SF6 Circuit Breaker
Sulfur Hexafluoride SF6 Circuit Breaker is a type of circuit breaker in which high-pressure sulfur hexa-fluoride (SF6) gas is used for extinguishing the Arc. Just like air, vacuum or oil sulfur hexa-fluoride is pure dielectric.
Due to its physical and chemical properties, it is used in many places with rating voltage up to 800Kv. Another circuit breaker (those containing, air or oil) function on high voltages was a little bit slower.
After the contact separation, the extinguishing force was slower than normal.While the function of SF6 Circuit Breaker was up to the mark even in high voltages, SF6 circuit breaker is mainly used in medium voltage switchgear.
Types of SF6 Circuit Breaker
SF6 Circuit Breakers are mainly divided into three types. This division is done on the dielectric medium inside the circuit breaker. We will discuss each type of the Sf6 breaker in detail.
Non-puffer type circuit breaker
This type of circuit breaker contains an Interrupter part, this part is used for the arc quenching process. While talking about the construction it consists of a fixed contact and moving contact. These contacts are like hollow cylinders. The fixed part has arc horns connected which limit switching components contact during flash-over. The moving part consists of a rectangular gas outlet. The gas goes through these holes after the arc extinction.
2.Single- puffer type circuit breaker.
In this type of Circuit Breaker movable cylinder which is also called a puffer cylinder is placed. While a fixed piston connects the puffer cylinder. The SF6 gas is filled between the fixed piston & movable cylinder. When the circuit breaker operates gas passes through both nozzles.
Double-puffer type circuit breaker.
In this type of circuit breaker, two pressure pistons are used as shown. The nozzles are placed current-carrying contacts. The placement of the nozzle is done in such a manner made up when gas flow increases, it passes through the nozzle.
Advantages of this Circuit Breaker
- As all the breakers are completely sealed & enclosed therefore no risk of fire or explosion.
- Also, SF6 is non-inflammable gas. It reduces the risk of fire.
- Quick operation and arcing time are very short.
- Uninterrupted and noiseless operation.
- Working in all type of weather conditions
- Less maintenance cost.
- It can be operated up to 800 kV.
Disadvantages of SF6 Circuit Breaker
- The first disadvantage is in the term of cost.
- For each operation, multiple types of equipment are needed.
- There exists the danger of gas leakage all time. While the gas is colorless and odorless.
- Internal parts need periodic cleaning.
