2-3 times more than the cost of a mineral oil filled transformer.
Air insulated substation means air acts as the dielectric medium but in case of gas insulated substation SF6 is the dielectric medium. Gas insulated substations are having more advantages than air insulated substations.
This seems like a question from an electrical course, and is probably best answered by your course materials. It's your test question, not ours, and there won't always be someone to ask for the answer. Earn your diploma.
SF6 is used in circuit breakers to help extinguish the arc when deenergizing parts of the system. It is a dense inert gas that will deionize the are.
vcb is have vaccume and sf6 cb is filled with sf6 gas which will have good arc quencing property
Gas insulated substations are in use in places where a normal, above ground substation would constitute an eye sore for the community. A gas (SF6) insulated substation may have underground feed lines and be nearly invisible to the average person -- except for the location where the transmission feed wires go underground from the transmission towers. distribution circuits supplied by gas insulated substations normally have an alternate feed from another substation, to allow maintenance work on the gas insulated site.
gas insulated substations are installed especially where floor area available is limited and maintenance cost is more
SF6 is sulphur-hexa-fluorine, it is used in gaseous form as an arc suppressent and also to insulated EHV busducts and switchgear.
Current transformer and voltage transformer . This transformers are actually measuring instruments which measures the quantity of current and voltage coming out of the substation.
Usually in a sealed tank, the switch contacts are in the tank too. The SF6 gas quenches any arcs that form when the switch contacts are opened.
Sulfur hexafluride (SF6).
Not pure SF6 but it can interact with other molecules under certain conditions to create powder.
SF6---- Sulphur hexa floride