Summer Trainning report(SUBMITTED IN PARTIAL FULFILLMENT OF THE
COURSE OF B.TECH.)
UNDERTAKEN AT
DELHI TRANSCO LIMITED
220 kV SUB-STATION
VASANT KUNJ
CH. DEVILAL MEMORIAL ENGG.
COLLEGEPANNIWALAMOTA(SIRSA)(ESTABLISHED BY GOVT. OF HARYANA-2003)
SUBMITTED TO:
SUBMITTED BY:
DEPARTMENT OF ELECTRICAL ENGG. OMENDER SINGHCDLMEC PANNIWALAMOTA
2606328(SIRSA) EE, FINAL YEAR
tABLE OF cONTENT1. Certificate
2. Acknowledgement3. About DELHI TRANSCO LIMITED4. Electric
power transmission5. DTL 220 kV sub-station Vasant kunj6.
Sub-station single line diagram7. Transformer8. Circuit breaker9.
Current Transformer10. Capacitive Voltage Transformer11. Potential
Transformer
12. Power Line Communication Carrier13. Shunt Capacitor Bank
14. Reactor
15. Lightning Arrestor
16. 220 kV Equipments17. 66 kV Equipments
18. 11 kV Equipments
19. 400 kVA Local Transformer20. Battery and Battery Charger
21. Protection of Transformer22. Protection of Feeder
23. BibliographyCERTIFICATE
This is to certify that OMENDER SINGH student of Batch 2006
Electrical Engineering IIIrd Year; Ch.Devi Lal Memorial Engg.
College, Panniwala Mota (Sirsa) has successfully completed his
summer training at Delhi Transco Limited 220 kV Sub-Station C-9
Vasant Kunj New Delhi for six week from 10th July to 20th August
2009 He has completed the whole training as per the training report
submitted by him.
Assistant Manager
DTL C-9 Vasant Kunj New DelhiAcknowledgement
With profound respect and gratitude, I take the opportunity to
convey my thanks to complete the training here.
I am extremely grateful to all the technical staff of the 220 kV
Substation Vasant Kunj for their co-operation and guidance that
helped me a lot during the course of training. I have learnt a lot
working under them and I will always be indebted of them for this
value addition in me.
I would also like to thank the training incharge of Ch.Devi Lal
Memorial Engg. College, Panniwala Mota (Sirsa) and the entire
faculty members for their effort and constant co-operation which
has been a significant factor in the accomplishment of my summer
training.
About DELHI TRANSCO LIMITED1. Introduction: - Electricity plays
a vital role in our day-to-day life. It powers our houses,
industries, hospitals and in fact our entire economy. Historically
speaking the modern electricity industry utility system was first
introduced to the world on the opening of Thomas Edisons Pearl
Street Electricity Generating Station on September 4th , 1882 at
New York (United States of America). Insofar as Delhi is concerned,
the position is that as per available records, the first diesel
Power Station was established in Delhi in the year 1905 when a
private English Company by name M/s. John Fleming was given
permission to generate electricity under the provisions of the
Indian Electricity Act 1903. The above mentioned Company was given
the responsibility both of generation and distribution of power in
a limited manner. That Company after obtaining license under the
provisions of Electricity Act 1903 had set up a small 2 MW Diesel
set at Lahori Gate in Old Delhi. Later on, this very Company was
converted as Delhi Electricity Supply and Traction Company. In the
Year 1911, the power generation was augmented by Steam Generation
Station. In the year 1932, the management of Central Power House
was handed over to New Delhi Municipal Committee (NDMC). In the
field of power generation and distribution, a major break through
was achieved in 1939 when Delhi Central Electricity Power Authority
(DCEPA) was established. This Company was responsible for the
supply of power to the areas covered by Local Bodies, namely, the
Municipal Committees of Delhi, West Delhi and South Delhi, the
Notified Area Committees of Red fort, Civil Lines, Mehrauli, Najaf
Garh, amd the District Board of Delhi. The supply of electricity to
the Municipal Committees of Delhi-Shahdara and the Notified Area of
Narela was done by different private agencies. In 1947 DCEPA took
over a Private Limited Company by name Delhi electric Supply &
traction Company Limited.
2. Promulgation of Electricity (Supply)Act 1948:- In the year
1948, electricity (Supply) Act 1948 came into force, which
inter-alia provided for the constitution of an electricity Board in
the States that was to function as a vertically integrated
electricity utility in the entire State, undertaking all the
functions of activities related to electricity, which included
electricity generation, transmission, distribution, supply,
planning coordination and also was to act as regulatory authority
for carrying out other functions incidental and ancillary thereto.
In other words, the Electricity (Supply) Act 1948 was entitled to
become a monopolistic undertaking in the field of electricity
control by an instrument of the state and not by private sector.
The principal objective behind the above policy decision of the
Government of India in providing for the constitution of State
electricity to all, particularly in semi-urban and rural areas
because till then the availability of electricity was confined to
urban areas and was mainly served by private electricity
distribution licenses issued under the Indian electricity Act
1910.
3. Formation of Delhi State Electricity Board: - In pursuance of
the provisions of the Electricity (Supply) Act, 1948, in Delhi, in
the year 1951 the Delhi State Electricity Board (DSEB) came into
existence and the responsibility of generation and distribution of
electricity was taken over by DSEB from DCEPA. The entire staff of
DCEPA and other agencies was absorbed by DSEB under the existing
terms & conditions of service.
4. Notification of Industrial Policy Resolution:- In the year
1952 the Government of India notified the Industrial Policy
Resolution under the Industries Development and Regulation Act 1951
where under the electricity industry, which included all aspects of
generation, transmission, distribution, and supply of electricity,
came to be reserved for State sector. In other words, the private
sector was not entitled to commence any business of generation,
transmission, distribution, and (or) supply of electricity.
5. Formation of Delhi Electric Supply Undertaking by
promulgation of DMC Act 1957:- After the promulgation of the Delhi
Municipal Corporation Act 1957, the DSEB was dissolved and the
functions of DSEB were taken over by Delhi Electric Supply
Undertaking (DESU), which came into existence in 1958. After the
formation DESU, the generation and distribution of electricity to
all the areas of Delhi came under DESU and the employees of
erstwhile DSEB were also absorbed by DESU.
6. Constitution of Delhi Vidyut Board: - The Government of the
National Capital Territory of Delhi vide notification No. F.11
(10)/92-LSG /PF (II) dated 24.02.1997, issued under the Electricity
(Supply) Act, 1948, constituted a separate Electricity Board, i.e.
the Delhi Vidyut Board (DVB) for the NCT of Delhi w.e.f. 24.02.1997
for the purpose of generation and distribution of power to the
entire area of NCT of Delhi except the areas falling within the
jurisdiction of NDMC and Delhi Cantonment Board.
7. Practical difficulties in the working of Delhi Vidyut Board:-
The activities of Delhi Vidyut Board from its inception, and as a
matter of fact even prior thereto when the activities were being
undertaken by DESU, were not financially viable on account of
several factors affecting the electricity industry including the
high level of losses in the system and the revenues being not able
to meet the cost with result that like other State electricity
Boards, Delhi vidyut Board suffered operating deficit in aggregate
to the tune of Rs.2,386.72 crore during the period from 1995-96 to
2000-01. In addition the Delhi Vidyut Board was required to make
adequate provision for bad and doubtful debts. The cumulative
effect of all these factors was that the Delhi Vidyut Board was not
in a position to meet its financial obligations and commitments
including the payment for power purchased from generation companies
and suppliers, such NTPC Limited, Nuclear Power Corporation
Limited, national Hydroelectric Corporation Limited, etc., etc.
8. Unbundling of Delhi Vidyut Board in six entities: - In the
recent for alleviating the concerns of consumers in the power
sector, some reforms started gaining momentum. In that very
direction with a view to safeguard the overall interests of the
consumers GNCTD took some policy initiatives as as a result of
which DVB was split into six Companies, viz., BSES Rajdhani Power
Limited, BSES Yamuna Power Limited, North Delhi Power Limited,
Delhi Transco Limited, Indraprastha Power Generation Company
Limited, and Delhi Power Company Limited, as per the provisions
contained in Delhi electricity reform Act 2000 read with Delhi
Electricity Reform (Transfer Scheme) Rules 2001.9. Growth in demand
of electricity:- Thus, starting the humble origin, i.e., Private
Limited Company having a few employees with primitive generation
process, the generation, transmission, and distribution of power to
the citizens of Delhi has now come in the hands of above mentioned
six Companies with an employee strength which has grown over the
years from a meager figure of few hundred to about 20,000. Prior to
1951, the demand of power in Delhi was about 27 MW which now has
grown to about 4,000 MW. Availability of reliable and cheap power
is absolutely essential for economic development of any developing
society and consumption of electricity is an important indicator of
the stage of development of agriculture, industry and commerce.
With the growth of population, industries, importance of Delhi
being the national Capital and with the advancement of technology,
life style and increased use of new electrical & electronic
gadgets, the demand of power has gone up enormously.
10. Present Scenario: - The role of Delhi Transco Limited is
confined to arrange and provide transmission network of 400 KV and
220 KV source from Northern Grig. The present infrastructure for
this purpose under 400 KV system is 4,725 MVA (2520 MVA with DTL
and 2205 with Power Grid Corporation). As against this, 220 KV sub
Stations have the capacity of 6,300 MVA is available for Delhi.
11. Future Plans :- In the 11th Plan ending 2011-12 the
transmission capacity is proposed to be augmented to meet the
future requirements. Under 400 KV system, it is proposed to
establish new Sub Stations at Mundka, South-East Delhi near Mandi
village and East Loni Road with a capacity of 630 MVA each by DTL
and also increase the capacity of existing sub-Station at Maharani
Bagh by 630 MVA b Power Grid Corporation of India Limited.
Similarly, under 220 KV system, augmentation and new addition in
capacity to the tune of 1660 MVA under the existing Sub Stations is
proposed. Further, new Sub Station at DSIDC Bawana-II (320MVA),
Chandrawal (200 MVA), Jhatikara More (320 MVA),. Ridge Valley (320
MVA), Rohini-II (480 MVA), Sultanpuri (320 MVA), Electric lane (200
MVA), Trauma Centre (200 MVA), Wazirpur Industrial Area (320 MVA)
and IGI Airport (320 MVA ) are proposed to be established. Thus,
the capacity of 2520 MVA and 5940 MVA will be added in the 400 KV
system and 220 KV system, respectively.
Electric Power TransmissionElectric power transmission is the
bulk transfer of electrical power (or more correctly energy), a
process in the delivery of electricity to consumers. A power
transmission network typically connects power plants to multiple
substations near a populated area. The wiring from substations to
customers is referred to as Electricity distribution, following the
historic business model separating the wholesale electricity
transmission business from distributors who deliver the electricity
to the homes.[1] Electric power transmission allows distant energy
sources (such as hydroelectric power plants) to be connected to
consumers in population centers, and may allow exploitation of
low-grade fuel resources such as coal that would otherwise be too
costly to transport to generating facilities.
Usually transmission lines use three phase alternating current
(AC). Single phase AC current is sometimes used in a railway
electrification system. High-voltage direct current systems are
used for long distance transmission, or some undersea cables, or
for connecting two different ac networks.
Electricity is transmitted at high voltages (110 kV or above) to
reduce the energy lost in transmission. Power is usually
transmitted as alternating current through overhead power lines.
Underground power transmission is used only in densely populated
areas because of its higher cost of installation and maintenance
when compared with overhead wires, and the difficulty of voltage
control on long cables.
Overhead conductors are not covered by insulation. The conductor
material is nearly always an aluminum alloy, made into several
strands and possibly reinforced with steel strands. Copper was
sometimes used for overhead transmission but aluminum is lower in
weight for equivalent performance, and much lower in cost. Overhead
conductors are a commodity supplied by several companies worldwide.
Improved conductor material and shapes are regularly used to allow
increased capacity and modernize transmission circuits. Thicker
wires would lead to a relatively small increase in capacity due to
the skin effect that causes most of the current to flow close to
the surface of the wire.
Today, transmission-level voltages are usually considered to be
220 kV and above. Lower voltages such as 66 kV and 33 kV are
usually considered sub-transmission voltages but are occasionally
used on long lines with light loads. Voltages less than 33 kV are
usually used for distribution. Voltages above 230 kV are considered
extra high voltage and require different designs compared to
equipment used at lower voltages.
DTL 220 kV Sub-Station
Vasant Kunj1. Vasant Kunj Sub-station receives electrical supply
from the Mehrauli 220 kV grid by two 220 kV three phase lines2. The
voltage is stepped down from 220 kV to 66 kV by 100 MVA
Transformer.The 66 kV transmission lines are for the following
circuits(C-Block Vasant Kunj Ckt I
(C-Block Vasant Kunj Ckt II
(D-Block Vasant Kunj Ckt I
(D-Block Vasant Kunj Ckt II
(Palam
(Ridge Valley Ckt I(Ridge Valley Ckt II
3. The voltage is further stepped down from 66 kV to 11 kV by 20
MVA Transformer.
The 11 kV transmission lines are for the following circuits
(Vasant Kunj C-8 s/s-1
(Vasant Kunj C-9 s/s-5
(Rang Puri
(IAAI Colony
(Vasant Kunj C-9 s/s-2
(Spinal Injury Hospital
(AV Hotel
(Vasant Kunj C-9 s/s-9 feeder 2(MahipalpurComponents of a
Substation
1. Power transformer
2. Circuit Breaker
3. Current Transformer
4. Isolator w/o earth
5. Isolator with earth
6. Capacitive Voltage Transformer
7. Potential Transformer
8. Power Line Communication Carrier9. Neutral Current
Transformer
10. Shunt Capacitor Bank11. Reactor
12. Lightning Assrestor
TransformerA transformer is a device that transfers electrical
energy from one circuit to another through inductively coupled
conductors the transformer's coils. Except for air-core
transformers, the conductors are commonly wound around a single
iron-rich core, or around separate but magnetically-coupled cores.
A varying current in the first or "primary" winding creates a
varying magnetic field in the core (or cores) of the transformer.
This varying magnetic field induces a varying electromotive force
(EMF) or "voltage" in the "secondary" winding. This effect is
called mutual induction.
If a load is connected to the secondary, an electric current
will flow in the secondary winding and electrical energy will flow
from the primary circuit through the transformer to the load. In an
ideal transformer, the induced voltage in the secondary winding
(VS) is in proportion to the primary voltage (VP), and is given by
the ratio of the number of turns in the secondary to the number of
turns in the primary as follows:
By appropriate selection of the ratio of turns, a transformer
thus allows an alternating current (AC) voltage to be "stepped up"
by making NS greater than NP, or "stepped down" by making NS less
than NP.
Losses in a Transformer
Winding resistance
Current flowing through the windings causes resistive heating of
the conductors. At higher frequencies, skin effect and proximity
effect create additional winding resistance and losses. Hysteresis
losses
Each time the magnetic field is reversed, a small amount of
energy is lost due to hysteresis within the core. For a given core
material, the loss is proportional to the frequency, and is a
function of the peak flux density to which it is subjected. Eddy
currents
Ferromagnetic materials are also good conductors, and a solid
core made from such a material also constitutes a single
short-circuited turn throughout its entire length. Eddy currents
therefore circulate within the core in a plane normal to the flux,
and are responsible for resistive heating of the core material. The
eddy current loss is a complex function of the square of supply
frequency and inverse square of the material
thickness.Magnetostriction
Magnetic flux in a ferromagnetic material, such as the core,
causes it to physically expand and contract slightly with each
cycle of the magnetic field, an effect known as magnetostriction.
This produces the buzzing sound commonly associated with
transformers, and in turn causes losses due to frictional heating
in susceptible cores. Mechanical losses
In addition to magnetostriction, the alternating magnetic field
causes fluctuating electromagnetic forces between the primary and
secondary windings. These incite vibrations within nearby
metalwork, adding to the buzzing noise, and consuming a small
amount of power. Stray losses
Leakage inductance is by itself lossless, since energy supplied
to its magnetic fields is returned to the supply with the next
half-cycle. However, any leakage flux that intercepts nearby
conductive materials such as the transformer's support structure
will give rise to eddy currents and be converted to heat.[30]
Components of a TransformerTerminal Bushings - The bushing is a
hollow insulator, allowing a conductor to pass along its centre and
connect at both ends to other equipment. Bushings are often made of
wet-process fired porcelain, and may be coated with a
semi-conducting glaze to assist in equalizing the electrical stress
along the length of the bushing. The inside of the bushing may
contain paper insulation and the bushing is often filled with oil
to provide additional insulation. Bushings for medium-voltage and
low-voltage apparatus may be made of resins reinforced with
paper.Buchholz Relay - A Buchholz relay, also called a gas relay or
a sudden pressure relay, is a safety device mounted on some
oil-filled power transformers and reactors, equipped with an
external overhead oil reservoir called a conservator. The Buchholz
Relay is used as a protective device sensitive to the effects of
dielectric failure inside the equipment. The relay has two
different detection modes. On a slow accumulation of gas, due
perhaps to slight overload, gas produced by decomposition of
insulating oil accumulates in the top of the relay and forces the
oil level down. A float operated switch in the relay is used to
initiate an alarm signal. If an arc forms, gas accumulation is
rapid, and oil flows rapidly into the conservator. This flow of oil
operates a switch attached to a vane located in the path of the
moving oil. This switch normally will operate a circuit breaker to
isolate the apparatus before the fault causes additional damage.
Buchholz relays have a test port to allow the accumulated gas to be
withdrawn for testing. Flammable gas found in the relay indicates
some internal fault such as overheating or arcing, whereas air
found in the relay may only indicate low oil level or a leak.
Conservator It is cylindrical tank connected to the main shell
of the transformer. When transformer oil expands due to the heat
generated in the windings, the oil travels to the conservator tank
via Buchholz Relay into the conservator tank. When oil cools down,
it travels back to the main shell from the conservator
tank.Breather The breather is connected to the conservator tank. It
consists of a small cylindrical chamber filled with silica gel.
When the oil expands, oil rushes to the conservator tank thus air
is expelled out of it via the breather. When oil cools down, it
travels back to the tank creating vacuum in the tank and sucking in
air from the atmosphere. The air sucked in passes through the
silica gel which absorbs the moisture from the air, hence air
entering the tank is devoid of any moisture which is essential in
maintaining the quality and insulation level of the oil.
Transformer Breathers eliminate oil thickening and deteriorating
when air space above it expands and contracts with climatic
variations.Marshalling Box It a box placed next to the transformer
which displays real time winding and oil temperature. It raises
alarm and also issues tripping if the temperature rises beyond safe
limits.Circuit BreakerA circuit breaker is an
automatically-operated electrical switch designed to protect an
electrical circuit from damage caused by overload or short circuit.
Its basic function is to detect a fault condition and, by
interrupting continuity, to immediately discontinue electrical
flow.
The most common insulating fluids used are :-1. Air at
Atmospheric Pressure
2. Compressed Air
3. Oil which produces hydrogen for Arc extinction
4. Ultra-high Vaccum
5. Sulphur hexafluoride gas
Arc interruptionMechanical low-voltage circuit breakers use air
alone to extinguish the arc. Larger ratings will have metal plates
or non-metallic arc chutes to divide and cool the arc. Magnetic
blowout coils deflect the arc into the arc chute. In larger
ratings, oil circuit breakers rely upon vaporization of some of the
oil to blast a jet of oil through the arc. [2]Gas (usually sulfur
hexafluoride) circuit breakers sometimes stretch the arc using a
magnetic field, and then rely upon the dielectric strength of the
sulfur hexafluoride (SF6) to quench the stretched arc. Vacuum
circuit breakers have minimal arcing (as there is nothing to ionize
other than the contact material), so the arc quenches when it is
stretched a very small amount (