Inplant training about 110kv/11kv substation

diploma final year electrical and electronic inplant training report files in pdf

1. INPLANT TRAINING 15EE67P
BRP, 6
thSem,DEEE 1 2017/18

CHAPTER-1
INTRODUCTION
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.
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.
The word substationcomes from the days before the distribution system became a grid.
As central generation stations became larger, smaller generating plants were converted to
distribution stations, receiving their energy supply from a larger plant instead of using their own
generators. The first substations were connected to only one power station, where the generators
were housed, and were subsidiaries of that power station.
Substations may be described by their voltage class, their applications within the power
system, the method used to insulate most connections, and by the style and materials of the
structures used. These categories are not disjointed; for example, to solve a particular problem, a
transmission substation may include significant distribution functions.[1]
1.1 DISTRIBUTION SUBSTATION
A distribution substation in Scarborough, Ontario disguised as a house, complete with a
driveway, front walk and a mown lawn and shrubs in the front yard. A warning notice can be
clearly seen on the "front door". Disguises for substations are common in many cities.
[3]

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.
The input for a distribution substation is typically at least two transmission or sub-
transmission lines. Input voltage may be, for example, 110 kV, or whatever is common in the
area. The output is a number of feeders. Distribution voltages are typically medium voltage,
between 11kV and 11 kV, depending on the size of the area served and the practices of the local
utility. The feeders run along streets overhead (or underground, in some cases) and power the
distribution transformers at or near the customer premises.
In addition to transforming voltage, distribution substations also isolate faults in either
the transmission or distribution systems. Distribution substations are typically the points of
voltage regulation, although on long distribution circuits (of several miles/kilometers), voltage
regulation equipment may also be installed along the line.

2. INPLANT TRAINING 15EE67P
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1.2 SINGLE LINE DIAGRAM OF 110/11KV SOMASAMUDRA
SUBSTATION

Fig:-2.1 Single Line Diagram of Substation [2]

3. INPLANT TRAINING 15EE67P
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CHAPTER-2
DETAILS OF SUBSTATION
2.1 INCOMER LINE
Incoming 110KV from Allipur substation to Somasamudra. By using ACSR conductor
in phase and one ground cable by using the steel tower there are two types of tower:-
 Anchor tower
 Tangent tower
For every 10
th
tower is to be one anchor tower is used
Insulator are used in 110KV
Suspension insulator: - 7 No
Strain insulator: - 8 No
2.2 LIGHTNING ARRESTER

Fig 2.2:- Lightning Arrester [5]
A lightning arrester is a device used on electrical power systems and
telecommunications systems to protect the insulation and conductors of the system from the
damaging effects of lightning. The typical lightning arrester has a high-voltage terminal and a

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ground terminal. When a lightning surge (or switching surge, which is very similar) travels along
the power line to the arrester, the current from the surge is diverted through the arrestor, in most
cases to earth.[3]
A lightning arrester (alternative spelling lightning arrestor) (also called lightning diverter)
is a device used on electric power systems and telecommunication systems to protect the
insulation and conductors of the system from the damaging effects of lightning. The typical
lightning arrester has a high-voltage terminal and a ground terminal. When a lightning surge (or
switching surge, which is very similar) travels along the power line to the arrester, the current
from the surge is diverted through the arrester, in most cases to earth.
In telegraphy and telephony, a lightning arrester is placed where wires enter a structure,
preventing damage to electronic instruments within and ensuring the safety of individuals near
them. Smaller versions of lightning arresters, also called surge protectors, are devices that are
connected between each electrical conductor in power and communications systems and the
Earth. These prevent the flow of the normal power or signal currents to ground, but provide a
path over which high-voltage lightning current flows, bypassing the connected equipment. Their
purpose is to limit the rise in voltage when a communications or power line is struck by lightning
or is near to a lightning strike.
If protection fails or is absent, lightning that strikes the electrical system introduces
thousands of kilovolts that may damage the transmission lines, and can also cause severe damage
to transformers and other electrical or electronic devices. Lightning-produced extreme voltage
spikes in incoming power lines can damage electrical home appliances or even produce death.
Lightning arresters are used to protect electric fences. They consist of a spark gap and sometimes
a series inductor.
2.2.1 TYPES OF LIGHTING ARRESTER
 Surge arrester
 Lightning rod
 Lightning strike
 Lockheed P-38 Lightning
 Lightning McQueen
 Surge protector(redirect from Power surge arrester)
 Shunt (electrical)(section Lightningarrestor)

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2.3 ISOLATOR

Fig 2.3 ISO [5]
SEECO offers a full range of group operated disconnect switches for substation switching
applications.
Voltage ratings for most SEECO disconnect switches range from 15 to 230 kV and all
switches can be supplied with continuous current ratings of 600, 1200, and 2000 amp. All
switches except the vertical break have copper live part construction. Check the individual web
pages and catalog literature for the ratings of each switch configuration.
The SEECO vertical break is available in both aluminum and copper. The voltage range
is 15 to 345 kV with available current ratings of 600, 1200, 2000 and 3000 amp. SEECO plans to
extend the voltage range to 500 kV and the current rating to 4000 and 5000 amp in the future.

6. INPLANT TRAINING 15EE67P
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Circuit breaker always trip the circuit but open contacts of breaker cannot be visible
physically from outside of the breaker and that is why it is recommended not to touch any
electrical circuit just by switching off the circuit breaker. So for better safety there must be some
arrangement so that one can see open condition of the section of the circuit before touching it.
Isolator is a mechanical switch which isolates a part of circuit from system as when required.
Electricalisolatorsseparate a part of the system from rest for safe maintenance works. So
definition of isolator can be rewritten as Isolator is a manually operated mechanical switch which
separates a part of the electrical power. Isolators are used to open a circuit under no load. Its
main purpose is to isolate one portion of the circuit from the other and is not intended to be
opened while current is flowing in the line. Isolators are generally used on both ends of the
breaker in order that repair or replacement of circuit breaker can be done without and danger.
2.3.1 OPERATION OF ELECTRICA L ISOLATOR
As no arc quenching technique is provided in isolator it must be operated when there is
no chance current flowing through the circuit No live circuit should be closed or open by isolator
operation. A complete live closed circuit must not be opened by isolator operation and also a live
circuit must not be closed and completed by isolator operation to avoid huge arcing in between
isolator contacts.
Isolator can be operated by hand locally as well as by motorized mechanism from remote
position. Motorized operation arrangement costs more compared to hand operation; hence
decision must be taken before choosing an isolator for system whether hand operated or motor
operated economically optimum for the system
2.3.2 CONSTRUCTIONAL FEATURES OF SINGLE BREAK ISOLATORS
The contact arm is divided into two parts one carries male contact and other female
contact. The contact arm moves due to rotation of the post insulator upon which the contact arms
are fitted. Rotation of both post insulators stacks in opposite to each other causes to close the
isolator by closing the contact arm. Counter rotation of both post insulators stacks open the
contact arm and isolator becomes in off condition. This motorized form of this type of isolators
is generally used but emergency hand driven mechanism is also provided.

7. INPLANT TRAINING 15EE67P
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2.4 EARTHING ROD

Fig2.4:-Earthing pole [5]
In an electrical installation an earthing system or grounding system connects specific
parts of that installation with the Earth's conductive surface for safety and functional purposes.
The point of reference is the Earth's conductive surface. The choice of earthing system
can affect the safety and electromagnetic compatibility of the installation. Regulations for
earthing systems vary considerably among countries, though many follow the recommendations
of the International Electrotechnical Commission. Regulations may identify special cases for
earthing in mines, in patient care areas, or in hazardous areas of industrial plants.
Electricity is the most common form of energy. Electricity is used for various
applications such as lighting, transportation, cooking, communication, production of various
goods in factories and much more. None of us exactly know that what is electricity?Theconcept

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BRP, 6
thSem,DEEE 8 2017/18

of electricity and theories behind it can be developed by observing its different behaviors. For
observing natureof electricity, it is necessary to study the structure of matters. Every substance in
this universe is made up of extremely small particles known as molecules. The molecule is the
smallest particle of a substance into which all the identities of that substance are present. The
molecules are made up of further smaller particles known as atoms. An atom is the smallest
particle of an element that can exist.[4]
2.4.1 EARTH ROD ELECTRODES
Earth rods are commonly made from solid copper or stainless steel with copper bonding. Copper
Bonded Earthing Rods or Copper Bonded Grounding Rods are commonly used due to strength,
corrosion resistance and comparatively low cost. Earth Rod
2.4.2 SOIL CONDITIONS
Achievinga good earth will depend on local soil conditions. A low soil resistivity is the main
aim. The factors affecting the resistivity are:-
1. Moisture content of the soil
Earth rods usually consist of compostable single rods with a length of 1.5 m. DEHN earth
rods have a self-locking coupling with bore and pin. Advantage of this construction is that the
coupling locks automatically during the driving process, thus implementing a mechanically high-
strength and electrically safe connection. Additional work steps such as screwing are not
necessary.
Different types of impact tool are used to drive in the earth rods. Driving-in should be carried out
at 1200 blows/min. At a considerably higher blow rate the power usually is not sufficient to
reach the required depth with the earth rod. At a too low blow frequency as typical for
compressed-air driven hammer tool, the blow power often is too high and the blow rate too low.
The own weight of the driving hammer should be ≥ 20 kg.
The possible driving depth of earth electrodes depends on the geological conditions. In
light soil areas, e.g. in coastal areas or in wetlands, depths of 30 m to 40 m can be reached. In
extremely heavy soils, e.g. sandy soils the driving depth often is max. 12 m.
The more the soil around the earth rod is compressed on driving in, the better the electrical
contact. An earth rod of 20 mm outer diameter provides less compression than an earth rod of 25
mm outer diameter.

9. INPLANT TRAINING 15EE67P
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2.5 SULPHUR HEXAFLUORID CIRCUIT BREAKER (SF6)

Fig 2.5:- SF6 Circuit Breaker[2]
2.5.1 DEFINATION OF SF6 CIRCUIT BREAKER
SF6 gas is electronegative and has a strong tendency to absorb free electrons. The contacts of the
breakerare opened in a high-pressure flow of sulphur hexafluoride gas, and an arc is struck
between them. ... Sulfur hexafluoride is generally used in present high-voltage circuit breakers at
rated voltage higher than 52 kV.
2.5.2 CONSTRUCTION OF SF6 CIRCUIT BREAKER
A sulphur hexafluoride (SF6) circuit breaker consists of fixed and moving contacts
enclosed in a chamber. The chamber is called arc interruption chamber which contains the

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sulphur hexafluoride (SF6) gas. This chamber is connected to sulphur hexafluoride (SF6) gas
reservoir. A valve mechanism is there to permit the gas to the arc interruption chamber. When
the contacts of breaker are opened, the valve mechanism permits a high-pressure sulphur
hexafluoride (SF6) gas from the reservoir to flow towards the arc interruption chamber.In SF6
Circuit breaker, sulphur hexafluoride gas is used as the arc quenching medium.

The sulphur hexafluoride gas (SF6) is an electronegative gas and has a strong tendency to
absorb free electrons. The contacts of the breaker are opened in a high-pressure flow sulphur
hexafluoride (SF6)gas and an arc is struck between them. The gas captures the conducting free
electrons in the arc to form relatively immobile negative ions. This loss of conducting electrons
in the arc quickly builds up enough insulation strength to extinguish the arc.

Construction of SF6 Circuit Breaker a sulphur hexafluoride (SF6) circuit breaker consists
of fixed and moving contacts enclosed in a chamber. The chamber is called arc interruption
chamber which contains the sulphur hexafluoride (SF6) gas. This chamber is connected to
sulphur hexafluoride (SF6) gas reservoir. A valve mechanism is there to permit the gas to the arc
interruption chamber. When the contacts of breaker are opened, the valve mechanism permits a
high-pressure sulphur hexafluoride (SF6) gas from the reservoir to flow towards thearc
interruption chamber.

The fixed contact is a hollow cylindrical current carrying contact fitted with an arcing
horn. The moving contact is also a hollow cylinder with rectangular holes in the sides. The holes
permit the sulphur hexafluoride gas (SF6) gas to let out through them after flowing along and
across the arc. The tips of fixed contact, moving contact and arcing horn are coated with a
copper-tungsten arc-resistant material. Since sulphur hexafluoride gas (SF6) gas is costly, it is
reconditioned and reclaimed using the suitable auxiliary system after each operation of the
breaker.
2.5.3WORKING OF SF6 CB
In the closed position of the breaker, the contacts remain surrounded by sulphur
hexafluoride gas (SF6) gas at a pressure of about 2.8 kg/cm2. When the breaker operates, the
moving contact is pulled apart and an arc is struck between the contacts. The movement of the
moving contact is synchronized with the opening of a valve which permits sulphur hexafluoride

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gas (SF6) gas at 14 kg/cm2 pressure from the reservoir to the arc interruption chamber.The high-
pressure flow of sulphur hexafluoride gas (SF6) rapidly absorbs the free electrons in the arc path
to form immobile negative ions which are ineffective as charge carriers.
The result is that the medium between the contacts quickly builds up high dielectric strength and
causes the extinction of the arc. After the breaker operation (i.e. after arc extinction), the valve is
closed by the action of a set of springs. [3]

2.5.4SF6 CIRCUIT BREAKER DESIGNS
SF6 gas CBs are of either the dead tank design for outdoor installations or live tank (or
modular design) for outdoor installations, and increasingly, dead tank breakers are integrated into
SF 6 insulated substations for indoor or outdoor installations.
2.5.5 ADVANTAGES OF SF6
Due, to the superior arc quenching properties of sulphur hexafluoride gas (SF6) gas, the
sulphur hexafluoride gas (SF6) circuit breakers have many advantages over oil or air circuit
breakers. Some of them are listed below:
1. Due to the superior arc quenching property of sulphur hexafluoride gas (SF6), such circuit
breakers have very short arcing time.
2. Since the dielectric strength of sulphur hexafluoride (SF6) gas is 2 to 3 times that operation
due unlike of air, such breakers can interrupt much larger currents.
3. The sulphur hexafluoride gas (SF6) circuit breaker gives noiseless operation due it's closed
gas circuit and no exhaust to atmosphere, unlike the air blast circuit breaker.
4. The compact design of SF6 gas CBs substantially reduces space requirements and building
installation costs.
5. The SF6 gas circuit breakers can handle all known switching phenomena.
6. SF6 gas circuit breakers perfectly can adapt to environmental requirements since they have
completely enclosed gas system that eliminates any exhaust during switching operations.
7. Contact separation in SF6 gas CBs is minimum due to dielectric

12. INPLANT TRAINING 15EE67P
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2.6CURRENT TRANSFORMER

Fig 2.6:- Current Transformer [2]
A current transformer (CT) is a type of transformer that is used to measure alternating
current (AC). It produces a current in its secondary which is proportional to the current in its
primary.
Current transformers, along with voltage or potential transformers are instrument
transformers. Instrument transformers scale the large values of voltage or current to small,
standardized values that are easy to handle for instruments and protective relays. The instrument
transformers isolate measurement or protection circuits from the high voltage of the primary
system. A current transformer provides a secondary current that is accurately proportional to the
current flowing in its primary. The current transformer presents a negligible load to the primary
circuit.

13. INPLANT TRAINING 15EE67P
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Like any transformer, a current transformer has a primary winding, a core and a
secondary winding, although some transformers, including current transformers, use an air core.
In principle, the only difference between a current transformer and a voltage transformer (normal
type) is that the former is fed with a 'constant' current while the latter is fed with a 'constant'
voltage, where 'constant' has the strict circuit theory meaning.
The alternating current in the primary produces an alternating magnetic field in the core,
which then induces an alternating current in the secondary. The primary circuit is largely
unaffected by the insertion of the CT. Accurate current transformers need close coupling
between the primary and secondary to ensure that the secondary current is proportional to the
primary current over a wide current range. The current in the secondary is the current in the
primary (assuming a single turn primary) divided by the number of turns of the secondary. In the
illustration on the right, 'I' is the current in the primary, 'B' is the magnetic field, 'N' is the number
of turns on the secondary, and 'A' is an AC ammeter.
Current transformers typically consist of a silicon steel ring core wound with many turns
of copper wire as shown in the illustration to the right. The conductor carrying the primary
current is passed through the ring. The CT's primary, therefore, consists of a single 'turn'. The
primary 'winding' may be a permanent part of the current transformer, i.e. a heavy copper bar to
carry current through the core. Window-type current transformers are also common, which can
have circuit cables run through the middle of an opening in the core to provide a single-turn
primary winding. To assist accuracy, the primary conductor should be centered in the aperture.
Current transformer shapes and sizes vary depending on the end user or switch gear
manufacturer. Low-voltage single ratio metering current transformers are either a ring type or
plastic molded case.
Split-core current transformers either have a two-part core or a core with a removable
section. This allows the transformer to be placed around a conductor without having to
disconnect it first. Split-core current transformers are typically used in low current measuring
instruments, often portable, battery-operated, and hand-held. [3]

14. INPLANT TRAINING 15EE67P
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2.7 POTENTIAL TRANSFORMER

Fig 2.7:- Potential Transformer [5]
In its most basic form, the device consists of three parts: two capacitors across which the
transmission line signal is split, an inductive element to tune the device to the line frequency, and
a voltage transformer to isolate and further step down the voltage for metering devices or
protective relay.
The tuning of the divider to the line frequency makes the overall division ratio less
sensitive to changes in the burden of the connected metering or protection devices. The device
has at least four terminals: a terminal for connection to the high voltage signal, a ground
terminal, and two secondary terminals which connect to the instrumentation or protective relay.

15. INPLANT TRAINING 15EE67P
BRP, 6
thSem,DEEE 15 2017/18

It is not an easy way to measure the high voltage and currents associated with power
transmission and distribution systems, hence instrument transformers are often used to step-down
these values to a safer level to measure. This is because measuring meters or instruments and
protective relays are low voltage devices, thereby cannot be connected directly to high voltage
circuit for the purpose of measurement and protection of the system.[3]
2.7.1VOLTAGE TRANSFORMER OR POTENTIAL TRANSFORMER THEORY
A voltage transformer theoryorpotential transformer theory is just like a theory of general
purpose step down transformer. Primary of this transformer is connected across the phase and
ground. Just like the transformer used for stepping down purpose, potential transformer i.e. PT
has lower turns winding at its secondary.
The secondary voltage of the PT is generally 110 V. In an ideal potential transformer or
voltage transformer, when rated burden gets connected across the secondary; the ratio of primary
and secondary voltages of transformer is equal to the turn‟s ratio and furthermore, the two
terminal voltages are in precise phase opposite to each other. But in actual transformer, there
must be an error in the voltage ratio as well as in the phase angle between primary and secondary
voltages. The errors in potential transformer or voltage transformer can be best explained by
phasor diagram, and this is the main part of potentialtransformer theory.[3]
2.7.2CAUSE OF ERROR IN POTENTIAL TRANSFORMER
The voltage applied to the primary of the potential transformer first drops due to the
internal impedance of the primary. Then it appears across the primary winding and then
transformed proportionally to its turns ratio, to the secondary winding. This transformed voltage
across the secondary winding will again drop due to the internal impedance of the secondary,
before appearing across burden terminals. This is the reason of errors inpotential transformer.

16. INPLANT TRAINING 15EE67P
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2.8SUPPORTING POLO & INSULATOR

Fig 2.8:- Supporting Polo &Insulator [2]
An electrical insulator is a material whose internal electric charges do not flow freely;
very little electric current will flow through it under the influence of an electric field. This
contrasts with other materials, semiconductors and conductors, which conduct electric current
more easily. The property that distinguishes an insulator is its resistivity; insulators have higher
resistivity than semiconductors or conductors.
Towers used for single-phase AC railwaytraction lines are similar in construction to those
towers used for 110 kV three-phase lines. Steel tube or concrete poles are also often used for
these lines. However, railway traction current systems are two-pole AC systems, so traction lines
are designed for two conductors (or multiples of two, usually four, eight, or twelve). As a rule,
the towers of railway traction lines carry two electric circuits, so they have four conductors.
These are usually arranged on one level, whereby each circuit occupies one half of the cross arm.
For four traction circuits, the arrangement of the conductors is in two-levels and for six electric

17. INPLANT TRAINING 15EE67P
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2.9 TRANSFORMER

Fig 2.9:- Transformer [5]
2.9.1 DEFINITION OF TRANSFORMER
Electrical power transformer is a static device which transforms electrical energy from
one circuit to another without any direct electrical connection and with the help of mutual
induction between two windings. It transforms power from one circuit to another without
changing its frequency but may be in different voltage level.
2.9.2 PRINCIPLE:A transformer consists of two electrically isolated coils and is induced in the
transformers secondary coil by the magnetic flux generated by the voltages and currents flowing
in operates on Faraday'slow principal of “mutual induction”, in which an EMF the primary coil
winding

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One of the main reasons that we use alternating AC voltages and currents in our homes and
workplace‟s is that AC supplies can be easily generated at a convenient voltage, transformed
(hence the name transformer) into much higher voltages and then distributed around the country
using a national grid of pylons and cables over very long distances.
The reason for transforming the voltage to a much higher level is that higher distribution
voltages implies lower currents for the same power and therefore lower I
2
R losses along the
networked grid of cables. These higher AC transmission voltages and currents can then be
reduced to a much lower, safer and usable voltage level where it can be used to supply electrical
equipment in our homes and workplaces, and all this is possible thanks to the basic Voltage
Transformer.
The Voltage Transformer can be thought of as an electrical component rather than an
electronic component. A transformer basically is very simple static (or stationary) electro-
magnetic passive electrical device that works on the principle of Faraday‟s law of induction by
converting electrical energy from one value to another.
The transformer does this by linking together two or more electrical circuits using a
common oscillating magnetic circuit which is produced by the transformer itself. A transformer
operates on the principals of “electromagnetic induction”, in the form of Mutual Induction.
Mutual induction is the process by which a coil of wire magnetically induces a voltage
into another coil located in close proximity to it. Then we can say that transformers
2.9.3 THE BASIC COMPONENTS OF A TRANSFORMER ARE: -
1. Laminated
2. core
3. Windings
4. Insulating materials
5. Transformer oil
6. Tap changer
7. Oil Conservator
8. Breather
9. Cooling tubes
10. Buchholz Relay
11. Explosion vent

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2.9.4 PARTS OF TRANSFORMER

Fig 2.9.4 Parts of Transformer [5]
2.9.5 CONSTRUCTION OF A TRANSFORMER
The transformer is simple in construction. It consists of two magnetically linked
windings, wound on two separate limbs of iron. It consists of the following basic parts:
2.9.6CORE
Usually the core of a transformer is constructed with a material having high permeability,
such as silicon steel laminations, so that the core losses such as eddy current loss and hysteresis
losses are reduced. Since the steel sheets have a very high resistivity, so the current losses are
greatly reduced.
A transformer core can be constructed in two ways, depending upon the arrangement of the
primary and secondary windings. These two ways are: [4]
1. Core Type construction
2. Shell Type Construction

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2.9.7CORE TYPE CONSTRUCTION
If the windings are wound around the core in such a way that they surround the core ring
on its outer edges, then the construction is known as the closed core type construction of the
transformer core. In this type, half of the winding is wrapped around each limb of the core, and is
enclosed such that no magnetic flux losses can occur and the flux leakages can be minimized.
This type of arrangement proves quiet useful for the flux circulation, such that each limb
is covered by the windings and hence the flux circulates through the complete core. But during
this circulations, a bit of leakages also occur.
2.9.8SHELL TYPE CONSTRUCTION
In shell type construction of the core, the windings pass through the inside of the core
ring such that the core forms a shell outside the windings. This arrangement also prevents the
flux leakages since both the windings are wrapped around the same center limb.




Fig 2.9.8:- Core Type and Cell Type Winding [4]

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2.9.9WINDINGS
Firstly, Arrangements of windings is also an important issue in the construction of a
transformer. The winding connected to the main AC power supply is called the primary winding,
while the one connected to the load or some external circuitry is called the secondary winding.
Windings of a transformer are made up of a conducting material to allow the magnetic
flux to build up and hence the current can be passes from one winding to another. These
windings are wound on two separate limbs of iron to increase the magnetic flux as iron is an
efficient conductor and exhibits excellent magnetic properties. These coils are also insulated
from each other. Since both these coils are wound on two separate limbs and due to the distance
between them, flux leakages also occur which reduce our magnetic flux density and results in a
reduced magnetic coupling between the two coil windings.
To avoid this situation, the distance between the two windings is reduced, so that the flux
leakages can be minimized and a strong magnetic induction can be created and sustained
between the two coils. But this arrangement also does not completely eliminate all the flux
problems, since the magnetic losses are still present.
In core type construction, these windings are arranged in a concentric manner on the limbs, while
in a shell type core construction, the same windings are arranged in a sandwich like pattern.
Other than these two main parts, Transformer tank and Conservatory tank are also used in
transformer construction:
2.9.10 STEP-UP TRANSFORMER
A transformer in which the output (secondary) voltage is greater than its input (primary)
voltage is called a step-up transformer. The step-up transformer decreases the output current for
keeping the input and output power of the system equal.The number of turns on the secondary of
the transformer is greater than that of the primary, i.e., T2> T1.Thus the voltage turn ratio of the
step-up transformer is 1:2. The primary winding of the step-up transformer is made up of thick
insulated copper wire because the low magnitude current flows through it

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2.9.11STEP DOWN TRANSFORMER
A transformer in which the output (secondary) voltage is less than its input (primary)
voltage is called a step-down transformer. The number of turns on the primary of the transformer
is greater than the turn on the secondary of the transformer, i.e., T2< T1. The step-down
transformer is shown in the figure below.
The voltage turn ratio of the step-down transformer is 2:1. The voltage turn ratio
determines the magnitude of voltage transforms from primary to secondary windings of the
transformer.
2.9.12 CONSERVATOR
Conservator is the most vital part of the transformer, because the Conservator tank takes up the
expansion & contraction of oil during running operation. When the load of the transformer is
increased, the temperature of oil also increases, hence total volume of the oil increases and
absorbs the increased volume of oil in upper space of the conservator tank.
2.9.13 BREATHER
When load on transformer increases or when the transformer under full load, the insulating oil of
the transformer gets heated up, expands and gets expel out in to the conservator tank present at
the top of the power transformer and subsequently pushes the dry air out of the conservator tank
through the silica gel breather. This process is called breathing out of the transformer. When the
oil cools down, air from the atmosphere is drawn in to the transformer. This is called breathing in
of the transformer.
2.9.14 USE OF SILICA GEL BREATHER
During the breathing process, the incoming air may consist of moisture and
dirt which should be removed in order to prevent any damage. Hence the air is
made to pass through the silica gel breather, which will absorb the moisture in
the air and ensures that only dry air enters in to the transformer. Silica gel in
the breather will be blue when installed and they turn to pink colour when they
absorb moisture which indicates the crystals should be replaced. These
breathers also have an oil cup fitted with, so that the dust particles get settled
in the cup.

Thus Silica gel breathers provide an economic and efficient means of controlling the level of
moisture entering the conservator tank during the breathing process.
Fig 2.9.14
Breather

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2.9.15 COOLING TUBE
Radiator is a bank of hollow pipe line which is used to transfer the thermal energy from one
medium to another for the purpose of cooling. Some Bank are used at the power transformer for
cooling the transformer oil as well as reduces the winding temperature under loading condition.
The radiators are connected to the transformer through pipe line at upper and lower side of the
transformer.
2.9.16 BUCHHOLZ RELAY
Buchholzrelay intransformeris an oil container housed the connecting pipe from main tank to
conservator tank. It has mainly two elements. The upper element consists of a float. The float is
attached to a hinge in such a way that it can move up and down depending upon the oil level in
the Buchholz relay Container. One mercury switch is fixed
on the float.
The alignment of mercury switch hence depends upon the
position of the float. The lower element consists of a baffle
plate and mercury switch. This plate is fitted on a hinge just
in front of the inlet (main tank side) of Buchholz relay in
transformer in such a way that when oil enters in the relays
from that inlet in high pressure the alignment
Baffle plate along with the mercury switch attached to it, will change.
2.9.17 TRANSFORMER OIL
Transformer oil or insulating oil is oil that is stable at high temperatures and has excellent
electrical insulating properties. It is used in oil-filled transformers, some types of high-voltage
capacitors, fluorescent lamp ballasts, and some types of high-voltage switches and circuit
breakers. Its functions are to insulate




Fig 2.9.16:- Buchholz Relay [5]
[[[[RRRRREArealy

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2.9.18 BUSHINGS
In electric power, a bushing is an insulated device that allows an electrical conductor to pass
safely through a grounded conducting barrier such as the case of a transformer or circuit breaker.

2.9.19 TAP CHANGER

The output voltages of transformers vary according to its input voltage and the load.
During loaded conditions, the voltage on the output terminal decreases, whereas during off-load
conditions the output voltage increases. In order to balance the voltage variations, tap changers
are used. Tap changers can be either on-load tap changers or off-load tap changers. In an on-load
tap changer, the tapping can be changed without isolating the transformer from the supply. In an
off-load tap changer, it is done after disconnecting the transformer. Automatic tap changers are
also available.
2.9.20 COOLING TUBES
Cooling tubes are used to cool the transformer oil. The transformer oil is circulated through
the cooling tubes. The circulation of the oil may either be natural or forced. In natural
circulation, when the temperature of the oil raises the hot oil naturally rises to the top and the
cold oil sinks downward. Thus the oil naturally circulates through the tubes. In forced
circulation, an external pump is used to circulate the oil.[3]
2.9.21 EXPLOSION VENT
The explosion vent is used to expel boiling oil in the transformer during heavy internal
faults in order to avoid the explosion of the transformer. During heavy faults, the oil rushes out
of the vent. The level of the explosion vent is normally maintained above the level of the
conservatory tank.

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2.9.22 LOSSES IN A TRANSFORMER
An ideal transformer is the one which is 100% efficient. This means that the power supplied
at the input terminal should be exactly equal to the power supplied at the output terminal, since
efficiency can only be 100% if the output power is equal to the input power with zero energy
losses. But in reality, nothing in this universe is ever ideal. Similarly, since the output power of a
transformer is never exactly equal to the input power, due a number of electrical losses inside the
core and windings of the transformer, so we never get to see a 100% efficient transformer.
Transformer is a static device, i.e. we do not get to see any movements in its parts, so no
mechanical losses exist in the transformer and only electrical losses are observed. So there are
two primary types of electrical losses in the transformer:
1. Copper losses
2. Iron losses
Other than these, some small amount of power losses in the form of „stray losses‟ are also
observed, which are produced due to the leakage of magnetic flux.
2.9.23 COPPER LOSSES
These losses occur in the windings of the transformer when heat is dissipated due to the
current passing through the windings and the internal resistance offered by the windings. So
these are also known as ohmic losses or I2R losses, where „I‟ is the current passing through the
windings and R is the internal resistance of the windings.
These losses are present both in the primary and secondary windings of the transformer
and depend upon the load attached across the secondary windings since the current varies with
the variation in the load, so these are variable losses.
2.9.24 IRON LOSSES
These losses occur in the core of the transformer and are generated due to the variations
in the flux. These losses depend upon the magnetic properties of the materials which are present
in the core, so they are also known as iron losses, as the core of the Transformer is made up of
iron. And since they do not change like the load, so these losses are also constant.

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There are two types of Iron losses in the transformer:
1. Eddy Current losses
2. Hysteresis Loss
2.9.25 EDDY CURRENT LOSSES
When an alternating current is supplied to the primary windings of the transformer, it
generates an alternating magnetic flux in the winding which is then induced in the secondary
winding also through Faraday‟s law of electromagnetic induction, and is then transferred to the
externally connected load. During this process, the other conduction materials of which the core
is composed of; also gets linked with this flux and an emf is induced.
But this magnetic flux does not contribute anything towards the externally connected load
or the output power and is dissipated in the form of heat energy. So such losses are called Eddy
Current losses and are mathematically expressed as:Pe = Ke f² Kf² Bm²
Where;
 Ke = Constant of Eddy Current
 Kf² = Form Constant
 Bm = Strength of Magnetic Field

2.9.26 HYSTERESIS LOSS
Hysteresis loss is defined as the electrical energy which is required to realign the domains
of the ferromagnetic material which is present in the core of the transformer.
These domains loose their alignment when an alternating current is supplied to the primary
windings of the transformer and the emf is induced in the ferromagnetic material of the core
which disturbs the alignment of the domains and afterwards they do not realign properly. For
their proper realignment, some external energy supply, usually in the form of current is required.
This extra energy is known as Hysteresis loss.

These are the different kinds of losses happened to occur in transformer and an electrical
engineer must take care of their losses and try to reduce them as low as possible.
Transformer has two states of operations, one is without load and the other is with load. Most of
these errors appear when the load is applied on the transformer. [4]

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2.10 11KV FEEDERS

Fig 2.10:- Feeders Bank [2]
The 11kV Town feeder can be extended to 11kV Shridargadda feeder from 110kV
substation, Shridargadda Usually this done by the field staff of Electrical section, Shridargadda
by closing the 11kV Delta AB. During the failure of 11kV PTPE feeder, the SHEP R-PND is
connected to the grid through 11kV Shridargadda feeder, the load in the Shridargadda feeder is
regulated by Electrical section Shridargadda for easy synchronization.
A feeder line is a peripheral route or branch in a network, which connects smaller or
more remote nodes with a route or branch carrying heavier traffic. The term is applicable to any
system based on a hierarchical network.
In telecommunications, a feeder line branches from a main line or trunk line.
In electrical engineering, a feeder line is a type of transmission line. In radio engineering,
a feeder connects radio equipment to an antenna, usually open wire (air-insulated wire line) or
twin-lead from a shortwave transmitter. In power engineering, a feeder line is part of an electric
distribution network, usually a radial circuit of intermediate voltage.
The concept of feeder lines is also important in public transportation. The term is
particularly used in US air travel and rail transport. Efficient, high-capacity routes connect
important nodes while feeder lines connect these nodes to departure and destination points.

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2.10.1THERE ARE MAINLY FOUR FEEDERS
1. Radial
2. Parallel feeders
3. Ring main
4. Meshed systems
2.10.1 RADIAL
Many distribution systems operate using aradial feeder system. A typical radial feeder
system is shown schematically in Figure 2. Radial feeders are thesimplest and least expensive,
both to construct and for their protection system.
This advantage however is offset by the difficulty of maintaining supply in the event of a fault
occurring in the feeder.
2.10.3PARALLEL FEEDERS
A greater level of reliability at a higher cost is achieved with a parallel feeder. A typical
parallel feeder system is shown schematically in Figure 3.
To improve the reliability factor it may be possible to have the separate sets of cables follow
different routes. In this case the capital cost is double that of a radial feeder but there is a greater
reliability factor for the line. This may be justified if the load is higher, more customers are being
supplied, or there are loads such as hospitals which require high levels of reliability.
2.10.4 RING MAIN
A similar level of system reliability to that of the parallel arrangement can be achieved by
using ring main feeders. This usually results from the growth of load supplied by a parallel
feeder where the cabling has been installed along different routes. These are most common in
urban and industrial environments.
In typical urban / suburban ring main arrangements, the open ring is operated manually and loss
of supply restored by manual switching.
2.10.5MESHED SYSTEMS
In transmission and sub-transmission systems, usually parallel, ring or interconnected
(mesh) systemsare used. This ensures that alternative supply can be made to customers in the
event of failure of a transmission line or element.
The extra expense can be justified because of the much greater load and number of
customers that are affected by failure of lines at transmission or sub-transmission levels.

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2.11 CAPACITOR BANK

Fig 2.11:- Capacitor bank [2]
The demand of active power is expressing Kilo Watt (kw) or mega watt (mw). This
power should be supplied from electrical generating station. All the arrangements in electrical
pomes system are done to meet up this basic requirement. Although in alternating power system,
reactive power always comes in to picture. This reactive power is expressed in Kilo VAR or
Mega VAR. The demand of this reactive power is mainly originated from inductive load
connected to the system. These inductive loads are generally electromagnetic circuit of electric
motors, electrical transformers, inductance of transmission and distribution networks, induction
furnaces, fluorescent lightings etc.
Capacitors are electrical/electronic components which store electrical energy. Capacitors
consist of two conductors that are separated by an insulating material or dielectric. When an
electrical current is passed through the conductor pair, a static electric field develops in the

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dielectric which represents the stored energy. Unlike batteries, this stored energy is not
maintained indefinitely, as the dielectric allows for a certain amount of current leakage which
results in the gradual dissipation of the stored energy.
A capacitor bank is a grouping of several identical capacitors inter-connected in parallel
or in series with one another as required.
The demand for power is expressed in units of Kilo watt (KW) or Mega watt (Mw). This power
is supplied by an electrical generating station. In alternating power system (AC), reactive power
always comes in to picture. This reactive power is expressed in Kilo VAR or Mega VAR. The
demand of this reactive power is mainly originated from inductive load connected to the system.
[4]

These inductive loads are generally electromagnetic circuit of electric motors, electrical
transformers, inductance of transmission and distribution networks, induction furnaces, etc. This
reactive power should be properly compensated, otherwise the ratio of actual power consumed
by the load, to the total power consumed i.e. vector sum of active and reactive power, of the
system becomes quite low. This ratio is known as electrical power factor, and lower ratios
indicates poor power factor of the system. If the power factor of the system is poor, the ampere
burden of the transmission, distribution network, transformers, alternators and other equipments
connected to the system, becomes high for required active power. On the other hand, the user
will be paying for much more than what is actually being used. And hence reactive power
compensation becomes so important. This is commonly done by addition of a capacitor bank.

In AC circuits, the power factor is the ratio of the real power that is used to do work and the
apparent power that is supplied to the circuit. Power factor correction is an adjustment of the
electrical circuit in order to change the power factor near 1 - known as unity power factor.
Power factor is defined as the difference in phase between voltage and current, or
simplified as the ratio of the real power (P) and the apparent power (S). People will often refer to
power factor as leading or lagging.
Lagging power factor is when the current lags the voltage, this means that the current waveform
comes delayed after the voltage waveform (and the power angle is positive).

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Leading power factor: when the current leads the voltage, this means that the current waveform
comes before the voltage waveform (and the power angle is negative).

Unity power factor: refers to the case when the current and voltage are in the same phase.
Neither lagging nor leading.

The physical significance of power factor is in the load impedance. Usually, Inductive loads (e.g.
coils, motors, etc) have lagging power factors, capacitative loads (e.g. capacitors) have leading
power factors and resistive loads (e.g. heaters) have close to unity power factors.

A power factor of one or "unity power factor" is the goal of any electric utility company since if
the power factor is less than one, they have to supply more current to the user for a given amount
of power use. In doing so, they incur more line losses. They also must have larger capacity
equipment in place than would be otherwise necessary. As a result, an industrial facility will be
charged a penalty if its power factor is much different from 1.

Imagine running a 10 KW electric motor and paying for 15 KW of power!

Industrial facilities tend to have a "lagging power factor", where the current lags the voltage (like
an inductor). This is primarily the result of having a lot of electric induction motors - the
windings of motors act as inductors as seen by the power supply. Capacitors have the opposite
effect and can compensate for the inductive motor windings. Some industrial sites will have
large banks of capacitors strictly for the purpose of correcting the power factor back toward one
to save on utility company charges. [3]

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2.12 EXLAR TRANSFORMER 11KV/440V (SUB STATION USES ONLY)

Fig 2.12:-Exlar Transformer [2]
Transformeris electromagnetic static electrical equipment (with no moving parts) which
transforms magnetic energy to electrical energy. It consists of a magnetic iron core serving as
magnetic transformer part and transformer cooper winding serving as electrical part. The
transformer is high efficiency equipment and its losses are very low because there isn‟t any
mechanical friction inside. Transformers are used in almost all electrical systems from low
voltage up to the highest voltage level. It operates only with alternating current (AC), because
the direct current (DC) does not create any electromagnetic induction. Depending on the
electrical network where the transformer is installed, there are two transformer types, three-phase
transformers and single phase transformers. The operation principle of the single-phase
transformer is: the AC voltage source injects the AC current through the transformer primary
winding.

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2.13 INDOOR PANEL
The switch gear on the supply or primary side will consist of oil circuit breaker only. The
high voltage supply is given to the primary of the transformer through a circuit breaker. From the
bus bar, various feeders emerge out. The panel on each feeder consists of an isolator switch and a
circuit breaker. In addition to isolator and circuit breaker, the panel also provided the measuring
instrument.
For the protection of feeders usually, reverse power relay is used. For the protection of oil filled
transformer Buchholz relay is used. The accessories of the indoors type substations are a storage
battery, firefighting equipment such as water, buckets, and fire extinguisher, etc., The battery is
used for the operation of protective gear and switching operating solenoids and emergency
lighting in substations in the case of failure of supply.Suppresscorona discharge and arcing, and
to serve as a coolant.

Fig 2.13 Microprocessor Based Annunciator [2]

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2.14 1KLA 110KV LINE CONTROL & RELAY PANEL


Fig 2.14:- This Panel Is Use to Control TheOutdoor 110kv Incoming Power By Using Relay [2]

For the protection of feeders usually, reverse power relay is used. For the protection of oil filled
transformer Buchholz relay is used. The accessories of the indoors type substations are a storage
battery, firefighting equipment such as water,

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2.15 FEEDER CONTROL PANEL

Fig 2.15:- This Panel Is Used To Control The Feeders And Sense The Fault and Displayed [2]
 1
ST
FEEDER ( NJY ) :- KORLAGUNDI
 2
ND
FEEDER ( IP set ) :- SOMASAMUDRA
 3
RD
FEEDER ( NJY ) :- SRIDHARAGADDE
 4
TH
FEEDER (IP set) :- KORLAGUNDI
 5
TH
FEEDER (ideal) :- EXTRA PURPOSE USE
 6
TH
FEEDER ( NJY ) :- CITY (PARVATHI NAGAR)
 7
TH
FEEDER ( DUMMY ):- CAPACITOR BANK

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2.16 SCADA

Fig 2.16:- Supervisory Control and Data Acquisition [2]
Supervisory control and data acquisition (SCADA) is a control system architecture that
uses computers, networked data communications and graphical user interfaces for high-level
process supervisory management, but uses other peripheral devices such as programmable logic
controllers and discrete PID controllers to interface to the process plant or machinery. The
operator interfaces which enable monitoring and the issuing of process commands, such as
controller set point changes, are handled through the SCADA supervisory computer system.
However, the real-time control logic or controller calculations are performed by networked
modules which connect to the field sensors and actuators. [5]

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A SCADA system usually consists of the following main elements: This is the core of the
SCADA system, gathering data on the process and sending control commands to the field
connected devices. It refers to the computer and software responsible for communicating with
the field connection controllers, which are RTUs and PLCs, and includes the HMI software
running on operator workstations. In smaller SCADA systems, the supervisory computer may be
composed of a single PC, in which case the HMI is a part of this computer. In larger SCADA
systems, the master station may include several HMIs hosted on client computers, multiple
servers for data acquisition, distributed software applications, and disaster recovery sites. To
increase the integrity of the system the multiple servers will often be configured in a dual-
redundant or hot-standby formation providing continuous control and monitoring in the event of
a server malfunction or breakdown.
Remote terminal units, also known as (RTUs), connect to sensors and actuators in the
process, and are networked to the supervisory computer system. RTUs are "intelligent I/O" and
often have embedded control capabilities such as ladder logic in order to accomplish boolean
logic operations.
Also known as PLCs, these are connected to sensors and actuators in the process, and are
networked to the supervisory system in the same way as RTUs. PLCs have more sophisticated
embedded control capabilities than RTUs, and are programmed in one or more IEC 61131-3
programming languages. PLCs are often used in place of RTUs as field devices because they are
more economical, versatile, flexible and configurable.
Communication infrastructure
This connects the supervisory computer system to the RTUs and PLCs, and may use
industry standard or manufacturer proprietary protocols. Both RTUs and PLCs operate
autonomously on the near-real time control of the process, using the last command given from
the supervisory system. Failure of the communications network does not necessarily stop the
plant process controls, and on resumption of communications, the operator can continue with
monitoring and control. Some critical systems will have dual redundant data highways, often
cabled via diverse routes.
More complex SCADA animation showing control of four batch cookers
The human-machine interface (HMI) is the operator window of the supervisory system. It
presents plant information to the operating personnel graphically in the form of mimic diagrams,

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which are a schematic representation of the plant being controlled, and alarm and event logging
pages. The HMI is linked to the SCADA supervisory computer to provide live data to drive the
mimic diagrams, alarm displays and trending graphs. In many installations the HMI is the
graphical user interface for the operator, collects all data from external devices, creates reports,
performs alarming, sends notifications, etc.
Mimic diagrams consist of line graphics and schematic symbols to represent process
elements, or may consist of digital photographs of the process equipment overlain with animated
symbols.
Supervisory operation of the plant is by means of the HMI, with operators issuing
commands using mouse pointers, keyboards and touch screens. For example, a symbol of a
pump can show the operator that the pump is running, and a flow meter symbol can show how
much fluid it is pumping through the pipe. The operator can switch the pump off from the mimic
by a mouse click or screen touch. The HMI will show the flow rate of the fluid in the pipe
decrease in real time.
The HMI package for a SCADA system typically includes a drawing program that the
operators or system maintenance personnel use to change the way these points are represented in
the interface. These representations can be as simple as an on-screen traffic light, which
represents the state of an actual traffic light in the field, or as complex as a multi-projector
display representing the position of all of the elevators in a skyscraper or all of the trains on a
railway.
A "historian", is a software service within the HMI which accumulates time-stamped
data, events, and alarms in a database which can be queried or used to populate graphic trends in
the HMI. The historian is a client that requests data from a data acquisition server.

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2.17 BATTERY BANK

Fig 2.17:- Battery Bank [2]
EACH CELL IS 2volts
55 CELLS ARE USED 110volts
Battery is an electrical element where electrical potential is produced due to chemical
reaction. Every electrochemical reaction has its limit of producing electric potential difference
between two electrodes. Battery cells are those where these electro-chemical reactions take place
to produce the limited electric potential difference.

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An electric battery is a device consisting of one or more electrochemical cells with
external connections provided to power electrical devices such as flashlights, smart phones, and
electric cars. When a battery is supplying electric power, its positive terminal is the cathode and
its negative terminal is the anode. The terminal marked negative is the source of electrons that
when connected to an external circuit will flow and deliver energy to an external device. When a
battery is connected to an external circuit, electrolytes are able to move as ions within, allowing
the chemical reactions to be completed at the separate terminals and so deliver energy to the
external circuit. It is the movement of those ions within the battery which allows current to flow
out of the battery to perform work. Historically the term "battery" specifically referred to a
device composed of multiple cells, however the usage has evolved additionally to include
devices composed of a single cell.
Primary (single-use or "disposable") batteries are used once and discarded; the electrode
materials are irreversibly changed during discharge. Common examples are the alkaline battery
used for flashlights and a multitude of portable electronic devices. Secondary (rechargeable)
batteries can be discharged and recharged multiple times using an applied electric current; the
original composition of the electrodes can be restored by reverse current. Examples include the
lead-acid batteries used in vehicles and lithium-ion batteries used for portable electronics such as
laptops and smartphones.
Batteries come in many shapes and sizes, from miniature cells used to power hearing aids
and wristwatches to small, thin cells used in smartphones, to large lead acid batteries used in cars
and trucks, and at the largest extreme, huge battery banks the size of rooms that provide standby
or emergency power for telephone exchanges and computer data centers.
Batteries have much lower specific energy (energy per unit mass) than common fuels
such as gasoline. In automobiles, this is somewhat offset by the higher efficiency of electric
motors in producing mechanical work, compared to combustion engines. The usage of "battery"
to describe a group of electrical devices dates to Benjamin Franklin, who in 1748 described
multiple Leyden jars by analogy to a battery of cannon (Benjamin Franklin borrowed the term
"battery" from the military, which refers to weapons functioning together). [3]

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CHAPTER: - 3
SKILLS OBTAINED BY TRAINING.
3.1 INTRODUCTION
I would like to share about skills obtained in substation (Somasamudra)
The junior engineer (JE) sir guided us regarding how to control the substation power,
How to maintain the substation, How the substation equipment will works,
We briefly understood the working of substation firstly about an Incomer lines, the
conductor size in the transmission line, the transmission line used is ACSR conductor,the size of
the transmission line is used 54A1/19st.
We learnt about safety devices that are used in substation like SF6 circuit breaker Lightning
arrester and Earthing Rod.
There are seven type of Lightning arrester in the substation in those we studied about
Horn gap Lightning arrester, it consists of two horns shaded piece of metal separated by a small
air gap and connected in shunt between each conductor and earth. We got an idea about SF6
circuit breaker, How the SF6 circuit breaker works practically. Current interruption in a high-
voltage circuit breaker is obtained by separating two contacts in a medium, such as sulfur
hexafluoride (SF6), having excellent dielectric and arc-quenching properties. We understand the
concept of earthing rod & why we need earthing rod in the substation inearthing is used to
protect you from an electric shock. It does this by providing a path (a protective conductor) for a
fault current to flow to earth. It also causes the protective device (either a circuit-breaker or fuse)
to switch off the electric current to the circuit that has the fault.
The transformer is an important part of in the substation incomer line is connected to the
primary winding of the transformer through the arrester‟s & circuit breakers. feeder‟s are
connected to the secondary winding of the transformer. Step down transformer is used to convert
the voltage (110kv/11kv) that output supply is connected to the feeders,
The basic principle on which the transformer works is Faraday‟s Law
ofElectromagneticInductionor mutual induction between the two coils. The working of the

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transformer is explained below. The transformer consists of two separate windings placed over
the laminated silicon steel core.
We study about transformer tap changer a tap changer is a mechanism in transformers
which allows for variable turn ratios to be selected in discrete steps. Transformers with this
mechanism obtain this variable turn ratio by connecting to a number of access points known as
taps along either the primary or secondary winding.
3.2 TROUBLESHOOTING
Your life as an electrical engineer will require you to manage systems and ensure they
work smoothly. One of the key components is to learn how to troubleshoot. This helps to
determine the causes of problems and decide how best to solve
3.3 TECHNOLOGICAL KNOWLEDGE
Your life as an electrical engineer requires you to be constantly up to date with the latest
technologies in your field of study and work. You must have the ability to adapt and generate
equipment and technology that will serve the user‟s needs.
Quality Control Analysis - Conducting tests and inspections of products, services, or
processes to evaluate quality or performance.
Equipment Selection - Determining the kind of tools and equipment needed to do a job.
Systems Analysis - Determining how a system should work and how changes in
conditions, operations, and the environment will affect outcomes.
Public Safety and Security - Knowledge of relevant equipment, policies, procedures, and
strategies to promote effective local, state, or national security operations for the protection of
people, data, property, and institutions.
The career life of an electrical and electronics engineer can be quite demanding. Apart
from having basic knowledge, it is mandatory for you to incorporate other skills like systems
analysis, judgment and decision-making, leadership, equipment selection and coordination
among others. These skills can be learned in school, and some need to be developed. Be keen on
the improvements that need to be made and keep working on these areas for a successful career.

43. INPLANT TRAINING 15EE67P
BRP, 6
thSem,DEEE 43 2017/18

CONCLUSION
Now from this report we can conclude that electricity plays an important role in our life. We are
made aware of how the transmission of electricity is done. We too came to know about the
various parts of the substation system. What are works of lightning How to operating the circuit
breaker, how can maintained circuit breaker, how it will works, The three wings of electrical
system viz. generation, transmission and distribution are connected to each other and that too
very perfectly, we know the briefly about transformer what are works of the transformer and
what are the maintenance of the transformer, we about known the of SCADA what are function
of SCADA, we got ideas feeder operating why we need to feeder in the substation we about that
of feeder.
Thus for effective transmission and distribution a substation must:
 Ensure steady state and transient stability
 Effective voltage control
 Prevention of loss of synchronism
 Reliable supply be feeding the network at various points
 Establishment of economic load distribution

44. INPLANT TRAINING 15EE67P
BRP, 6
thSem,DEEE 44 2017/18


REFRENCE
1. TRANSMISSION AND DISTRIBUTION
2. SUBSTATION 110/11kv
3. ELECTRICAL 4U.COM
4. WIKIPEDIA
5. GOOGLE

45. INPLANT TRAINING 15EE67P
BRP, 6
thSem,DEEE 45 2017/18