The document is a seminar report on gas insulated transformers presented by Chandan Kumar Sinha at the National Institute of Technology. It discusses how gas insulated transformers use SF6 gas instead of oil as both an insulating and cooling agent. It provides an overview of SF6 gas properties, the applications and features of gas insulated transformers, and compares them to oil insulated transformers. The report concludes that ongoing research and developments have made larger capacity gas insulated transformers possible and SF6 is an eco-friendly insulating gas that can increase transformer efficiency and reliability.

1. SEMINAR REPORT ON
“GAS INSULATED
TRANSFORMER”
Submitted By:-
CHANDAN KUMAR SINHA
[1222004]
NATIONAL INSTITUTE OF TECHNOLOGY
ELECTRICAL ENGINEERING
(POWER SYSTEM)
18-02-2014

2. SF6 GAS INSULATED
TRANSFORMER
EMPLOYS SF6 GAS
INSTEAD OF THE
CONVENTIONAL OIL
BOTH AS AN
INSULATING AND
COOLING AGENT.
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

3. CONTENTS
SF6 ---AN OVERVIEW
GAS PROPERTIES
APPLICATIONS OF A GAS INSULATED
TRANSFORMER(GIT)
FEATURES OF A GIT
LAYOUT
COOLING APPARATUS OF A GAS
INSULATED TRANSFORMER
DIFFERENCE BETWEEN OIT $ GIT
CONCLUSION
NATIONAL INSTITUTE OF TECHNOLOGY
18-02-2014

4. SF6 – AN OVERVIEW
 SF6 or sulfur hexafluoride gas molecules are
combined by one sulfur and six fluorine atoms
S + 3F2 = SF6 + 262 KCal.
Each sulphur atom in SF6 molecule creates covalent
bond with 6 fluorine atoms.
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

5. SF6 GAS PROPERTIES
 It is colourless, odourless, nonflammable, non-
corrosive and chemically stable.
 High dielectric strength.
 Quenches arc effectively and has excellent cooling
properties.
 Good thermal conductivity and excellent thermal
stability.
 It’s eco-friendly and not poisonous.
 It can be recycled.
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

6. APPLICATIONS OF SF6 GAS
INSULATED TRANSFORMER
 Hospitals, underground shopping centers,
substations where a high level of fire safety is
required.
 Water treatment plants and hydroelectric
power plants where waterways must be kept
unpolluted.
 Thermal power plants, chemical plants, public
works facilities etc where high reliability is
required.
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

7. FEATURES OF A GAS
INSULATED TRANSFORMER
Highly flame resistant and non explosive.
High resistance to moisture.
Reduced installation space.
High reliability.
Causes no pollution.
Explosion proof tank.
Easy inspection and maintenance work.
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

8. LAYOUT OF A GAS
INSULATED TRANSFORMER
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

9. Oil immersed
transformer
Gas insulated
transformer
Insulation/cooling Insulating oil SF6 gas(Pressure 0.14
or 0.43MPa-g(20ˆ))
Solid Insulation
Material
Oil Impregnated Paper,
Pressboard
PET Film,PPS Film,
Aramide Paper,
Pressboard
Conservator Necessary Unnecessary
18-02-2014
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
Difference between oil immersed
transformer and gas insulated
transformer

10. Pressure rise on internal fault
Significant tank pressure increases do not occur
during internal failures due to the Gas
characteristics.
The risk of a tank explosion or fire incident can
be completely eliminated.
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

11. COOLING APPATARTUS
 Employs a cooling
medium in liquid phase
such as a Refrigerant
R113 otherwise known as
Trifluorotrichloroethane
or C2F3Cl3.
 SF6 gas is obviously used
as the second cooling
medium.
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

12. CONCLUSION
 Incessant research and continuous developments
have made construction of large capacity gas
insulated transformer possible.
 With the eco-friendly aspects of SF6 gas and
considering the huge advantages of the gas, long
strides can be made in this regard to further utilize
it and increase the efficiency of the transformer
and making the power system more reliable and
safer.
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014

13. REFERENCE
http://www.electrical4u.com/sulfur-hexafluoride-
sf6-gas-properties/
http://www.engineeringtoolbox.com/refrigerants-d_
https://www.toshiba.com/ind/data/tag_files/GIT_
Brochure.pdf
18-02-2014
NATIONAL INSTITUTE OF TECHNOLOGY PATNA

14. Thank you
NATIONAL INSTITUTE OF TECHNOLOGY PATNA
18-02-2014