very help full report of 220 kv gss similarly working model to every student of electrical engineering

1. 1
A
PROJECT REPORT
ON
“220 KV GSS WORKING MODEL”
Submitted in partial Fulfillment of the requirements
For the award of the degree
BACHELOR OF TECHNOLOGY
In
ELECTRICAL ENGINEERING
Session 2013 – 17
Submitted To: Submitted By:
Mr. Sudhanshu Gupta Mr. Giriraj Bairwa
Associate Proffesor (13EKTEE032)
Dept. Of Electrical Engg.
ELECTRICAL ENGG. DEPARTMENT
KAUTILYA INSTITUTE OF TECHNOLOGY & ENGINEERING
RAJASTHAN TECHNICAL UNIVERSITY
KOTA (RAJ.)

2. 2
CERTIFICATE
This is to certify that the Project tilted “220 KVGridSubstationWorking
Model”submitted by “Mr. Giriraj Bairwa ” is in partial fulfilment ofthe
requirements of the award of “Degree of Bachelor of Technology”, is a
record of bonafide work done under the guidance of “Mr. Sudhanshu
Gupta”, Asso.Prof., Department of Electrical Engineering, KITE, Jaipur.
The content of this report, in full or in parts, have neither been taken from
any other sourcenorhave been submitted elsewhere forthe award of degree.
Prof. K.C. Roy
(Head, Department of Electrical Engineering)

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ACKONWLEDGEMENT
The satisfaction and euphoria that accompany the successfulcompletion of
any task would be incomplete without mentioning of the people whose
constant guidance and encouragement made it possible.
We take pleasure in presenting before you, our project, which is result of
studied blend of both research and knowledge. We express our earnest
gratitude to our guide, “Mr. Sudhanshu Gupta”,Asso.Prof. Department of
Electrical Engineering, and Mr. Surender Choudhary, Lab Incharge
(Project Lab.), for his constant Support and encouragement. We are grateful
for their cooperation and valuable suggestions.
Finally, we express our gratitude to all other persons who are involved either
directly or indirectly for the completion of this project.

4. 4
DECLARATION
We , the undersigned , declare that the project entitled ‘220 KV GRID SUB-
STATION WOKING MODEL’ , being submitted in partial fulfilment for
the award of Degree of Bachelor of Technology in Electrical engineering ,
Affiliated to Rajasthan Technical University, is the work carried out by us.
Submitted By:
Mr.Giriraj Bairwa (13EKTEE032)
B.Tech (IV year)
Batch – (2013-17)

5. 5
ABSTRACT
The present day electrical power system is AC. i.e. electric power is generated,
transmitted and distributed in the form of Alternating current. The electric power
is produced at the power station, which are located at favorable places, generally
quite away from the consumers. It is delivered to the consumer through a large
network of transmission and distribution system. At many place in the line of
power system, it may be desirable and necessary to change some characteristic
(e.g. Voltage level, frequency and p. f. etc.)ofelectric supply. This is accomplished
by suitable apparatus, which are installed in a sub-station. Forexample, generation
voltage (11KV or 66KV) at the power station is stepped up to high voltage (Say
11KV to 33/220/440KV) for transmission of electric power. Similarly near the
consumer’s localities, the voltage may have to be stepped downto utilization level.
This job is again accomplished by a sub-station.
A power substation is a subsidiary station ofan electricity generation, transmission
and distribution system where voltage is transformed from high or medium to low
or the reverse using transformers. Electric power flows through several substations
between generating plant and consumer changing the voltage level in several
stages.
A substation that has a step-up transformer increases the voltage level with
decreasing current, while a step-downtransformer decreases the voltage level with
increasing current. The word substation comes from the days before the
distribution system became a grid.
At first substations were connected to only one power station where the generator
was housed and were subsidiaries of that power station.

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CONTENTS
Sr. No. Content Page No.
1. List of Figure 7-8
2. Abbreviations 9
3. Introduction To grid sub-station system 10
1.1 Types of sub-station 11
1.2 Characteristics of GSS System 12
1.3 Block Diagram of 220 KV GSS 13
1.4 Circuit Diagram Of 220 KV GSS Working
model
14
1.5 Equipment Rating Table 15
4. Hardware Requirement 16
5. Transmissionline Tower 17-20
6. Bus-Bar 21-22
7. Relay 23-24
8. Circuit Breaker 25-28
9. Transformer 29-33
10. Current Transformer 34-35
11. Potential Transformer 36-37
12. Microcontroller 38
13. Isolator 39-40
14. Control room 41-42
15. Load 43-44
16. Conclusion 45
17. Reference 46

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LIST OF FIGURE
1. Fig. 1.1:- working model of 220 KV GSS
2. Fig, 1.2:- Block diagram of 220 KV GSS
3. Fig. 1.3:- circuit diagram of working model of 220 KV GSS
4. Fig. 1.4:- Woodenpole
5. Fig. 1.5:- RCC pole
6. Fig. 1.6:- Steel Pole
7. Fig. 1.7:- line pole using in working model
8. Fig. 1.8:- Bus-bar arrangement in working model
9. Fig. 1.9:- Basic Relay
10.Fig. 1.10:- Relay(12v)
11.Fig. 1.11:- Sf6 circuit breaker
12.Fig. 1.12:- Circuit Breaker in Working Model of 220 KV GSS
13.Fig. 1.13:- Power Transformer in 220 KV GSS
14.Fig. 1.14:- Radiator with fan
15.Fig. 1.15:- Buchholz Relay
16.Fig. 1.16:- Micro switch type Winding & oil temperature indicator
17.Fig. 1.17:- Silica Gel
18.Fig. 1.18:- Step-down transformer used in working model
19.Fig. 1.19:- Current Transformer in 220 KV GSS
20.Fig. 1.20:- Current Transformer use in working model
21.Fig. 1.21:- Current Transformer circuit in GSS working model

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22.Fig. 1.22:- Potential Transformer
23.Fig. 1.23:- P.T use in working model 220 KV GSS
24.Fig. 1.24:- P.T Circuit
25.Fig. 1.25:- Microcontroller circuit
26.Fig. 1.26:- Isolator in 220 KV GSS
27.Fig. 1.27:- Isolator circuit
28.Fig. 1.28:- Control room 220 KV GSS
29.Fig. 1.29:- Rural or Urban load
30.Fig. 1.30:- Industrial load

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ABBREVIATIONS
S.No. Abbreviation Full form
1.
PT Potential Transformer
2.
CT Current Transformer
3.
CB Circuit breaker
4.
PR Protective Relay
5. MCB Main Circuit breaker
6. GSS Grid Sub-station

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INTRODUCTION OF GRID SUB-STATION
Electrical power is generated, transmitted in the form of alternating current. The
electric power produced at the power stations is delivered to the consumers
through a large network of transmission & distribution. The transmission network
is inevitable long and high power line are necessary to maintain a huge block of
power source of generation to the load centers to inter connected. Power house
for increased reliability of supply greater.
The assembly of apparatus used to change some characteristics (e.g. voltage, ac
to dc, frequency, power factor etc.) of electric supply keeping the power constant
is called a substation.
An electrical substation is a subsidiary station of an electricity generation,
transmission and distribution system where voltage is transformed from high to
low or the reverse using transformers. Electric power may flow through several
substations between generating plant and consumer, and may be changed in
voltage in several steps.
Other Definition “A substation is a part of an electrical generation, transmission,
and distribution system. Substations transform voltage from high to low, or the
reverse, or perform any of several other important functions. Between the
generating station and consumer, electric power may flow through several
substations at different voltage levels. A substation may include transformers to
change voltage levels between high transmission voltages and lower distribution
voltages, or at the interconnection of two different transmission voltages.”

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Types of sub-station:-
Substations may be described by their voltage class, their applications within the
p Power system, the method used to insulate most connections, and the style and
m materials of the structures used.
1) Transmissionsubstation
A transmission substation connects two or more transmission lines. The
simplest case is where all transmission lines have the same voltage.
2) Distribution substation
A distribution substation transfers power from the transmission system to
the distribution system of an area. It is uneconomical to directly connect
electricity consumers to the main transmission network, unless they use
large amounts of power, so the distribution station reduces voltage to a
level suitable for local distribution.
3) Collector substation
In distributed generation projects suchas a wind farm, a collector substation may
be required. It resembles a distribution substation although power flow is in the
opposite direction, from many wind turbines up into the transmission grid.
4) Converter substations
Converter substations may be associated with HVDC converter plants, traction
current, or interconnected non-synchronous networks. These stations contain
power electronic devices to change the frequency of current, or else convert from
alternating to direct current or the reverse.
5) Switching station
A switching station is a substation without transformers and operating only at a
single voltage level. Switching stations are sometimes used as collector and
distribution stations. Sometimes they are used for switching the current to back-
up lines or for parallelizing circuits in case of failure.

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Chacterstics ofgrid sub-station
Substations generally have switching, protection and control equipment, and
transformers. In a large substation, circuit breakers are used to interrupt any short
circuits or overload currents that may be and occur on the network. Smaller
distribution stations may usereclosed circuit breakers orfuses for protectionequip.
of distribution circuits. Substations themselves a do not usually have a generators,
although a power plant may have a substation nearby. Other devices such
as capacitors and voltage regulators may also be located at a substation.
A grounding (earthing) system must be designed. The total ground potential rise,
and the gradients in potential during a fault (called touchand step potentials), must
be calculated to a protectpassers-byduring a short-circuit the transmission system.
Earth faults at a substation can cause a ground potential rise. Currents flowing in
the Earth's surface during a fault can cause metal objects to have an significantly
different voltage than the ground under a person's feet;this touch potential presents
a hazard of electrocution. Where a substation has a metallic fence, it must be
properly grounded to protect people from this hazard.
Substations may be owned and operated by an electrical utility, or may be owned
by a large industrial or commercial customer. Generally substations are
unattended, relying on SCADA for remote supervision and control.
Working model of 220 KV GSS is as shown below.
Fig1.1-working model of 220 KV GSS

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BLOCK DIAGRAM of 220 KV GSS
Fig1.2:-Block diagram of 220 KV GSS
Above shown Block diagram is of 220 KV GSS, Sitapura which shows mainly
circuit diagram of GSS.

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CIRCUIT DIAGRAM of 220 KV GSS WORKING MODEL
Fig1.3:-circuit diagram of 220 KV Grid sub-station
Working model

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EQUIPMENT RATING TABLE
EQUIPMENT
NAME
GSS Equipment
Rating
Working Model
Equipment rating
CURRENT
TANSFORMER
100 amp. 2 amp.
POTENTIAL
TRANSFORMER
220 V 2 amp. / 5 v
CIRCUIT BREAKER 2000 amp. 2 amp.
PROTECTIVE
RELAY
12v/30ma 12v
TANSFORMER
(220/110 V SIDE)
100/110 mva 2amp(220/110v)
CONDUCTER WIRE 0.4 kv 8 sq. mm
BUS BAR 220/110 kv 220/110V
MICRO-
CONTROLLER
- 5 v
LOAD
TRANSFORMER
O/P VOL.
1.RURAL LOAD-
O/P (v)
55 v
2.URBAN LOAD
O/P VOL.
55 V
3.INDUSTRIAL
LOAD O/P VOL.
55V
INPUT SUPPLY - 220/230 V
(1 phase-
supply)

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HARDWARE REQUIRMENT
I. Pole
II. Bus – Bar
III. Relay
IV. Transformer
V. Circuit Breaker
VI. Current Transformer
VII. Potential Transformer
VIII. C.T Circuit
IX. P.T Circuit
X. Load
XI. L.E.D Display
XII. Microcontroller
XIII. Ply-wood (6x4)
XIV. Wire
XV. Input Supply (220/230v)
XVI. Glue-Gun

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TRANSMISSION LINE TOWER
Electrical Transmission Tower Types and Design
The main supporting unit of overhead transmission line is transmission tower.
Transmission towers have to carry the heavy transmission conductorat a sufficient
safe height from ground. In addition to that all towers have to sustain all kinds of
natural calamities. So transmission tower designing is an important engineering
job where all three basic engineering concepts, civil, mechanical and electrical
engineering concepts are equally applicable .A power transmission tower consists
of the following parts,
1. Peak of transmission tower
2. Cross arm of transmission tower
3. Boom of transmission tower
4. Cage of transmission tower
5. Transmission Tower Body
6. Leg of transmission tower
7. Stub/Anchor Bolt and Base plate assembly of transmission tower.
The main parts among these are shown in the pictures.
1. Peak of Transmission Tower
The portion above the top cross arm is called peak of transmission tower.
Generally earth shield wire connected to the tip of this peak.
2. Cross Arm of Transmission Tower
Cross arms oftransmission tower hold the transmission conductor. Thedimension
of cross arm depends on the level of transmission voltage, configuration and
minimum forming angle for stress distribution.
3. Cage of Transmission Tower
The portionbetween tower bodyand peak is known as cageof transmission tower.
This portion of the tower holds the cross arms.
4. Transmission Tower Body
The portion from bottom cross arms up to the ground level is called transmission
tower body. This portion of the tower plays a vital role for maintaining required
ground clearance of the bottom conductor of the transmission line.

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Types of pole:
1. Woodenpoles: Thesearemade of seasoned wood (salor chir) and are suitable
for lines of moderate X-sectional area and of relatively shorter spans, say upto 50
meters. Such supports are cheap, easily available, provide insulating properties
and, therefore, are widely used for distribution purposes in rural areas as an
economical proposition. The woodenpoles generally tend to rot below the ground
level, causing foundation failure.
Fig1.4:-Wooden pole
2. Steel poles: The steel poles are often used as a substitute for wooden poles.
They possess greater mechanical strength, longer life and permit longer spans to
be used. Such poles are generally used for distribution purposes in the cities. This
type of supports need to be galvanized or painted in order to prolong its life.
The steel poles are of three types
(i) Rail poles
(ii) Tubular poles and
(iii) Rolled steel joints.

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3. RCC poles: The reinforced concrete poles have become very popular as line
supports in recent years. They have greater mechanical strength, longer life and
permit longer spans than steel poles. Moreover, they give good outlook, require
little maintenance and have good insulating properties. Figure shows R.C.C. poles
for single and double circuit.
Fig1.5:-RCC Pole
4. Steel towers: In practice, wooden, steel and reinforced concrete poles are used
for distribution purposes at low voltages, say upto 11 kV. However, for long
distance transmission at higher voltage, steel towers are invariably employed.
Steel towers have greater mechanical strength, longer life, can withstand most
severe climatic conditions and permit the use of longer spans.

20. 20
Fig1.6:-Steel pole
Fig1.7:- line pole using in working model

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BUS BARS
Bus Bars are the common electrical component through which a large no of
feeders operating at same voltage have to be connected. Ifthe bus bars are of rigid
type (Aluminum types) the structure height are low and minimum clearance is
required. While in case of strain type of bus bars suitable ACSR conductor are
strung/tensioned by tension insulators discs according to system voltages. In the
widely used strain type bus bars stringing tension is about500-900 Kg depending
upon the size of conductor use Here proper clearance would be achieved only if
require tension is achieved.
Loosebus bars would affect the clearances when it swings while over tensioning
may damage insulators. Clamps or even effect the supporting structures in low
temperature conditions. The clamping should be proper, as loose clamp would
spark under in full load condition damaging the bus bars itself.
(6.1) Bus Bar Arrangement May be of Following Type
Which is Being Adopted by RVPNL:-
(6.1.1) Single bus bar arrangement
(6.1.2) Double bus bar arrangement
(a) Main bus with transformer
(b) Main bus-I with main bus-II
(6.1.3) Double bus bar arrangement with auxiliary bus.
(6.1.1) Single bus Bar Arrangement:
This arrangement is simplest and cheapest. It suffers, however, from major
defects.
1. Maintenance without interruption is not possible
2. Extension of the substation without a shutdown is not possible

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(6.1.2) Double Bus Bar Arrangement:
1. The load circuit may be divided in to two separate groups if needed
Operational consideration. Two supplies from different sources can be put.
2. Either bus bar may be taken out from maintenance of insulators.
3. The normal bus selection insulators cannot be used for breaking load currents.
The arrangement does not permit breaker maintenance without causing stoppage
of supply.
(6.1.3) Double Bus Bar Arrangements Contains Main Bus with Auxiliary
Bus
The double bus bar arrangement provides facility to change over to either bus to
carry out maintenance on the other but provide no facility to carry over breaker
maintenance. The main and transfer bus works the other way round. It provides
facility for carrying out breaker maintenance but does not permit bus
maintenance. Whenever maintenance is required on any breaker the circuit is
changed over to the transfer bus and is controlled through bus coupler breaker.
As shown below double bus-bar arrangement used in 220 KV GSS working
model.
Fig. 1.8:-Bus-bar use in working model

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PROTECTIVE RELAYS
Relays must be able to evaluate a wide variety of parameters to establish that
corrective action is required. Obviously, a relay cannot prevent the fault. Its
primary purposeis to detect the fault and take the necessary action to minimize the
damage to the equipment or to the system. The most common parameters which
reflect the presence of a fault are the voltages and currents at the terminals of the
protected apparatus or at the appropriate zone boundaries. The fundamental
problem in powersystem protection is to define the quantities that can differentiate
between normal and abnormal conditions. This problem is compounded bythe fact
that “normal” in the present sense means outside the zone of protection. This
aspect, which is of the greatest significance in designing a secure relaying system,
dominates the design of all protection systems.
Fig1.9:-Relays
(7.1) Distance Relays:
Distance relays respond to the voltage and current, i.e., the impedance, at the relay
location. The impedance per mile is fairly constant so these relays respond to the
distance between the relay location and the fault location. As the power systems
become more complex and the fault current varies with changes in generation and
system configuration, directional over current relays becomedifficult to apply and
to setfor all contingencies, whereas the distance relay setting is constantfor a wide
variety of changes external to the protected line.

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(7.2) Types of Distance relay:-
(7.2.1) Impedance Relay:
The impedance relay has a circular characteristic centered. It is non directional
and is used primarily as a fault detector.
(7.2.2) Admittance Relay:
The admittance relay is the most commonly used distance relay. It is the tripping
relay in pilot schemes and as the backup relay in step distance schemes. In the
electromechanical design it is circular, and in the solid state design, it can be
shaped to correspond to the transmission line impedance.
(7.2.3) Reactance Relay:
The reactance relay is a straight-line characteristic that responds only to the
reactance of the protected line. It is non directional and is used to supplement the
admittance relay as a tripping relay to make the overall protection independent of
resistance. It is particularly useful on short lines where the fault arc resistance is
the same order of magnitude as the line length.
As shown below relay (12v) used in working model.
Fig1.10:- relay (12v)

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CIRCUIT BREAKER
The function of relays and circuit breakers in the operation of a power system.
Prevent or limit damage during faults or overloads, and to minimize their effect
on the remainder of the system. This is accomplished by dividing the system into
protective zones separated by circuit breakers. During a fault, the zone which
includes the faulted apparatus is de-energized and disconnected from the system.
In addition to its protective function, a circuit breaker is also used for circuit
switching under normal conditions.
Each having its protective relays for determining the existence of a fault in that
zone and having circuit breakers for disconnecting that zone from the system. It
is desirable to restrict the amount of system disconnected by a given fault; as for
example to a single transformer, line section, machine, or bus section. However,
economic considerations frequently limit the number of circuit breakers to those
required for normal operation and some compromises result in the relay
protection.
Various types of circuit breakers:-
(1) SF6 Circuit Breaker
(2) Air Blast Circuit Breaker
(3) Oil Circuit Breaker
(4) Bulk Oil Circuit Breaker (MOCB)
(5) Minimum Oil Circuit Breaker
(1) SF6 Circuit Breaker:-
Sulphur hexafluoride has proved its-self as an excellent insulating and arc
quenching medium. It has been extensively used during the last 30 years in circuit
breakers, gas-insulated switchgear (GIS), high voltage capacitors, bushings, and
gas insulated transmission lines. In SF6 breakers the contacts are surrounded by
low pressure SF6 gas. At the moment the contacts are opened, a small amount of
gas is compressed and forced through the arc to extinguish.

26. 26
Fig1.11:- Sf6 circuit breaker
(2) Air Blast Circuit Breaker:
The principle of arc interruption in air blast circuit breakers is to direct a blast of
air, at high pressure and velocity, to the arc. Fresh and dry air of the air blast will
replace the ionized hot gases within the arc zone and the arc length is considerably
increased. Consequently the arc may be interrupted at the first natural current
zero. In this type of breaker, the contacts are surrounded bycompressed air. When
the contacts are opened the compressed air is released in forced blast through the
arc to the atmosphere extinguishing the arc in the process.
(3) Oil Circuit Breaker:
Circuit breaking in oil has been adopted since the early stages of circuit breakers
manufacture. The oil in oil-filled breakers serves the purposeofinsulating the live
parts from the earthed ones and provides an excellent medium for arc interruption.
Oil circuit breakers of the various types are used in almost all voltage ranges and
ratings. However, they are commonly used at voltages below 115KV leaving the
higher voltages for air blast and SF6 breakers.
The advantages of using oil as an arc quenching medium are:
1. It absorbs the arc energy to decompose the oil into gases, which have excellent
cooling properties.
2. It acts as an insulator and permits smaller clearance between live conductors
and earthed components.

27. 27
The disadvantages of oil as an arc quenching medium are:
1. Its inflammable and there is risk of fire
2. It may form an explosive mixture with air.
(4) Bulk oil Circuit breaker:
Bulk oil circuit breakers are widely used in power systems from the lowest
voltages up to115KV. However, they are still used in systems having voltages up
to 230KV.The contacts ofbulk oil breakers may be ofthe plain-break type, where
the arc is freely interrupted in oil, or enclose within arc controllers.
(5) Minimum oil Circuit Breaker:
Bulk oil circuit breakers have the disadvantage of using large quantity of oil.
With frequent breaking and making heavy currents the oil will deteriorate and
may lead to circuit breaker failure. This has led to the design of minimum oil
circuit breakers working on the same principles of arc control as those used in
bulk oil breakers. In this type of breakers the interrupter chamber is separated
from the other parts and arcing is confined to a small volume of oil.
Advantages:
An air blast circuit breaker has the following advantages oil circuit breaker:
• The risk of fire is eliminated
• The arcing products are completely removed by the blast whereas the oil.

28. 28
As shown below circuit breaker used in working model:
Fig1.12:-Circuit Breaker Used in Working Model of 220 KV GSS

29. 29
POWER TRANSFORMER
Power transformers are called auto transformers.
(9.1) Windings:
Winding shall be of electrolytic grade copperfree from scales & burrs. Windings
shall be made in dust proofand conditioned atmosphere. Coils shall be insulated
that impulse and power frequency voltage stresses are minimum. Coils assembly
shall be suitably supported between adjacent sections by insulating spacers and
barriers. Bracing and other insulation used in assembly of the winding shall be
arranged to ensure a free circulation of the oil and to reduce the hot spot of the
winding. All windings ofthe transformers having voltage less than 66 kV shall be
fully insulated. Tapping shall be so arranged as to preserve the magnetic balance
of the transformer at all voltage ratio. All leads from the windings to the terminal
board and bushing shall be rigidly supported to preventinjury from vibration short
circuit stresses.
Fig1.13:- Power Transformer in 220 KV GSS

30. 30
(9.2) Tanks and fittings:
Tank shall be of welded construction & fabricated from tested quality low carbon
steel of adequate thickness. After completion of welding, all joints shall be
subjected to dye penetration testing.
At least two adequately sized inspection openings one at each end ofthe tank shall
be provide for easy access to bushing & earth connections. Turrets & other parts
surrounding the conductor of individual phase shall be non-magnetic. The main
tank body including tap changing compartment, radiators shall be capable of
withstanding full vacuum.
(9.3) Cooling Equipment:
Cooling equipment shall confirm to the requirement stipulated below.
(a.) Each radiator bank shall have its own cooling fans, shut off valves at the top
and bottom(80mm size) lifting lugs, top and bottom oil filling valves, air release
plug at the top, a drain and sampling valve and thermometer pocket fitted with
captive screw cap on the inlet and outlet.
(b.) Cooling fans shall not be directly mounted on radiator bank which may cause
undue vibration. These shall belocated so as to prevent ingress ofrain water. Each
fan shall be suitably protected by galvanized wire guard.
Fig1.14:- Radiator with fan

31. 31
(9.4) Transformer Accessories:
(9.4.1) Buchholz Relay:
This has two Floats, one of them with surge catching baffle and gas collecting
spaceat top. This is mounted in the connecting pipe line between conservatorand
main tank. This is the most dependable protection for a given transformer.
Gas evolution at a slow rate that is associated with minor faults inside the
transformers gives rise to the operation or top float whose contacts are wired for
alarm..
Fig1.15:- Buchholz Relay
(9.4.2) Temperature Indicators:
Most of the transformer (small transformers have only OTI) are provided with
indicators that displace oil temperature and winding temperature. There are
thermometers pockets provided in the tank top coverwhich hold the sensing bulls
in them.
This is done by adding the temperature rise due to the heat produced in a heater
coil (known as image coil) when acurrent proportionalto that flowing in windings

32. 32
is passed in it to that ortop oil. Forproper functioning orOTI & WTI it is essential
to keep the thermometers pocket clean and filled with oil.
Fig1.16:- Micro switch type Winding and oil temperature indicator
(9.4.3) Silica Gel Breather:
Both transformer oil and cellulosic paper are highly hygroscopic. Paper being
more hygroscopic than the mineral oil The moisture, if not excluded from the oil
surface in conservator, thus will find its way finally into the paper insulation and
causes reduction insulation strength of transformer. To minimize this conservator
is allowed to breathe only through the silica gel column, which absorbs the
moisture in air before it enters the conservator air surface.
Fig1.17:- Silica Gel

33. 33
(9.4.4)Conservator:
With the variation of temperature there is corresponding variation in the oil
volume. To account for this, an expansion vessel called conservator is added to
the transformer with a connecting pipe to the main tank. In smaller transformers
this vessel is open to atmosphere through dehydrating breathers (to keep the air
dry). In larger transformers, an air bag is mounted inside the conservatorwith the
inside of bag opento atmosphere through the breathers and the outside surface of
the bag in contact with the oil surface.
As shown below step-down transformer used in working model
Fig1.18:-Step-down transformer (220/110V)

34. 34
CURRENT TRANSFORMER
As you all know this is the device which provides the pre-decoded fraction of the
primary current passing through the line/bus main circuit. Now a day mostly
separate current transformer units are used instead of bushing mounting CT’s on
leveled structure they should be foroil level indication and baseshould be earthed
properly. Care should be taken so that there should be no strain as the terminals.
When connecting the jumpers, mostly secondary connections is taken to three
unction boxes where star delta formation is connected for three phase and final
leads taken to protection metering scheme.
It can be used to supply information for measuring power flows and the electrical
inputs for the operation of protective relays associated with the transmission and
distribution circuit or for power transformer. These current transformers have the
primary winding connected in series with the conductorcarrying the current to be
measured or controlled. The secondary winding is thus insulated from the high
voltage and can then be connected to low voltage metering circuits.
Fig1.19:- current transformer in GSS

35. 35
As show below current transformer and his circuit used in working model
Fig1.20:- current transformer use in working model
Fig1.21:- current transformer circuit in GSS working model
Current transformers are also used for street lighting circuits. Street lighting
requires a constant current to prevent flickering lights and a current transformer
is used to provide that constantcurrent. In this casethe current transformer utilizes
a moving secondarycoil to vary the output so that a constant current is obtained.

36. 36
POTENTIAL TRANSFORMER
A potential transformer (PT) is used to transform the high voltage of a power line
to a lower value, which is in the range of an AC voltmeter or the potential coil of
an AC voltmeter. The voltage transformers are classified as under:
• Capacitive voltage transformer or capacitive type
• Electromagnetic type.
Capacitive voltage transformer is being used more and more for voltage
measurement in high voltage transmission network, particularly for systems
voltage of 220KV and above where it becomes increasingly more economical. It
enables measurement of the line to earth voltage to be made with simultaneous
provision for carrier frequency coupling, which has reached wide application in
modern high voltage network for tale-metering remote control and telephone
communication purpose.
The capacitance type voltage transformers are of two type:
• Coupling Capacitor type
• Pushing Type
Fig1.22:- potential transformer

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As shown below potential transformer and his circuit
Fig1.23:- P.T use in working model 220V GSS
Fig1.24:- P.T circuit
The performance of CVT is affected by the supply frequency switching transient
and magnitude of connected Burdon. The CVT is more economical than an
electromagnetic voltage transformer when the nominal supply voltage increases
above 66KV. The carrier current equipment can be connected via the capacitorof
the CVT. There by there is no need of separate coupling capacitor. The capacitor
connected in series act like potential dividers, provided, the current taken by
burden is negligible compared with current passing through the series connected
capacitor.

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MICROCONTROLLER
A microcontroller (or MCU for microcontroller unit) is a small computer on a
single integrated circuit. In modern terminology, it is a System on a chip A
microcontroller contains one or more CPUs (processorcores)along with memory
and programmable input/output peripherals. Program memory in the form
of Ferroelectric RAM, NOR flash or OTP ROMis also often included on chip, as
well as a small amount of RAM. Microcontrollers are designed for embedded
applications, in contrast to the microprocessors used in personal computers or
other general purpose applications consisting of various discrete chips.
Microcontrollers are used in automatically controlled products and devices, such
as automobile engine control systems, implantable medical devices, remote
controls, office machines, appliances, power tools, toys and other embedded
systems. By reducing the size and costcompared to a design that uses a separate
microprocessor, memory, and input/output devices, microcontrollers make it
economical to digitally control even more devices and processes. Mixed
signal microcontrollers are common, integrating analog components needed to
control non-digital electronic systems.
Fig1.25:- microcontroller circuit

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ISOLATER
“Isolator" is one, which can break and make an electric circuit in no load
condition. Theseare normally used in various circuits for the purposes ofIsolation
of a certain portion when required for maintenance etc. Isolation of a certain
portion when required for maintenance etc. "Switching Isolators" are capable of
• Interrupting transformer magnetized currents
• Interrupting line charging current
• Load transfer switching
Its main application is in connection with transformer feeder as this unit makes it
possible to switch out one transformer, while the other is still on load. The most
common type of isolators is the rotating center pots type in which each phase has
three insulator post, with the outer posts carrying fixed contacts and connections
while the center post having contact arm which is arranged to move through 90`
on its axis.
The following interlocks are provided with isolator:
(a) Bus 1 and2 isolators cannot be closed simultaneously.
(b) Isolator cannot operate unless the breaker is open.
(c) Only one bay can be taken on bypass bus.
(d) No isolator can operate corresponding earth switch is on breaker.
Now then decided by the relay. Because in this working model fully relay control
based. Now then the relay control circuit is control to voltage limit and current
limit to flow in working model of GSS.

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Fig1.26:- isolator in 220 KV GSS.
As shown below Isolator circuit used in working model
Fig1.27:-Isolator circuit

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CONTROL ROOM
Controlpanel contain meters, controlswitches and recorders located in the control
building, also called the dog house. These are used to control the substation
equipment to send power from one circuit to another or to open or to shut down
circuits when needed.
Fig1.28:- Control room 220 KV GSS
Measuring Instrument Used:
(1) Energy Meter:To measure the energy transmitted energy meters are fitted
to the panel to different feeders the energy transmitted is recorded after one hour
regularly for it MWHr, meter is provided.
(2) Wattmeter’s:It is attached to each feeder to record the power exported from
GSS.

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(3) Frequency Meter: To measure the frequency at each feeder there is the
provision of analog or digital frequency meter.
(4) Voltmeter: It is provided to measure the phase to phase voltage .It is also
available in both the analog and digital frequency meter.
(5) Ammeter: It is provided to measure the line current. It is also available in both
the forms analog as well as digital.
(6) Maximum Demand Indicator: There are also mounted the control panel to
record the average power over successive predetermined period.

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LOADS
An electrical load is an electrical component or portion of a circuit that
consumes electric power. This is opposedto a power source, such as a battery or
generator, which produces power. In electric powercircuits examples of loads are
appliances and lights. The term may also refer to the power consumed bya circuit.
Electrical Load Classification and Types:
The electrical loads can be classified into various categories according to various
factors as follows:
1- According To Load Nature-1
 Resistive Electrical Loads.
 Capacitive Electrical Loads.
 Inductive Electrical Loads.
 Combination Electrical Loads.
2- According To Load Nature-2
 Linear Electrical Load.
 None-Linear Electrical Load.
3- According To Load Function
 Lighting Load.
 Receptacles / General / Small Appliances Load.
 Power Loads.
4- According To Load Consumer Category
 Residential Electrical Loads (Dwelling Loads).
 Commercial Electrical Loads.
 Industrial Electrical Loads.
 Municipal / Governmental Electrical Loads (Street Lighting, Power
Required For Water Supply and Drainage Purposes, Irrigation Loads And
Traction Loads).
5- According To Load Grouping
 Individual Loads (Single Load).
 Load Centres (Area Loads).

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As shown below different type of load
Fig1.29:- Rural or Urban load
fig1.30:- Industrial load

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CONCULISION
This Working model present the design of 220 KV GSS with similar technology
based. About working model to completely work as on 220KV GSS work. In
working model various types of equipment used (Relay, Step-down transformer,
double-bus bar arrangement, loads, micro-controller, isolator circuit, circuit
breaker, L.E.D Display, input supply etc.). In 220 KV working model design..
The efficiency of this working model is good and also it reduces the costas well
as fault occurrence and also it reduces the human errors.
A 220KV GSS working model mainly represent of how to work a substation in
transmission or distribution system. The substation includes the primary
equipment (such as circuit breakers, transformers, instrument transformers, etc.)
and the secondary equipment (monitoring, control and protection devices) which
are installed in control room.
In working model the voltage and current above base limit sense to relay and cut
supply automatically. In any operation perform of working model as compare to
substation like that bus-bar operation, load switching, etc.
We studied lot of about knowledge GSS working model and his instumation of
protection required.

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REFERENCE
ONLINE SOURCES
WWW.RVPN.COM
WWW.WIKIPEDIA.COM
WWW.ELECTRICALHUB.COM
WWW.SLIDESHARE.COM
http://www.it.iitb.ac.in/~abhisheka/btp/BTech_Project_Report.doc
RVPNL HOME SITE:
http://www.rvpn.co.in/aboutus/amis.shtml
Gathering During The Traning Period in 220 KV GSS.
REPORTS:
Constructional manual of 220 KV GSS Sitapura (revised in 2016)

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