SF6-gas (sulphur hexafluoride)

What is SF6-gas (sulphur hexafluoride)?

Sulphur hexafluoride. SF6 is a gas that is used in electrical power equipment. It is colourless, odourless, non-flammable and chemically stable. This means that at room temperature it does not react with any other substance. Stability comes from the symmetrical arrangement of the six fluorine atoms around the central sulphur atom.

This stability is just what makes the gas useful in electric equipment. SF6 is a very good electrical insulator and can effectively extinguish arcs, which makes high and medium voltage apparatus filled with SF6 highly popular.

SF6 is a non-flammable gas that is used in electrical apparatus.
SF6 is not poisonous.

Advantages of SF6-gas:

There are two reasons for using SF6 in electrical equipment:
SF6 provides extremely good electrical insulation and very effectively quenches electric arcs. These properties of SF6 make it possible to build electrical equipment and apparatus that are compact, use a small amount of material, are safe and will last a long time.

Complete gas insulated substations, GIS or RMU, are used where space is restricted or the environment is severe. They are virtually maintenance-free. Electrical equipment filled with SF6 has been in use for about 40 years and the service experience is very good.

SF6 has a very high dielectric withstand capability.
SF6 effectively quenches arcs in circuit breakers.
SF6 apparatus is compact and almost maintenance-free.
SF6 equipment is extremely safe in operation and for users.

SF6-gas is used:

SF6 is used as an insulating gas in substations, as an insulating and cooling medium in transformers and as an insulating and arc quenching medium in switchgear for high and medium voltage applications. These are all closed systems which are extremely safe and unlikely to leak.

In electrical power systems, high and medium voltage switchgear is required to cut off the power in case of a fault, in order to protect people and equipment. When power is switched, an electric arc strikes between the circuit-breaker contacts. Breakers filled with SF6 are electrically insulating and effectively control arcing.

Gas isolated substations are mainly found in urban areas where you want them to take up as little room as possible and often integrate them into buildings. These substations reduce the magnetic field and remove the electrical field completely. This is a real advantage for installers, maintenance personnel and people who live in the vicinity of substations.