1. 132KV GSS (GIS) JODHPUR A Training Presentation On
Submitted in partial fulfillment
for the award of the Degree of
BACHELOR OF TECHNOLOGY In
Department of Electrical Engineering
Submitted to:
Submitted by:
Mr.
10-Sep-12

2. 132 KV GSS GIS (GAS INSULATED SUB STATION)
OLD POWER HOUSE JODHPUR
RAJASTHAN

3. GAS INSULATED SUBSTATION

5. Contents:
Substation Conventional substations (AIS) Limitations of AIS The need for GIS Introduction to GIS Properties of SF6 GIS assembly Advantages of GIS Design features Drawbacks SF6 – Environmental concerns SF6 /N2 mixtures Future trends in GIS Conclusion.

6. A:Primary power lines' side B:Secondary power lines' side
Substation:
 An assembly of apparatus installed to control transmission and distribution of electric power.
A:Primary power lines' side B:Secondary power lines' side
1.Primary power lines 2.Ground wire 3.Overhead lines 4.Transformer for measurement of electric voltage 5.Disconnect switch 6.Circuit breaker 7.Current transformer 8.Lightning arrester 9.Main transformer 10.Control building 11.Security fence 12.Secondary power lines

7. Air Insulated Substation(AIS):
Air used as a dielectric. Normally used for outdoor substations. In very few cases used for indoor substations. Easy to expand (in case that space is not an issue) Excellent overview, simple handling and easy access.

8. Limitations of AIS:
Large dimensions due to statutory clearances and poor dielectric strength of air. Insulation deterioration with ambient conditions and susceptibility to pollutants. Wastage of space. Life of steel structures degrades. Seismic instability. Large planning & execution time. Regular maintenance of the substation required.

9. INTRODUCTION TO GAS INSULATED SUBSTATION What is GIS?
A gas insulated substation is an electrical substation in which the major structures are contained in a sealed environment with sulfur hexafluoride gas (SF6) as the insulating medium.
Where and why Gas Insulated Substations are used ?
Gas Insulated Substations are used where there is space for providing the substation is expensive in large cities and towns. In normal substation the clearances between the phase to phase and phase to ground is very large. Due to this, large space is required for the normal or Air Insulated Substation (AIS).
But the dielectric strength of SF6 gas is higher compared to the air, the clearances required for phase to phase and phase to ground for all equipments are quite lower. Hence, the overall size of each equipment and the complete substation is reduced to about 10% of the conventional air insulated substation

10. The need for G.I.S:
Non availability of sufficient space. Difficult climatic and seismic conditions at site. Urban site (high rise building). High altitudes. Limitations of AIS.

11. Properties of SF6: Non-toxic, very stable chemically. Man-made.
Lifetime – Very long (800 to years!).
Insulating properties 3-times that of air.
Colorless & heavier than air.
Almost water insoluble.
Non inflammable.

12. Kalisindh Thermal Power
10-Sep-12

13. GIS Assembly:
ESSENTIAL PARTS OF GIS: 1. Bus bar 2. Circuit Breaker 3. Disconnector (line or bus) 4. Earthing switch (line or bus) 5. Current transformer (feeder / bus) 6. Voltage transformer (feeder/ bus) 7. Feeder Disconnector 8. Feeder Earthing switch 9. Lightning / Surge Arrester 10. Cable termination 11. Control Panel.

14. BUS BAR
When a number of lines operating at the same voltage have to directly connect electrically bus bar are used as the common electrical component.
There are following bus at the 132 gss:-
132 kv main bus bar
132 kv auxiliary bus bar
ISOLATOR
Isolator is used to break the circuit under off-load where as on-load circuit breaking is done by circuit breaker
Isolators are classified as:-
Off load isolator
On load isolator

15. CIRCUIT BREAKER

16. CIRCUIT BREAKER
An automatic switch that stops the flow of electric current in a suddenly overloaded or otherwise abnormally stressed electric circuit.
Types of circuit breaker:-
Vaccum circuit breaker
SF6 Circuit breaker
Air blast circuit breaker
Oil circuit breaker

17. CURRENT TRANSFORMER

18. CURRENT TRANSFORMER
Current transformer is used for measurement of alternating electric current.
The objective of C.T. is :-
Reduce the scale of the metering scale.
Insulated the measuring instrument from
voltage.
Used for protective system

19. POTENTIAL TRANSFORMER

20. POTENTIAL TRANSFORMER
Potential transformer is used for step down the line voltage. PT is connected in prallel with line. Secondary voltage of the PT is generally 110v.

21. LIGHTENING ARRESTER

22. It is the first equipment in a substation.
LIGTHNING ARRESTOR
Lightening arrester is used to protect the power station sub station and transmission line against the voltage wave reaching there.
It is also known as surge diverter which is connected between line and earth to divert the incoming high voltage to earth.
It is the first equipment in a substation.
Generally arresters are connected in parallel with the equipment to be protected, typically between phase and earth for three phase installations.

23. GIS assembly:

24. Supervisory Control And Data Acquisition (SCADA)
Supervisory Control and Data Acquisition (SCADA) offers the ease of monitoring of sensors placed at distances, from one central location.
SCADA systems are used to monitor and control a plant or equipment in industries such as telecommunications, water and waste control, energy, oil and gas refining and transportation.
A SCADA system gathers information, such as where a leak on a pipeline has occurred, transfers the information back to a central site, alerting the home station that the leak has occurred, carrying out necessary analysis and control, such as determining if the leak is critical, and displaying the information in a logical and organized fashion.
SCADA systems can be relatively simple, such as one that monitors environmental conditions of a small office building, or incredibly complex, such as a system that monitors all the activity in a nuclear power plant or the activity of a municipal water system.
SCADA systems were first used in the 1960s.

25. Advantages :
Occupies very less space (1/10th) compared to ordinary substations. Hence, most preferred where area for substation is small (eg: Cities) Most reliable compared to Air Insulated Substations. Number of outages due to the fault is less Maintenance Free. Can be assembled at workshop and modules can be commissioned in the plant easily. Pollution free Explosion proof & fire proof installation Increased safety Easy operation & long life

26. GIS Failure Statistics:

27. Main Drawbacks: High cost compared to conventional substation(AIS).
Excessive damage in case of internal fault.
Diagnosis of internal fault and rectifying takes very long time (high outage time).
SF6 gas pressure must be monitored in each compartment.
Reduction in the pressure of the SF6 gas in any module results in flash over and faults.
SF6 causes ozone depletion and global warming.

28. SF6/N2 Mixtures for GIS?
SF6 gas – specifically mentioned in Kyoto protocol.
Small quantities of SF6 in N2 can improve dielectric strength drastically.
All of the dielectric strength of SF6, nearly, can be achieved by adding less than 20% SF6 into N2.
SF6/N2 mixtures less susceptible to effects of field non uniformity than pure SF6.
Thus mitigating the effects of particles and surface protrusions.

29. Future trends:
Compact design of switch gear by using three phase modules.
Use of vacuum circuit breaker cells in the medium high voltage GIS.
Optimization of GIS design to allow easier maintenance.
Development of DC GIS for incorporating into expanding national/international HVDC systems.
Search for replacement gases for SF6.
The most promising - an 80%/20% N2/SF6 mixture.
Replacement of existing AIS by GIS will accelerate especially near urban centers.

30. CONCLUSION: GIS – necessary for Extra HV & Ultra HV
Some important areas to be studied include:
More conservative design.
Improved gas handling.
Decomposition product management techniques.
Achieving & maintaining high levels of availability require – more integrated approach to quality control by both users and manufactures.

31. Thanks for your Patience!