1200 kV system

DESIGN OF 1200 KV TRANSMISSION LINE

R. N. Nayak, Executive Director

M. Krishnakumar, General Manager

Anish Anand, Chief Design Engineer

Power Grid Corporation of India Ltd.Gurgaon, INDIA

Indian Power System – 2025 & Beyond• Peak Demand : 4,50,000 MW (3

times of 2012)• Installed Capacity : 6,00,000MW

(3 times of 2012)• Power from ER/NER to

NR/WR/SR : 80,000-90,000 MW (4 times of 2012)

• Inter Regional Capacity : 1,40,000MW (3.5 times of 2012)

• Next Level Transmission Network i.e. 1200kV UHVAC Network

• Main Transmission Level : 1200kV UHVAC/800kV HVDC Network

• 765kV EHVAC and 500kV HVDC System would be used as support Tr. Network

• 400kV AC System would be used as Sub-transmission Network

RAICHUR VIJAYAWADA

MADRAS

TEHRI

BANGALORE

HYDERABAD

DHULE

ITARSI

BINA

JAIPUR LUCKNOW

JEYPORE

KISHENPUR

AGRA

MOGA

BAREILLY

DEHGAM

LEGEND

MEERUT

1200KV UHVAC LINES

765KV UHVAC LINES

800kV HVDC BIPOLE

SATNA

SEONI

SASARAM

SIPAT

GWALIORBALIA

KOTA

RANCHI

WARDHA

SOLAPUR

PUNE

NKSTPP

FATEHPUR

SASAN

INDORE

GAYA

MUNDKA

IB VALLEY

PURNEA

MUMBAI

SILIGURINERPOOLINGPOINT

DESIGN & OPTIMIZATION OF 1200 KV TRANSMISSION

LINE

Review ofExisting systems

& Practices

Bundle Conductor studies

Selection of clearances

Insulator string design

Tower Configuration

Analysis

Tower Design Study

Tower Fdn. Design/Study

Line Cost & Optimization

Economic Evaluation Of

Line

Results

TYPICAL TRANSMISSION LINE DESIGN OPTIMIZATION FLOW CHART

1200 KV TRANSMISSION LINE DESIGN- STUDIES UNDERTAKEN

PRELIMINARY STUDIES UNDERTAKEN

Clearances & Tower Configuration Analysis

Thermal Rating & Surge Impedance Loading

Conductor Surface Gradients & Corona Onset-gradients

Insulation / insulator string design

Electric Fields at ground

Interference PerformanceRadio InterferenceAudible Noise

1200 KV TRANSMISSION LINE DESIGN- STUDIES UNDERTAKEN

CONDUCTOR-BUNDLES ANALYSED

Hexagonal ACSR Lapwing (Conductor Dia. 38.16 mm)

Octagonal ACSR Moose (Conductor Dia. 31.77 mm)

Octagonal ACSR Bersimis(Conductor Dia. 35.05 mm)

Octagonal ACSR Lapwing(Conductor Dia. 38.16 mm)

1200 KV TRANSMISSION LINE DESIGN- CONFIGURATION FEATURES

Basic Configuration : I – V – I ; Delta

Air-gap / Live – metal Clearance Requirements

Power Frequency Clearance : 2.3 m (under Maxm. Swing – 55 deg)

Switching Surge Clearance : 10 m (under stationary condition / Swing – 10 deg)


Insulation Requirements Total Required Creepage Distance : 21600 mm (18 mm/kV)

Insulation / String length : 10 / 11 m

Required Number of Insulators 320 kN : 55 Nos.

(195 mm spacing, 390/400 mm creepage)

420 kN : 50 Nos.

(205 mm spacing, 525 mm creepage)


Phase to Phase SpacingMinimum Electrical Requirement : 12 m

Phase to Phase spacing based on Live-metal clearances : 27.5 - 30 m

Ground Clearance Minimum Ground Clearance as per IE Rules : 16 m

Ground Clearance proposed : 23 m (based on 10 kV/m electric field limit)

25 m

20 m

77m

15 m 15 m

16 m

12 m

11 m

15 m Sag

GCL = 23 m

2.3 m

10 m

1200 kV Tower ConfigurationConfiguration Considered: I V I – Delta

4°

10°55°


Right of Way RequirementsMinimum Horizontal Clearance as per IE Rules : 13 m

Right of way Requirement : 100 m (based on 13 m clearance & maximum Swing – 55 deg)

Right of way Requirement based on Electric Field Limitation : 110 m

(considering 2 kV/m electric field limit)

Lateral Distribution of Electric Field for 1200 kV & 765 kV Transmission Line

02468

1012

-60 -50 -40 -30 -20 -10 0 10 20 30 40 50 60

Distance from Centre Line (m)

Elec

tric

Fie

ld a

t 1.8

m

abov

e gr

ound

(k

V/m

)

1200 kV TL 765 kV TL

25 m

20 m

77m

15 m 15 m

16 m

12 m

11 m

15 m Sag

GCL = 23 m

2.3 m

10 m

1200 kV Transmission LineRight of Way

4°

10°55°

Minm.Clearance

13 m

Right of Way = 100 m

50 m

35 m

55°

1200 KV TRANSMISSION LINE DESIGN- CONDUCTOR-BUNDLE STUDIES

Conductor Surface Gradients & Corona Onset Gradients for 1200 kV Line

Conductor-bundle Conductor Surface Gradient (kV/cm)

Corona On-set Gradient (kV/cm)

Mean Max Fair Weather

Foul Weather

1 Hexa Lapwing 14.76 17.84 20.73 14.642 Octa Moose 14.34 17.01 21.10 14.893 Octa Bersimis 13.02 15.70 20.89 14.754 Octa Lapwing 12.00 14.67 20.73 14.64

Quad Bersimis (765 kV)-Horizontal 15.77 18.33 20.89 14.75

Quad Bersimis (765 kV)- Delta 14.9 17.3 20.89 14.75

Alt


Radio Interference for 1200 kV Line

Conductor-bundle Radio Interference (dB/1uV/m)

Max. At 50m ROW

1 Hexa Lapwing 45.8 38.42 Octa Moose 39.1 31.63 Octa Bersimis 36.5 29.14 Octa Lapwing 34.8 27.4

Quad Bersimis (765 kV)-Horizontal 50.9 38.5 (at 42.5m)

Quad Bersimis (765 kV)- Delta 46.8 40.4(at 32m)

Alt


Audible Noise for 1200 kV LineConductor-bundle Audible Noise (dBA)

–L5 levelAudible Noise (dBA) –L50 level

Max At 50m ROW

Max At 50m ROW

1 Hexa Lapwing 64.6 62.0 62.5 59.82 Octa Moose 61.3 58.6 57.6 54.93 Octa Bersimis 60.3 57.6 55.9 53.24 Octa Lapwing 59.4 56.7 54.4 51.6

Quad Bersimis (765 kV)-Horizontal

60.5 56.9(at 42.5m)

57.8 54.2(at

42.5m)Quad Bersimis (765 kV)- Delta 59.1 56.9

(at 32m)55.9 53.7

(at 32m)

Alt


ACCEPTABLE ALTERNATIVE OPTIONS

Octagonal ACSR Moose

Octagonal ACSR Bersimis

Lateral Distribution of Radio Interferencefor 1200 kV Transmission Line

20

25

30

35

40

45

-60 -45 -30 -15 0 15 30 45 60


Rad

io In

terf

eren

ce

(dB

/1uV

/m)

Octa Bersimis

Octa Moose

Lateral Distribution of Audible Noisefor 1200 kV Transmission Line

50

52

54

56

58

60

-60 -45 -30 -15 0 15 30 45 60


Aud

ible

Noi

se -

L50

W

et (d

BA

)

Octa Bersimis

Octa Moose

Acceptable Radio Interference levels : 40-45 dB/1uV/m

Acceptable Audible Noise levels : 55 – 58 dBA


Conductor Current Carrying Capacity & Thermal rating of 1200 kV Line

Conductor-bundle Conductor Current carrying capacity (Amp) – Ambient Temp. 45 deg C

Thermal Rating of 1200 kV Line (MVA)

Maxm. Conductor Temp. 75 deg C 85 deg C 75 deg C 85 deg C

1 Octa Moose 614 787 10209 13086

2 Octa Bersimis 710 917 11806 15248

Alt

Thermal Rating of 1200 kV Line : More than 10000 MVA

Surge Impedance Loading of 1200 kV Line : Around 6000 MW

1200 KV TRANSMISSION LINE DESIGNTECHNICAL PARTICULARS OF 1200 kV AC LINE

ELECTRICAL SYSTEM DATANominal System Voltage 1200 kV

Maximum Voltage 1250 kV

Switching Impulse Withstand Voltage (Wet) 2100 kV

Lightning Impulse Withstand Voltage > 3000 kVp

CONDUCTOR-BUNDLEConductor-bundle Octagonal ACSR Bersimis / Moose

457-600 mm spacing

ELECTRICAL CLEARANCESPower Frequency live-metal clearance 2.3 m (55 deg swing)

Switching surge clearance (1.75 pu) 10 m (Stationary/10 deg swing)

Phase to Phase Spacing 27.5-30 m

Ground Clearance 23 m (10 kV/m elect field limit)

INSULATOR STRINGSFor Suspension Towers (I – V – I) I- Double Suspension, 300/320 kN

(2x55), V – Single V, 420 kN (2x50)

For Tension Towers Quad Tension, 320 kN (4x55)

1200 KV TRANSMISSION LINE DESIGN

Preliminary Line Design ConsiderationsWind Zone – 4 (47 m/sec basic wind speed)

Reliability Level – 2 (150 yr. return period loads)

Ruling Span – 400 m

Maxm. Wind Span – 400 m ; Maxm. Weight Span – 600 m

Estimated Tower WeightStandard Suspension Tower : I-V-I Octa Bersimis : 53 MT

Octa Moose : 50 MT( Comparative 765 kV Suspension Tower Wt. : 23 MT)

Estimated Transmission Line Cost : Rs. 30 – 33 million/km

1200 KV TRANSMISSION LINE DESIGN1200 kV vis-à-vis 765 kV

1200 kV Tower Size : Approx. 30% more than 765 kV


1200 kV vis-à-vis 765 kVPower Flow Capacity - Thermal Rating

3800

12000

0

2000

4000

6000

8000

10000

12000

14000

1

Ther

mal

Rat

ing

(MVA

)

765 kV Line

1200 kV Line

1200 kV vis-à-vis 765 kVPower Flow - Surge Impedance Loading

2000

6000

01000200030004000500060007000

1

SIL

(MW

) 765 kV Line

1200 kV Line

POWER FLOW CAPACITY

Thermal Rating : 3 Times

SIL : 3 Times


RIGHT OF WAY

Right of Way Requirement : Approx. 55% more

Power Flow per Unit ROW : 2 Times

1200 kV vis-à-vis 765 kVRight of Way Requirement

64

100

0

20

40

60

80

100

120

1

RO

W (m

) 765 kV Line

1200 kV Line

1200 kV vis-à-vis 765 kVRight of Way Utilization

30

60

0

20

40

60

80

1Pow

er F

low

- SIL

per

uni

t R

OW

(M

W/m

) 765 kV Line

1200 kV Line

ROW Utilization


1200 kV vis-à-vis 765 kVCost Effectiveness

7500

5500

4000

5000

6000

7000

8000

9000

1Line

Cos

t per

uni

t Pow

er

Flow

- SI

L (R

s/km

-MW

)

765 kV Line

1200 kV Line

LINE COST

Capital Line Cost : 2 – 2.2 Times

Line Cost per Unit Power Flow : Approx. 70 %

COST EFFECTIVENESS

1200 kV vis-à-vis 765 kVCapital Line Cost

15

33

0

10

20

30

40

50

1

Estim

ated

Lin

e C

ost

(Rs

mill

ion/

km)

765 kV Line

1200 kV Line

1200 KV TRANSMISSION LINE DESIGN- Detailed Studies

Detailed Studies to be undertaken in respect of followingReliability considerations

Air-Gap Optimization

Insulation Co-ordination

Switching Surge Control

Capital cost & line optimization

Right of Way reduction measures

Alternate insulation systems

Low noise conductor

Asymmetrical conductor-bundle

Expandable (variable) conductor-bundle

THANK YOUTHANK YOUTHANK YOU

EVOLUTION OF INDIAN TRANSMISSION GRID

TRANSMISSION GRID AT THE TIME OF INDEPENDENCE

• Installed Capacity : 1349 MW

• Local Grid Feeding to Local Load

• No State/ Regional Grid

MUMBAI

CHENNAI

DELHI

KOLKATA

• 1960s - State Grids • 1970s - Regional Grids• 2000 - Limited Inter- Regional

Capacity

TRANSMISSION GRID DEVELOPMENT OVER THE

YEARS

TRANSMISSION LINE DEVELOPMENTS

• Late 1970s - First 400 kV Lines• 1980s onward – Standardized 400

kV Lines (twin bundle)• Late 1980s-1990 – First 500 kV

HVDC Line• Late 1990s-2000 – First 765 kV

Lines • Triple Bundle 400 kV Lines

400 kV Twin Bundle Transmission Lines 400 kV Triple Bundle Transmission Line

765 kV S/C Transmission Line(Horizontal Configuration)

+/- 500 kV HVDC Transmission Line

POWER MAP OF INDIA NATIONAL GRID BY 2007

• Peak Demand : 1,00,000 MW• Installed Capacity :

1,40,000MW• Inter Regional Capacity :

18,400MW• Power Mainly Flows on

400kV Network• 765 kV UHVAC Line in

operation


• 765 kV Delta Configuration Lines

• 400 kV Quad Bundle Lines• 400 kV Multi-circuit Lines• 400 kV Pole Structures

400 kV Multi-circuit Transmission Line

400 kV D/C Pole Structure

765 kV S/C Transmission Line(Delta Configuration)

INDIAN TRANSMISSION GRID – FUTURE DEVELOPMENTS

POWER MAP OF INDIANATIONAL GRID BY 2012

• Peak Demand : 1,57,000 MW (1.5 times of 2007)

• Installed Capacity : 2,12,000MW (1.5 times of 2007)

• Power from ER/NER to NR/WR/SR : 20,000-25,000 MW (4 times of 2007)

• Inter Regional Capacity : More than 40,000MW (2.5 times of 2012)

• Strong 765kV EHVAC Network with backup 400kV Network


• +/- 800 kV 6000 MW HVDC

+/- 800 KV HVDC TRANSMISSION LINE TOWER

1200 KV TRANSMISSION LINE DESIGN- Calculations

Power Frequency ClearanceMinm. Air-gap , L = Sqrt(2/3)*1200*1.1/(500*0.95)

= 2.3 mBasis : 500 kV/m – Discharge gradient of air gap

1.1 – factor for decrease in strength of total v/s single gap

0.95 – air density correction factor (assumed)

Switching Surge ClearanceCFO = 1.32*1.75*sqrt(2/3)*1200 = 2263 kV

Basis : Switching surge S2 = 1.75pu, σs = 10% , σ = 5%

Switching surge flashover rate : 1 per 1000

R = CFO/S2 = 1.32 (From EPRI)

Air-gap , D = 10 mBasis : EPRI Formula CFO = 1.2 * 3400 / (1 + 8/D)

1200 KV TRANSMISSION LINE DESIGN- Calculations

Minimum Ground Clearance as per IE RulesGround Clearance = 5.2 + 0.3 * (1200 – 33)/33

= 16 mMinimum Horizontal Clearance as per IE Rules

Ground Clearance = 2.0 + 0.3 * (1200 – 33)/33

= 13 mCorona On-set Gradients

Ec = 21 * m *б * (1 + 0.3 /sqrt(б* r)) kV/cmBasis : б = Air density = 0.95

r = conductor radius in cm

m = surface roughness factor

=0.85 for fair weather

= 0.6 for foul weather


Parameters ACSR Moose ACSR Bersimis ACSR Lapwing

Stranding 54/3.53mm Al+7/3.53mm St

42/4.57mm Al+7/2.54mm St

45/4.77mm Al+7/3.18mm St

Conductor Dia (mm) 31.77 35.05 38.16

Weight (kg/m) 2.004 2.181 2.667

UTS (kN) 161 154 188Rdc @ 20 deg C (ohm/km)

0.05552 0.0418 0.036

CONDUCTOR PARAMETERS

TRANSMISSION LINE DEVELOPMENTSTECHNICAL PARTICULARS OF +/- 800 kV HVDC LINE

ELECTRICAL SYSTEM DATA

System Voltage +/- 800 kV DC

Maximum Voltage 820 kV

Switching Impulse Withstand Voltage (Wet) 1850 kV

Lightning Impulse Withstand Voltage 2250 kVpeak

Minm. Corona Extinction Voltage (Dry) 880 kV

RIV at 1 MHz for 22 kV/cm conductor surface gradient (under dry condition)

1000 uV

CONDUCTOR-BUNDLE

Conductor-bundle Hexa ACSR Lapwing457 mm spacing

ELECTRICAL CLEARANCES

Live-metal clearance 6.5 m

Pole to Pole Spacing 25-28 m

Ground Clearance 18-20 m (15 kV/m charge free elect field limit)

INSULATOR STRINGS

For Suspension Towers (V – V) Single V Suspension, 400/420 kN(2x61)

For Tension Towers Quad Tension, 300/320 kN (4x61)


TECHNICAL PARTICULARS OF 765 KV S/C LINE

ELECTRICAL SYSTEM DATA

Nominal Voltage 765 kV

Maximum System Voltage 800 kV

Power Frequency Withstand Voltage (Wet) 830 kVrms

Switching Impulse Withstand Voltage (Wet) 1550 kVrms

Lightning Impulse Withstand Voltage 2400 kVpeak

Minm. Corona Extinction Voltage (Dry) 510 kVrms

RIV at 1 MHz for 510 kVrms phase to earth 1000 uV

CONDUCTOR-BUNDLE

Conductor-bundle Quad ACSR Bersimis457 mm spacing


TECHNICAL PARTICULARS OF 765 KV S/C LINEELECTRICAL CLEARANCES

Power Frequency live-metal clearance 1.3 m (55 deg swing)Switching surge clearance (1.75 pu) 4.4 m (25 deg swing)Air-gap/stationary live-metal clearance 5.1 / 5.6 m Phase to Phase Spacing 15 mGround Clearance 15 m

(10 kV/m elect field limit)

INSULATOR STRINGSFor Suspension Towers (I – V – I) I- Double Suspension, 120

kN (2x40)V – Single V, 210 kN (2x35)

For Tension Towers Quad Tension, 210 kN(4x35)


TECHNICAL PARTICULARS OF +/- 500 kV HVDC LINESELECTRICAL SYSTEM DATA

System Voltage +/- 500 kV DCMaximum Voltage 525 kVPower Frequency Withstand Voltage (Wet) 700 kVSwitching Impulse Withstand Voltage (Wet) 1000 kVLightning Impulse Withstand Voltage 1800 kVpeakMinm. Corona Extinction Voltage (Dry) 550 kVRIV at 1 MHz for 22 kV/cm conductor surface gradient (under dry condition)

1000 uV

CONDUCTOR-BUNDLEConductor-bundle Quad ACSR Bersimis

Quad ACSR Lapwing457 mm spacing


TECHNICAL PARTICULARS OF +/- 500 KV HVDC LINES

ELECTRICAL CLEARANCES

Live-metal clearance 3.75 m

Pole to Pole Spacing 12.5 – 13.5 m

Ground Clearance 12.5 m (10 kV/m charge free elect

field limit)

INSULATOR STRINGS

For Suspension Towers (V – V) Single V Suspension, 160/210 kN (2x38/41)

For Tension Towers Quad Tension, 160/210 kN(4x38/41)

1200 KV TRANSMISSION LINE DESIGN- Variations in TL Parameters w.r.t. Sub-conductor Spacing

1200 kV Transmission Line Parameters- Variation w.r.t. Sub-conductor Spacing

0.180.2

0.220.240.260.280.3

300 450 600 750 900

Sub-conductor Spacing (mm)

Indu

ctiv

e/C

apac

itive

R

eact

ance XL (Ohms/km)

XC (Ohms-km)

1200 kV Transmission Line Parameters - Variations w.r.t. Sub-conductor Spacing

200

225

250

275

300

300 450 600 750 900

Sub-conductor Spacing (mm)

Surg

e Im

peda

nce

(Ohm

s)

4000

5000

6000

7000

8000

Surg

e Im

peda

nce

Load

ing

(MW

)SISIL


CONDUCTOR – BUNDLES ADOPTED IN OTHER COUNTRIES FOR 1000 - 1200 KV LINES

Country System Voltage Conductor-Bundle Adopted

ITALY 1000 kV Octagonal 31.5 mm ACSR

JAPAN 1000 kV Octagonal 36.4 / 34.2 mm ACSR

USA (BPA) 1200 kV Octagonal 42.4 mm

USSR 1200 kV Octagonal 24.1 mm

TRANSMISSION LINE DEVELOPMENTSComparative

Line CostCost as per FR

Quad ACSR Bersimis

Octa ACSR Bersimis Factor

Octa ACSR Moose Factor

765 kV S/C line

per km cost (765 kV)

per km cost-estimated


(Rs lacs) (Rs lacs/km) (Rs lacs/km) (Rs lacs/km)325 kms

Tower Steel 15833 48.72 112.26 2.30 106.88 2.19

Conductor 15007 46.18 92.35 2.00 84.70 1.83

Earthwire 194 0.60 0.60 1.00 0.60 1.00

Insulator 2390 7.35 23.11 3.14 23.11 3.14

Hardware Fittings 1270 3.91 7.82 2.00 7.82 2.00

Conductor & E/W Acc 500 1.54 3.08 2.00 3.08 2.00

Sub-total Supply 35194 108.29 239.21 226.18

F&I & Taxes 4526 13.93 30.76 29.09

TRANSMISSION LINE DEVELOPMENTSComparative

Line CostCost as per FR

Quad ACSR Bersimis

Octa ACSR Bersimis Factor

Octa ACSR Moose Factor

765 kV S/C line

per km cost (765 kV)



(Rs lacs) (Rs lacs/km) (Rs lacs/km) (Rs lacs/km)325 kms

Erection 1564 4.81 11.09 2.30 10.56 2.19

Stringing 1071 3.30 6.59 2.00 6.59 2.00

Civil works 5321 16.37 37.73 2.30 35.92 2.19

River X-ing 473 1.46 3.35 2.30 3.19 2.19

Total Cost 48149 148.15 328.74 2.22 311.53 2.10


1200 KV VIS-A-VIS 765 KV

1200 KV S/C LINE 765 KV S/C LINE COMPARISONPOWER FLOW CAPACITY – THERMAL RATING

Approx. 12000 MVA Approx. 3800 MVA Approx. 3 times

POWER FLOW – SURGE IMPEDANCE LOADING

Approx. 6000 MVA Approx. 2000 MVA Approx. 3 times

RIGHT OF WAY (ROW) REQUIREMENT

100 m 64 m Approx. 55 % more

CAPITAL LINE COST

Approx. Rs. 30-33 million per km

Approx. Rs. 15 million per km

Approx. 2 – 2.2 times


1200 KV VIS-A-VIS 765 KV

1200 KV S/C LINE 765 KV S/C LINE COMPARISON

RIGHT OF WAY UTILIZATIONNormal Power Flow per Unit ROW

Approx. 60 MVA per m

Approx. 30 MVA per m

Approx. 2 times

COST EFFECTIVENESSLine Cost per Unit Power Flow

Approx. Rs. 5000-5500 per km per

MVA

Approx. Rs. 7500 per km per MVA

Approx. 70 %

GROWTH OF POWERGRID

Growth achieved through Internal resources & Borrowings

634983

2533

355428312805

1770

1009

236 275643

444748 786

0

500

1000

1500

2000

2500

3000

3500

4000

1992-93 1995-96 1998-99 2002-03 2003-04 2004-05 2005-06

Rs. in Crore

TurnoverNet ProfitTurnover & Profit

46461

22228

27244

35119

40289

4945944836

54400

34288

28820

12,201

22748

55100

507454775746245

0

10,000

20,000

30,000

40,000

50,000

60,000

1992-93 1995-96 1998-99 2001-02 2002-03 2003-04 2004-05 2005-06

MVA CKMs

Circuit Kms & Transformation Capacity

35215492

8851

13877

1987621930

24888

0

5000

10000

15000

20000

25000

30000

1992-93

1995-96

1998-99

2001-02

2002-03

2004-05

2005-06

Rs. in CroreAsset Base

Manpower

6167

66246811

69236828 6881

7103

5600

5800

6000

6200

6400

6600

6800

7000

7200

Transferred

Manpower1995-96 1998-99 2001-02 2003-04 2004-05 2005-06

Year ---->

No.

of E

mpl

oyee

s ---

-->

Growth in last 13 years Transformation Capacity - 345 %Circuit Kilometer - 148 %Asset Growth POWERGRID - 606 %Turnover - 460 %Profit - 328 %Manpower - 15 %

1200 kV system

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