determination of minimum right-of- way (row) width for · pdf filedetermination of minimum...

Determination of

Minimum Right-of-

Way (ROW) Width

for Overhead

Power

Transmission

Lines

May 2013

TransCo

Bienvenido D. Valeros

John C. Placente

ME TDSGA 2013, Bangkok, Thailand

2

Objective

Study aims to:

1. Provide the technical basis of transmission line

right-of-way (ROW) width based on applicable

electrical and safety codes.

2. Determine opportunities on cost-savings by

paying only the ROW width that is needed by

TransCo.


Mindanao

TRANSMISSION LINE LENGTH (in CKT-KM)

As of CY2011

Luzon

9,482

Visayas

4,979

Mindanao

5,361

PHILIPPINES 19,822

3 ME TDSGA 2013, Bangkok, Thailand

4

Voltage

(kV)

Luzon

(km)

Visayas

(km)

Mindanao

(km)

Total

(km)

500 491.15 0 0 491.5

350 214.79 259 0 473.79

230 3,136.07 171.92 0 3,307.99

138 0 1,296.24 2,269.50 3,565.74

115 209.45 0 0 209.45

69 & Below 2,632.90 2,148.47 2,076.55 6,857.92

Transmission Line Length As of December 31, 2011


5

Right-of-Way (ROW) is to provide

an access corridor for maintenance of

transmission lines, with consideration to

safety clearances and EMF exposure limits.

ROW Width

ROW Width


6

ROW Width Determination

40 Meters

230 kV Voltage

Level

(kV)

FIXED

Width

(m)

69 15

115 30

138 30

230 40

345 50

500 65

12 m


Proposed ROW Width Determination

ROW= Design, EMF

230 kV

12 m


8

References for Determination


9

22

301.0

mVWW LL

RESTRHCL

Horizontal Clearance at Rest Formula Above 36 kV, Altitude ≤ 1000 m

Philippine Electrical Code Rule 3.4.5.7(a)

WHCL-R is the effective horizontal clearance (@ rest), meters

WREST is the horizontal clearance on PEC Table 3.4.5.3(a)(1)

for open supply conductors, 2.3 meters

VLL is the line to line voltage, kV

m is the maximum voltage multiplier;

1.05 (69-345kV) and 1.10 (500kV and above)


10

Nominal

Voltage Level,

in kV

Maximum

Voltage Level,

in kV

Horizontal Clearance At

Rest, Altitude ≤ 1000 m,

in Meters

(Based on PEC)

69 72 2.50

115 121 2.78

138 145 2.92

230 242 3.47

345 362 4.17

500 550 5.26

Horizontal Clearance at Rest

(Computed)


11

Horizontal Clearance,

Conductor Displaced by Wind Formula for Above 36 kV, Altitude ≤ 1000m, Wind

Philippine Electrical Code Rule 3.4.5.3

22

301.0

mVWW LL

WINDWHCL

WHCL-W is the horizontal clearance requirement when displaced by wind

WWIND is the minimum wind clearance requirement as listed in Table 3.4.5.2(a)(2); for overhead conductor, 1.4 meters.

VLL is the line to line voltage.

m is the maximum voltage multiplier; 1.05 (69-345kV) and 1.10 (500kV)


12

Nominal

Voltage Level, in kV

Maximum Voltage Level,

in kV

Horizontal Clearance With

Wind Displacement, Altitude ≤

1000 m,

in Meters

(Based on PEC)

69 72 1.60

115 121 1.88

138 145 2.02

230 242 2.57

345 362 3.27

500 550 4.36

Horizontal Clearance When Conductor

is Displaced by Wind (Computed)


13

Conductor Swing Angle Calculation IEC 60826, Philippine Electrical Code

agm

aDGVC

C

WLRCC

21 2/

tan

ØC is the swing angle of the conductor blown by wind

ρ is the air density (1.14-1.29, assumption: 1.16 kg/m3)

CC is the drag factor equal to 1.0 for stranded conductor

VR is the wind speed/velocity (meters/second)

GL is the span factor taking into account the effect of span length (Values are 1.0 to 0.875 for 200 m to 600 m)

D is the conductor diameter (meters)

mC is the conductor mass per unit length (kg/m)

g is the gravitational acceleration constant (9.8 m/s2)

aW is the wind span

a is the conductor span length (assumption: a=aW)


14

Span Factor, GL

IEC 60826

Wind Span, aW (meters)

Span Factor, GL

200 1.000

250 0.984

300 0.969

350 0.953

400 0.938

450 0.922

500 0.906

550 0.891

600 0.875


15

Example Condor (795 MCM), 270 KPH or 75 m/s

agm

aDGVC

C

WLRCC

21 2/

tan

as

m

m

km

km

kg

ams

mm

kg

W

C

2

23

1

8.91000

11523

0277.0984.0750.12

16.1

tan

Assumption: conductor span, a is assumed equal to wind span, aW; therefore,

5.80C


Conductor Swing Angles Per KPH Philippine Electrical Code 2, 2009

Condor (795 MCM) @ Span = 250 m

Wind Speed

Zone Swing Angle

270 KPH 75 m/s

Zone 1 80.5O

240 KPH 67 m/s

Zone 2 78.2O

160 KPH 44.45m/s

Zone 3 64.5O

270

KPH 240

KPH

160

KPH


17

The 230 kV double circuit

overhead conductors are

supported by two towers with

dimensions as shown. The two

towers are on same elevation

and the span between them is

250 meters. Surveyed data

from the field indicates that the

total insulator length and

conductor sag amounts to 6.0

meters. Conductor is in Zone 1

(270 KPH).

Recommend a minimum right-

of-way (ROW) based on

clearances of conductors at rest

and under wind displacement.

Example

1.5 m 1.5 m

4.5 m

250 m

NOT TO SCALE

FOR ILLUSTRATION ONLY

TOWER

‘A’

TOWER

‘B’


80.5o

18

A. Compute for the Horizontal

Clearance at Rest

B. Compute for the Horizontal

Clearance, with Wind

22

3

05.123001.03.2RHCLW

mmW RHCL 5.347.3

22

3

05.123001.04.1WHCLW

mmW WHCL 6.257.2

3.5

m

5.92 m

2.6

m

Cle

ara

nce

With

Win

d

Cle

ara

nce

At R

est

4.5 m

1.5 m


19

Illustration #1

29.2 m


HO

RIZ

ON

TAL

CLE

ARAN

CE

AT R

EST

HO

RIZ

ON

TAL

CLE

ARAN

CE,

WIT

H W

IND

DIS

PLAC

EMEN

T

HO

RIZ

ON

TAL

CLE

ARAN

CE,

WIT

H W

IND

DIS

PLAC

EMEN

T

20

Illustration #2

29.04 m

12

5.92

2.6 2.6 3.5 3.5 2.42 2.42

5.92 2.6 2.6


21

Voltage Level (kV)

CURRENT (Fixed)

PROPOSED*

(Design Dependent)

69 15 6-12

115 30 11-26

138 30 11-26

230 40 20-32

345 50 23-38

500 65 33-53

ROW WIDTH ESTIMATES


22

LATEST EMF EXPOSURE LIMITS

PARAMETER VALUE

Electric Field

Magnetic Field

General Public, 60 Hertz, 2010 ICNIRP* *International Commission on Non-Ionising Radiation Protection

*1998 Value = 833 mG

4.17 kV/m

2000 milliGauss*


Calculated EMF Levels Information: 230 kV, Bundle of 4, 820 Amps Per Cond, Double Ckt

Distance from

Conductor

Centerline

(m)

0 2.5 5 7.5 10 12.5 15 17.5 20

Electric Field

(kV/m) 0.172 0.451 0.796 1.048 1.177 1.185 1.1 0.959 0.796

Magnetic Field

(mG) 186.44 184.06 177.71 167.53 154.09 138.43 121.88 105.68 90.69

Measured EMF Levels @ 5 m from Conductor Centerline Transmission Line Electric Field Magnetic Field

Sucat-Araneta-Balintawak 230 kV 0.04 3.15

Limits: Electric Field = 4.17 kV/m

Magnetic Field = 2000 mG


24

Benefits

Reduction of area

acquisition cost of

28-32%.


25

Way Forward

1. Status. Completed 10 Consultation meetings

with distribution utilities and other power

experts. Preparing for 2 more technical

consultations and then legal consultations.


2. Board Approval. Seek final

approval/recommendation from management

team.

3. Program Development. Create a software

and database system (tower design data, sag,

span) which will compute for ROW acquisition.

26

FOR COMMENTS

Email:

MR. BIENVENIDO D. VALEROS [email protected]

MR. JOHN C. PLACENTE [email protected]

MS. SHELYMAR F. AURIGE [email protected]

MS. DIVINA I. CUSTODIO [email protected]


mailto:[email protected]












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