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.
ME TDSGA 2013, Bangkok, Thailand
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
ME TDSGA 2013, Bangkok, Thailand
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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
ME TDSGA 2013, Bangkok, Thailand
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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
ME TDSGA 2013, Bangkok, Thailand
Proposed ROW Width Determination
ROW= Design, EMF
230 kV
12 m
7 ME TDSGA 2013, Bangkok, Thailand
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References for Determination
ME TDSGA 2013, Bangkok, Thailand
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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)
ME TDSGA 2013, Bangkok, Thailand
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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)
ME TDSGA 2013, Bangkok, Thailand
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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)
ME TDSGA 2013, Bangkok, Thailand
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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)
ME TDSGA 2013, Bangkok, Thailand
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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)
ME TDSGA 2013, Bangkok, Thailand
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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
ME TDSGA 2013, Bangkok, Thailand
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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
ME TDSGA 2013, Bangkok, Thailand
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
ME TDSGA 2013, Bangkok, Thailand
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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’
ME TDSGA 2013, Bangkok, Thailand
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
ME TDSGA 2013, Bangkok, Thailand
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Illustration #1
29.2 m
ME TDSGA 2013, Bangkok, Thailand
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
ME TDSGA 2013, Bangkok, Thailand
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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
ME TDSGA 2013, Bangkok, Thailand
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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*
ME TDSGA 2013, Bangkok, Thailand
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
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Benefits
Reduction of area
acquisition cost of
28-32%.
ME TDSGA 2013, Bangkok, Thailand
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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.
ME TDSGA 2013, Bangkok, Thailand
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]
ME TDSGA 2013, Bangkok, Thailand