1. JAIN INSTITUTE OF TECHNOLOGY,
DAVANGERE.
DEPARTMENT OF ELECTRICAL & ELECTRONICS
P R E S E N TAT I O N O N
“STUDY OF WORKING PRINCIPLE AND MAINTANACE OF 400kV STATION”
Under The Guidance Of
Mr. Chetan H R M.Tech
Assistant Professor
Department of Electrical and Electronics Engineering
PROJECT PRESENTED BY,
KISHOR K M 4JD18EE016
SANTHOSH S 4JD19EE035
VINAYAKA B S 4JD20EE422

2. • Introduction
• Single Line Diagram
• Limitations of AIS
• Gas Insulated Substation
• Major Components of GIS
• Transformer
• Advantages & Disadvantages of GIS
• Conclusion
Contents:

3. Introduction:
For maintaining proper voltage levels at transmission and distribution level
and for providing greater stability a number of electrical transformation and
switching setups have to be created in between generating station and
consumer ends. These transformation and switching setups are generally
known as electrical substations. Based on nature of dielectric medium a
substation is of two types as following :
1. AIS (Air insulation sub-station )
2. GIS ( Gas insulation sub-station )

4. Single Line Diagram:
• Single Line Diagrams do not show the exact electrical connections of the
circuits.
• As the name suggests, SLDs use a single line to represent all three phases.
They show the relative electrical interconnections of generators,
transformers, transmission and distribution lines, loads, circuit breakers,
etc., used in assembling the power system.
• The amount of information included in an SLD depends on the purpose for
which the diagram is used.

6. Limitations of AIS:
• Equipment's deteriorates when exposed to ambient atmospheric conditions.
• Equipment's becomes contaminated when exposed to pollutants such as
airborne particulate matter.
• Requires a lot space, which can be expensive to acquire in dense urban areas.
• Less stable and reduced safety of operation compared to GIS.
• Requires regular maintenance.
• The poor dielectric properties of air, as well as secondary factors such as
humidity, pollutants, salt, and moisture means that more space is needed.

7. Gas Insulated Substation:
• A gas insulated substation (GIS) is a high voltage substation in which the
major conducting structures are contained within a sealed environment
with a dielectric gas known as SF6, or sulfur hexafluoride gas as the
insulating medium.
• In comparison, a conventional (AIS) or Air-Insulated Substation,
atmospheric air is the dielectric medium, as these types of substations are
almost always located at outdoor locations.

8. Major components of GIS:
• Current transformer
• Potential transformer
• SF6 Circuit breaker
• SF6 Bus Bar
• SF6 Bus Coupler
Fig:SF6 Current Transformer

9. Fig: SF6 circuit breaker
Fig: SF6 Potential Transformer
Fig: GIS Bus Coupler

10. Transformer:
A transformer is static device which transfers electric power from one
circuit to another circuit without a change in frequency.
Fig.6.6: 500MVA Transformer in H.M.Hole

11. Major Components of Transformer:
1.Conservator Tank
2.Dry out unit system (DOS)
3.Pressure release valve (PRV)
4.Fiber optic temperature sensor (FOTS)
5.Transformer Gas analyser (TGA) or Dissolved Gas analyser(DGA)
6.Nitrogen Injection Fire Protection System (NIFPS)
7.Buchholz Relay

12. • It occupies much less space (1/10th) compared to AIS substations.
• More reliable than AIS where by the number of outages for GIS due to
faults is far less.
• Maintenance is less compared to AIS.
• Can be assembled at the manufacturer’s facilities, and modules can be
placed and commissioned at the plant quite easily.
Advantages of GIS over AIS:
• Cost is much higher compared to AIS substations.
• Care should be taken that no dust particles enter into the live compartments,
which could result in flashovers.
• When a fault occurs internally, diagnosis of the fault is difficult and then
rectifying this would take a long time (outage time is high).
• SF6 gas pressure must be monitored in each compartment.
GIS Disadvantages:

13. Conclusion:
Establishing receiving stations and substations near the load center makes
it possible to supply quality and reliable power by the utilities competitive
prices by minimizing losses in transmission and distribution. Selection of
site plays a very important role in construction of substation. Proper design
of receiving stations and substation and by the use of efficient equipment
provides a high level of service continuity.

14. THANK YOU