GSS report

1. EE DEPT. ,SSCE 1
CHAPTER 1
1. INTRODUCTION
The 220kv GSS Madri, Udaipur is a grid of Rajasthan vidhyut vitran Nigam limited
(RVVNL). This grid substation is main supplier of electricity in Udaipur district. The total grid
capacity is 200MVA.
Government of Rajasthan on 19th July 2000, issued a gazette notification unbundling
Rajasthan State Electricity Board into Rajasthan Rajya Vidyut Utpadan Nigam Ltd., which will
be the generation Company; Rajasthan Rajya Vidyut Prasaran Nigam Ltd., which will be the
transmission Company and the three regional distribution companies namely Jaipur Vidyut
Vitran Nigam Ltd., ; Ajmer Vidyut Vitran Nigam Ltd. and Jodhpur Vidyut Vitran Nigam
Limited.
Fig. No. (1.1) location of GSS
.

2. EE DEPT. ,SSCE 2
CHAPTER 2
2. INCOMMING AND OUTGOING LINES OF MADRI
Table No. (2.1) Incoming and Outgoing
INCOMING
LINES 220KV
OUTGOING LINES
220 KV
INCOMING
LINES
132KV
OUTGOING
LINES 132 KV
OUTGOING
LINES
33KV
1.DEBARI 1.BANSWARA 1.DEBARI 1.DEBARI 1.HIRAN
MAGRI,SEC-4-
1
2.ZAWAR MINES 2.ZAWAR MINES 2.HIRAN
MAGRI,SEC-4-
2
3.PRATAP
NAGAR
3.PRATAPNAGA
R
3.SAVINA-1
4.RSMM 4.SAVINA-2
5.RELIANCE
CHEMOTEX
5.MIA-1
6.MIA-2
7.MATOON-1
8.MATOON-2

3. EE DEPT. ,SSCE 3
CHAPTER 3
3. TRANSFORMERS
3.1 DEFINATION:
Transformer is a static device by means of which electric power in one circuit is transformed
into electric power of same frequency in another circuit.
3.2 Transformers used in GSS:
Fig. No. (3.1) 220/132 KV, 100 MVA Transformer
Fig. No. (3.2) 132/33 KV40/50 MVA Transformer

4. EE DEPT. ,SSCE 4
Fig. No. (3.3) 132/33 KV20/25 MVA Transformer
3.3 Transformer parts:
Core:
In an electrical power transformer, there are primary, secondary and may be tertiary windings.
The performance of a transformer mainly depends upon the flux linkages between these
windings. For efficient flux linking between these windings, one low reluctance magnetic path
common to all windings should be provided in the transformer.
Windings:
The windings consist of the current-carrying conductors wound around the sections of the
core, and these must be properly insulated, supported and cooled to withstand operational and
test conditions.
Conservator tank:
This is a cylindrical tank mounted on supporting structure on the roof the transformer main
tank. The main function of conservator tank of transformer is to provide adequate space for
expansion of oil inside the transformer.
Fig. No. (3.4) Conservator tank

5. EE DEPT. ,SSCE 5
Breather:
Whenever electrical power transformer is loaded, the temperature of the transformer insulating
oil increases, consequently the volume of the oil is increased. As the volume of the oil is
increased, the air above the oil level in conservator will come out.. The natural air always
consists of more or less moisture in it and this moisture can be mixed up with oil if it is allowed
to enter into the transformer
Fig. No. (3.5) Breather:
Cooling equipment:
The radiator of transformer accelerates the cooling rate of transformer. Thus, it plays a vital
role in increasing loading capacity of an electrical transformer. This is basic function of radiator
of an electrical power transformer.
Fig. No. (3.6) Cooling equipment:

6. EE DEPT. ,SSCE 6
CHAPTER 4
4. EARTHING
The Earthing is of two principal types viz.
 Neutral Earthing and
 Equipment Body Earthing
The neutral point of star-connected 3-phase winding of power transformers is connected to
low resistance ground, such a connection is called 'Neutral grounding'. It gives advantages of
stable neutral point, relatively simple earth fault relaying, discharge of over-voltages to earth
due to lightning, control over earth fault current etc.
SPECEFICATION OF TRANSFORMER:
Fig. No. (4.1) 40/50 MVA Transformer
Fig. No. (4.2) 100 MVA Transformer:

7. EE DEPT. ,SSCE 7
CHAPTER 5
5. SWITCH YARD
5.1 Single line diagram (SLD):
Fig. No. (5.1) Single line diagram

8. EE DEPT. ,SSCE 8
5.2 YARD VIEW OF 220/132KV
Fig. No. (5.2) YARD VIEW OF 220/132KV
5.3 EQUIPMENT
ISOLATOR
Fig. No. (5.3) Isolators
5.4 LIGHTENING ARRESTOR
A surge arrester or lightning arrester is a device connected between line and earth, i.e., in
parallel with the equipment to be protected at the substation. It limits the magnitude of
lightning and switching over voltages at the substation and provides a low resistance path for
the surge current to flow to the ground.

9. EE DEPT. ,SSCE 9
Fig. No. (5.4) LIGHTENING ARRESTOR
5.6 CIRCUIT BREAKERS
SF6 Circuit Breaker:
SF6 is a heavy chemically inert nontoxic noninflammable gas. Its other
properties, which make it ideal for circuit breaking, are:
 At atmospheric pressure its dielectric strength is two to three times that of air.
Because of excellent insulating properties of the gas, reduced electrical clearances
are needed.
 Its heat transferability at atmospheric pressure is 2 to 2.5 times that of air; therefore
smaller conductor sizes needed.
Fig. No. (5.5) SF6 Circuit Breaker

10. EE DEPT. ,SSCE 10
Advantage of SF6 Circuit Breaker
 Low gas velocity and pressure employed prevent current chopping; capacity currents
are interrupted without restriking.
 There is no exhaust of high pressure gas to atmosphere, and their operation is silent.
 No carbon deposition takes place and as such, there is no insulation tracking.
 The smaller size of conductor and clearances lead to small overall breaker size; and
these have ample overload margin.
VACUUM CIRCUIT BREAKER:
In such breakers vacuum is used as the arc quenching medium. Since vacuum offer the highest
insulating strength. It has for superior arc quenching properties than any other medium.
Fig. No. (5.6) VACUUM CIRCUIT BREAKER
5.7 INSTRUMENT TRANSFORMER:
CURRENT TRANSFORMER:
These instrument transformers are connected in AC power circuits to feed the current coils of
indicating and metering instruments (ammeter, wattmeter’s, and watt hour meters) and
protective relays. Thus the CTs Borden the limits of measurements and maintain a watch over
the currents flowing in the circuit and over the power loads. In high voltage installation CTs in
addition to above, also isolate the indicating and metering instruments from high voltage. The
current transformer basically consists of an iron core on which are wound a primary and one
or two secondary windings

11. EE DEPT. ,SSCE 11
Fig. No. (5.7) CURRENT TRANSFORMER:
SPECIFICATION OF C.T.:
Fig. No. (5.8) SPECIFICATION OF C.T
POTENTIAL TRANSFORMER:
The potential transformers are employed for voltage above 380 volts to feed the potential coils
of indicating and metering instruments (volt meters, wattmeter’s, and watt hour meters) and
relays.
The primary winding of the potential transformers is connected to the main bus-bars of the
switch gear installation and to the secondary windings; various indicating and metering
instruments and relays are connected.

12. EE DEPT. ,SSCE 12
Fig. No. (5.9) POTENTIAL TRANSFORMER
5.8 CAPACITOR VOLTAGE TRANSFORMER CVT:
 Capacitor voltage transformer (C.V.T) can be effectively employed as potential
source of measuring protection carrier communication and other function of an
available for system voltage 33 KV to 400 KV
 The performance of capacitance voltage transformer is inferior to that of electro
magnet voltage transformer. Its performance affected by the
Rating of CVT:
Fig. No. (5.10) CVT

13. EE DEPT. ,SSCE 13
Advantage of CVT:
 Simple design and easy installation.
 Frequency independence voltage distribution.
 Provides isolation between the high voltage terminal and low voltage metering.
5.9 LINE TRAP/WAVE TRAP:
Line trap also is known as Wave trap. What it does is trapping the high frequency
communication signals sent on the line from the remote substation and diverting them to the
telecom/teleportation panel in the substation control room (through coupling capacitor and
LMU).
Fig. No. (5.11) LINE TRAP/WAVE TRAP
6. PROTECTION OF TRANSFORMER:
Buchholz Relay:
The Buchholz relay is fitted in the pipe leading to the conservator. The gas gets collected in the upper
portion of the relay, thereby the oil in the relay drops down. The float, floating in the oil in the relay
tilts down with the lowering oil level. While doing so the mercury switch attached to the float is closed
and the mercury switch closes the alarm circuit. The testing of gas gives clue regarding the type of
insulation failure.
When a serious short circuit occurs in the transformer, the pressure in the tank increases. The
oil rushes towards the conservator. While doing so the it passes through the Buchholz relay.
The baffles (plates) in the relay get pressed by the rushing oil. Thereby they close another
switch which in turn closes the trip circuit of circuit-breaker.

14. EE DEPT. ,SSCE 14
Fig. No. (5.12) Buchholz Relay
Differential Protection
The 'Differential protection' responds to the vector deference between two similar quantities.
In protection of transformer, CT's are connected at each end of the transformer. The CT
secondary are connected in star of delta and between the CT's of each end. The CT connections
and CT ratios are such that currents fed into the pilot wires from both the ends are equal during
normal conditions and for through fault

15. EE DEPT. ,SSCE 15
CHAPTER 6
6. PLCC SECTION
 PLCC is used for communication between stations. In power station, receiving stations
and substations telephones are provided. These are connected to carrier current
equipment and conversion can be carried out by means of ‘Power Line Carrier
Communication. Each end of the line is provided with identical carrier current
equipment consisting of transmitter, receiver, line-tuning unit, master oscillator, power
amplifier, etc.
 The carrier equipment is connected to the transmission line through 'coupling capacitor'
which is of such a capacitance that it offers low reactance to carrier frequency but high
reactance to power frequency. 'Line trap unit' is inserted between bus bar and
connection of coupling capacitor to the line. It is a parallel tuned circuit comprising L
and C. The unit prevents the high frequency signals from entering the neighboring line,
and the carrier currents flow only in the protected line.
 In a PLCC panel, there are three sections transmitter, receiver and speech sections. At
the time of communication 'speech section' connects both transmitter and receiver to
the telephone.

16. EE DEPT. ,SSCE 16
CHAPTER 7
7. DC BATTERY SYSTEM
Nests for (110v DC supply), one set is used for main supply and other is used for CB and
control room operation.
Fig. No. (7.1) DC BATTERY SYSTEM

17. EE DEPT. ,SSCE 17
CHAPTER 8
8. LOAD FLOW DIAGRAM
Fig. No. (8.1) LOAD FLOW DIAGRAM

18. EE DEPT. ,SSCE 18
CHAPTER 9
9. REACTIVE POWER MANAGEMENT (power factor
improvement)
9.1 CAPACITOR BANK:
The capacitor gives following functions
1. Voltage rise
2. Energy storage
3. Power factor improvement
 Three capacitor banks of 7.2 MVAR are used for power and voltage improvement.
When the voltage level due to lagging load, the capacitor bank gets connected in EH
line and capacitive reactance is more than inductive reactance of circuit and hence
impedance of the line is reduced and the line voltage is maintained to desired level.
Fig. No. (9.1) CAPACITOR BANK

19. EE DEPT. ,SSCE 19
CHAPTER 10
10. PROTECTIVE RELAY SYSTEM
10.1 OVER CURRENT RELAY
A digital overcurrent relay is type of protective relay which operates when the load current
exceeds a pickup value. In a typical application the over current relay is connected to current
transformer and calibrated to operate at or above a specific current level. When the relay
operates, one or more contacts will operate and energize to trip (open) a circuit breaker. There
are two basic forms of overcurrent relays: the instantaneous type and the time-delay type.
The instantaneous overcurrent relay is designed to operate with no intentional time delay when
the current exceed the relay setting. None less, the operating time of this type of relay can vary
significantly. It may be as low as 0.016 seconds or as high as 0.1 seconds.
The time-overcurrent relay has an operating characteristic such that its operating time varies
inversely as the current flowing in the relay. It is the backup relay for the 220KV and 132KV
system. It is also not present in the 33kv system.
10.2 EARTH FAULT PROTECTION RELAY
Earth-fault relay is used to protect feeder against faults involving ground. It is connected
commonly to the three phases. The value at which it gets tripped is kept very low so that a
small fault can be easily detected. It is also the backup relay for the 220KV and 132KV system.
It is also not present the 33kv system.
10.3 DISTANCE RELAY
The working principle of distance relay or impedance relay is very simple. There is one voltage
element potential transformer and a current element fed from current transformer of the system.
The deflecting torque is produced by secondary current of CT and restoring torque is produced
by voltage of potential transformer. In normal operating condition, restoring torque is more
than deflecting torque. Hence relay will not operate

20. EE DEPT. ,SSCE 20
CHAPTER 11
11. LOAD DISPATCH CENTER (LDC)
11.1 NATIONAL LOAD DISPATCH CENTER
The main functions assigned to NLDC are:
 Supervision over the Regional Load Dispatch Centers.
 Scheduling and dispatch of electricity over the inter-regional links in- accordance with
grid standards specified by the authority and grid code specified by central
 Dissemination of information relating to operations of transmission system in
accordance with directions or regulations issued by central government from time
to time.
11.2 Regional Load Dispatch centers
The main responsibilities of RLDCs are:
 System parameters and security.
 To ensure the integrated operation of the power system grid in the respective
region.
 System studies, planning and contingency analysis.
 Daily scheduling and operational planning.
Fig. No. (11.1) Regional Load Dispatch center

21. EE DEPT. ,SSCE 21
CHAPTER 12
12. MAINTENANCE SCHEDULE:
12.1 FOR LIGHTING ARRESTOR:
Table No. (12.1) FOR LIGHTING ARRESTOR
ITEM NO FREQUENCY ITEM TO BE
INSPECTED
INSCEPTION ACTION REQUIRRED IF
INSPECTION SHOWS
UNSATISFACTORY
CONDITON
1 2 3 4 5
1 Quarterly Surge counter Reading of
Surge counter
Normal counting rate is 0-5
counts a year. More than 10
counts is abnormal
2 Half yearly Surge
Arrestor:
cleaning
3 Half yearly LA Measurement
of insulation
Resistance
The basic value more than
1000 M Ω with a 100
megger.
4 Half LA Measure Earth
resistance and
check earth
connection.
5 yearly LA Check with
current leakage
meter
A change of grading
current of more than 500
12.2 FOR CURRENT TRANSFORMER:
Table No. (12.2) FOR CURRENT TRANSFORMER
ITEM
NO
FREQUENCY ITEM TO BE
INSPECTED
INSCEPTION ACTION REQUIRRED IF
INSPECTION SHOWS
UNSATISFACTORY
CONDITON
1 2 3 4 5

22. EE DEPT. ,SSCE 22
1 Daily Junction box Close/open If open than closed
2 Monthly Oil leakage checking If necessary add oil and plug
leakage
3 Monthly Healthiness of
Junction box
Checking If not proper replace gasket
4 Monthly Oil level in CT Checking
5 Monthly CT Cleaning If necessary add oil and plug
leakage
6 Half yearly CT Checking Compare with guaranteed
value, if low take up with
manufacturer
7 Half yearly Primary
connection
I.R. measurement
DA ratio
Compare with guaranteed
value, if low take up with
manufacturer
8 Half yearly Secondary
conection
Measurement of
Tan delta &
capacitance
9 Half yearly Continuity of
CT Secondary
wiring
tightening
10 Half yearly Oil level gauge Tightening/
cleaning
11 Half yearly CT Secondary
Resistnce
Checking
12 Yearly CT Checking
13 Yearly CT Magnetization
characteristics.
14 Yearly CT CT ratio test
15 Yearly OIL D.G.A

23. EE DEPT. ,SSCE 23
12.3 FOR CVT (capacitor voltage transformer):
Table No. (12.3) FOR CVT (capacitor voltage transformer)
ITEM
NO
FREQUENCY ITEM TO BE
INSPECTED
INSCEPTION ACTION REQUIRRED
IF INSPECTION
SHOWS
UNSATISFACTORY
CONDITON
1 2 3 4 5
1 Weekly Base unit Oil level If necessary add oil and
plug leakage
2 Weekly Top
unitearthing of
HF point
Oil level If necessary add oil and
plug leakage
3 Quarterly Dust deposits Oil level
4 Quarterly Oil leaks Visual checking If crack than replace
5 Quarterly Metring point Checking Plug the leakage
6 Quarterly Healthiness of
gasskets
CVT terminal
voltage
7 Quarterly Tightness of
terminal
Checking
8 Half Yearly All connection Cleaning &
tightening
9 Half Yearly Junction box Cleaning &
tightening
10 Half Yearly Capacitor
stacks
Cleaning &
tightening
11 Yearly CVT Tan delta
measurement of
CVT
If temp. high. Replace
CVT

24. EE DEPT. ,SSCE 24
12 Yearly Oil Testing of EMU
tank oil for BDV
Compare with
guaranteed values and
take action as
recommended
13 Yearly If BDV is low replace oil
by new one
12.4 FOR SF6 CIRCUIT BREAKER:
Table No. (12.4) FOR SF6 CIRCUIT BREAKER
ITEM
NO
FREQUENCY ITEM TO BE
INSPECTED
INSCEPTION ACTION
REQUIRRED IF
INSPECTION
SHOWS
UNSATISFACTORY
CONDITON
1 2 3 4 5
1 Daily Status of
closing
Closing spring shall
be in charged
condition
If not charge the
closing spring
2 Monthly SF6 gas is
pressure if
pressure
gauge is
provide
Filling pressure If low check the SF6
gas leakage
3 Monthly Operation
status
Check the no of
operations
If there has been no
operation of breaker in
the past month
4 Quarterly Insulator Clean the isolators
and check for any
cracks
Replaced the cracked
insulator
5 Quarterly Clamp and
connector
Tightining all the
clamp and
connectors on the
breaker
Replace the damage
clamps and nuts and
bolts

25. EE DEPT. ,SSCE 25
6 Quarterly Operation of
breaker
Check the mannual
operation also
electrical operation
for local
Check the control
wring and mechanism
7 Quarterly Operation of
breaker
Lubricate all the
moving parts
Replaced the defactive
parts
8 Quarterly SF6gas
monitring
circuits
Tighten all the
connection on the
terminal blocks
Replaced the damaged
scrobes on the terminal
blocks
9 Quarterly Operation
counter
Check that it is
working
Rectify defect on
replaced
10 Quarterly Air
compressor
Check oil level and
oil quality
Adjust tension if
required
11 Half Yearly For
penumatic
operated
mechaism
Mannualoperation
of air compressor
Adjust the pressure
switch if required
12 Half Yearly For hydrallic
operated
mechaism
Check the pressure
marking time
Adjust the pressure
switch if required
13 Yearly Opening and
closing
timings
Measurethe
oppening and
closing
Time on the circuit
breaker
14 Yearly Foundation
bolts
Check the tightness Tighten fondation
bolts if required
15 Yearly Earthing Check the tightness
of the earthing
connection
tightness of the
earthing connection
16 Yearly Spring
charging
Check the tightness
of wire connection
Replaced the old out
bushes

26. EE DEPT. ,SSCE 26
CONCLUSION
In conclusion to all the mentioned design aspects of the 220/132KV sub-station there are
several other factors that are needed to be considered. This includes socio-economic factor of
the surrounding locality, political developments, union of workers and contractors. Economic
factors become chief aspect in any project which can take a prolonged period to complete. An
assumption of price hike of all the materials to a higher precision is needed to be made in order
to estimate the budget of this project. The mechanical and civil designs are also an essential
part of any electrical substation design. Thus a lot of other engineering brains in those fields
are also employed for the construction. Experts in the field of commerce and law are also
employed to meet the various challenges that may rise up.