SURVEY & TOWER SPOTTING FOR TRANSMISSION LINES

BY

G. EMMANUEL MADHUKAR

APTRANSCO

TRANSMISSION LINES

TRANSMISSION LINES

TRANSMISSION LINES

• Extra High Voltage – 110 kV, 132 kV, 220 kV, 400 kV

• Ultra High Voltage– 765kV

• High Voltage Direct Current– ±500kV

TRANSMISSION LINES

• Survey is the most important activity Survey is the most important activity

• Best possible routeBest possible route

• Right of WayRight of Way

• Techno-Economical ProjectTechno-Economical Project

• Timely completion of the projectTimely completion of the project

• Increasing DemandIncreasing Demand

PRELIMINARY SURVEY AND WALK OVER SURVEY

• Topographical map

• Bee line

• Identify possible routes

• Familiarize

• Indicate the feasibile routes

TOPO MAP

TOPO MAP

Sending end SSSending end SS

Receiving end SSReceiving end SS

AP 1AP 1

AP 2AP 2

AP 3AP 3

AP 4AP 4

Bee LineBee Line

PRELIMINARY SURVEY – SELECTION OF ROUTE

• Shortest possible route

• Less number of deviations

DETAILED SURVEY – TOOLS

• Theodolite & Ranging rods

• Dummpy level & Measuring staff

• Measuring chain

• Megger

DETAILED SURVEY – Theodolite

DETAILED SURVEY

• Fixing of Alignment

• Fixing of Line Points

• Fixing of Angles of deviation

• Fixing of Angle Points

• Fixing of Direction Points

• Measuring of distance between Angle Points

• Levels at every 10 M interval or where there is level difference of 30 Cm

DETAILED SURVEY

• Details of Roads

• Details of Villages

• P & T Lines Crossings

• All Power Lines Crossings – LT to 765 kV

• Railway Crossings

• River Crossings

• Agricultural wells, Field bunds & Earth bunds etc.

• Measuring Soil resistivity at 1 Km interval

• Trial Pits

• Crop & Tree enumeration

DETAILED SURVEY-OBLIGATORY POINTS

• Avoid

• Reserve Forest Area

• Military Firing Ranges

• Aerodromes

• Inhabited and thickly populated areas

• Hilly terrain

• Marshy, Low lying & Submersible areas

• Higher & 90 degrees angle turnings

• Oil & Gas storage areas

DETAILED SURVEY – CORRIDORS

• 132 kV Line 27 M

• 220 kV Line 35 M

• 400 kV Line 52 M

DETAILED SURVEY –LINE PROFILES

• Graphical representation

• Scale

X-axis 1 Cm = 20 M

Y-axis 1 Cm = 2 M

• Plot Plan of Alignment of Line from AP to AP

• Plot Distances

• Plot Levels with respect to distance

DETAILED SURVEY –LINE PROFILES

• Indicate all Power Lines crossings: LT to 765 kV

• Indicate all P & T Lines crossings

• Indicate all Railway crossings

• Indicate all River crossings

• Indicate all Roads: Cart Tracks to National Highways

• Indicate all Villages

DETAILED SURVEY –LINE PROFILES

• Indicate all Agricultural wells

• Indicate all Field bunds & Earth bunds

• Indicate all Boulders

• Indicate all Ponds & Lakes

• Indicate type of Soil

• Indicate Crops & Trees

DETAILED SURVEY –LINE PROFILES

DETAILED SURVEY –LINE PROFILES

DETAILED SURVEY –LINE PROFILES

DETAILED SURVEY –LINE PROFILES

TOWER SPOTTING –SAG TEMPLATE

TOWER SPOTTING

• Identify the position of Terminal Tower

• Start from Terminal Tower

• Match the tower footing curve with the position of TT

• Adjust the position of template

• Ensure Ground Clearance

• Identify the position of next tower

• Move the template to the next tower

• Repeat the procedure

TOWER SPOTTING

• NORMAL SPAN: It is the design span

• ACTUAL SPAN: It is the actual distance between two adjacent towers

• NULL POINT: It is a point in a span where the position of the conductor is lowest (or) It is a point in a span where the sag is maximum

• WEIGHT SPAN: The distance between two adjacent null points

• WIND SPAN: It is the distance between the two centre points of adjacent spans

TOWER SPOTTING –SPAN LIMITATIONS

SPAN 132 kV 220 kV 400 kV

NORMAL SPAN 320 M 350M 400 M

WIND SPAN

Both 320 M 350 M 400 M

Single 192 M 210 M 240 M

WEIGHT SPAN

Both 400 M 450 M 600/800 M

Single 240 M 270 M 300/400 M

TYPE OF TOWERS

ANGLE (in degrees)

132 kV

220 kV

400kV

0 to 2 P A DA

2 to 15

R

B DB

15 to 30 C DC

Above 30 S D DD

TYPE OF TOWERS

ANGLE (in degrees)

132 kV

220 kV

400 kV

0 to 2 K X MA

2 to 30 L Y MC

Above 30

M Z MD

132 kV TOWERS Suspension

3900

3860

3860

14653

4200

Tension

7200

3900

4000

12583

7750

220 kV TOWERS Suspension

4865

5050

5050

19380

6295

Tension

7795

5050

5082

17048

10800

400 kV TOWERS Suspension

3000

8000

8000

25800

12000

Tension

6800

8000

8100

22000

15000

RIVER CROSSING TOWERS JC

4729

5127

5268

6357

17670

AT/400 kV

6900

9000

9000

46570

25000

EHV TRANSMISSION LINES CROSSING

CLEARANCES

132 kV 220 kV 400 kV

Ground Clearance 6.1 M 8.5 M 9.0 M

LT to 132 kV and P& T Lines

3.1 M 4.6 M 5.5 M

220 kV 4.6 M 4.6 M 5.5 M

400 kV 5.5 M 5.5 M 5.5 M

CLEARANCES

132 kV 220 kV 400 kV

Highway Crossing 9 M 9 M 9M

Railway Crossing 14.6 M 15.4 M 17.9 M

Railway Crossing Span (Max)

2/3 of NS 2/3 of NS 2/3 of NS

Distance between Tower & Railway

Track (Min)TH+6 M TH+6 M TH+6 M

TOWER SCHEDULES

Location No.

Type of Tower

Angle of Deviation (degrees)

Span (M)

Left Wt. Span (M)

Right Wt. Span(M)

Total Wt. Span (M)

Remarks

SS Boom - - - - Boom at sending end SS

70

1 TT S 35 L - 75 -Terminal tower at sending

end SS

210

2 P - 135 150 285

300

3 R 22 R 150 130 280 Near village

280

4 P+3 - 150 125 255 33 kV Line crossing

250

CHECK SURVEY

• Marking of Tower Location

• Forward & Backward Line Points

• Pit Marking

• Excavation

MODERN TECHNIQUES

• Global Positioning System

• Total Station

• PLS CADD

GLOBAL POSITIONING SYSTEM

• Satellite dependent

• Latitude & Longitude coordinates of the position

• Starting coordinates and ending coordinates

• Map Source Software

• Google Earth

• Topo sheet can be generated

• Bee Line & Routes can be marked

GLOBAL POSITIONING SYSTEM

TOTAL STATION

• Similar to Theodolite

• Not dependent on satellite

• Arbitrary Coordinates of the position

• Coordinates of the position obtained from GPS

• Alignment, Distance & Levels are recoded simultaneously

• Horizontal & Vertical Angles can be recorded

TOTAL STATION

• Raw data

• Text

• Auto Plotter

• Auto CAD

• Line Profile can be generated

PLS CADD

• Data from Total Station

• Sag calculation data

• Tower Spotting

• 2-D Model can be generated

• 3-D Model can be generated

PLS CADD

PLS CADD

IMPORTANT POINTS- Survey

• Length of the line

• Levels in the corridors

• Crossings

• Markings in check survey

Thank You&

God Bless You