PROPERTIES AND USES OF SF6 GAS

PROPERTIES OF SF6 GAS: 

SF6 Structure

Sulfur hexa-fluoride (SF6): Sulfur hexa-fluoride gas is a chemically stable and inert gas (up to 500°C).

It is available in gas form at normal temperature and pressure (NTP) and in liquid form when temperature less than 10°C.The central atom of sulfur hexa-fluoride gas is sulfur atom and surrounded by six fluorine atom.

The properties of Sulfur hexa-fluoride (SF6) is given below:

• Its density is five times higher than air.
• It is non-inflamable.
• It is colorless.
• It is odorless.
• It is non-poisonous.But it is toxic in impure form.
• It has high insulating property.
• It has cooling property.
• It has high dielectric strength at high pressure.
• It has arc extinguishing property.
• It is thermally stable.
• It has low arc-time constant.So, it extinguish the arc instantly.
• It has high heat convention property.

Uses of Sulfur hexa-fluoride (SF6): Due to above given properties it is mainly used in electrical equipment.It is used in switch gears, circuit breakers, current transformers, bushing, cables, capacitors etc.It is used for electrical equipment those work on 3.6 KV to 765 KV.

Advantages of Sulfur hexa-fluoride (SF6) gas contain electrical equipment: The advantages of sulfur hexa-fluoride gas contain electric equipment is given below:

• Compactness: This type of equipment compact in size as compare to other type of equipment ( vacuum, oil, air type etc).Thus it saves the installation land cost.
• Maintenance free: This type of equipment is maintenance free.Only the visual checking of gas monitoring system of equipment is necessary.
• Less installation time: Due to compact size.This type of equipment required less installation time in comparison to other type of equipment.Thus it also reduces the installation cost.
• High safety factor: In this type of equipment all the metal part of the equipment earthed.So, the safety factor of this type of equipment is high.

More information about Earthing in electrical system click on the link.

Disadvantages of Sulfur hexa-fluoride (SF6) gas contain electrical equipment: The disadvantages of sulfur hexa-fluoride gas contain electric equipment is given below:

• High initial cost: The cost of this type of equipment is higher than other type of equipment.
• Difficult repairing work: The repairing work of this type of equipment is difficult and it takes long time.
• Requirement of cleanliness: This type of equipment required more cleanliness.Because due to the dust particle and moisture, flash-over may be occur.
• Problem of gas procurement: There is lot of difficulties in procuring and storing of Sulfur hexa-fluoride (SF6) gas.

Conclusion: Due to high dielectric strength and non-inflamable property.It is mainly used in electric system.In the world most of the country used SF6 gas contain electric equipment.