuit breaker.

Drawbacks: The drawbacks of air circuit breaker is given below:

• The air - compressor is require.
• More possibility of re-striking voltage. 
• More possibility of over voltage, due to current chopping.

3.Water circuit breaker (wcb): In this type of circuit breaker the arc quenching medium is distilled water.

Water circuit breaker

Operation: In this type of circuit breaker, there are two parts.First is known as pressure chamber in which fixed contact situated.Second is known as pressure chamber in which movable contact situated.When the circuit breaker operate means contact of circuit breaker separate.Then arc and heat produced between contact.This heat vapourise the water and this water vapours increases the pressure in bottom chamber.So, this chamber is known as pressure chamber.

When moving contact move, the vapour comes between the contact and suppress the arc.After extinguishing arc it condense and expand in upper chamber.So, this chamber is known as expansion chamber.

Rating of water circuit breaker: It is used for low voltage (up to 6.6 KV) for low current carrying circuit.

Features: The features of air circuit breaker is given below:

• It is compact in size as compare to oil circuit breaker for same rating.

Drawbacks: The drawbacks of air circuit breaker is given below:

• Maintenance cost is high.
• It is used in low current carrying circuit.

Oil circuit breaker (ocb): In this type of circuit breaker arc quenching medium is oil (dielectric oil, transformer).

We can read the properties of transformer oil on clicking this link.

Oil circuit breaker

Operation: In this type of circuit breaker fixed and movable contact situated in oil tank.When the circuit breaker operate means contact of circuit breaker separate.Then oil comes between these contacts and extinguish the arc and also provide cooling.

Rating of oil circuit breaker: Due to high breaking capacity.This type of circuit breaker used up to 220 KV.

Features: The features of air circuit breaker is given below:

• The oil provide insulation between contact and tank body.
• The oil provide cooling.
• The oil transfer the heat.
• The cost of oil circuit breaker is less as compared to air circuit breaker.

Drawbacks: The drawbacks of air circuit breaker is given below:

• The installation and maintenance cost is high.
• The oil contain moisture at rainy season.Due to this dielectric strength of oil decreases.
• The testing of oil is necessary after 1 year.
• Periodically inspection is necessary.

Vacuum circuit breaker (vcb): In this type of circuit breaker the arc is extinguish in vacuum.

Vacuum circuit breaker

Operation: In this type of circuit breaker the fixed and movable contact situated in a chamber.This chamber is known as vacuum interrupter (in which closing or opening of circuit breaker take place).When the circuit breaker operate means contact of circuit breaker separate.Then arc produced between contact is suppress in vacuum interrupter.

→The mechanical life = 5 lac operation

Rating of vacuum circuit breaker: The vacuum circuit breaker is mainly used for 11 KV, 33 KV (rms voltage).

Features: The features of air circuit breaker is given below:

• It is compact in size.
• It can be operated in open as well as closed place.
• Less maintenance required.
• High operating speed.
• It is more reliable.
• High making and breaking capacity as comparison to air circuit breaker, oil circuit breaker.

Drawbacks: The drawbacks of air circuit breaker is given below:

• We cannot check vacuum in interrupter without test.

Sulfur hexa fluoride (SF6) breaker: In this type of circuit breaker arc extinguishing medium is sulfur hexa fluoride gas.

More information about Sulfur hexa fluoride (SF6) gas click on given link.

SF6 breaker

Operation: In this type of circuit breaker fixed and movable contact situated in a chamber that is filled with sulfur hexa fluoride gas.When the circuit breaker operate means contact of circuit breaker separate.Then arc produced between contact is suppress by sulfur hexa fluoride gas in chamber.

Rating of vacuum circuit breaker: This circuit breaker is used up to 750 KV.

Features: The features of air circuit breaker is given below:

• It is compact in size.
• It can be operated in open as well as closed place.
• Less maintenance required.
• High operating speed.
• It is more reliable.
• High making and breaking capacity as comparison to air circuit breaker, oil circuit breaker.

Drawbacks: The drawbacks of air circuit breaker is given below:

• High initial cost.
• Problem of gas procurement.
• Difficult repairing work.

Conclusion: The final conclusion is that circuit breaker is necessary for electric circuits.But at the time of selection of circuit breaker, we should keep some point in mind like rating, cost, installation place, type etc.