A TRAINING REPORT ON PLCC “132KV GSS Hawa sarak, Jaipur (Raj.)” Submitted In partial fulfillment of the of the Requirements for Award of Requirements for Award of the Degree of the Degree of BACHELOR OF TECHNOLOGY BACHELOR OF TECHNOLOGY IN IN ELECTRONICS&COMMUNICATION ELECTRONICS&COMMUNICATION From Rajasthan Technical University From Rajasthan Technical University Submitted To Submitted To Submitted By Submitted By Mr.NITIN GUPTA Mr.NITIN GUPTA ANTIMA GARG ANTIMA GARG (HOD of EC deptt.) (HOD of EC deptt.) 4 th th year E.C year E.C 1
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ATRAINING REPORT
ON
PLCC“132KV GSS Hawa sarak, Jaipur (Raj.)”
Submitted In partial fulfillment of the Requirements for Award of of the Requirements for Award of
From Rajasthan Technical University From Rajasthan Technical University
Submitted ToSubmitted To Submitted BySubmitted By Mr.NITIN GUPTA Mr.NITIN GUPTA ANTIMA GARG ANTIMA GARG (HOD of EC deptt.) (HOD of EC deptt.) 4 4thth year E.C year E.C R.C.E.W R.C.E.W
DEPARTMENT OF ELECTONICS&COMMUNICATIONDEPARTMENT OF ELECTONICS&COMMUNICATIONRAJASTHAN COLLEGE OF ENGINEERING FOR WOMENRAJASTHAN COLLEGE OF ENGINEERING FOR WOMEN
"Rajasthan state electricity board" started working from Ist July, 1957. This is the body of big organization and is to function under provision electricity act, like public limited companies. The board does not have article and memorandum of association.
In order to carry out its function, its rules & regulation and his mad other necessary administrative arrangement. After the acting of RSEB six dimensions along with 64 offices & about 300 employees were transferred to its control by the state Govt.
The aim of RSEB is to supply electricity to entire Rajasthan State in the most economical way. There are no possibilities of staking or electricity so the target of board is to distribute the energy in the new area as possible. The board has to carry the business on profit without losses.
After an efficient starting, for the better service privatization of RSEB has been done recently, it has been divided in five main parts, they are:
1. Electricity production authority: RRVUNL
2. Electricity transmission authority: RRVPNL
3. Distribution authority for Jaipur: JVVNL
4. Distribution authority for Jodhpur: JDVVNL
5. Distribution authority for Ajmer: AVVNL
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CHAPTER-1
INTRODUCTION
POWER LINE CARRIER COMMUNICATION (PLCC)
voltage transmission lines, distributed over medium voltage, and used inside buildings at
lower voltages. Power line communications can be applied at each stage. Most PLC
technologies limit themselves Electrical power is transmitted over high to one set of wires
(for example, premises wiring), but some can cross between two levels (for example, both
the distribution network and premises wiring). Typically the transformer prevents
propagating the signal so multiple PLC technologies are bridged to form very large
networks.
Electrical power is transmitted over high voltage transmission lines, distributed over
medium voltage, and used inside buildings at lower voltages. Power line communications
can be applied at each stage. Most PLC technologies limit themselves to one set of wires
(for example, premises wiring), but some can cross between two levels (for example, both
the distribution network and premises wiring). Typically the transformer prevents
propagating the signal so multiple PLC technologies are bridged to form very large
networks
BASIC PRINCIPLE OF PLCC
In PLCC the higher mechanical strength and insulation level of high voltage power lines
result in increased reliability of communication and lower attenuation over long distances.
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Since telephone communication system cannot be directly connected to the high voltage
lines, suitably designed coupling devices have therefore to be employed. These usually
consist of high voltage capacitors or capacitor with potential devices used in conjunction
with suitable line matching units (LMU’s) for matching the impedance of line to that of the
coaxial cable connecting the unit to the PLC transmit-receive equipment.
Also the carrier currents used for communication have to be prevented from entering the
power equipment used in G.S.S as this would result in high attenuation or even complete
loss of communication signals when earthed at isolator.. Wave traps usually have one or
more suitably designed capacitors connected in parallel with the choke coils so as to
resonate at carrier frequencies and thus offers even high impedance to the flow of RF
currents.
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PLCC technology is used for the following these places which are given
below:-
1. point to point communication (hot line comm.)
2. Data telemetry purpose
3. Tele protection purpose
Point to point communication :- point to point communication states that the
communication in between two particular stations now the question is arises that why we go
towards that communication when mobile and telephone are available . two problems are
arises in mobile communication.
First is when we are using mobile that the networking problems may arises.
Second thing is someone at any stations may busy talking with another person while
/when you are try to call him.
Data telemetry :- PLCC terminals can be used for sending and receiving data signal for
telemetry etc. The input for this channel will be in 2000-3000Hz.
Tele Protection :- Protection coupler Equipment can be used along with PLCC terminals
telemetry purpose.
During line fault other fault occurring between sub station trip
Signals can be transmitted or received by a protection coupler
through PLCC terminal for activation distance protection Relaying Equipment.
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In PLCC the higher mechanical strength and insulation level of high voltage power line
communication and lower attenuation over long distance. The idea is to use the power line
as a transmission line for communication purpose
CHAPTER-2
COUPLING DEVICES
Earliest coupling devices used were antenna as similar to these used in radio work. This
was because capacitors capable of withstanding the high voltages used in transmission of
electrical power were not available at that time. The antennas used for coupling the PLC
equipment to the transmission lines were usually erected below the line and parallel to it.
They were usually more then 300 ft long and were tuned to the carrier frequency employed.
These were rather inefficient and the systems were affected but interference from nearby
long wave radio transmitters.
By about 1930, suitably paper and oil capacitors were developed which could withstand the
high voltage and serve as affectidive coupling units to PLC equipments.
A modern coupling capacitor consists of stack of flat would elements of pure cellulose
paper and aluminium coils held between insulating roads under optimum pressure to
minimize capacitance the changes with time and temperature. The interconnection is
designed to obtain.
Highest possible range withstands capacity and highest cut-off frequency. The entire stack
assembly as placed in a suitable pro claim insulating shall fill with insulation coils and
hemetically sealed by metallic flanges and gaskets of synthetic rubber with a dry nitrogen
gas cushion. The mechanical strength of the shell and flanges are carefully matched.
Coupling capacitors are designed for outdoors use and withstand normal atmospheric
phenomenon such as temperature and humidity rain, shown etc. The capacitor's used in
modern PLCC systems have a capacity between 2000 and 8000 ft. The usual value is
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between 3000 and 5000 ft. The units are designed to have a very low (<0.5dB). There are
usually mounted on pedestals below the line conductors.
In many cases the capacitive voltage dividers are used for communication system and
voltage is used for synchronizing purpose or voltage measurement.
Coupling is necessary because, if power of power line is flow through the communication
line it cause the burning of PLCC equipment. So overcome this problem a coupling
capacitor is used to block the flow of power into the carrier signal line.
TYPE OF COUPLING
(A)Phase To Ground Coupling
(B)phase to phase coupling
(C)inter circuit coupling
(A)Phase To Ground Coupling
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As can be seen from the figure, the wave traps and coupling capacitors are all connected to
one conductor of the power line. The remaining two conductors, though not directly
connected to the.
Line carry a portion of the returning carrier current because these two conductors do not
have wave traps, a portion of the carrier energy is 1 lost. Also radiation losses are goes
high as earth forms a part of the circuit and the noise pickup is correspondingly higher. The
method of connecting is inefficient and the connection at the receiving and can not be made
to match the line perfectly. This is because the impedance of the line can not be calculated
correctly as it depends partly on the soil conductivity enrote the line which varies from place
to place and time to time and parity on station switching condition.
b)Phase To Phase Coupling
This type of coupling was formally being used to improve the reliability of communication
case of breakage of one of the coupled conductors the system used double the number of
wave traps and coupling capacitors used in phase to ground and hence is costlier. This
coupling capacitor at each and have the line are connected in parallel to the LMUs as
shown in this sketch figure-
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Through this type coupling increase the reliability of communication, the attenuation,
interference from radio transmission and monitoring possibilities are all-higher than those of
phase to ground coupling. Hence this type of coupling has been discontinued and super
sided by the phase to phase coupling system.
(C)Inter Circuit Coupling
This type is coupling uses the same number of wave traps and the capacitor as two
phase coupling but the capacitance are not connected in parallel as in the case of that type
of coupling. The two power conductors used in this case may be considered as metallic go
and return lines for the carrier currents. The conductor has no appreciable influences on the
carrier currents. The third has no appreciable influence on the carrier current transmission.
Hence the switching conditions attention is less because two conductors are used instead
of one conductor and earth. This type of coupling is more reliable over longer distance and
is generally used load dispatch work, though is lightly costlier than the two phase system.
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COMPARISON OF PHASE TO PHASE AND PHASE TO GROUND
COUPLING
The phase-to-ground coupling has the advantage of requiring only half the number of wave
traps and coupling capacitors in comparison to phase-to-phase coupling. But it is inferior to
many respects as would be evident from the following points:
1. The phase-to-ground coupling has higher attenuation and unlike phase-to-phase
coupling, the attenuation varies with station switching conditions.
2. The variation of attenuation function with changes in weather condition is greater in
phase-to-ground coupling.
3. Reflection and echoes due to mismatch difficulties are much greater in phase-to-
ground coupling.
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4. Signal-to-noise ratio is poorer due to longitudinal noise voltages induced in the line.
In phase-to-phase coupling thee noise voltages tend to cancel themselves as equal
voltages are induced in the coupled conductors, which oppose each other in the
circuit.
5. Radiation from phase-to-ground case is about double than that in the other case.
6. A break or fault of some other kind will hamper the transmission in phase-to-ground
coupling much more seriously than in phase-to-phase coupling.
Hence, phase-to-ground coupling is used due to its cheapness, especially when frequency
used and distances to be covered are suitable, and radiation not particularly objectionable,
as may be the situation in sparsely populated areas.
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CHAPTER-3
THE YARD
The yard is spread in very long area. The yard of 220 KV GSS at Heerapura has various
equipment installed at the yard of 220 KV GSS, Heerapura are:-
. PLCC equipment including coupling capacitance
Lighting Arrester
Wave Trap
Circuit Breaker
Isolater
Bus Bars
Insulator
Static earthling system
PLCC equipment including coupling capacitance
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Switch Yard
Switch yard
THE YARD
BUS BAR SYSTEM
This bus bar arrangement is very useful for working purpose as every GSS. It is a
conductor to which a number of cut .Are connected in 220 KV GSS there are two bus
running parallel to the each other, one is main and another is auxiliary bus is only for stand
by, in case of failure of one we can keep the supply continues.
If more loads are coming at the GSS then we can disconnect any feeder through circuit
breaker which is connected to the bus bar. This remaining all the feeders will be in running
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position .if we want to work with any human damage. In this case all the feeders will be on
conditions.
According to bus voltage the material is used .Al is used because of the property &
features and it is cheap. With the help of bus bar arrangement we can connect all the
incoming supply which is coming from different higher order GSS.
PROPERTIES
COPPER ALUMINIUM
1. Electricity resistively at 0.0172410.00403
2. Temp coff. of resistively 0.0041 0.00403
3. Softening tem.200
4. Thermal conductivity.932.503
5. Meting point1083657
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CHAPTER-4
LIGHTENING ARRESTER
Lightening arrester is first equipment of GSS. It is protecting all the equipment against
the HV. The ground wire or earthing does not provide protection against the high voltage
waves reaching the terminal equipment .so some protective device is necessary to produce
power station, sub-station and transmission lines against the high voltage wave reaching
here.This is connected between line and earth it acts as a safty value.
Through the surge impedance of line limits the amplitude of the line to earth over voltage
to a value which wills safe guard the insulation of the protected equipment.
An ideal L.A should have following characteristics:-
1. It should not take any current under normal condition .i.e. its spark over voltage
must be higher than the system voltage.
2. Any abnormal transient voltage above the break down voltage must caused it to
break as quick as possible in order to provide an alternate path to earth.
3. It must be able to carry the resultant discharge current without causing damage
to itself.
For high voltage system the thirties type L.A are used .The value type is also known as non
linear diverter .These arrester consist of a spark gape and a non linear resistance. Both
resistance and spark gape are accommodated in series with a completely light porcelain
condition humidity etc.
SPARK GAPE:-
They include a number of identical elements connected in series .Each element consist
of with pre ionization device between each grounding resistance of high ohmic value
connected in parallel.
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NON LINEAR RESISTER :-
The resister disc comprises inorganic material having a silicon carbide base in a clay
board. These discs form a block. The ohmic value of which decreases rapidly when the
applied voltage and current increases as soon as the current wave resulting from the over
voltage has been discharged. The resister block subjected to the sole. Alternating Voltage
and resistance assumes great value .So that the amplitude of the resulting current becomes
zero.
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Lightning arrester
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CHAPTER-5
WAVE TRAP
It is used to trap the communication signals & send PLCC room through CVT.
Rejection filters are known as the line traps consisting of a parallel resonant circuit ( L and
C in parallel) tuned to the carrier frequency are connected in series at each and of the
protected line such a circuit offer high impedance to the flow of carrier frequency current
thus preventing the dissipation. The carrier current used for PLC Communication have to be
prevented from entering the power equipments such as attenuation or even complete loss
of communication signals. For this purpose wave trap or line trap are used between
transmission line and power station equipment to-
Avoid carrier power dissipation in the power plant reduce cross talks with other PLC
Circuits connected to the same power station. Ensure proper operating conditions and
signal
levels at the PLC transmit receive equipment irrespective of switching conditions of the
power circuit and equipments in the stations.
Line Matching Filter & Protective Equipments
For matching the transmitter and receiver unit to coupling capacitor and power line
matching filters are provided. These flitters normally have air corral transformers with
capacitor assumed.
The matching transformer is insulated for 7-10 KV between the two windings and perform
two functions. Firstly, it isolates the communication equipment from the power line.
Secondly, it serves to match .
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Figure-4.1 Line Matching Filter & Protective Equipments
Transmitter
The transmitter consists of an oscillator and a amplifier. The oscillator generates a
frequency signal with in 50 to 500 HZ frequency bands the transmitter is provided so that it
modulates the carrier with protective signal. The modulation process usually involves taking
one half cycle of 50 HZ signal and using this to create block to carrier.
Receivers
The receivers usually consist of and alternate matching transformer band pass filter and
amplifier detector.
The amplifier detector converts a small incoming signal in to a signal capable of operating a
relatively intensive carrier receiver relay. The transmitter and receiver at the two ends of
protected each corresponds to local as far as transmitting.
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CHAPTER-6
CIRCUIT BREKER
Breakers are switching and current interrupting devices. Basically a circuit breaker
comprises a set of fixed and movable contacts. The contacts can be separated by means of
an operating an arc. The arc is extinguished by a suitable medium such as dielectric oil
vacuum, SF6 gas.
The circuit breakers play an important role in the design and performance of a power
system, in that these are the key pieces of apparatus protecting the system and thus
ensure continuity of supply from consideration of cost, the circuit breakers represent a
major items, and are, next only to the generator and transformer, since their quantity is
greater than that of generators/transformer in a power system owing to the services
required for control of transmission lines, bus-bar etc. in addition to control of transformers
and generator.
Circuit breakers
FUNCTION OF CIRCUIT BREAKER
The expected functions of a circuit breaker are: -
i. It must be capable of closing on to and carrying full load currents for long period of time.
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ii. Under proscribed condition, it must open automatically to disconnect the load or some small
overload.
iii. It must successfully and rapidly interrupt the heavy current, which flow when a short circuit
has to be cleared from the system.
iv. It must be capable of closing on to a circuit in which a fault exists and immediately re-
opening to clear the fault from system
It must be capable of carrying current of short circuit magnitude until, and for such time as,
the fault is cleared by another breaker nearer to the pint of fault.
Types of Circuit Breaker
i. Bulk oil Circuit Breakers
ii. Minimum oil Circuit Breakers.
iii. Air blast Circuit Breakers
iv. Sulphur hexafluoride (SF6) Circuit Breakers.
v. Vacuum Circuit Breakers
Bulk oil circuit breaker:-
Bulk oil circuit breakers are enclosed in metal-grounded waterproof tanks that are referred
to as dead tanks. The tank type circuit breakers had 3 separate tanks for 72.5 KV and
above (Fig. 12a). For 36 KV and below, single tank construction, phase barriers were
provided between phase.
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Figure 19 Schematic diagram of bulk oil circuit
breaker
The contact separation takes place in steel tanks filled with oil. The gases formed, due
to the heat of the arc, expand and set the turbulent flow in the oil. The arc was drawn
directly inside of the container tank without any additional arc extinguishing but the one
provided by the gas bubble surrounding the arc. Plain break breakers were superseded by
arc controlled oil breakers.
To assist arc extinction process, arc control devices were fitted to the contact assembly.
These were semi-enclosed chamber of dielectric materials.The purpose of the arc control
devices is to improve operating capacity, speed up the extinction of arc, and decrease
pressure on the tank. The performance of oil circuit breaker depended on the effectiveness