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PREFACE
The Damodar Valley Corporation, popularly known as DVC, is the
first multipurpose river valley project of independent India. Among
the many divisions working under DVC we visited the following:
1. P.R.O. (PUBLIC RELATION OFFICER,DVC,MAITHON)
2. C.L.D. (CENTRAL LOAD DISPATCH,DVC,MAITHON)
3. CE(T.S.C), DVC, MAITHON
4. TRANSMISSION,DVC,MAITHON
We have been especially indebted to all DVC staff for their
valuable advice and time to time suggestions for drafting this
report of vocational training, otherwise it would not have been
possible.
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CONTENTS
SERIAL NO. TOPICS
1 ACKNOWLEDGEMENT
2 PREFACE
3 ABOUT DVC
4 CENTRAL LOAD DISPATCH
5 TSC
6 TRANSMISSION
7 CONCLUSION
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INTRODUCTION Damodar Valley Corporation(DVC)is the first multipurpose river valley of
independent India.
Since begning,DVC has given due emphasis on power generation and distribution,besides flood controll and irrigation,eco-conservation and socio-
economic devlopment.
Total DVC power is a vital input to the core sectors including steel
plants,railways,collieries alongwith State Electricity Boards of Jharkhand and West Bengal, big and medium industries within and beyond the Damodar Valley.
BRIEF HISTORY:
DVC, a legacy to the people of India, emerged as a culmination of attempts made
over a whole century to control the wild and erratic Damodar river. The river spans over an area of 25,000 km2 covering the states of Bihar (now Jharkhand) & West Bengal.
The Damodar Valley has been ravaged frequently by floods of varying intensities and the first of the major recorded flood dates back to 1730. Thereafter serious
floods occurred at regular intervals, but it was the flood of 1943 that left the worst devastation in its wake. As a result, the Governor of Bengal appointed a Board of Inquiry headed by the Maharaja of Burdwan and the noted physicist Dr. Meghnad
Saha as member. In their report, the Board suggested creation of an authority similar to the Tennessee Valley Authority (TVA) of United States of America. The
Government of India then appointed Mr. W.L. Voorduin, a senior engineer of the TVA to make recommendations for comprehensive development of the valley.
Accordingly, in August, 1944, Mr. Voorduin submitted his "Preliminary Memorandum on the Unified Development of the Damodar River".
Mr. Voorduin’s "Preliminary Memorandum" suggested a multipurpose
development plan designed for achieving flood control, irrigation, power generation and navigation in the Damodar Valley. Four consultants appointed by
the Government of India examined it. They also approved the main technical
4
features of Voorduin’s scheme and recommended early initiation of construction beginning with Tilaiya to be followed by Maithon.
By April 1947, full agreement was practically reached between the three Governments of Central, Bengal and Bihar on the implementation of the scheme
and in March 1948, the Damodar Valley Corporation Act (Act No. XIV of 1948) was passed by the Central Legislature, requiring the three governments – the Central Government and the State Governments of West Bengal and Bihar (now
Jharkhand) to participate jointly for the purpose of building the Damodar Valley Corporation.
The Corporation came into existence on 7 July 1948 as the first multipurpose river valley project of independent India.
INTRODUCTION
Indian Power Industry
Pre- Independence :-
Prior to independence, the power sector was completely controlled by the British
.The policies and the legal system then gave more significance to private
ownership and much regard was not given to operational safety .
Post – Independence :-
After Independence the country suffered from capacity constraints. Adopting a
socialistic pattern for economic growth, India had nationalized most of the energy
companies by 1970’s and these industries were regulated by the public sector. The
decline in public finance coupled with the balance of payment crisis forced the
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government to adopt a policy of liberalization during the 1990’s and thus allow
greater private investment. All these efforts led to an increase in the installed
capacity in the power sector from 1300 MW to 90,000 MW. The government has
taken a lot of steps to boost the power sector, as it has a direct influence on the
employment and the economic development of a country.
The above mentioned facts emphasize on the state of power sector in India .The
project gives an insight into Damodar Valley Corporation , which was the first
multipurpose river valley project of independent India , the regulatory aspects of
DVC as well as the working capital management in DVC . Of late, there has been a
paradigm shift in the regulation and operation of DVC caused due to increased
globalization and competition.
SIGNIFICANCE OF POWER SECTOR IN INDIA
The power sector in India has an installed capacity of 211.766 GW as of January
2013, which is the fifth largest in the world. The power plants generate an
additional 31.5 GW. Non Renewable Power Plants constitute 87.55% of the
installed capacity and 11.45% of Renewable Capacity. India generated a total 855
BU (855 000 MU i.e. 855 TWH) electricity during the financial year 2011-12. In
terms of fuel, power plants using coal account for 57% of India's installed
electricity capacity, compared to South Africa's 92%; China's 77%; and Australia's
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76%. Renewal hydropower accounts for 19%, renewable energy for 12% and
natural gas for about 9%.
The per capita average annual domestic electricity consumption in India in 2009
was 96 kWh in rural areas and 288 kWh in urban areas for those with access to
electricity, in contrast to the worldwide per capita annual average of 2600 KWH
and 6200 KWH in the European Union. India's total domestic, agricultural and
industrial per capita energy consumption estimates vary depending on the source.
In a developing country like India, the power sector is crucial for the overall
development of the economy. The various reasons are enlisted below:-
Major PSUs are involved in heavy and basic industries which require a huge
capital and have a long gestation period. Such industries form the backbone
of the country and help in the overall development of the country.
These industries have huge amount of resources and support and help from
the government.
The changes in the economic and the technological environment have
challenged the performance and the profitability of these power sector
companies which also face tough competition from the private sector.
COMPANY PROFILE
Damodar Valley Corporation was born as a culmination of attempts made over a
whole century to control the wide and the erratic river Damodar and use its vast
resources towards development activities in the river valley basin that lay across
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West Bengal and Jharkhand (then Bihar). This river which covered a total distance
of 290 km was earlier described as the ‘Sorrow of Bengal’ for causing untold
miseries through devastating floods – a regular and common feature in monsoons
.To arrest the fury of this river , a ten member committee led by Dr . Meghnad
Saha, the noted Physicist and the Maharaja of Burdwan. This was followed by the
adoption of the Tennessee Valley Authority model of USA and induction of Mr.
W. L. Voorduin, who submitted the ‘Preliminary Memorandum’. Based on these
recommendations, DVC came into existence on July 7, 1948 by an act of
Constituent Assembly as the first multipurpose river valley project of independent
India.
DVC was set up with the intent of promoting and operating the schemes which
would cause social and economic uplift in the valley region. DVC has its
command area of approximately 24,235 square km spreading across the Damodar
basin which covers the states of West Bengal and Jharkhand. DVC has already
established its existence in discharging its obligations in perfect harmony for more
than five decades. The effective and proficient management of water resources
through dams, canals and barrages by the Corporation has turned the devastating
river Deodar from being a ‘River of Sorrow’ to a ‘River of Prospects and
Opportunities’. Apart from this, DVC also facilitated irrigation as well as domestic
and industrial water supply which benefitted the region at large. It also contributed
significantly in soil conservation and promotion of other social integration schemes
in the valley region.
DVC has been generating, transmitting and distributing electrical energy since
1953 and has succeeded in meeting the expectations of its consumers and also
elevated its level of performance to a great height. As mentioned earlier, DVC
was set up with the preliminary motives of flood control, irrigation and water
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supply. With the passage of time and meeting the requirements of development,
power generation dominated over the other motives in DVC.
DVC has become a successful power manufacturer in the eastern region which
also provides power to consumers like Steel Plants, Railways, State Electricity
Boards of Jharkhand and West Bengal as well as big and medium industries in and
around the Damodar region. As of now , DVC has a total installed capacity of
2796.5 MW which is distributed across 5 thermal power stations with a total
installed capacity of 2570 MW, 3 hydel power stations with a total installed
capacity of 144 MW and one gas turbine station with a capacity of 82.5 MW .
These five dams also irrigate 5.69 lakhs hectares of land and have a flood reserve
capacity of 1292 million cubic meters.
Pandit Jawaharlal Nehru , the then Prime Minister of India , Dr. B.C.Roy , the then
Chief Minister of West Bengal and Sri Krishna Sinha, the then Chief Minister of
Bihar , took personal interest for the implementation and early success of the
project.
MISSION
Damodar Valley Corporation, the first major multipurpose integrated river valley
project of the country , designed in the line of Tennessee Valley Authority ( TVA )
, came into existence on July 7th , 1948 by an act of the Constituent Assembly. The
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assigned mission of the Damodar Valley Corporation under Section 12 of the DVC
Act, 1948:
Flood control
Promotion and operation of schemes for irrigation
Water supply for industrial and domestic use
Navigation and drainage
Generation , transmission and distribution of electrical energy
Promotion of a forestation and control of soil erosion in the valley area
Promotion of public health, agriculture, industrial, economic and general
well – being in the valley region.
In keeping with industrialization in the DVC command area, power generation,
distribution and transmission gained priority for providing electricity to the
core industries like steel, coal, railways and State Electricity Boards. However,
other mandated objectives also received equal importance as part of overall
responsibility and commitment of DVC.
VISION
To foster integrated development of Damodar Valley Command Area and achieve
par excellence in its multifaceted activities of control of floods, provision of
irrigation, generation, transmission and distribution of electrical energy and also
soil conservation, unified tourism, fisheries, socio-economic & health development
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The need to view development.
EVOLUTION
DVC, a legacy to the people of India, emerged as a culmination of attempts made
over a whole century to control the wild and erratic Damodar river. The river spans
over an area of 25,000 sq. kms covering the states of Bihar (now Jharkhand) &
West Bengal.
The Damodar Valley has been ravaged frequently by floods of varying intensities
and the first of the major recorded flood dates back to 1730. Thereafter serious
floods occurred at regular intervals, but it was the flood of 1943 that left the worst
devastation in its wake. As a result, the Governor of Bengal appointed a Board of
Inquiry headed by the Maharaja of Burdwan and the noted physicist Dr. Meghnad
Saha as member. In their report, the Board suggested creation of an authority
similar to the Tennessee Valley Authority (TVA) of United States of America.
The Government of India then appointed Mr. W.L. Voorduin, a senior engineer of
the TVA to make recommendations for comprehensive development of the valley.
Accordingly, in August, 1944, Mr. Voorduin submitted his "Preliminary
of villages within a radius of 10 KM of its projects.
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Memorandum on the Unified Development of the Damodar River".
Mr. Voorduin’s "Preliminary Memorandum" suggested a multipurpose
development plan designed for achieving flood control, irrigation, power
generation and navigation in the Damodar Valley. Four consultants appointed by
the Government of India examined it. They also approved the main technical
features of Voorduin’s scheme and recommended early initiation of construction
beginning with Tilaiya to be followed by Maithon.
By April 1947, full agreement was practically reached between the three
Governments of Central, Bengal and Bihar on the implementation of the scheme
and in March 1948, the Damodar Valley Corporation Act (Act No. XIV of 1948)
was passed by the Central Legislature, requiring the three governments – the
Central Government and the State Governments of West Bengal and Bihar (now
Jharkhand) to participate jointly for the purpose of building the Damodar Valley
Corporation.
The Corporation came into existence on 7th July, 1948 as the first multipurpose
river valley project of independent India.
Act No. XIV Of 1948:-
(The Act received the assent of the Governor General on the 27th of March, 1948)
An Act to provide for the establishment and regulation of a Corporation for the
development of the Damodar Valley in the provinces of Bihar and West Bengal.
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Whereas it is expedient to provide for the establishment and regulation of a
Corporation for the development of the Damodar Valley in the provinces of Bihar
and West Bengal.
CORPORATE OBJECTIVES
To realize DVC’s Mission, the following corporate objectives have been identified for persuasion:
Generate maximum on sustainable basis through implementation of best
O&M practices.
Rejuvenate old generating units through refurbishment / replacement /
comprehensive overhauling programme.
Capacity augmentation through extension and green field projects.
Strengthening of the existing transmission and distribution network and
augmentation to match with the capacity addition.
Transmit, distribute and supply reliable and quality power at competitive
tariff.
Improve the financial health of the Corporation by adoption of efficient
industrial, commercial and human resource management practices.
Ensure optimum utilization of available water resources through effective
and efficient management and harnessing the remaining potential of
Damodar basin.
Adopt measures for pollution abatement of Damodar River.
Ensure environmental protection at plant level.
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Strengthen activities of eco-conservation in the valley area & to make
Damodar valley more Green.
Unified socio-economic development for the inhabitants of villages
neighboring major projects of DVC.
To pursue with development of tourism at Maithon, Panchet, Tilaiya and
Hazaribagh.
Revival of Fish Farming in DVC reservoirs.
Skill development training to local youth around DVC Projects to improve
their employability & upgrading infrastructural facilities at existing Industrial
Training Institute (ITI) at Purulia, Durgapur & Chhatna in West Bengal &
Chas and Hazaribagh in Jharkhand and also setting up of the Jharkhand Govt.
proposed new ITI at Kodarma as well as new ITI at existing Chandrapura
Training Institute of DVC.
Landmarks Achieved:-
DVC is the first multipurpose river valley project taken up by the Govt. of
India.
DVC, the only GOI organization generating power through three sources-
coal, water and liquid fuel.
India’s first underground hydel station set up at Maithon.
Bokaro TPS, the nation’s biggest thermal power plant in the 50s of the last
century
BTPS boilers, first to burn untapped low-grade coal in pulverized fuel
furnaces.
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The first re-heat units in India, utilizing high steam parameter at
Chandrapura TPS.
Mejia, first of its kind in Eastern India with tube mills in service for zero
reject. Direct ignition of pulverized coal (DIPC) system for reducing oil
consumption in the boiler conceived for the first time in Eastern India at
Mejia TPS.
DVC INFRASTRUCTURE
The initial objectives of DVC included flood control , irrigation , generation ,
transmission and distribution of energy, eco – conservation and forestation as well
as creating jobs for the socio- economic well being of the people living in the
Damodar valley . However over the past few decades, power generation has gained
priority while the other objectives still remain a part of its primary responsibility.
DVC has created irrigation potential of 3640 sq km.
The first dam was built at Tilaiya in 1953 across the Barakar
river which is a tributary of the Damodar River.
The second dam was built at Konar in 1955.
The third dam was constructed at Maithon in 1957 across the
river Barakar and another dam was built in Panchet in 1959
across the Damodar River.
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Both the dams are some 8 km upstream of the confluence point of the Rivers.
These four major dams are controlled by DVC. Durgapur barrage was constructed
in 1955 across the Damodar River with canals and distributaries on the either side.
In 1978, the Government of Bihar constructed the Tenughat dam across the
Damodar River, which was outside the control of DVC.
DVC proposes to construct a dam across the Barakar River at Bel Pahari in the
state of Jharkhand. There are three hydro – electric power stations at Tilaiya,
Maithon and Panchet with a total installed capacity of 144 MW. The one at
Maithon was India’s first underground hydro-electric power station.
DVC has five thermal power stations at Bokaro, Chandrapura, Durgapur, Mejia
and Andal with a total capacity of 2570 mw. The power station at Bokaro was the
biggest in the country when it was built in the fifties.
DVC is expanding its thermal power capacity and aims to generate 11000 MW of
power by 2015 .The upcoming projects include Raghunathpur Thermal Power
Station, Kodarma Thermal Power Station, and Maithon RB Thermal Power
Station.
The upper valley consists of the district of Hazaribagh, Kodarma, Giridih, Chatra,
Dhanbad and Bokaro and some stations of Plamu, Ranchi, Lohardaga and Dumka
district in the state of Jharkhand. The lower valley consists of the two districts of
Burdwan and Hoogly and some areas of Howrah, Bankura and Puruliya districts in
the state of West Bengal.
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DVC is planning a new capacity addition to the tune of 2780 mw during the five –
year plans which involves a total capital expenditure of Rs. 16,667crores. The
Corporation also reviewed the preliminary project report of Kalahari dam on the
river Barakar. Stage -1 of this project is estimated to cost Rs. 440 crores.
LOCATION
The total valley area covered by DVC is arround 24,235 sq. kms. Upper valley
covers six districts fully i.e. Hazaribagh,Koderma,Giridih,Chatra,Dhanbad,Bokaro
and other four districts partially i.e.Palamau,Ranchi,Lohardaga and Dumka in the
state of Jharkhand.Lower valley falls into two districts fully i.e.Burdwan,Hoogly
and three districts partially i.e. Howrah,Bankura,Purulia in the state of West
Bengal.
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Power Generation
Entrusted with the responsibilities of providing the vital input power for
industrial growth in the resource rich Damodar Valley region, DVC has
been practically operating as a pioneer, using latest available
technologies to supply bulk power at reasonable rates to the major industries.
DVC has maintained its lead role in the eastern region by adopting
itself to the challenges of time and technology during the course of last
59 years. DVC has been generating and transmitting power since 1953
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and has succeeded not only in meeting the needs of consumers but
has also helped to increase the demand of power which itself is an index of development.
Joint Venture Project
MAITHON POWER LIMITED a joint venture company by DVC and
Tata Power has been formed to implement 1000 MW Maithon Right
Bank Thermal Power Project for meeting the energy needs of power
deficient regions on export basis.
BOKARO POWER SUPPLY CO LTD (BPSCL) a joint venture company
of DVC and SAIL has been established to operate and maintain the
captive power and steam generation plant, hived off by SAIL and its
Bokaro Steel Plant and supply power and steam exclusively to Bokaro
Steel Ltd.
DVC EMTA COAL MINES LTD, a joint venture company formed with
Eastern Minerals & Trading Agency for development and operation of
Captive Coal Mine Blocks and supply of coal exclusively to DVC Thermal Power Projects of 10th and 11th plan.
WATER MANAGEMENT
Major Dams and Barrage Tilaiya, Konar, Maithon Panchet dams and Durgapur Barrage
Irrigation Command Area (gross) 5.69 lakh hectares
Irrigation Potential Created 3.64 lakh hectares
Flood Reserve Capacity 1292 million Cu.m.
Canals 2494 kms
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Dams
Subject Tilaiya Konar Maithon Panchet
Inauguration 21.02.53 15.10.55 27.09.57 06.12.59
On River Barakar Konar Barakar Damodar
District Hazaribagh Hazaribagh Dhanbad Dhanbad
State Jharkhand Jharkhand Jharkhand/ W. Bengal
Jharkhand/ W.Bengal
Height above river bed (meters) 30.18 48.77 50.00* 40.84*
44.00** 45.00**
Length (meters) 366 4535 4860 6777
Width of roadway (meters) 3.81 5.79 6.78 10.67
Power generating capacity 2 x 2 MW - 3 x 20 MW 2 x 40 MW
Storage capacity (million cu.m.)
To dead storage 75.25 60.4 207.24 170.37
To top of gates 394.74 336.76 1361.84 1497.54
Allocation of storage capacities (MCM)
For irrigation & power 141.86 220.81 611.84 228.21
For flood control 177.63 55.51 542.76 1086.76
Drainage area (sq. km.) 984.2 997.1 6293.17 10966.1
Reservoir (sq. km.)
At dead storage level 15.38 7.49 24.28 27.92
At maximum conservation pool 38.45 23.15 71.35 121.81
Area top of gates 74.46 27.92 107.16 153.38
*Earthen Dam **Concrete Dam
Durgapur Barrage
Year of construction 1955
Length 692 m
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Number of gates 34 (including under sluice)
Size of gates 18.3m x 4.9m [60 ft x 16 ft]
Left & right under sluice 18.3m x 5.5 m [60 ft x 18 ft]
Operating levels Between RL. 64.5 m [211.5 ft] to RL. 63.4 m
[208.0 ft]
Details of Canal Network.
Length
(Km)
Discharge at Head
Regulator (Cumec)
LBMC (Left Bank Main Canal)(Canal
originating from Durgapur Barrage) 136.8 260
RBMC (Right Bank Main Canal) (Canal
originating from Durgapur Barrage) 88.5 64.3
Total length of main and branch canals 2494
Water for Irrigation
Water from DVC dams is regulated by the Durgapur barrage through the existing network of 2494 kms of canals. This has created irrigation potential for 3.64 lakh
hectares of land annually.
3.42,000 hectares of Kharif Crop, 22,000 hectares of rabi crop and 30,000 hectares of boro crop are irrigated annually in the districts of Barddhaman, Hooghly,
Bankura and Howrah in the state of West Bengal.
About 30,000 hectares of land in the upper valley is irrigated annually by lift-
irrigation with water available from over 16,000 check dams constructed by DVC.
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Industrial and Civic water provisions
About 625 cusec of water is released every year to meet the demand of approximately 150 industries, civic bodies and railways in Jharkhand and West
Bengal.
11 1.5 SOCIAL SECTOR DEVELOPMENT Damodar Valley Corporation has initiated a number of new activities to further the process of development.
INTEGRATED DEVELOPMENT AND UTILIZATION OF DVC WATER
RESOURCES:
WAPCOS has been entrusted with preparation of a Master Plan of integrated
development and utilization of Damodar Valley water resource and unified operation and
control of all reservoirs, including Tenughat Dam for effective and optimum utilization of
the available water resources and harness untapped potential including surface water flow
during Monsoon season. CWC has been entrusted with preparation of detailed project
report for the proposed Balpahari Dam Project on Barakar river between Maithan and
Tilaiya, on first track basis. AFFORESTATION AND SOIL CONSERVATION :
Damodar Valley mission has been constituted under the chairmanship of Chief Secretary,
Government of Jharkhand with members from the participating Governments. A Master
Plan for eco-conservation and Green Development in valley area prepared by engaging
FRI, Dehradun. Discussions are on, with participating Government. NEERI, Nagpur is
working out action plan for pollution abatement in Damodar river system.
‘DVC FOUNDATION ’ FOR SOCIAL SECTOR DEVELOPMENT:
22
The foundation seeks to design, manage, implement the social integration program (SIP)
of DVC. IIT Kharagpur has been entrusted with preparation of a Master Plan for socio -
economic development of the inhibitants in the valley area.
DEVELOPMENT OF TOURISM:
To tap the bright prospect and opportunity, DVC has signed a MOU with IL &FS IDC to
venture into “development of Tourism”(so far untapped) jointly, as commercial activity. Accrued economic benefits (direct and indirect) will aid the social-economic
development of the region.
REVIVAL OF FISH FARMING IN RESERVOIR:
To provide protein food to the project people and rehabilitate the displaced villagers
affected due to impoundment of their villages. Serious efforts are in to revive fish
farming. The combined area of the four major reservoirs, which is about 25,000 hectares
is a huge potential resource to be put under organized pisciculture program.
Based on the recommendation of CIFRI, DVC needs to take some advance actions for
setting up a base of organized fishery in the reservoirs. DVC has prepared a reservoir
fishery project as per the guidelines set by National Fishery Development Board (NFDB),
Hyderabad and approached for founding the project. NFDB has already granted Rs.10.1 crores for utilization within five years.
23
1.6 OTHER INFORMATIONS JOINT VENTURE PROJECTS:
Maithon Power Ltd. : With Tata Power Ltd. at Madandih, Maithon 1050 MW
Mega Thermal Project under construction.
Bokaro Power Supply Corporation Ltd. :- With Bokaro Steel Ltd. at Bokaro
50 MW thermal plant already in operation.
ONCOMING PROJECTS:
1. Raghunathpur Thermal Power Project at Raghunathpur,
Purulia (W.B.)
2×660 MW under
construction
2. Durgapur Steel Thermal Power Project at Andal
(W.B.)
1000 MW under
construction
3. Koderma Thermal Power project at Banjhidih,
Koderma (Jharkhand)
2×600 MW under
construction
EXPANSION OF EXISTING PLANTS:
More units of 250 MW each in CPTS, Chandrapura (Jharkhand)
More units of 250 MW each as well as 2 Nos. 500 MW capacity ( Stage-II) is
being demarcated MTPS, Mejia (W.B.) as export oriented.
Modernization of old bokaro „A‟ plant with 500 MW capacity has been taken up.
DVC is committed to add 8500 MW more generation capacity in its system within this
11th 5 year plan.
POWER GENERATION MAP OF DVC :
24
SALE OF POWER :
DVC supplies bulk power at 25 kv (for railway), 33 kv, 132kv and 220 kv at different locations to
industries and distributing licensees. Among these industries figure some core sector industries
like Railway, Steel. Coal etc, which form integral parts of our national economy.
SALE OF WATER :
DVC supplies raw water for industrial and domestic purposes. Water tariff charged
for municipality water supply(domestic purpose) is Rs 1.15 per KL . water tariff
charged for industrial consumer is as follows (with effective from 01.10.2012)
(In Rs/KL)
Source of Drawal
Tier-1 Tier-2 Tier-2 Tier-4
(Up to 5 MGD) (5+ to 10
MGD) (10+ to 20
MGD) (Above 20
MGD)
Reservoir/River 5.4 5.5 5.6 5.7
Canal/pond 5.95 6.05 6.15 6.25
MGD = Million Gallon Per Day.
25
Power tranmission :
Transmission
DVC had a humble beginning: a small generating unit with a few connected lines. Today it has a vast network of transmission lines and substations spread across the states of Jharkhand and West Bengal, extending beyond its command area up to Jamshedpur and Howrah,
DVC supplies bulk power at 33 KV, 132 KV and 220 KV through a network covering more than 5500 circuit kilometers.
The DVC grid is interconnected with the State Electricity Boards of Jharkhand (JSEB, erstwhile BSEB) and West Bengal (WBSEB), Grid Corporation of Orissa and Power Grid Corporation of India Ltd.
Existing Lines (Ckt Kms.)
State 33 KV 132 KV 220 KV
Jharkhand 690 2533 780
West Bengal 380 1096 1037
Orissa
35
TOTAL 1070 3629 1852
Existing Sub-stations (Nos.)
State 33 KV 132 KV 220 K
Jharkhand 9 18 5
West Bengal 7 10 5
26
TOTAL 16 28 10
Sub-stations, replacing old electromagnetic relays by numerical relays, installation of high accuracy meters, to quote a few examples. VC has undertaken a major
initiative to renovate and update the existing infrastructure: replacing old circuit breakers by new generation breakers of high capacity, increasing transformer
capacities at various.
POWER GRID MAP OF DVC TRANSMISSION :
27
OBJECTIVE:
POWER FOR ALL :
“The scenario of power generation and distribution in our country increasing
fast.We will have to provide power to all by 2012.DVC has already taken
necessary steps to meet the challenge in the eastern region as a mega pithead
power generation and distributor.DVC has already stepped into export of surplus
power to the deficit of the country.’
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CLD (CENTRAL LOAD DISPATCH)
29
INTRODUCTION
Power sector is reforming day by day to give us the uninterrupted & continuous
supply up to our homes. No. of new equipments are coming forth for fulfilling the
above purpose along with the simulation studies like load flow, economic load
dispatch, control units, tariff measurements etc. Power sector is a key
infrastructure sector & is the backbone of Indian economy. Installed power
generation capacity in India has grown to 87 times since independence. Until
1980’s Indian power sector was in growth phase with many achievements to its
credit. But by late 1980’s almost all SEB’s (state electricity board) started showing
signs of financial technical & governance failure. But after the mergence of private
companies SEB’s were restructured with financial support like IPP’s (independent
power producers).Before knowing about Load dispatch center it is important to
know about what is about electricity and how the electricity is related with
countries economy. Today electricity plays a key role in a society. In house,
offices, factories or farms electricity powers so many gadgets. It is the most
versatile form of commercial energy & it has been a key input to economic
growth in turn improving quality of life. It can be economically transported over
long distances & easily converted to heal, light, or shaft power. It does work for
us, cannot be seen, heard, smelt but still it is always with us without polluting the
atmosphere. The Indian Power System was demarcated in early sixties in five
regions for the purpose of planning, development and operation with a view to
optimally utilize the unevenly Distributed power resource in the country, as well
as to achieve economy, reliability and Security of supply. Five Regional Electricity
Boards, viz., Northern, Southern, Eastern, Western and North-Eastern were
constituted to ensure integrated operation of regional grids formed with
progressive interconnection of contiguous state power systems. Five Regional
Load Dispatch Centers were also set up to coordinate the operations of the
Regional girds in real time. The regional grids were strengthened with the
establishment of large thermal, hydro and nuclear stations in the Central Sector in
which the states of the concerned region have shares. Central Sector transmission
system was constructed for Evacuation of power from these central projects to
the beneficiary states. The contiguous Regions have also been interconnected
30
through AC and HVDC back-to-back systems with the ultimate objective of
achieving a National Grid. Eastern & Northern-Eastern Regions operate in
synchronous mode while other regions operate independently and exchange
power asynchronously through HVDC back to back systems or through AC lines in
radial mode. Infrastructural Analysis of Load Dispatch Centre
EFFECT OF ECONOMY ON POWER SECTOR
In our country 70% of population living in villages. India is country of villages; on
the other hand India has many cities with excellent infrastructure, good industrial
base and many R & D centers & excellent academic institutions. All these need
electricity continuously in villages plus in cities which shows our economic
aspects. Everyone needs energy in some or other form like agriculture, homes,
industries, government offices, commercial buildings, transport facilities, different
operating machines etc. It is also true that half of the population of India depends
upon non commercial sources of energy as they are not using any appliance or
advanced equipment for their daily routines e.g. Use of gobar gas in rural places,
hand operated water lifting pulley etc. The main users of commercial energy are
industries, agriculture, domestic users & transport sectors. Different power
stations are in work to supply energy
to us like Hydro, Nuclear, thermal, diesel, bio gas, bio mass, solar stations, wind
farms, tidal powers etc. We know that power is the backbone of Indian economy
and power sector is also Doubling every 10-15 years like other infrastructure
sectors. Before looking actually towards the LDC it is important to know about the
power system, its Structure & the main components taking part to make its flow
successful.
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power system and its function
Right from generation to distribution or up to our premises power is not directly
coming but it has to go through ups and downs the whole journey. Main wonder
is how electricity generated reaches up to our homes thousands of miles away.
The main contribution is by the thing called power system and to know about the
power system it is essential to know its block diagram and each component.
Power system
Network of generating stations, substations, and power lines is called as power
system it spans a large area. It has a 5 major blocks which are efficient in
transforming power to End user. Electrical power production is the very important
part of the complete electrical power system. Once it is produced it must be
distributed to location where it will be used. Controlling of power is done by using
no. of devices and equipments. To convert it to different forms particular types of
loads are used and the last block is for measurement of energy without which
control & conversion is difficult. Power system may be a huge or a small
network.eg. a small generating station operating on a waterfall at the edge of
village with power lines running to village square from where they branch off to
village homes a small power system or a system like Niagara falls. The whole
power system also uses different devices for different functions like data loggers,
data acquisition devices, SCADA, security monitoring systems etc. Monitoring of
power quality is another issue which decides the thing that whether the provided
power is of harmonic free or not. Loads which are creating harmonics are many so
the harmonic mitigation is of utmost importance. Hence quality monitoring is
essential. For this purpose many computer based measurement & automation
products aid scientists and engineers in research, design, valid production testing
and field monitoring of industrial power sectors. Other things like data
transmission logging, acquisition, receiving, and economic load Dispatch, load
forecasting and load allocation is also important for power system.
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Sub systems of the power system
The summarization of 3 major blocks of a power system is:
Generation:- production of a power (fuels or inputs are different)
Transmission and distribution:- produced power is transmitted or distributed as
per the consumers need.(underground or overhead)
Utilization: - use of electricity for different purposes.
For the healthy operation of a power system G, T, D, and U must work in close Co-
ordination. As per the requirement the generated voltage can be lowered or
raised for transmission purposes. Incase of a distribution levels are decided for
different users like 33, 22, 11, 415 etc. It may be AC or DC hence distribution
system is a 1s t inter phase of utility with consumer. So power system is like a
drama with many actors & director calling the tune. Power system performs
smoothly if all actors dance to same tune. Any abnormality may lead to grid
collapse as this drama is going all over the country, spread over thousands of
kilometers.
load dispatch centre
At state level minute to minute operation of a power system is co-ordinate from a
LDC which at the receiving end or load side. In one way LDC is a wonderland as it
33
is handling no. of changes, demand supply irregularities daily. It gives safe and
secure grid operation. It is located in state capital. It is further connected to 3/4
sub LDC’s which in turn are connected to major substations and generating
stations, hence LDC will get information about major changes in generating
station plus whether condition information from different locations in the state.
In earlier days it was only with few telephones and few engineers to keep the
record. State LDC is connected to regional LDC (RLDC), where RLDC monitors a
whole region e.g. Southern RLDC in Bangalore monitors A.P. tamilnadu,
Karnataka, Kerala and Pondicherry. RLDC also gets information from generating
station & substations of central utilities (NTPC, NPC, POWER GRID etc). LDC at
state plus regional level is connected to all these locations using reliable
communication media that can carry information and voice.
ESSENTIAL FACILITIES AT CLD
Reliable and far reaching communication network
Accurate SCADA system
Fast data processor and data formatting system
Reliable power supply for LDC equipment for all the time
Visual display of important system data
Integrity of operating engineers
Basic amenities, utilities and logistics
OUTCOMES OF CLD
An hourly generation schedule for each generating station in advance.
The maintenance schedule which is needed for relative power gen. cost.
Contractual agreements.
Water/fuel availability.
Load requirement forecast.
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MAIN AND IMPORTANT FUNCTIONS OF CLD
Load generation balance and quality of supply
Maintenance scheduling of generating units and transmission lines
Economic load dispatch
Grid discipline
Load forecasting or demand estimation
System security and islanding facility
Black start preparedness
Energy distribution and load pattern study
Communication and SCADA management
Event analysis and preventive measures
Coordination with neighbor grids
Public relations and consumer interaction dispatchers study for load patterns
Industrial category of consumers (industries working in all 3 shifts)
Industries working in day time with high power demand.
Commercial category consumers like shops, offices, show rooms operates during day time (9to 20.00 hrs.)
Railway traction load have generally steady nature whole day.
Water works require power for pumping drinking water for urban and rural areas during early morning hours.
Farmers also requires power for irrigation during day time
Seasonal nature industries like sugar factory, cotton ginning industries, vegetable oil industries, rice mills etc.
USE OF SCADA IN CLD
There are multiple agencies within a state engaged in generation, transmission,
and distribution of electricity. State Load Dispatch Centre monitors these
operations and keeps the account of quantity of electricity transmitted through
the state grid. SCADA is a part of it. Supervisory Control and Data Acquisition
System (SCADA) is a high tech computer system with associated communication
network that enables supervision and control o f power system network. SCADA
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is the technology that enables a user to collect data from one or more distant
operator to stay or visit frequently to the work locations. It includes the man
machine interface. It allows an operator to make set point changes on distant
process
Controllers, to open or close valve or switches, to monitor alarms to collect
measurement information
SCADA is best applicable to processes that are spread over large areas and it is
suitable for
Groups of small hydroelectric generating stations that are turned on and off.
Oil and production facilities ,pipelines for gas , oil, chemicals, water which are located at far distances
Electric transmission systems irrigation system etc.
Direct benefits of a modern SCADA system are:
Constant access to Real Time picture of entire network showing power system voltage, frequency, MW, MVAR, etc.
Supervision, monitoring and control of power in Real Time.
Optimal operation of power system, i.e. generation and associated resources.
Minimum of outage and faster restoration of the system in the event of Grid disturbances.
Improvement in the quality of supply through better control of frequency, voltage and other parameters.
Less dependence on basic telephone system, when it comes into existence
FUTURE SCENARIO
The main things are make load dispatch center operations more complex than
earlier years are changes in system network, growth in consumer population, mix
of fuel used etc. also problems related to security , integration of various grids,
forces the load dispatcher to attain new dimensions. Load dispatch center has to
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handle and face no. of problems regarding the electricity changes. In earlier days
the methods used to communicate oral instruction and manual intervention were
somewhat unreliable in critical situations. And this thing make necessary to adopt
the new methods and techniques like:
Automatic control on generating units as well as important load centers. This is for effective and timely control to avoid the major occurrences of black out. This aspect will also require the foolproof arrangement of reliable interlocks and back
up protection to ensure safe grid working.
Also the transmission switchyard will be properly equipped and no interference of local staff except the experts.
Control actions taken by load dispatcher can not be bypassed.
The remote control of generation should be done through the governor controls to improve generation. In recent years it is done by the automatic governor control.
Now a days as we have seen SCADA is in use to control and monitor all the things which
is the most effective communication media. Also a regular and timely communication
about power supply schedule and generation schedule is the heart of healthy power
system and this happens only when there is a proper communication.
Central load dispatch (CLD) :
Central Load Dispatch can be considered as the ‘heart of DVC ’.Its
main purpose is to maintain a balance between the generation end and
consumption end. Any imbalance between two causes the frequency to
deviate from India’s rated frequency 50Hz.CLD acts as a regulatory
body which coordinates the two ends of electrical transmission
system.
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The above operation done through an inter-connected grid. According
to the Indian Electricity Act 2003.a grid connects all the different
sub-divisions of the Eastern region which is turn is connected to the
other regions of India. A supreme governing body called the National
Load Dispatch Centre(NDLC) situated at Delhi monitors the entire
grid system through-out India.
Fig: CENTRAL LOAD DISPATCH CENTRE
As we know that
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I. Generation = Demand ; frequency
=50Hz(required)
II. Generation > Demand ; frequency>50Hz(required)
III. Generation < Demand ; frequency<50Hz(required)
Fig: Generation Vs. Time curve of 24 hours
Fig: Balanced generation and demand to get required
frequency 50Hz
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MAIN OPERATION OF CLD
The main operation of CLD is to maintain a balance between the
generation curve and the load curve. The load curve attains the peak
value at a day time and evening time, whereas our generation curve
remains constant. So CLD takes several steps to match the two.
Presently this is done through bilateral trade. The other alternate
methods include load shedding and breaking down. Whenever
generation exceeds demand, frequency decreases from the rated
50Hz.So power is supplied to the grid through bilateral export. When
demand exceeds generation, power is drawn from the grid. For an
efficient functioning of this system, a schedule is prepared a day
earlier. Deviation from this schedule results in penalty or bonus. in
minority terms.
Unscheduled interruption & it’s role in cld
Unscheduled interruption generally known as UI is the difference
between scheduled and the actual.
UI rate ∞ frequency
The prime object is to keep UI at zero position. But practically, this
may not be possible. Hence CLD tries to keep a minimum UI.THE
operation are at present controlled in a manual instruction manner, i.e.
on any event on increase or decrease of load demand the operators at
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CLD manually instruct the operations at the generation units to
regulate their generation according to the demand .Also, in case when
the generating limit is achieved nearly, the operators instruct the
operates at the corresponding sub-stations to regulate the demand
accordingly by use of breakers.
Power scheduling and role of cld :
It is the method in which a power schedule is drawn for the next day.
The power schedule is drawn according to the demands placed by the
various consumers. According to the demands placed for the next day
CLD decides that how many generating uni9ts have the next day and
for how many hours. It also has a record of the rate at which the
power brought by the consumers. It also regulates where the extra
generated power has to be diverted incase if the consumer back.
However the consumer payment is not refunded. It also monitors the
frequency of generation and regulates it in order to stabilize the
rotational frequency thus aiding the concept of UI.
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42
TSC
COMPENDIUM OF TRANSMISSION SYSTEM CONSTRUCTION
1. Transmission System Construction criteria:
The objective of system planning is to develop a power system with a level of
performance characterized by an acceptable degree of adequacy and security.
The salient features for the transmission system shall be as summarized below:
1.1. The transmission system shall be planned in an integrated manner
and optimized considering the total network under CTU and STU.
1.2. The adequacy of the transmission system shall be tested for one or
more load generation scenarios comprising of peak and off peak conditions in
summer, winter and monsoon seasons.
1.3. Right of way for transmission lines shall be optimized keeping in view
the corridor requirement for the future by adopting suitable alternative of multi -
circuit or multi-voltage lines as applicable.
The Transmission system of DVC operates and maintains the DVC power system with a level of performance characterized by an acceptable degree of
adequacy and security. The salient features of the functioning of the transmission
system of DVC are –
1. Evacuation of power from the Generating stations to the load end through
interconnected H.T Transmission lines.
2. Importation of power from other system into DVC system to meet its
contractual demand.
3. Ensuring security of the system through interconnection of sub-stations to
more than
one source point in a ring main system.
4. Maintaining voltage at the consumer end within permissible limit i.e. within +
10 %.
5. Passing messages/ instructions of Central Load Despatch to the c onsumers
(i.e regulation of over drawl, load restriction, load shedding etc.) in order to
maintain grid discipline. 6. Emergency restoration of system after fault (i.e. tripping of feeder/line,
transformer etc., snapping of line conductor, collapse of towers etc.).
43
2. Rules and regulations/CEA Guidelines
As per notification of Ministry of power (Central Electricity Authority) dated
21.02.2007 the following guideline/Rules & Regulations are to be maintained:-
2.1. Applicability of Regulations
These regulations should be applicable to all the users, requesters, Central
Transmission Utility and State Transmission Utility.
2.2. Objectives
2.2.1. The aim of these regulations is to ensure the safe operation, integrity and
eliability of the grid.
2.2.2. The new connection shall not cause any adverse effect on the grid. The
grid shall continue to perform with specific reliability, security and quality as per
CEA (Grid standard for operation and Maintenance of Transmission line)
regulations,
as and when they come in to force. However these regulations are not to be
relied upon to protect plant and equipment of the requester or user.
2.2.3. A requester is required to be aware, in advance, of the standards and conditions his system has to meet for being integrated in to grid.
2.3. Standards
The equipment shall be meet the requirements in accordance with the
provisions of technical standards for Connectivity to the Grid as given in the
Schedule of these regulations and CEA regulations as and when they come into
force, and Grid Code and the State Grid Code(s) as specified by the appropriate
commission.
2.4. General Connectivity Conditions
2.4.1. The requester shall be responsible for the planning, design, construction
and safe operation of its own equipment subject to the regulations for
construction operation and maintenance and connectivity and other statutory provisions.
2.4.2. The requester and user shall furnish data as required by the Appropriate
Transmission Utility with whose system the interconnection is proposed, for
permitting interconnection with the
grid.
44
2.4.3. The requester and user shall make integration of the contro ls and tele-
metering feature of his system into the Automatic Generation Control, Automatic
load Shedding, Special protection system, Energy Measurement Systems and
supervisory Control and Data Acquisition System of the respective state or
region.
2.4.4.1. Every connection of a requester’s system to the grid shall be covered
by a connection between the requester and
i. Appropriate Transmission Utility in case of connection to Inter-state transmission system or intra state transmission system as the case may be;
ii. Distribution Licensee in case of inter-connection to distribution licensee’s
system; and
iii. Transmission licensee and Appropriate Transmission Utility in case of
connection to a Transmission license (Tripartite agreement).
2.4.4.2. The connection agreement shall contain general and specific technical
conditions, applicable to that connection.
2.5. Site responsibility
2.5.1. Site responsibility Schedule (SRS) for every connection point shall be prepared by the owner of the S/S where connection is taking place.
2.5.2. Following information shall also be furnished in the SRS for each item of
equipment installed at the connection site, namely:-
2.5.2.1. The ownership of equipment;
2.5.2.2. The responsibility for control of equipment;
2.5.2.3. The responsibility for maintenance of equipment;
2.5.2.4. The responsibility for operation of equipment;
2.5.2.5. The manager of the site;
2.5.2.6. The responsibility for all matters relating to safety of persons at site;
and
2.5.2.7. The responsibility for all matters relating to safety of equipment at site;
2.6. Access at Connection Site:
The requester or user, as the case may be, owing the electrical plant
shall provide reasonable access and other required facilities to thelicensee or Appropriate Transmission Utility, whose equipment is installed or proposed to be
installed at the connection site for installation etc. of the equipments.
2.7. Site common drawing:
Site common drawings shall be prepared for each connection point by
the owner of the sub-station where connection is taking place.
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2.3.1. Standards and course of practice:
2.3.1.1 Sub Station grounding:
Each transmission Sub station must have a ground mat solidly connected to all
metallic structures and other nonenergized metallic equipment. The mat shall
limit the ground
potential gradient to such voltage and current level that will not endanger the safety of people or damage equipment which are in or immediately adjacent to
the sub-station under normal and fault condition. The ground mat size and type
shall be based on local soil condition and available fault current magnitudes. In
areas where ground mat voltage rises beyond the acceptable and safe limits (for
example due to high soil resistivity or limited sub station space), ground rods and
ground wells may be use to reduce the ground grid resis tance to acceptable
levels. Sub station grounding shall be
done in accordance with the norms of IEEE 80.
2.3.1.2. Metering: Meter shall be provided as per specified CEA (installation and
operation of Meters) regulation 2006.
2.3.1.3. The basic insulation level and insulation co-ordination BIL of various
items of equipment and ratings of surge arresters for lines and sub station shall be decided on thefollowing order of priority;
01. Ensure safety to public and operating personnel.
02. prevent failure of costly equipment
03. minimize circuit interaction
04. minimize interruption of power supply to consumer
Insulation co-ordination of equipment and line on both side ofa connection point
belonging to the requester and the grid shall be accomplished and the
coordination shall be done by the appropriate transmission utility.
2.3.1.4. Protection system & co-ordination:
01. Protection system shall be designed to reliably detect faults on various
abnormal conditions and provide appropriate means to isolate the equipment or
system automatically. Protection system must be able to detect power system fault within the protection
zone. The protection system should also abnormal operating condition such as
equipment failures or open phase condition.
02. Each element of power system shall be protected by a standards protection
system having the required reliability, selectivity speed, discrimination and
sensitivity. Where failure of a protective relay in requester system has substantial
46
impact on the Grid, it shall connect an additional protection as back up protection
besides the main protection.
03. Notwithstanding the protection system provided in the grid, requester and
user shall provide requisite protection for safeguarding his system from the fault
originating in the Grid.
04. Bus bar protection and breaker failed protection or local back up protection
shall be provided wherever stipulated in the regulation.
05. Special protection scheme such as under frequently relay for load shedding, voltage instability angular instability ,generation backing down or islanding
scheme may also be
required to be provided to avoid system disturbance.
06. Protection coordination issues shall be finalized by the regional power
committee.
07. The requester and user shall develop protection manuals conforming to
various standards for reference and use of its personnel.
2.3.1.5. Disturbance recording & event logging facility:
Every sub station connected to the grid and 220 KV or above shall be provided
with disturbance recording and event logging facilities. All such equipment shall
be provided with time synchronization facility for global common time reference.
2.3.1.6. Schematic Diagrams:
The requester and user shall prepare single line schematic diagram in respect of
its system facility and make the same available to the appropriate transmission
utility or licenses to which this system is connected and appropriate load dispatch
centre.
2.3.1.7. Inspection test calibration and maintenance prior to connection:
Before connecting, the requester shall complete all inspection and test finalized
in consultation with the appropriate transmission utility or licensee to which this
equipment is connected. The requester shall made available all drawings
specifications and test record of the project equipment pertaining to integrated
operation to the appropriate transmission utility or licenses or generation station
as the case may be.
2.3.2. Grid connectivity standards applicable to the transmission line and Sub
station:
The transmission line and sub station connected to the Grid shall comply with the
following additional requirements besides the general connectivity conditions
under these regulations and general standards for connectivity to the Grid as
specified in the
2.3.1.
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2.3.2.1 Bus bar protection shall be provided on all sub station at an above 220
KV levels for all new sub station. For existing sub station this shall be
implemented in a
reasonable time frame.
2.3.2.2. Local breaker back up (LBB) protection shall be provided for all sub
station for 220 KV and above.
2.3.2.3. Two main numerical distance protection scheme shall be provided on all the transmission lines of 220 KV and above for all new sub station. Fr existing
sub station,
this shall be implemented in a reasonable time frame.
2.3.2.4. Circuit breakers isolators and other or current carrying equipment shall
be capable of carrying normal and emergency load current without damage. The
equipment shall not become a limiting factor on the ability of transfer of power of
the inter-state and intrastate transmission system.
2.3.2.5. All circuit breaker and other fault interrupting devices shall be capable of
safety interrupting fault currents for any faults that they are required to interrupt.
The circuit breaker shall have this capability without the use of internal time delay
in clearing the fault .Minimum fault interrupting requirement need be specified by
the appropriate transmission utility. The circuit breaker shall be capable of
performing all other switching duties such as, but not limited to, capacity current
switching, load current switching and out of step switching. The circuit breaker shall perform all required duties without reating transient over voltage that could
damage the equipment provided elsewhere in the Grid. The short circuit capacity
of the circuit breaker shall be based on short term and rerspective transmission
plans as finalized by the authority.
2.3.2.6. Power supply to sub station auxiliary:
(a) For alternating current supply ( applicable to new sub station): 220 KV and
above: two high tension (HT) supply shall be arranged from independent
source. On of the two high tensions supply shall be standby to the others. In
addition an emergency supply from diesel generating source of suitable capacity
shall be provided.
66KV and below 220 KV: There shall be one HT supply and one diesel
generating source.33 KV and below 66 KV: There shall be one HT supply.
(b) For direct current (DC) supply (applicable to new sub station): Sub station of
transmission system for 132 KV and above and sub station of all genera ting sub station.
There shall be two sets of batteries each equipped with its own charger.
For sub station below 132 KV: There shall be one set of
battery & charger.
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2.3.2.7. Earth fault factor for an effectively earth system shall be not more than
1.4.
3. Preliminary Route survey
Before commencing actual survey, it is very essential to perform the feasibility
survey for the route of the line for finding the possible corridor. At least two
possible routes of the line should be sketched on a key plan showing the feathers
viz., village, paddy fields, rivers, canals, P& T lines and other power lines along the routes. This reconnaissance is usually carried out in light vehicle (e.g. jeep,
car etc.) and on foot.
After selection of the corridor of the line it is necessary to do preliminary survey
for alignment of the route and preparation of drawing showing different features
as mentioned above. In this survey tentative angle points and the distance
between them are to be measure with the help of Theodolite/Total Station,
Ranging Rods and chain. The route of the line will also to be drawn on the topo
sheets of mouza maps of the areas through which the line will be passed.
considered:-
For fixing of the alignment of an overhead line the following points to be
i) The alignment will be short and straight as par as practicable.
ii) The alignment will be parallel and near to railway tracks and high ways if
possible. iii) Angle Tower should be as minimum as possible.
iv) Agricultural lands, undulating areas, airports, buildings, ponds, forests etc.
should be avoided as far as practicable.
v) Expenses related to acquisition, clearing of Right-of-Way (ROW) should be
kept as minimum as possible.
vi) Alignment should be fixed up as far away from telecom lines as possible. If
crossing with the telecom line is a must, then the alignment of the power line
should be such as the crossing angle should be as nearly as possible to 900 and
also never be less than 600 angles.
vii) Efforts should be taken to avoid crossing of railway tracks. However, in
unavoidable circumstances railway crossing may be done and angle of crossing
should be taken as nearly as possible as 900 and as never be less than 600
viii) Difficult and dangerous approaches should be avoided.
ix) The alignment of the power line should be away from buildings having
explosives.
4. Specification of Transmission System Equipments
Transmission line construction
(a) Construction of a transmission line shall be carried out generally as per
relevant IS meeting stipulated requirements and under other latest applicable
standards and prudent utility practices.
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(b) Crossing of a transmission line with roads or a rai lway or a river or a power
line or a telecommunication line shall be finalized as per applicable rules &
regulations specified by the concerned authorities.
(c) Clearances from ground, buildings, roads, power lines, telecommunication
lines etc. shall be provided in conformity with Central Electricity Authority
(Measures Relating to Safety and Electricity Supply) Regulations as and when
these are notified by the
Authority. (d) Clearances from trees, forest clearance etc. shall be provided in accordance
with Forest Conservation Act and guidelines issued by Ministry of Environment &
Forests.
(e) Normal design span for various voltage level transmission lines shall
generally be as follows:
Table:
Voltage (kV) Normal span (M) 400 400 220 335, 350, 375 132 315, 325, 335
33 (AAAC Panther) 84 Span is depending on mainly Pole/Tower and conductor to be used.
For 400KV Span will also depend on Angle of line/route.
As per IS: 5613 (Part II/Sec-1)-1976 given bellow: Minimum clearances
Construction of Electric Lines and Associated Equipment
(1) The system shall be constructed so as to ensure:
(a) Voltage conditions are within permissible levels.
(b) Improvement of reliability and security of power supply.
(c) Improvement in quality of supply.
(d) Adequate capacity for load growth for next 5 years.
(2) Independent feeders may be provided for essential loads of 5 MVA and above such as water works, hospitals, defense and other sensitive
installations as per as practicable.
(3) Separate rural feeders for feeding irrigation load and domestic load shall
normally be provided.
4) Composite lines (i.e. lines having different voltage levels), twin and quad
conductors, multi-circuit and for bulk supply of power shall be adopted by the
Owner as per requirement.
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Supports (Poles and Towers)
(1) The supports shall be poles or narrow based lattice towers with fully
galvanized structure as per site requirement.
(2) Poles may be used for 33 kV, 22 kV, 11 kV and LT lines (lines below 500 V)
as per requirement. The poles shall be pre-cast concrete (PCC) pole,
prestressed cement concrete (PSCC) pole, rolled steel joist, rail pole or steel
tubular pole as required, provided PCC and PSCC poles shall not be used at cut-points and as end poles.
(3) Poles shall conform to relevant IS as the case may be.
(4) Concrete poles shall be preferred in plain areas.
(5) In hilly areas appropriate snow or ice loading shall be considered for design of
poles and towers.
(6) For locations involving long spans or higher clearances on account of
crossing of power or communication lines or a railway line, specially
designedpoles/lattice towers may be used.
(7) For angles of deviation of more than 10 degree, double pole structure shall be
used.
(8) The height of the pole above the ground level, length of pole below ground
and working load shall be decided taking into consideration wind zone, terrain,
topography, and the statutory clearances required to be maintained and these
shall conform to relevant IS.
Erection of Poles
Erection of poles shall be carried out in accordance with the provisions of
relevant IS.
Earthing of Poles
(1) All metallic supports shall be permanently and effectively earthed. The
earthing arrangement shall conform to relevant IS.
(2) Metal cross arms and insulator pins for PCC and PSCC poles shall be
bonded together and normally earthed at every pole for 33 kV or 22 kV or 11 kV
lines and at every 5th pole for lines below 500 volts.
(3) The support on each side of a road crossing, railway crossing or river
crossing shall be earthed.
(4) Normally plate earthing shall be provided except for locations involving
railways, telegraph line, power line crossings and special structures where pipe/rod type earthing shall be provided. Whenever the electric lines pass close
to a well or a permanently moist place, an earth should be provided in the well or
the marshy place and connected to the electric line pole.
(5) All steel poles on which switches, transformers, fuses etc. are mounted shall
be earthed.
(6) All poles above 650 volts, irrespective of inhabited areas, shall be earthed.
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For poles below 650 V guarding with continuous earth-wire shall be provided
invariably, connected to earth at three equidistant points in one km.
Stay Arrangements
(1) To prevent tilting of a pole from its normal position due to abnormal wind
pressure and deviation of alignment, the pole shall be kept in position by stays.
The stays shall be provided at:
(a) Angle locations
(b) Dead end locations (c) Tee off points
(d) Steep gradient locations
(e) Cut – point
(f) Along the straight run at minimum 2 locations in 1 km
(2) Galvanized iron stay wires and stay rods of adequate size shall be used. The
individual wire used to form “stranded stay-wire” shall have a minimum tensile
strength of 700 N/sq mm as per IS. For double pole structure, four stays along
the line, two in each direction and two stays along the bisection of the angle of
deviation or as required depending on the angle of deviation shall be provided.
(3) When two or more stays are provided on the same pole, each stay shall be
grouted entirely separate from the other.
(4) The angle between the pole and stay wire shall be about 45 degrees and in
no case it shall be less than 30 degrees.
(5) Stays shall be anchored either by providing base plates, angle iron or rail. (6) Stay wires shall be connected to the pole with a Porcelain Guy Strain
Insulator. The standard Guy Strain insulators shall be as per relevant IS. The
Porcelain insulator shall be inserted in the stay wire at a height of minimum 3 m
vertically above the ground level. The strain insulators shall be free from defects,
thoroughly vitrified and smoothly glazed.
(7) Wooden insulators shall not be used for stay/guy wire.
Protective Guard
Guard wire shall be used where an overhead line crosses or is in proximity to any
telecommunication line or any other overhead line and in populated localities.
Every guard wire shall be connected to earth wherever its electrical continuity is
broken. The minimum factor of safety for stay wires, guard and bearer wires shall
not be less than 2.5 based on ultimate strength of the wire.
Anti Climbing Devices
Anti climbing devices shall be provided on the supports. For this purpose barbed
wire conforming to relevant IS for a vertical distance of 30 to 40 cm. at a height of
3.5 to 4 meters from ground level or clamps with protruding spikes at a height of
3 to 4 meter shall be used.
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Danger Plates
Danger Plates shall be provided on electric lines in accordance with Central
Electricity Authority (Measures Relating to Safety and Electricity Supply),
Regulations as and when these are notified by the Authority.
Insulators, Insulator Strings and Hardware Fittings
(1) Pin insulators shall generally be used on the straight stretch of a line. The pin
insulators shall conform to relevant IS. The pin insulators may be used on lines
up to 33 kV voltage level. The pin insulator shall consist of a single piece of
porcelain mounted rigidly on a supporting structure on a pin.
(2) Shackle insulators shall be used in lines below 500 volts and these shall
conform to IS. Strap type fittings shall be used for a dead end location, while U-
clamp fittings shall be used at tangent locations.
(3) Requisite type of suspension and tension insulator strings with disc
insulators or long rod insulators offering equivalent performance shall be used on
33 kV or 22 kV or 11 kV lines. The number of insulators and creepage distance
shall be selected based on electrical system parameters taking into account altitude of site, expected environmental and pollution conditions etc.
(4) Disc insulators shall conform to relevant IS. Polymer/composite
insulators conforming to relevant IEC/other International Standards may also be
used.
(5) Disc insulators shall be of Ball and Socket type or Tongue and Clevis
type.
(6) Insulator strings shall be complete with all required hardware fittings.
The fittings shall conform to relevant IS.
(7) Insulator and insulator string rating shall be selected such that:
(a) Under ultimate design wind / snow loading conditions, the load on insulator
string shall not exceed 70% of its selected rating.
(b) Under everyday temperature and no wind / snow conditions, the load on the
insulator string shall not exceed 25% of its selected rating.
(8) The insulation shall be designed to avoid excessive concentration of electrical stresses in any section or across leakage surfaces.
Cross-Arms
Cross arms shall be provided in accordance with the requirement. In case, they
are made of mild steel, the cross-arms and the clamps shall be hot dipped
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galvanized conforming to relevant IS, after completion of fabrication. Welding at
site should be avoided as far as possible, in case welding becomes necessary,
the joint shall be covered with cold galvanizing paint.
Conductor
(1) The size of the conductor shall depend upon the voltage
regulation,factor of safety, power to be transmitted, length of line, line voltage
and mechanical strength desired. (2) Steel Reinforced Aluminum Conductors (ACSR) or equivalent All
Aluminum Alloy Conductors (AAAC), AAC (All Aluminum Conductor), AACSR
(Aluminum Alloy Conductor Steel Reinforced) shall be used according to
requirement.
(3) Required accessories for conductor and earthwire viz. mid-span
compression joints, repair sleeve, T-connector, flexible copper bond, vibration
dampers, spacer/spacer-dampers, earthwire clamps etc. shall conform to
relevant IS.
(4) The configuration of conductors on the line can be triangular, horizontal
or vertical depending upon the voltage level of the lines, terrain, right of way and
clearances to be maintained. In case clearance from a building is difficult to
secure, vertical arrangements of the conductor shall be adopted.
(5) The installation of the conductor on the poles shall be carried out in
accordance with the methodology given in relevant IS. (6) Suitable insulating paint shall preferably be provided on bare conductors
in coastal areas to prevent corrosion as well as in power theft prone areas.
Name of conductor Size of conductor
AAAC Dog 19/2.89
ACSR Lark 37/2.92
AAAC Panther 37/2.88(Rail Pole), 37/3.15(Tower)
ACSR Zebra (54+7)/3.18
AAAC Zebra 61/3.31
ACSR Moose (54+7)/3.53
LT Spacers
To avoid clashing and accidental mutual touching of bare overhead conductors
on LT lines, spacers, which can be either spiral or composite shall be provided in between conductors at appropriate locations in different spans (particularly for
lines having longer spans or lines having large sags encountering high winds).
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Cables
(1) Underground cables or aerial bunched cables (ABC) of adequate rating
can also be used for supplying power. Cables shall conform to relevant Indian
Standards.
(2) PVC cables shall not be used in systems other than LT system.
(3) Aerial bunched cables shall be used in the theft and accident-prone areas.
(4) Direct burying of underground cables shall not be adopted except where cables enter and take off from a trench.
(5) The underground cables shall be segregated by running in separate
trenches or on separate racks.
(6) The cable trenches shall be properly sloped so as to drain freely any water,
which may enter.
(7) Cable trenches shall not be run through oil rooms.
(8) Cables shall not be laid directly on trench floor.
(9) Adequate number of spare cores shall be included in all control cables.
Service Line
(1) The service line shall be provided with insulated conductor, armoured
cable or underground cable. The service line shall have adequate margin to take
care of load growth for at least five years. (2) Over head service connection shall be provided either through
independent service connection or through LV box. No tapping of service line
shall be permitted for supplying power to any other consumer. Feeder pillar-box
shall be used for providing under ground service connection through cable to
more than three or four consumers.
(3) The supplier shall provide and maintain on the consumer’s premises for
the consumer’s use a suitable earthed terminal in an accessible position at or
near the point of commencement of supply in accordance with Central Electricity
Authority (Measures Relating to Safety and Electricity Supply), Regulations as
and when these are notified by the Authority.
(4) The meters for the consumer connections shall be provided in
accordance with the Central Electricity Authority (Installation and Operation of
Meters) Regulations, 2006.
Lightning Protection
(1) The surge arresters (SAs) shall be placed at the terminal points of the
lines and also at the junction points of cables and bare overhead conductor lines.
(2) For 33 kV, 22 kV and 11 kV lines, surge arresters having rated voltage
of 30 kV (rms), 20 kV (rms) and 9 kV (rms) and discharge current rating of 10 kA,
7.5 kA and 5 kA, complying with relevant IS, shall be used respectively.
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(3) The earthwire of appropriate size to take care of predicted/design fault
currents and lightning shall be used. The earth wire shall be either of galvanized
stranded steel (GSS) or alternatively ACSR/AACSR conductor.
(4) The earthing lead for the surge arrester shall not pass through any iron
or steel pipe, but shall be taken directly to a separate earth electrode.
4.1. Electrical Design Parameters of the Transmission Lines
Para-meter 33 kV 132 kV 220 Kv 400 Kv
AC AC AC AC
Nominal Voltage (kV) 33 132 220 400
Highest System Voltage 36 145 245 420 (kV) Full wave Impulse 170 650 1050 1550 withstand voltage (1.2/50microsec.) (kVpeak) Full wave Impulse 75 275 460 680 withstand voltage (1.2/50microsec.) (kVpeak) Switching Surge Withstand - - - 1050 Voltage under Wet condition (kVrms) Minimum Corona - - 156 320 Extinction Voltage under Dry condition (kVrms phaseto earth) Maximum Radio - 1000 AT 1000 AT 1000 Interference Voltage at 1 267 KV 510 KV AT 22 KV MHz (microvolts) for phase to earth voltage of … kV under Dry condition
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4.2. Conductor
The conductor of appropriate size shall be selected considering power flow
requirements and other system considerations in consultation with neighboring
transmission and generation utilities. For transmission lines of 400 kV or higher
voltage class, bundle conductors (minimum two conductors per phase for 400 kV
AC and four conductors per phase for 500 kV DC & 765 kV AC) shall be used for
satisfactory performance of transmission lines from corona and interference aspects.
The conductors may be of type ACSR, AAAC or other and shall generally
conform to relevant IS or IEC standards. Other new technology conductors
conforming to International standards and specifications may also be used
depending on system requirements.
4.3. Earth wire
The earth wire of appropriate size to cater to predicted and design fault currents
and lightning shall be used. The earthwire shall be either of galvanized stranded
steel (GSS) or alternatively ACSR or AACSR conductor type. Optical fiber
ground wires may also be used as earthwire. Other new technology earthwires
conforming to international standards and specifications may also be used.
Generally, one earthwire shall be used for transmission lines upto 220 kV and
two earthwires shall be used for transmission lines of 400 kV and higher voltage
classes.
4.4. Towers
The towers shall be self-supporting lattice steel type and shall be a fully
galvanised structure. Alternatively, guyed or pole structure towers may also be
used. Type of towers, design and ruling span, wind & weight spans, extension
and truncation provisions etc. shall be selected by the Owner as per prudent
utility practices.
Live-metal clearances, mid-span clearance, shielding angle etc. shall be decided
as per prudent utility practices following applicable standards and codes and
keeping in view electrical system parameters and requirements, line altitude and
other service
conditions and factors. Ground clearance shall be as per requirements of
Central Electricity Authority (Measures relating to Safety and Electricity Supply)
Regulations as and when these are notified by the Authority.
4.5. Design of towers
The following specify the minimum requirements for design of towers. The Owner
may adopt any additional loading or design criteria for ensuring reliability of the
line, if so desired and/or deemed necessary. The towers shall be designed to
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meet all design requirements and design criteria stipulated in latest revision of
relevant IS or IEC
standards, considering wind loading corresponding to applicable wind zone for
the transmission line as per relevant IS. The towers shall also be designed for
appropriate snow or ice loads, if applicable. The loads at conductor and
earthwire points under different loading conditions viz. reliability conditions
(normal condition), security
conditions (broken wire condition), safety conditions, anti -cascading condition etc. (as per relevant IS or IEC Standards) considering various combinations of
design temperatures, wind and snow loads shall be calculated and tower designs
developed accordingly. Reliability level– 1 corresponding to 50 year return
period design
loads due to wind as per relevant IS shall be considered for design of towers for
transmission lines upto 400 kV. For higher voltage level transmission lines,
reliability level–2 corresponding to 150 year return period wind loads shall be
considered. Triple and quadruple circuit towers and towers with more than two
sub- conductors per
phase upto 400 kV shall be designed corresponding to the reliability level– 2 (150
year return period). Normal towers shall be prototype tested as per relevant IS. It
may not
be mandatory to have prototype testing of tall river crossing towers and other
special towers designed for reliability level– 3 (500 year return period). (ii) Materials
Mild steel and high tensile steel sections of tested quality in conformity with
relevant IS shall be generally used in towers and their extensions. Other
equivalent grade of structural steel angle sections and plates conforming to
International Standards may also be used. Fasteners, bolts and nuts shall be
generally as per relevant IS.
(iii) Tower fabrication
Tower fabrication shall generally conform to relevant IS. Tower parts shall be
galvanized as per relevant IS.
(iv) Tower accessories
Various tower accessories viz. danger plates, number plates, phase plates,
circuit plates, anti-climbing devices, bird guards etc. shall be provided conforming
to relevant IS. Remedial measures shall be taken by the Owner to put spike type
Bird guards on the Upper (tie members), Lower main members and also on Plan
bracings in the barrel of the tower at all the cross arm levels to prevent birds from making nests. This measure will also help to improve the performance and
availability of the system.
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(v) Earthing
Each tower shall be earthed such that tower footing resistance does not exceed
10 ohms. Pipe type or Counterpoise type earthing shall be provided in
accordance with relevant IS.
(vi) Aviation requirements and warning signals Day and/or night visual aids and
markers for denoting transmission line or structures as per requirements of
Directorate of Flight Safety or relevant IS or ICAO shall be provided.
4.6. Foundations
(i) Depending upon soil and site conditions, economy and feasibility of
construction at site, appropriate type of foundations (viz. open cast, pile, well or
other alternative types) shall be considered for transmission line towers.
(ii) The design of foundations shall be as per applicable Indian Standards and
Codes.
Structural design of foundations shall be done by limit state method with
minimum overload factor as 1.1. The minimum factor of safety for design of pile
or well foundations shall be 2.5.
(iii) The cement concrete used for the foundations shall be generally as per
relevant IS.
(f) Insulators, Insulator Strings and Hardware Fittings (i) Requisite type of suspension and tension insulator strings with disc insulators
or long rod insulators offering equivalent performance shall be used. Number of
insulators and creepage distance shall be selected based on electrical system
parameters and requirements taking into account other factors and conditions
viz. line altitude, expected environmental and pollution conditions etc. However,
for critical locations with high pollution level, antifog type insulators or polymer
insulators may be used for better performance. For voltage levels upto 400kV,
specific creepage distance shall be elected from Table: III-6 at clause 47 based
on the site requirement. For 765kV, specific creepage distance shall be decided
judiciously by the Owner.
(ii) Insulators shall generally conform to relevant IS or IEC standards. Polymer or
composite insulators conforming to relevant IEC or other international standards
may also be used. Insulators for HVDC lines shall be of anti-fog type having
sacrificial zinc sleeve. These shall generally conform to relevant IEC standard.
(iii) Insulator & insulator string rating shall be selected such that: • Under ultimate design wind loading conditions, the load on insulator string shall
not exceed 70 % of its selected rating.
• Under everyday temperature and no wind conditions, the load on insulator
string shall not exceed 25% of its selected rating.
(iv) Insulator strings shall be complete with all required hardware fittings. The
fittings shall generally conform to relevant IS.
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4.7. Accessories for Conductor and Earthwire
The accessories required for the conductor and earthwire viz. midspan
compression joints, repair sleeve, T-connector, flexible copper bond, vibration
dampers, spacer or spacer-dampers, earthwire clamps etc. shall be used as
suitable for type and size of conductor and earthwire used for the transmission
line. The accessories shall generally conform to relevant IS.
5. Tendering Procedure
5.1. Objective
Main objective is to ensure procurement of right quantity, right quality of
Material from right source at right price and at right place and time, keeping
transparency in contractual process.
5.2. Pre-enquiry Activity
5.2.1. Before tendering process starts, Administrative and financial estimate is
obtained from competent Authority based on preliminary estimate for Supply
and/or Erection.
5.2.2. Contemporary market price and/or last P.O., W.O. is used to
prepare final Estimate. 5.2.3. Technical Sanction Order is taken from competent authority on the
above estimate.
5.2.4. Administrative Approval for floating of NIT.
5.2.5. Selecting the mode of tendering.
5.2.6. Fixing the qualifying requirements, if required, for the indent/proposal.
5.2.7. Fixing the cost of tender documents.
5.2.8. Fixing the amount of Earnest Money.
5.2.9. Finalizing the enquiry details for advertisement in Newspaper and
Website, for open tendering.
5.2.10. Preparation of Tender Document sets.
5.3. Checklist for Preparation of Tender Enquiries
The following points are to be taken care of by concerned Officer of contracts
department before issuing of any tender enquiry. 5.3.1. Time and date for receipt and opening of tenders is indicated as per the
guidelines.
5.3.2. The prescribed time has been allowed to the tenderers to submit their
quotations depending on the type of enquiry being issued i.e., Single Tender
Enquiry, Limited Tender Enquiry, Open Tender Enquiry, Global Tender Enquiry,
etc.
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5.3.3. The amount to be furnished against EMD as per provision in this manual
has been calculated correctly and indicated including mode of submission of the
same.
5.3.4. Description of stores including specifications / drawing is
correctly indicated. (Specifications are to be finalized keeping the End use in
mind). Description of works/services with detailed scope of work, list of statutory
requirements, scope on the part of DVC etc. are to be indicated.
5.3.5. Relevant drawing / specification is to be enclosed with the enquiry, wherever possible.
5.3.6. A Clause for pre-dispatch inspection at supplier’s works shall be
incorporated wherever felt necessary by the indenter.
5.3.7. Where sample is required to be furnished along with the tender, the
authority to whom it should be sent for testing/approval and the time within which
the sample
should be submitted are indicated correctly in the enquiry.
5.3.8. Quality Assurance Authority (DVC/3rd party) is correctly indicated along
with address.
5.3.9. Conditions of contract are correctly indicated in the enquiry.
5.3.10. The General and Special Conditions of contract, if any, are not to be
reproduced in the tender enquiry. They are the part of the bid document.
5.3.11. Delivery schedule for supply items / completion schedule for
Works/turnkey contacts are clearly indicated. 5.3.12. Insertion of Liquidated Damages Clause in tender enquiry for claim
against the delay in supplies /delay in completion of works/services.
5.3.13. Insertion of clause for the cancellation of contract and effecting risk
purchase.
5.3.14. In case of purchase of imported stores, the appropriate shipping clauses
are to be incorporated. Other special conditions viz. payment terms for Free on
Board (FOB)/Free alongside Ship (FAS) basis, etc., should also be indicated in
the enquiry.
5.3.15. Any other special clauses, as felt necessary by TIA to be incorporated in
the tender enquiry.
5.3.16. Value and Period of validity of performance guarantee (whether to cover
warranty period) should also be mentioned.
5.3.17. The correct quantity and unit with consignee-wise distribution should be
mentioned.
5.4. Qualifying Requirements:
The Qualifying Requirement of bidders intending to take part for any contract for
works related to Civil/Mechanical/Electrical through tendering may be considered
as detailed below:
5.4.1. For works upto DE of Rs.5 Lacs : To be decided by TIA.
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5.4.2. For works with DE above Rs.5 Lacs upto Rs.50 Lacs:
Experience of having completed similar works during last 7 years ending last
day of month previous to the one in which offers are invited shall be either of the
following:
(a) Three similar completed works each costing not less than the amount equal
to 30% of the estimated cost. or
(b) Two similar completed works each costing not less than the amount equal to 40% of the estimated cost. or
(c) One similar completed work costing not less than the amount equal to 70% of
the estimated cost.
5.4.3. For works with DE above Rs.50 Lacs :
Experience of having completed similar works during last 7 year s ending last day
of month previous to the one in which offers are invited should be either of the
following:
(a) Three similar completed works each costing not less than the amount equal
to 40% of the estimated cost .or
(b) Two similar completed works each costing not less than the amount equal to
50% of the estimated cost. or
(c) One similar completed work costing not less than the amount equal to 80% of
the estimated cost. 5.5. Mode of Tendering
Mode of tendering will be selected considering the following in general:
i) The total estimated cost of Purchase/ estimated value of works/services to be
made.
ii) Type of materials (proprietary or otherwise)
iii) No. of proven sources known and available.
iv) Urgency of requirement.
Depending on the above, followings are the mode of tendering which can be
adopted for the purpose of procurement / works contract /service contract:
5.5.1. Single Tender
5.5.1.1. Through press advertisement in most possible open manner.
5.5.1.2. For Works / services having estimated value below Rs.25 Lacs, the
following may also be reckoned as Open Tendering when delegation of power is concerned.
5.5.2. Limited Tender
5.5.3. Single Tender
5.6. Earnest Money Deposit
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Earnest Money Deposit for Tenders
In all cases of open tendering, Earnest Money Deposit shall be applicable and
regulated as follows: -
(i) For cases of estimated value up to Rs.5 crores:- 2% of the estimated Value.
(ii) For cases of estimated value above Rs.5 crores:- 1% subject to minimum of
Rs.10 lacs.
Earnest Money is not to be insisted in case of single tender enquiry of any value and limited tender enquiry for packages of estimated value upto Rs.15.00 lakhs.
In case of limited tender enquiry for packages of estimated value above Rs.15.00
lakhs, Earnest Money may be imposed at above rate at the discretion of TIA.
Small scale Industries registered with NSIC shall be exempted from payment of
EMD. SSI Units seeking such exemption must enclose valid registration
certificate from appropriate Govt. authority giving details such as validity, stores
etc.
5.7. Tender Opening
Tender will be opened on the due date and time indicated in the NIT. The
authorized representatives of the bidders may remain present during tender
opening.
For Single Stage Two Part bidding Techno-commercial Bid is opened and Price Bid is kept in sealed condition. Offered bid is evaluated by the Tender
Evolution committee based on the comparati ve Statement of the bid. After tender
evolution techno-commercially qualified bidders are informed for price bid
opening.
Price bid is opened on due date mentioned in the above letter. The
authorized representatives of the bidders may remain present during tender
opening.
After price bid open a comparative statement is made place to TEC/WSTC-
I/WSTC-II for evolution. There L1 bidder is decided and if the TEC/competent
authority feels that the price offered by the L1 bidder is high then negotiation may
be made with the l1 bidder as per proposal of the TEC and discretion of the
competent authority.
After successful negotiation, LOA/LOI/W.O./P.O. is placed.
Security Deposit Bank Guarantee as per approved format of DVC for
Erection/Supply will be submitted by the contractor/supplier and after acceptance
of the same an agreement is done before starting the Erection work only.
Salient features:
63
Liquidated Damage (LD): The provision has been kept in the contract/Purchase
Order that in case of delay in completion, for the reasons attributable to the
contractor, Purchaser/owner reserves the right to recover from the Vendor a sum
equivalent to 0.5% of the value of the delayed materials / work / equipment /
spares for each
week of delay and part thereof subject to maximum of 5% of the total value of the
contract as Liquidated Damage (LD).
Security for DVC supplied Materials: An Indemnity Bond as per approved format
of DVC for an amount equivalent indemnify value of materials to be supplied by
DVC free of cost to contractor is taken from contractor before issuance of DVC
materials to contractor.
6. Construction of Transmission lines and consumer service lines
Construction of transmission line of DVC is generally done by the out side
agency/contractor under supervision of DVC. But generally the consumer service
lines are constructed by the consumers itself under supervision of DVC. Some
Government consumer’s line is done by DVC with help of out side agency as a
deposit work.
The scope of work for the contractor is as follows:
6.1 Check Survey including detailed survey (if required), preparation and submission of Survey Sheet and line chart, Tower schedules plotting of towers in
route profile etc.
6.2 Excavation of Pits for foundation.
6.3 Stub setting/rail pole, concreting and backfilling.
6.4 Earthing of Tower bases.
6.5 Erection of Super structure checking, punching and tack welding up to bottom
X-arm.
6.6 Fixing of insulators with hardwares.
6.7 Stringing of power conductors and earthwire including fixing of vibration
dampers.
6.8 Fixing of anti-climbing devices, phase plates, number plates and danger
plates.
6.9 Right of way, tree cutting, Jungle clearance, Rly clearance, PTCC clearance,
forest clearance etc.
7. Construction of Sub-Station:
For Sub-station contractors are engaged for construction under supervision of
DVC. Following works are done by the contractors:
7.1. Constructions of civil foundations as per drawing, design and direction of
the engineer-in-charge.
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7.2. Erection and alignment of equipment support structures (wherever
required) as per DVC design.
7.3. Erection, alignment and adjustment of all equipments like CB, CT, isolator,
etc.
7.4. Erection and alignment of pipe Bus Support Insulators and 3”/2.5” /1.5”
IPS AL tubes including connection with respective equipment and buses.
7.5. Erection, alignment and stringing of the swing buses including dropper
and jumper connection between ‘A’ frame and gantries, Stringing of earth wires between gantries.
7.6. Painting of structural steel works, steel cable racks/trays etc including
supply of paints.
7.7. Erection, testing & commissioning of different equipments like
Transformer, circuit breaker, current transformer, isolators, control & relay panels
(for transformer), RTCC panels.
7.8. Laying, dressing, cleating, clamping and termination of all Control and
Power cables including supply of the termination, cleating, crimping, clamping
and dressing materials.
7.9. Supply of all consumables including bolts, nuts, washers etc. as required
for the complete job.
7.10. Erection and alignment of duplex Control & Relay Panels, and other
miscellaneous Panels inside the sub-station Control Room Building/Switchyard.
7.11. Arrangement of insurance coverage for all equipment in stores including those to be supplied by DVC during transit, storing, erection and commissioning
at site (the amount of insurance charges will be reimbursed by DVC).
7.12. Commissioning in presence of DVC team of representatives and carrying
out of all rectification repair or adjustment work found necessary during
inspection, testing, commissioning and trial run.
7.13. Return of all excess materials to the DVC specified stores at Maithon.
7.14. The contractor shall submit ‘BAR CHART’ showing the commencement
and completion of all activities.
8. Commissioning:
After Completion of all work related to installation, Erection GOMD is called for
Pre-commissioning and in the mean time an application is made to CEA for
inspection. After receipt of observation from GOMD and CEA, compliance report
is sent to GOMD and CEA (with CEA charge). CEA send an approval for
energization. GOMD may again check for the compliance. Then GOMD call CTC for testing and commissioning. After Testing all equipments Line or Substation
charged.
Before line is energized, visual examination of the line shall be carried out to
check that all nuts and bolts are tight and insulators and accessories are in
65
position. The earth connections shall also be checked to verify that these are in
order.
Before commissioning of the lines, the following tests may be carried out:
a) Conductor continuity test – The objective of this test is to verify that each
conductor of the overhead line is properly connected electrically (that is, the
value of its electrical resistance does not vary, abnormally from that of a continuous conductor of the same size and length). The electrical resistance of
the conductor shall be measured with a
wheatstone bridge or other suitable instrument.
b) Insulation resistance test – This test may b carried out with the help of a 5 KV
megger preferably driven to ascertain the insulation condition of the line.
The line may then be kept charged on no load at the power frequency voltage
preferably for 72 Hrs. for the purpose of full scale testing.
Note: The statutory authorities shall be informed before commissioning the lines
and their approval may be obtained in accordance with Rules 63 to 69 of IE
Rules 1956.
.
Transmission
66
Transmission
DVC had a humble beginning: a small generating unit with a few connected lines. Today it has a vast network of transmission lines and substations spread across the states of
Jharkhand and West Bengal, extending beyond its command area up to Jamshedpur and Howrah. DVC supplies bulk power at 33 KV, 132 KV and 220 KV through a network covering more than 5500 circuit kilometers. The DVC grid is interconnected with the State Electricity Boards of Jharkhand (JSEB, erstwhile BSEB) and West Bengal (WBSEB), Grid Corporation of Orissa and Power Grid Corporation of India Ltd.
Existing Lines (Ckt Kms.)
Existing Sub-stations (Nos.)
67
Sub-stations, replacing old electromagnetic relays by numerical relays, installation of high accuracy meters, to quote a few examples. VC has undertaken a major initiative to renovate and update the existing infrastructure: replacing old circuit breakers by new generation breakers of high capacity, increasing transformer capacities at various Sub-
stations. Transmission System
Charged with the responsibilities of providing electricity, the vital input for industrial growth in the resource-rich Damodar Valley region, DVC over the last 60 years has developed a big and robust transmission network consisting of 132 KV and 220 KV gri ds. DVC grids operates in unison with the eastern regional grid through 132 KV and 220 KV tie lines. All the power stations and substations of DVC are connected with the DVC grids. DVC power consumers are provided supply at 25 KV, 33 KV, 132 KV and 220 KV
pressure. DVC Transmission Lines in service at a glance
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Interconnecting Tie Lines with DVC Network
*Out of service.
DVC Substations in service (Nos.) at a glance
Transmission & Distribution Projects A. Renovation & Augmentation of existing infrastructure:
1. Transformer capacity augmentation- 2 nos. 80 MVA at Giridih and 1 no. 80 MVA at CTPS- completed.
2. Augmentation of 33 KV power supply to WBSEB at Belmuri Substation- completed. 3. Reconductoring of D/C 132 KV Putki-Nimiaghat lines- completed. 4. Reconductoring of D/C 132 KV Bokaro-Konar-Barhi lines- almost completed. 5. Reconductoring of 132 KV Putki-CTPS lines. 6. Replacement of 25 MVA Transformers for Railways supply- 1 no. each at
Pathardih,
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Ramkanali and Koderma and 2 nos. at Kumardhubi.
7. Retrofitting of Protection Relays (Phase-II). B. New Projects under construction:
1. 220/132/33 KV Barjora Substation: 220/33 KV infrastructure developed and in service since 06.01.2006- Creation of 220/132KV infrastructutre is in progress. 2. 220 KV D/C MTPS-Durgapur line completed. 3. 220/132/33 KV Dhanbad substation and allied works of LILO of 220 KV CTPS-
Kalyaneswari D/C lines at Dhanbad substation. 4. Diversion of D/C 220 KV DTPS-Parulia, 132 KV DTPS-Kalipahari & 132 KV DTPS-CTPS lines at Durgapur Steel Project area. 5. 132/33 KV Jamuria substation and allied LILO of 132 KV CTPS-DTPS line at Jamuria substation. 6. D/C 220 KV MTPS-Gola line extension upto 220 KV Ramgarh substation.
7. 33 KV Koderma Receiving Station. 8. 33 KV BIADA Receiving Station at Bokaro and allied 33 KV CTPS-BIADA line. C. New Projects being taken up for construction:
1. 220/132/33 KV Substation at Gola Substation. 2. 220/132/33 KV Uluberia Substation. 3. 220/132/33 KV Giridih Substation. 4. 220 KV D/C LILO of BTPS-Jamshedpur at Gola Substation and extension upto Ramgarh Substation.
5. 132/33 KV Poradih Substation. 6. Construction of 220 KV D/C Dhanbad-Giridih and Koderma-Giridih lines and D/C 132 KV Govindpur-Dhanbad. 7. 400 KV power evacuating lines from Durgapur Steel Project and Raghunathpur Project.
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Gridmap
Substations
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At 33 KV Receiving Stations
Kumardubi Sub-Station
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Fig. Single Line Diagram Of Kumardubi Sub-Station
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SWITCH YARD –
A switch yard is a junction connecting the transmission and distribution system to the power plant. The switch yard houses transformers, circuit breaker ,isolator, earth switch, current transformer, capacitor voltage transformer, wave trap, surge arrestor. The supply to the bus-bars from alternators is taken though transformers and circuit
breakers of suitable ratings. Control, protection and monitoring for the switchyard will be located in the switchyard control room. Switch yard is a place where power is transmitted from one place to another place. Switch yard consists of many protective and metering device for smooth transmission of line and for protection of unit.
TRANSFORMER –
A transformer is a device that transfers electrical energy from one circuit to another through inductively coupled conductors- the transformer’s coils. 50 MVA transformers have been used to step-down the voltage in switch yard.
Fig. Transformer
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CURRENT TRANSFORMER (C.T.) – Current transformers are commonly used in metering and protective relays in the electrical power industry. When current in a circuit is too high to directly apply to
measuring instruments, a current transformer produces a redu ced current accurately proportional to the current in the circuit, which can be conveniently connected to measuring and recording instruments. A current transformer also isolates the measuring instruments from what may be very high voltage in the monitored circuit.
Fig. Current Transformer
It is a step down transformer minimizing current 800 A to 5 A. These instrument transformer are connected in AC power circuit to feed the current coils of indicating and metering instrument (Ammeter, Wattmeter) and protective relays.
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POTENTIAL TRANSFORMER –
A potential transformer (PT) is used to transform the high voltage of a power line to a
lower value, which is in the range of an ac voltmeter or the potential coil of an ac voltmeter.
Fig. Potential Transformer
It is a step down X-mer which step down (minimizing) the voltage to fed the controlling system of the unit for safe value. It is used for protection of the unit and metering also.
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BUS BAR –
Fig. Bus Bar
In switch yard two group of bus bars used.
1. Transfer bus bar 2. Main bus bar The protection of bus bars is very important since they form a vital role in supply system and if a fault develops in this part considerable damage occurs. The bus bar area for the purpose of protection includes circuit breakers, isolating
switching & lighting arresters.
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CIRCUIT BREAKERS –
Circuit breakers consists of essentially of current carrying contacts called electrodes.
These are normally engaged but under fault condition separate to interrupt the circuit
when the contacts are separated on arc is set up between them. The function of
relays and circuit breakers in the operation of a power system is to prevent or limit
damage during faults or overloads, and to minimize their effect on the remainder of
the system. This is accomplished by equipments into various arrangements Bus bar is
a term used for main bar of conductor carrying an electric current to which many
connections may be made. These are mainly convenient means of connecting
switches another. dividing the system into protective zones separated by circuit
breakers.
During a fault, the zone which includes the faulted apparatus is de-energized and
disconnected from the system. In addition to its protective function, a circuit breaker
is also used for circuit switching under normal conditions.
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Each having its protective relays for determining the existence of a fault in that zone and having circuit breakers for disconnecting that zone from the system. It is desirable to restrict the amount of system disconnected by a given fault; as for example to a single
transformer, line section, machine, or bus section. However, economic considerations frequently limit the number of circuit breakers to those required for normal operation and some compromises result in the relay protection. Some of the manufacturers are ABB, AREVA, Cutler-Hammer (Eaton), Mitsubishi Electric, Pennsylvania Breaker, Schneider Electric, Siemens, Toshiba, Končar HVS and others.
Circuit breaker can be classified as "live tank", where the enclosure that contains the breaking mechanism is at line potential, or dead tank with the enclosure at earth potential. High-voltage AC circuit breakers are routinely available with ratings up to 765,000 volts.
Fig. Circuit Breaker
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LIGHTNING ARRESTER –
Fig. Lightning Arrester
A lightning arrester (also known as surge diverter) is a device connected between line and earth i.e. in parallel with the over headline, HV equipments and substation to be protected. It is a safety valve which limits the magnitude of lightning and switching over
voltages at the substations, over headlines and HV equipments and provides a low resistance path for the surge current to flow to the ground. The practice is also to install lightning arresters at the incoming terminals of the line. All the electrical equipments must be protected from the severe damages of lightning strokes. The techniques can be studied under:-
1. Protection of transmission line from direct stroke. 2. Protection of power station and sub-station from direct stroke. 3. Protection of electrical equipments from travelling waves.
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Types of Arrestors – 1. Rod/Sphere gap - It is a very simple protective device i.e. gap is provided across the stack of Insulators to permit flash -over when undesirable voltages are
impressed of the system.
2. Expulsion type LA - It have two electrodes at each end and consists of a fiber tube capable of producing a gas when is produced. The gas so evolved blows the arc through the bottom electrode.
3. Valve type LA - It consists of a divided spark-gap in series will a non-linear resistor. The divided spark gap consists of a no. of similar elem ents, each of it two electrode across which are connected high resistor.
WAVE TRAP – Line trap also is known as Wave trap. What it does is trapping the high frequency communication signals sent on the line from the remote substation and diverting them to the telecom/teleprotection panel in the substation control room (through coupling capacitor and LMU). It is an electronic filtering device designed to exclude unwanted signals or interference from a receiver. It is a tuned (RLC) circuit that reduces
interference between stations.
Fig. Wave Trap
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This is relevant in Power Line Carrier Communication (PLCC) systems for communication among various substations without dependence on the telecom company network. The signals are primarily teleprotection signals and in addition, voice and data communication signals. 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.
ISOLATOR – Isolator switch is used to make sure that an electrical circuit can be completely de-
energized for service or maintenance. High-voltage isolation switches are used in electrical substations to allow isolation of apparatus such as circuit breakers and transformers, and transmission lines, for maintenance. “Isolator" is one, which can break and make an electric circuit in no load condition. These are normally used in various circuits for the purposes of Isolation of a certain portion when required for maintenance etc. Isolation of a certain portion when required
for maintenance etc. "Switching Isolators" are capable of - • Interrupting transformer magnetized currents • Interrupting line charging current • Load transfer switching
Fig. Isolators
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Its main application is in connection with transformer feeder as this unit makes it possible
to switch out one transformer, while the other is still on load. The most common type of
isolators is the rotating centre pots type in which each phase has three insulator post, with
the outer posts carrying fixed contacts and connections while the centre post having
contact arm which is arranged to move through 90` on its axis.
The following interlocks are provided with isolator -
a) Bus 1 and 2 isolators cannot be closed simultaneously.
b) Isolator cannot operate unless the breaker is open.
c) Only one bay can be taken on bypass bus.
d) No isolator can operate when corresponding earth switch is on breaker.
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CONCLUSION
DVC is one of the biggest sectors of the country to know about different
power generation processes. Through the project works on different
power generation and their auxiliary units we can gain a lot of practical
knowledge. They are very useful for the future carrier of ELECTRICAL
ENGINEERING student because of the fact of the practical raining
being on this important subject is boon for the younger generation.
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