Volume 5, Issue 8, August – 2020 International Journal of Innovative Science and Research Technology

ISSN No:-2456-2165

Construction Management of
EVH & UVH Transmission Lines
A Practical Guide
Biswanath Sahu
B.Sc. Engg. PGDM (HRM), PGDM ( E&E), Gmpe(Iim-I)
Country:- India

Abstract:- Generation projects are generally located in Keywords:- The key words in this paper are Right of Way
areas nearer to availability of inputs required for power (ROW); Crop, Tree and land compensation; clearances;
generation such as water, coal, approach roads and Government stipulations; commercial issues, Farmer
having rail transport facilities. The load centers are at issues; soil conditions; Forest, Highways, Rly ways
different locations depending its own convenience load approvals etc.
requirement. Hence there is necessity of transmission of
bulk power from generation sites to load or consumer I. INTRODUCTION
points.
 Power supply has become essential for day to day life
Hence the utility of power transmission through sustenance in a society.
EHV/UHV transmission lines. Further for transmission  Global climatic developments demand supply of
of bulk power from one region of country to another reliable and quality power at minimum cost having
region also warrants establishment of Transmission minimum impact on environment.
lines. The technical as well as social and commercial  It is s a tough challenge to maintain balance among
criteria are very important while construction and mutually opposing issues such as reliability in bulk
erection of EHV and UHV transmission lines. These power transmission, maintenance of environmental
issues are of public as well as organization importance sustainability with economic efficiency.
and hence efforts have been made in this presentation to  The above tricky Situations can be tackled by focusing
elaborate in detail. our action in the following areas.

Adopting innovative and advanced technologies in areas

of power transmission suchas:
 HVDC (High voltage Direct current) Power Transmission
System.

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 FACTs (Fl exi bl e AC Power Transmission System) by smart appliances, renewable & energy efficient
make use of Series and Shunt capacitors. resources.
 SMART Grids. Exploring wide usage of Super  Electronic power conditioning & control of the
conductors in Transmission Sectors. production and distribution of electricity are important
 Transmitting power at Ultra high Voltage level and aspect of smart grid.
reducing comparative transmission losses.  It makes use of state estimation that improves fault
detection and self-healing & ensures reliable supply of
 Series & Shunt Compensation electricity and reduced vulnerability to natural disasters
 FACTS for series compensation modify line impedance or attack.
 X is decreased so as to increase the transmittable active  It ensures Flexibility in Network topology.
power.  Ensures efficiency of energy infrastructure including
 P=V Square/X-Xc (Sin delta) DSM
 In Shunt compensation reactive current is injected into
line tomaintain voltage magnitude.  ULTRA HIGH VOLTAGE TRANSMISSION:
 Transmittable active power is increased.  Operating at greater than 800KV to expand T&D
 P=2V square/XSin(delta/2) capacity and reduce losses.
 Power flow in case of EHVAC &UHVAC  1150KV UHVAC in Russia 2362 Km length
P=0.5(Vs.Vr)/xl ,Vs= Sending end voltage & Vr=Receiving line,1000KV UHVAC in Japan. In China 1000KV
end voltage. UHVAC and 800KVUHVDC are in operation.
 (xl is reactance of line per km & per phase.)& xl/Km of  HV-33KV, EHV-110-400KV and UHV- 800KV&
line 400KV-0.327,765KV- 0.272,1000&1200KV-0.231 above.
 Allows Generation plants closer to fuel source and away
 HVDC Transmissionlines from population centers.
 HVDC also called electrical super highway used for bulk  Ability to integrate widely dispersed renewable power
transmission of electrical power. sources into a national distribution network.
 Long distance power transmission may be less expensive  Biswanath chariali (Assam)-Agra 800KV UHVDC
& have lower losses. capacity 6000MW, length 1728 Kms To be
 1100KV link in china completed in 2019 over distance commissioned
of 3300kmwith power flow 12GW. 1200KV UHVAC link at Testing Station Bina under
 HVDC allows power transmission between testing.
unsynchronized Ac transmission systems.
 HVDC allows power flow between grids running in  Technology & System advancement
different frequencies such as 50 Hz & 60Hz and  Introduction of 400KV lines in 1977
improves stability & economy of each grid.  Beginning of 765 KV lines in 2000
 Longest HVDC link Rio in Brazil +600KV bipolar 2375  Introduction of HVDC Back to Back-1989& HVDC
Km having power flow 3150 MW. Bipole-1990
 HVDC have low resistive loss (3% ) which is 30 to 40%  Introduction of Electricity new Act-2003 & Open
less than AC due to low current ,less conductor, no skin Access-2004
effect.
 Disadvantage with HVDC are conversion, control, II. FIELDWORKSFORCONSTRUCTIONOF
availability & maintenance. TRANSMISSIONLINES
 HVDC CB are difficult to build because of arching in
comparison toAC because of voltage of inversion in AC.  Survey
 A ReconnaissanceSurvey:
 TYPES OFHVDC  shortest routefrom dispatchendtoreceivingendoflineistobe
 Monopole- Between two AC systems one DC Line with drawnonSurveyOfIndiaMapwhichiscalled”BeeLine”
earth return.  Walk down survey is to be carried out along the line
 Bipolar-Two conductors are used in opposite polarity wrt the BEE line approaching all possible approaches to
hence negligible earth current. line.
 Back to Back- It is a plant in which both converters are  Close to BEE line tentative line is to be marked
in the same building. (DC line length is as short as avoiding passing of line through villages, towns,
possible) It is used for coupling of grids of different unapproachable hillocks, forests, air ports, Rly stations.
frequencies, different phase relationship or both.  While walking various crossings such as unavoidable
 Multi-terminal system- can be series, parallel or hybrid. forests, Rail tracks, Rivers, power lines etc.&
approximate distances from airport Station major villages
 SMART GRID & towns are marked and noted.
 Smart grid is an Electrical grid which includes a variety  Earth resistivity is taken wherever soil strata changes.
of operations & energy measures such as smart meters, (SR=2pieSR)
S=50mtr (4 Electrode methods)

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 In line with Sec 164 of E. Act-2003 Gazette Notification III. TECHNICAL DETAILS
is published in State Gazette and a copy of notification is
published in local newspapers.  Type of Towers:
 Communication to be given to state Highway, National There are four types of Towers depending upon angle of
High way, Rail ways, PTCC authority, forest and airport deviation.
authorities and Transco’s regarding power line crossings. A type upto2 degree, B-2 to 15, C-15to 30&D-upto 60 and
DEAD END(DE)
 PRELIMINARY SURVEY (ROUTEALIGNENT) Section Towers: without angle
 Actual survey with theodolite or total station is carried Any angle towers after every 15 spans or 5Kms whichever
out along the Tentative route marked during is less for plain areas and 10 spans or 03 Kms in hill areas.
reconnaissance survey. Basic span: Distance between towers
 Fixing of angle tower locations done. 400KV-400mtrs,220KV-350mtrs,132KV-335mtrs.
 Finalization of crossing locations (River, Power lines, River crossings& road crossings span is 300mtrs or 80% of
Rail way tracks SHW& NHW, P&T lines etc. normal.
 Concrete pillars of size 200x200x300mm are fixed at
angle locations 50mm below ground. Rail track, NH & P&T line crossings angle 90 deg and
 Wooden pegs of size 50x50x150mm are embedded on angle tower on either sides or distance of towers H+6
where H is tower height.
ground along the line in between angle locations at
750mtrs intervals at prominent places.
 DETAILED SURVEY&PLOTING OF PROFILE
 Direction pegs are marked for angle &section tower
• Levels of ground profile along route is taken at 30 mtrs &
locations.
wherever terrain changes.
 Earth resistivity along the route is taken. • Levels are marked on profile sheet taking starting point
as RL100
 APPROVALS SOUGHT • Detail levels of all crossings taken.
 Approval from local forest authority to carry out survey • Heights of all salient features 50 mtrs on either side of
and trimming some trees if required. line are taken.
 Proposal in prescribed format to be submitted to forest • Profile is plotted in 1cmsq graph sheet taking
dept. For obtaining approval to lay line inside forest land. 1cm=20mtrs Horizontal & 1cm=2mtr in vertical.
 Route approval from internal Authority. • Profile shows longitudinal as well as cross section view
 Submission of route with soil data to PTCC, RLY, of line.
AVIATION • All crossings with angle of crossing, heights are plotted
in profile.
(if tower height is more than 45 meters), chief
Electrical Inspector of state & center, Transco for power line
crossings, SHW& NHW for road crossings, etc.

 TOWERSPOTTING&TOWERSCHEDULE

Fig 1

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• Sag Template is prepared specific to line voltage and
conductor used.
• Template is prepared as per I E Rule taking care of
vertical& wind load and is approved by competent
authority.
• The following set of Parabolic curves are drawn on a
transparent celluloid or acrylic clear sheet:
• 1 Cold or uplift curve-sag at minimum temp -2.5deg
&still wind.
• 2 Hot or max sag curve-Max temp &still wind.
• 3 Ground clearance curves.4.Tower footing curve.

Fig 3

Fig 2

 CLEARANCE DETAILS
• As per I E Rule -77 the Ground clearances are:
• 132 KV-6.10 mtrs,
• 220 KV-7.00mtrs
• 400KV-8.84mtrs
• 800KV-12.40 mtrs

• Rail way crossings (above rail level):

 66KV-132KV-14.60mtrs&132-220KV-15.40mtrs
 220-400 KV-17.90&400-500KV-19.30mtrs500KV-
800KV-23.40mtrs.

Fig 4:- Profile

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 POWER LINE TO POWER LINE CLEARANCE

132KV 220KV 400KV 800KV

• 11KV-66KV 3.05 4.58 5.49 7.94
• 132 KV 3.05 4.58 5.49 7.94
• 220KV 4.58 4.58 5.49 7 94
• 400KV 5.49 5.49 5.49 7.94
• 800KV 7.94 7.94 7.94 7.94
Table 1

 OTHERCLERANCES
• Minimum Clearance between Conductor & Tree
• 400KV-5.5mtr
• ,500KV-7.4mtr,
• 765 KV-9.0mtr
• 800KV-10.6 mtrs
• 1200KV-13.0mtr
• Clearance Between Lowest cross arm and Traction
Mast:
• 400KV-9.71mtrs
• 500KV-11.45mtrs
• 800KV-16.67 mtrs

 OTHER CRITERIAS
• To meet ground clearance tower with extension or Fig 5
reduced span whichever is economical is to be used.
• Span should be as close to as design span. • Stub setting is done with stub template.
• Power line crossings double suspension and tension • Stub and other accessories required along with
Insulators used. concreting materials are to be made available at site.
• River crossings:
• Non-Navigated- clearance 3mtrs from High Flood
Level.
• Navigated-approval from authority is required.
• Road crossings: NH & Major SH- span 250mtrs(double
tension & suspension insulators for clearance & ODC
consignment.

 SPAN &SAG
• Normal span-Design span
• Wind Span-On either side of a tower 50% spans
• Weight span- Tower either side lowest conductor point
distance.
• Max Sag =(l square d q)/8f where l=length of
conductor=W/A (weight/mtr of conductor, A-area of cross
section) q=Loading factor=01 for still wind. F= Stress
on conductor cross section.
• Sag at basic span/ sag at any span= Basic Span
square/Span Square
• From profile Location wise tower schedule that is no of
different towers and extensions are prepared. Fig 6

 CHECK SURVEY( Location marking on ground) & stub  RIGHT OF WAY(PowerCorridor)

setting • Trees coming in Power corridor need to be numbered. A
• Location of angle towers and suspension towers are statement detailing height, girth and nature& yield to be
marked on ground. prepared with owner details for assessing compensation.
• Direction pegs are fixed on ground for angle towers. • ROW for 132 KV-
• During stub setting again location points are checked 15x2=30mtr,220KV=35mtr,400KV=52mtr &765
and confirmed. KV=85 mtrs.
• Pit marking for trial pit excavation to classify soil is • In forest areas the ROW required is:
done.

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• 11KV-07mtr,33KV-15,66KV-18,110KV-22,132KV-  TOWER ERRECTION
27,220KV-35
• 400KVS/c-46, D/C -46mtr,500KV-52,765KV-S/C-
64,D/C-67
• 800KV-69mtr &1200KV-89 mtrs

 PAYMENT OF COMPENSATION
• After route is finalised ownership of land and crop and
trees affected or going to be affected during foundation,
tower erection & stringing need to be got certified by
revenue officials (Patwari , Tahsildar)
• Notices need to be issued to the owners that they are to
be suitably compensated as assessed, certified and
approved by revenuedept.
• Statement for Damaged crops & trees to be submitted to
revenue/Horticulture/forest dept. for finalisation of
amount.
• For crop &tree as many times these are damaged to be
compensated.
• For land for tower & overhead conductor as decided by Fig 7
collector to be compensated.
• Foundations are classified as:  Methods of Tower erection:
• For Normal soil-Dry, Wet, Partially submersed, Fully • 1 Built up method or piece method by Deric & Gi pole(
submerged. widely used)
• This is the most difficult part of Execution in • Section wise by crane.
Transmission line works. • Ground assembly and total tower lifting by crane-Rarely
used, for small height towers feasible.
 SOIL CLASSIFICATION • It is a very specialized and skilled job can be done by
• SOIL at tower location is classified as: experienced gangs.
• Normal soil-(If the soil is no other types given below)
• Black Cotton
• Fissured Rock
• Hard Rock
• Sandy soil

 FOUNDATION CLASSIFICATION
• Dry- soil is normal, water is not met up to bottom of pit
at 3.0 mtr in worst season.
• Wet-Soil is normal, water met on surface like paddy field
after that no water up to 1.5 mtr from GL.
• PS-Soil normal, water met with in 0.75 to 1.5 mtr from
GL
• FS-Soil normal, water met with in GL to 0.75 mtr
• WBC-soil is Black cotton (at least 1.0 mtr from bottom
of pit)
Fig 8
• FR-If soil is Fissured rock, marram (at least 1.0 mtr
from bottom of foundation. If water within 1.5 mtr from
• Proper supervision to ensure safety of people on job is
GL special foundation.
essential.
• HR- Soil HR at least 1.0mtr from bottom. Sandy soil-
• Tack welding at least up to bottom cross arm & applying
special.
cold galvanized paint is required.

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 STRINGING ARRANGEMENT: • The following are activities:
• Checking of Insulators and other line hardware &
accessories.
• Fixing of rollers/Travelers, running blocks, D-sackal,
yoke plates.
• All DE and angle towers are to be provided stay/anchors.
• Double stay for cross arms& single for peak to be given.

Fig 9

Fig 10

• Up to 220 KV Tractors used for pulleying, 400Kv- • Tension is calculated on equivalent span=Sqroot of(
Tensioner& pullers. sigmaL3/sigmaL)
• Rough sagging done first with winch,4way ( L is individual spans) Tension is given from Sag
pulley/Equalizing pulley& dynamometer. Tension chart and sag is checked in last span.

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 EARTHING&FINALCHECKING IV. CONCLUSION

Construction & erection management of intra country,

inter region and international transmission lines are no
doubt very tough now a days because of awareness of
people, pollical interferences, environment and technical
stringent criteria. But it needs prudent people supporting
attitude of officials executing the work and support of all
stakeholders to complete this very difficult task. The norms
of compensation for trees to be felled and standing crops to
be damaged and utility of land to be affected need to
standardize through deliberation of experienced people of
different segments so that the issues can get resolved with
less litigation and full satisfaction of all in a collaborative
approach with less time. Otherwise generating stations gets
ready for commercial operation of plant but due to non-
availability of proper transmission networks plant remains
idle which is a mere national waste. Similarly, the people
also should carry an impression that the project is for them
and for greater befit of nation so it is also their duty to
come to an agreeable solution without becoming much
greedy. Government norms also should finalize with
positive approach with a view to bring the project faster
Fig 11 with supportive approach to affected people.

• Tower footing resistance is to be maintained as less than REFERENCES

10 ohm.
• Two types of earthing is done for towers: [1]. Construction manual of Rajasthan TRANSCO
 Pipe type if soil is normal as per IS 5613/IS 3043 in [2]. Construction manual of AP TRANSCO
Leg-1 if required Leg-3 also. With 25mmGI pipe. [3]. Internet
 Counter poise if soil is rocky/FR $ GI wires from 04 [4]. Self-work Experience
legs 25 mtr each or more if required(7/3.66mm)

Fig 12

• Fixing of all accessories & final checking

• To megger of line.
• Charging.

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