power station projecy report
TRANSCRIPT
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A
TRAINING REPORT
AT
132 KV SUBSTATION
JIND (NEW)
(24 July 2010 to 21 August 2010)
Submitted to: Submitted by:
Mr. Jugal Kishor Vikash Singh (0805809903)
(H.O.D. of ELE Dept.) Branch ELE
SCR Polytechnic GohiyanJind (Haryana)
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FOREWORD
I was required to undergo on four weeks training during the July 2010
to September 2010 towards the partial fulfillment of my diploma Being a
student of Electrical Engineering. I choose to undertake this training at an
Electrical Engineering, since it is a highly progressive sector these days, and
the demand for power is on a rise. Therefore, I landed up at 132 KV
substation Jind one of the good substation in Northern India and a fine
source of Electric power distribution for the local areas The training was a
great learning experience and I have tried to put what I learnt, through these
pages.
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PREFACE
Electricity is one of the most convenient and important source of energy
electricity is used at home and in industry for various purposes such as
lighting, heating operating machine and so on.
Therefore, generation of electricity holds important place in our
society. The generation of electricity and its per capita consumption is an
index to the prosperity of a nation. Man has found a no. of ways to generate
electricity. He began by tapping the energy generated by chemical reaction
for e.g., in a Daniel cell. However, this form was suitable only for very small
application. In addition, large amount of electricity could not be generated
using this method and the output voltage was not suitable. Therefore, man
sought new ways of electric power generation. In this question he invented
huge power plants. The early plants used wood to generate steam for water,
which in term used to drive an electric generation. However, this quick
depletion of forests led man to look for alternative source of power. The
power of falling water was used to generate electricity. However, a need was
felt for more power generation. In addition, the Hydel-power station was
costlier and tougher to establish, even though the cost of operations was
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lower consequently, in the mid twentieth century, coal was found to be a
technologically and economically viable option for steam power generation.
Today, most of the world's electric energy needs are met using coal
Nevertheless, the progress can never stop. Even this cheap alternative has
some limitation. The greatest problem is that of ash disposal. A huge amount
of ash is generated in a coal-based station and it is highly harmful for man
and his environment. Therefore, must of the new power station coming up in
India are natural gas based. According to some experts, for sustainable
development because of its low long-term availability can only be a
transition fuel. Indeed, hydrogen is stipulated to be the fuel of the future.
Clearly, the electric power requirement of man kind is on rise and therefore
the need of looking at alternate and unconventional source of energy is being
best. There are a no. of such sources, for instance, solar, geothermal, tidal
wind etc. these source, though not sufficient all by themselves, can
contribute significantly to our power needs.
As such the consistent growth of power is vital to meet our day-to-
day- requirements and improve the living standards.
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ACKNOWLEDGEMENT
We as a group would like to express our heart filled gratitude to the various
People those who have he pad us curing the entire training period. First of all
We would spastically like to extend a word of thanks to J.E. Mr.Jyoti
Sharma, Haryana Vidyut Para saran Nigam limited 132KV substation, Jind.
It was under his able guidance and leadership that we are permitted to be a
Part of this esteemed substation.
We also would like to thanks ALM Mr.Rajbir Nain & Mr. Virender Kundu
(SA), of the substation for their Instrumental in guiding us to the various
Processes in the substation and Thus played vital role in enriching our
Knowledge in the technical field.
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CONTENTS
1. Introduction to HPGCL
2. Introduction to substation JIND
3. Switchyard
Lightening Arrestor
Capacitor Voltage Transformer
Wave trap
Current Transformer (CT)
Potential Transformer (PT)
Circuit Breaker
Isolators
Insulator
Buses
Power Transformer
Neutral Current Transformer
4. Power line Carrier Communication (PLCC)
5. Battery Room
6. Control Room
7. Substation Auxiliaries Supply
8. Earthing of Substation
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INTRODUCTIO N TO HPGCL
Haryana Power Generation Corporation Limited (HPGCL) wasincorporated as a company under companies Act 1956on 17th March 1997
and certificate for commencement of business was granted on 5 th August
1997. The business of generation of power of erstwhile Haryana State
Electrically Board was transferred to Haryana Power Generation
Corporation Limited on 14th August 1998 pursuant to the implementation of
power reforms in the state of Haryana. The main objective of HPGCL is to
generate power in the state of Haryana from the existing station in most
efficient manner on commercial lines and shell whole of the power
generated exclusively to Haryana Vidyut Parasaran Nigam Limited and to
setup new power project on the state sector.
The main objectives of HPGCL are as under:
1. To generate power from its existing Generating Stations in the
most efficient manner on commercial lines and to sell the same to
distribution companies.
2. To setup new power generation projects.
3. from June 2005 HPGCL is also responsible for the work of powertrading i.e. Procurement of power on long term and short term
basis, signing of power purchase agreements with power
producers/traders
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SUBSTATION (JIND)
Haryana Vidyut Power Generation Corporation Limited (HVPNL) 132 KV
substation Jind is an undertaking of Haryana Power Generation Corporation
Limited Panchkula (HPGCL). Substation serve as a source of energy supply
for the local areas of distribution in which these are located. Their main
functions are to receive energy transmitted at high voltage from the
generating stations, reduce the voltage to a value appropriate for local
distribution and provide facilities for switching.
It is established near milk plant on HANSI road, JIND. This substation
required area of 15 acres. The input of the substation is mainly from threesubstations which are as follows:
1. 132 KV from JHANJ
2. 132 KV from PANIPAT
3. 132 KV from SAFIDON
Then this input power is stepped down and passes to the nearest substation.
So the output of this substation is also going to the three substations which
are as follows:
1. 132 KV to JIND (OLD)
2. 132 KV to KHERI
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SWITCHYARD
Haryana Vidyut Power Generation Corporation Limited (HVPNL) 132 KV
switchyard JIND is an undertaking of Haryana Power Generation (HPGCL)
Corporation Limited Panchkula (HPGCL). Switchyard serve as a source of
energy supply for the local areas of distribution in which these are located.
Their main functions are to receive energy transmitted at high voltage from
the generating stations, reduce the voltage to a value appropriate for local
distribution and provide facilities for switching.
A Highlight of Switchyard Of substation is given in Table Below:
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LIGHTNING ARRESTER
The lightning arrester as a surge diverter is used forthe protection of power system against the high
voltage surges. It is connected between the line and
earths and so diverts the incoming high voltage wave
to the earth. Lightning arrester act as safety valves
designed to discharge electrical surges resulting from
lightening strokes, switching or other disturbances,
which would other wise flash over insulator or
puncture insulation, resulting in a line voltage and
possible failure of equipment. They are designed to
absorb enough transient energy to prevent dangerousreflection and to cut off the flow of power frequency
follow (or dynamic) current at the first current zero
after the discharge of transient. They include one or
more sets of gaps to establish the breakdown voltage,
aid in interrupting the power follow current, and prevent any follow of
current under normal condition(except that gap shunting resistor when
used ton assume equal distribution of voltage across the gap, permits a
very small leakage current). Either resistance element to limit the power
follow current of values the gap can interrupt, or an additional arcextinguishing chamber of interrupt the power follow current are
connected in series with gaps. Arresters have a short time lag of
breakdown compared with the insulation of apparatus, the breakdown
voltage nearly independent of the steepness of the wave front.
Lightning protection by means of lightning arrestors and gaps and
overhead ground wire is a mean of reducing outages and preventing
damage to station equipments from lightning disturbances.
The ground wire or earthling screen does not provide protection againstthe high voltage wave reaching the terminal equipment, so some
protective devices are necessary to provide protection of power stations,
substation and transmission line against the voltage wave reaching there.
The most common device used for the protection of power system
against the high voltage surge is sure diverter.
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CAPACITOR VOLTAGE TRANSFORMER
A capacitor voltage transformer (CVT) is a transformer used in power
system to step down extra high voltage signal and provide low voltagesignals either for measurement or to operate a protective relay. In its
basic form the device consist of three parts: two capacitor across which
the voltage signals is split, an inductive element to tune the device to the
supply frequency and a transformer used to isolate and further step down
the voltage for the instrumentation and protective relay. The device has at
least four terminals, a high voltage terminal to connection to the high
voltage signal, a ground terminal and at least one set of secondary
terminals for the connection of the instrumentation and the protective
relay. CVTs are typically single phase devices used for measuring
voltage in excess of one hundred kilovolts where the use of voltagetransformer would e uneconomical. In practice the first capacitor, C1, is
often replaced by a stack of capacitor connected in series. This result in
large voltage drop across the stacks of capacitors that replaced the first
capacitor and a comparatively small voltage drop across the second
capacitor C2, and hence the secondary terminals.
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WAVETRAP
Wave trap is a parallel tuned inductor capacitor tank Circuit made to be
resonant at the desired communication frequency. It is the effort to utilizethe same transmission line between two substations for the purpose of
communications. At these communication frequencies the tank ckt provides
high impedance and does not allow passing through them & onto the
substation bus & into transformers.
The Line trap offers high impedance to the high frequency communication
signals thus obstructs the flow of these signals in to the substation bus bars.
If there were not to be there, then signal loss is more and communication
will be ineffective/probably impossible.
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CURRENT TRANSFORMER
These instrument transformers are connected in ac power circuits to feed
the current coil of indicating and metering instrument (ammeter,wattmeter, and watt hours meter) protective relays. Thus the CTs
broaden the limit of measurements and maintain a watch over the current
flowing in the circuit and over the power loads. In high voltage
installation CTs in addition to above, also insolate the indicating and
metering instruments from high voltage. The current transformer
basically consists of an iron core on which arc wound a primary and one
or two secondary windings. The primary is directly inserted in the power
circuit (the circuit in which the current is to be measured) and ton the
secondary winding or windings the indicating and metering instruments
and relays are connected. When the rated current of CT flows through itsprimary winding a current of 5 amperes will appears in its secondary
windings. The primary windings are single turn windings and the number
of turns on secondary winding depends upon the power circuit current to
be measured. The larger current to be measured, more the number of
turns on secondary. The ratio of primary current to the secondary current
is known as the transformation ration.
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POTENTIAL TRANSFORMER (PT)
The potential transformer are employed for voltage above 380 volts to feed
the potential coils of indicating and metering instrument (voltmeter,Wattmeter, and watt hours meter) and relays. These transformers make the
ordinary low voltage instrument suitable for measurement of high voltage
and isolate them from high voltage.
The primary windings of the potential transformer is connected to the main
bus bar of the switchgear installation and to the secondary windings, various
indicating and metering instrument and relays are connected.
When rate high voltage is applied to the primary of PT the voltage of 10V
appear at the secondary windings. The ration of rated primary voltage to the
rated secondary voltage is known as turn or transformation ration.
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CIRCUIT BREAKER
A circuit breaker is a mechanical device designed to close or open
contact members, thus closing or opening an electrical circuit under
normal or abnormal conditions. It is so designed that it can be operatemanually under normal condition or automatically under faulty condition.
An automatic circuit breaker is equipped with a trip coil connected to a
relay or other means designed to open or break automatically under
abnormal condition, such as over current. When the circuit breaker is
closed considerably energy stored in the springs. The connects are held
together by means of toggles. To open the circuit breaker only a small
pressure is required to be applied on the trigger. When t6hw trigger is
actuated by the protective relay, it trips and potential energy of the
springs is released and the contacts open in the fraction of second.
HIGH VOLTAGE CIRCUIT BREAKER
High voltage circuit breakers are broadly classified by the medium used to
extinguish the arc.
Oil filled (dead tank and liver tank)
Oil filled, minimum oil volume
Air blast
SF6 Vacuum circuit breaker (manufacturing in ABB, AREVA, cutler-
hammer (Eaton), Siemens, Toshiba)
High voltage circuit breakers are routinely available up to 765 KV AC.
Live tank circuit breaker are where the enclosure that contains the breaking
mechanism is at line potential, that is, live. Dead tank circuit breaker
enclosures are at earth potential.
[Interrupting principle of high voltage circuit breakers
Current interruption in high voltage circuit breaker is obtained by separating
two contacts in a medium, such as SF6 having excellent dielectrical and arc
quenching properties.
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SULPHUR HEXAFLUORIDE (SF6) CIRCUIT BREAKER
In many type of circuit breakers the extinguishing
force built up relatively slowly after the moment of
contact separation, and hence arc is extinguishingafter a few half cycles current have passed zero. The
prevention of arc re-igintioin needs a high
dielectrical strength of the arc path and its fast
recovery current zero. In the case of high voltage
circuit breaker these properties are particularly
required to have quick arc extinction and have less
time for quick recovery voltage build up. Vacuum
circuit breaker and Sf6 circuit breaker havebetter
properties in this regard compared to conventional
bulk oil minimum oil as well as air blast circuitbreakers hence modern trend is to employ vacuum
circuit breaker and SF6 circuit breakers in HV
system.
Modern circuit breaker employs heavy gas SF6 as the medium for quenching
the arc. Sf6 gas because its excellent dielectric, arc quenching, chemical and
other physical properties, has proved its superiority over other mediums
such as oil or air for use in circuit breakers. Several types of SF6 circuit
breakers have been developed by different manufacturers during last two
decades for rated voltages 3.6 to 760 Kv.
Rated voltage 245 KV
Frequency 50 HZ
Current 200 A
Opening voltage 220 V DC
Total wt. 2400 KG
Gas wt. 21 WG
Include gas SF6
Pressure 16.5 KG/cmg
Short circuit 40 KV -3 sec.
Made by Siemens, India
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ISOLATOR
Isolator (or
disconnect switches)are not equipped with
arc quenching device
and, therefore, not
used to open circuits
carrying current. As
the name implies
isolator isolates one
portion of the circuit
from another and is
not intended to beopened while current
is flowing. Isolators
must not be opened
until the circuit is interrupted by some other means. If an isolator is
opened carelessly, when carrying a high current, the resulting arc could
easily cause a flash over the earth. This may shatter the supporting
insulator and may even cause a fatal accident to the operator, particularly
in high voltage circuits. While closing a circuit, the isolator is closing
first, then the circuit breaker. Isolators are necessary on supply side ofcircuit breaker in order to ensure isolation (disconnection) of the circuit
breaker from the live parts for the purpose of maintenance.
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INSULATOR
The porcelain insulators employed in substations
are of the post and busing type. They sever as
supports and insulation of the bus-bars.
A post insulator consists of porcelain body, cast
iron cap and flanged cast iron base, as shown in
fig. the hole in the cap is threaded so that the bus-
bar are either directly bolted to the cap or fixed by
means of bus-bar clamp. Post insulators are
available with round oval and square flanged bases
for fixing respectively, with aid of one, two or four
bolts. Each base in addition also has an earthing bolt. A bushing insulator consists of porcelain-
shell body ,upper and lower locating washers used
for fixing the position of the bus bar in shell, and
mounting flange with holes drilled for fixing bolts and supplied with an
earthing bolt, as shown in fig.
For current rating above 2,000A, the bushings are designed to allow the
main bus bars to be passed directly through them. Each phase of the bus bars
is located with paint according to a fixed color code red, yellow and blue so
that phase of main bus bars can be identified. But at Jind substation disk
type insulators are used which is shown in fig.
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BUS-BARS
Bus bar term is used for a main bar or conductor carrying an electric currentto which many connections may be made.
Bus bars are merely convenient
means of connecting switches and other equipment in to various
arrangements .the usual arrangement of connections in most of the
substations permits working on almost any piece of equipment without
interruption to incoming or outgoing feeders.
In some arrangement two
buses are provided two which the incoming or outgoing feeder and theprincipal equipment may be connected. One bus is usually called the main
bus and the other auxiliary or transfer bus. The main bus may have a more
elaborate system of measuring instruments, relay etc.associated with it. The
switches used for connecting feeders or equipment to one bus or the other
are called transfer switches.
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POWER TRANSFORMER
Power transformer are used for stepping-up the voltage for transmissionat generating stations and for stepping-down voltage for further
distribution at main step down transformer substation. Usually naturally
cooled, oil immersed, known as ON type, two winding, three
transformers are used up to the rating of 10 MVA. The transformers of
rating higher than 10MVA are usually cooled. For very high rating, the
forced oil, water cooling and air blast cooling may be used. For
regulating they voltage of transformers used are provided with on load
tap changer. They are put in operation during load hours and disconnect
during light load hours i.e. they are usually operated at approximately full
load. This is possible because they are arranged in blank and can bethrown in parallel with other units or disconnect at will. So power
transformers are designed to have maximum efficiency at or near full
load (i.e. with iron loss to full load copper loss ratio of 1:1). Power
transformer are designed to have considerable leakage reactance then is
permissible in distribution transformer because in power transformers
inherent voltage regulation is not as much important as current limiting
of the higher leakage reactance. At 132 KV substation Jind two
transformers are used for the stepping down purpose. Each of them is of
100 MVA. These transformers steps down the voltage 132 KV into 33KV. This voltage is then transmitted to the 33 KV substations of KHERI
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NEUTRAL CURRENT TRANSFORMER
This transformer is used after the power transformer. This transformer is asafety device. If there is any extra current in the transformer then this current
is taken by the neutral current transformer and this current is grounded by
the transformer. This is connected to the power transformer for grounding
the extra current. If there is any type of current that current will be grounded
by the neutral current transformer.
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CONTROL ROOMS
The control room (or the operating room) is the nerve center of the power
station. The various control performed from here are voltage adjustment,
load control, emergency tripping of turbines etc. and the equipment and
instruments housed in a control room are synchronizing equipment, voltage
regulators, relays, ammeters, voltmeters, watt meters, KWh meters, kVARh
meters, temperature gauges, water level indicator and other appliances, as
well as a mimic diagram and suitable indicating equipment to show the
opened or closed position of circuit breaker, isolators etc. the location of
control room in relation to other section of the power station is also very
important. It should be located away from the sources of noise and it should
be near the switch house so as to save multi-core cablesUsed for interconnections. Of course, if there is any fire in switch house, the
control room should remain unaffected. Also there is an access from the
control room to the turbine house. The control room should be neat and
clean, well ventilated, well lighted and free from draughts. There should be
no glare and the color scheme should be soothing to eyes. The instrument
should have scales clearly marked and properly calibrated and all the
apparatus and circuit should be labeled so that they are clearly visible.
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BATTERY ROOM
All power plant and substation require dc power supply for protection and
control purposes and dc supply is obtained from secondary or storagebatteries. Battery room is the heart of a substation. Lead acid batteries are
most commonly used in po0wer stations and substations because of their
high cell voltage and lower cost.
Station batteries are assembled of a certain number of accumulator cells
depending on the operating voltage if the respective de circuits. Storage
batteries are of two types viz lead acid and alkaline batteries. Lead acid
batteries are most commonly used in power stations and substations because
of their higher cell voltage and low cost. At substation 132KV Jind 110 cells
are used each of 2 volts. And nickel cadmium alkaline batteries are used.
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TRANSMISSION TOWER
MATERIAL USED IN LINE CONDUCTORS
Aluminum conductor steel reinforced (or
ACSR) cable is a specific type of high
capacity, high strength standard cable
used in overhead power lines. The outer
standards are aluminum, chosen for its
excellent conductivity, low weight, and
low cost. The centre strand is of steel,
providing extra strength. Simultaneously
however, the tower electricalconductivity of the steel core has only a
minimum effect on the overall current
carrying capacity of the cable. Due to a
skin effect, most of the current is carried
by the outer, aluminum portion of the
cable, so the higher Resistance of the
inner, steel strand is largely immaterial.
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POWER LINE CARRIER COMMUNICATION (PLCC)
Power line carrier communication (PLCC) is mainly used for
telecommunication, tele-protection and tele-monitoring between electrical
substations throughpower lines at high voltages, such as 110 Kv, 220 Kv,
400 Kv. PLCC integrates the transmission of communication signal and
50/60 Hz power signal through the same electric power cable. The major
benefit is the union of two important applications in a single system.
In a PLCC system the communication is established through the power line.
The audio frequency is carried by a carrier frequency and the range of carrierfrequency is from 50 kHz to 500 kHz. The modulation generally used in
these systems is amplitude modulation. The carrier frequency range is
allocated to include the audio signal, protection and the pilot frequency. The
pilot frequency is a signal in the audio range that is transmitted continuously
for failure detection.
The voice signal is converted/compressed into the 300 Hz to 4000 Hz range,
and this audio frequency is mixed with the carrier frequency. The carrier
frequency is again filtered, amplified and transmitted. The transmission of
these HF carrier frequencies will be in the range of 0 to +32db. This range isset according to the distance between substations.
PLCC can be used for interconnecting PBXs. The electricity board in India
has an internal network PLCC between PBXs.
Contents
1 Line trap
2 Coupling capacitor
3 Line matching unit 4 Digital power line carrier
http://en.wikipedia.org/wiki/Telecommunicationhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Power_linehttp://en.wikipedia.org/wiki/High_voltagehttp://en.wikipedia.org/wiki/Audio_frequencyhttp://en.wikipedia.org/wiki/Carrier_frequencyhttp://en.wikipedia.org/wiki/Amplitude_modulationhttp://en.wikipedia.org/wiki/Private_branch_exchangehttp://en.wikipedia.org/wiki/Power_line_carrier_communication#Line_trap%23Line_traphttp://en.wikipedia.org/wiki/Power_line_carrier_communication#Coupling_capacitor%23Coupling_capacitorhttp://en.wikipedia.org/wiki/Power_line_carrier_communication#Line_matching_unit%23Line_matching_unithttp://en.wikipedia.org/wiki/Power_line_carrier_communication#Digital_power_line_carrier%23Digital_power_line_carrierhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Electrical_substationhttp://en.wikipedia.org/wiki/Power_linehttp://en.wikipedia.org/wiki/High_voltagehttp://en.wikipedia.org/wiki/Audio_frequencyhttp://en.wikipedia.org/wiki/Carrier_frequencyhttp://en.wikipedia.org/wiki/Amplitude_modulationhttp://en.wikipedia.org/wiki/Private_branch_exchangehttp://en.wikipedia.org/wiki/Power_line_carrier_communication#Line_trap%23Line_traphttp://en.wikipedia.org/wiki/Power_line_carrier_communication#Coupling_capacitor%23Coupling_capacitorhttp://en.wikipedia.org/wiki/Power_line_carrier_communication#Line_matching_unit%23Line_matching_unithttp://en.wikipedia.org/wiki/Power_line_carrier_communication#Digital_power_line_carrier%23Digital_power_line_carrierhttp://en.wikipedia.org/wiki/Telecommunication -
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LINE TRAP
It is also called Wave trap. It is connected in series with the power
(transmission) line. It blocks the high frequency carrier waves (24 kHz to
500 kHz) and let power waves (50 Hz 60 Hz) to pass through. It is
basically an inductor of rating in mili henry.
COUPLING CAPACITOR
It provides low impedance path for carrier energy to HV line and blocks the
power frequency circuit by being a high impedance path.
LINE MATCHING UNIT
LMU is a composite unit consisting of Drain Coil, Isolation transformer with
Lightning Arrester on its both the sides, a Tuning Device and an earth
switch. Tuning Device is the combination of R-L-C circuits which act as
filter circuit. LMU is also known as Coupling Device. Together with
coupling capacitor, LMU serves the purpose of connecting effectively the
Audio/Radio frequency signals to either transmission line or PLC terminal
and protection of the PLCC unit from the over voltages caused due to
transients on power system.
DIGITAL POWER LINE CARRIER
A power line carrier using a power line as transmission media needs to
change its transmission system from analog to digital to address rapid
diffusion of IP devices and digital telecommunication devices. With this
view, digital power line carrier (DPLC) was developed featuring several
technological measures which enable digital transmission via power lines
and performed a field evaluation test. As a result, DPLC has the required
quality of bit error rate characteristics and transmission ability such as
transmitting information from monitoredelectric-supply stations and images.
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SUBSTATION AUXILIARIES SUPPLY
In small unattended substation only a small amount of power for electric
lighting during regular periods of inspection, maintenance and repair is
required. In regional substation the electric power is required for theauxiliaries:- the lighting circuit, air blast fan of transformer, battery
charging sets oil servicing facilities, compressor unit in case of air blast
circuit breakers, ventilating fans of the substation buildings water supply
and heating system equipment etc. substation incorporating synchronous
condensers the supply is also required for the operation of auxiliaries
equipment of the synchronous condensers.
At 132 KV substation Jind a stepping down transformer is used which
step down 33 KV into 11 KV which is used for the substation auxiliaries
supply. Feeders are also taken from this voltage.
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EARTHING OF SUBSTATION
The term earthing mean connecting of the non current carrying parts ofthe electrical equipment or the neutral point of the supply system to the
general mass of the earth in such a way that at all times am immediate
discharge of electrical energy take place without a danger. The earthing is
provided by the following activities:-
1. for the safety of personnel form of electrical shock- insuring
that non current carrying parts, such as equipment frames are
always safely at ground potential even though insulation fails.
2. For the safety of equipment and personnel against lightning and
voltage surges- providing the discharge path for the lightningarresters, gaps and similar devices.
3. For providing the ground connection for ground neutral system.
4. For provide a mean of positively discharging or highly de-
energizing feeders or equipment before proceeding with
maintenance of them. The station earthing system should have
low resistance.
Grounding of power system is highly important. A substational and adequate
ground that will not burn off or permit danger rise in voltage under abnormalconditions essential.
Equipment earthing also help in the earth fault protection.
Solid grounding will be done it means a direct connection of the neutral to
the earth.
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