24-09-2012, 03:51 PM
GAS INSULATED SUBSTATION
GAS INSULATED.ppt (Size: 1.45 MB / Downloads: 66)
Introduction
It is a one type of switchgear.
The term switchgear, used in association with the electric power system, or grid, refers to the combination of electrical disconnects.
There are 3 types of switchgear.i.e
AIS
HYBRIT GIS
GIS
Gas Insulated Substations (GIS) is a compact,multicomponent assembly enclosed in a ground metallic housing in which the primary insulating medium is compressedSulphur hexafluoride (SF6)gas.
SF6acts as an insulation between live parts & the earthed metal closure.
Gas insulated switchgear is used in industrial areas to fulfil high-energy demands by space saving design with a minimum of cost
SF6 switchgear installed in Canada in a 550 kV substation with 100 kA
Comparison between AIS &GIS
AIS
Air-insulated substation:- An electric power substation that has the busbars and equipment terminations generally open to air.
It utilizes insulation properties of ambient air for insulation to ground.
Very fast electromagnetic transients (VFT) in air insulated substations (AIS)
Air Insulated Substation (AIS) makes it possible to install High Voltage substations that take-up less space
These are more cost-efficient than conventionally designed outdoor infrastructures.
GIS
Gas Insulated Substations (GIS) is a compact,multicomponent assembly enclosed in a ground metallic housing in which the primary insulating medium is compressedSulphur hexafluoride (SF6)gas.
SF6acts as an insulation between live parts & the earthed metal closure.
Gas insulated substations are particularly suitable for underground construction beneath public buildings.
Gas insulated substation mainly used for a power transmission system or a sub-station system, of which outgoing bus bar is shortened to reduce consumption of the outgoing bus bar
Sulfur Hexafluoride
A colorless, odorless, non-toxic, liquified gas. Shipped as a liquid under its own vapor pressure.
Sulfur Hexafluoride gas, which is itself inert.
It disassociates in the presence of an RF field to form reactive fluorine ions.
SF6acts as an insulation between live parts & the earthed metal closure.
The dielectric strength of SF6 gas at atmospheric pressure is approximately three times that of air.
pace requirement is only 10 to 25 percent of what is required is a conventional substation.
Circuit Breakers
A circuit breaker is an automatically-operated electrical switch designed to protect from damage caused by overload or short circuit.
Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow.
Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.
Current interruption in a high-voltage circuit-breaker is obtained by separating two contacts in a medium, such as SF6, having excellent dielectric and arc quenching properties.
After contact separation, current is carried through an arc and the arc is interrupted & cooled by a gas blast of sufficient intensity.
Disconnecting switches
Disconnector switches are safety devices used to open or to close a circuit when there is no current through them.
These are used to isolate a part of a circuit, a machine, a part of an overhead line or an underground line so that maintenance can be safely conducted.
The opening of the line isolator or busbar section isolator is necessary for safety, but not sufficient.
GAS INSULATED.ppt (Size: 1.45 MB / Downloads: 66)
Introduction
It is a one type of switchgear.
The term switchgear, used in association with the electric power system, or grid, refers to the combination of electrical disconnects.
There are 3 types of switchgear.i.e
AIS
HYBRIT GIS
GIS
Gas Insulated Substations (GIS) is a compact,multicomponent assembly enclosed in a ground metallic housing in which the primary insulating medium is compressedSulphur hexafluoride (SF6)gas.
SF6acts as an insulation between live parts & the earthed metal closure.
Gas insulated switchgear is used in industrial areas to fulfil high-energy demands by space saving design with a minimum of cost
SF6 switchgear installed in Canada in a 550 kV substation with 100 kA
Comparison between AIS &GIS
AIS
Air-insulated substation:- An electric power substation that has the busbars and equipment terminations generally open to air.
It utilizes insulation properties of ambient air for insulation to ground.
Very fast electromagnetic transients (VFT) in air insulated substations (AIS)
Air Insulated Substation (AIS) makes it possible to install High Voltage substations that take-up less space
These are more cost-efficient than conventionally designed outdoor infrastructures.
GIS
Gas Insulated Substations (GIS) is a compact,multicomponent assembly enclosed in a ground metallic housing in which the primary insulating medium is compressedSulphur hexafluoride (SF6)gas.
SF6acts as an insulation between live parts & the earthed metal closure.
Gas insulated substations are particularly suitable for underground construction beneath public buildings.
Gas insulated substation mainly used for a power transmission system or a sub-station system, of which outgoing bus bar is shortened to reduce consumption of the outgoing bus bar
Sulfur Hexafluoride
A colorless, odorless, non-toxic, liquified gas. Shipped as a liquid under its own vapor pressure.
Sulfur Hexafluoride gas, which is itself inert.
It disassociates in the presence of an RF field to form reactive fluorine ions.
SF6acts as an insulation between live parts & the earthed metal closure.
The dielectric strength of SF6 gas at atmospheric pressure is approximately three times that of air.
pace requirement is only 10 to 25 percent of what is required is a conventional substation.
Circuit Breakers
A circuit breaker is an automatically-operated electrical switch designed to protect from damage caused by overload or short circuit.
Its basic function is to detect a fault condition and, by interrupting continuity, to immediately discontinue electrical flow.
Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation.
Current interruption in a high-voltage circuit-breaker is obtained by separating two contacts in a medium, such as SF6, having excellent dielectric and arc quenching properties.
After contact separation, current is carried through an arc and the arc is interrupted & cooled by a gas blast of sufficient intensity.
Disconnecting switches
Disconnector switches are safety devices used to open or to close a circuit when there is no current through them.
These are used to isolate a part of a circuit, a machine, a part of an overhead line or an underground line so that maintenance can be safely conducted.
The opening of the line isolator or busbar section isolator is necessary for safety, but not sufficient.