TRIBHUVAN UNIVERSITY
INSTITUTE OF ENGINEERTNG
PASCHIMANCHAL CAMPUS
LAMACHAUR-16, POKHARA
DEPARTMENT OF ELECTRICAL ENGINEERING
PROJECT REPORT ON: Design of 200MW 160Km
Transmission Line
SUBMITTED BY
:
SUBMITTED TO:
MADHUSUDHAN PANDEY
DEPARTMENT OF ELECTRICAL ENGINEERING
Date of Submission: SHRWAN 17, 2071 B.S
1|Page
DESIGN OF 200 MW, 160 KM TRANSMISSION LINE
Most Economical Voltage Selection
The most economical voltage is given by the following empirical formula:
Economical Voltage (V eco)
Lt
P * 1000

1.6 cos  * Nc * 150
=5.5*
Where,
Lt = length of transmission line =160 Km
P = Power to be transmitted =200 MW
cosØ = Power factor =0.96
Nc = number of circuit = 1S
Then, using the above values
V eco
=5.5*
160 200 *1000

1.6 0.96 *1 *150
= 212.22 KV
Nearest Standard Voltage= 220 kV
Taking 220 kV, as required voltage as it is more near to the obtained economical voltage, So
standard voltage level of transmission line =220 kV.
Checking technical criterion:
Surge impedance Loading (SIL) = V2 /400
= 2202/400 =121
Multiplying factor (MF) =
P max
= 200/121 = 1.65
SIL
MFlimit for 160 KM from provided standard table = 2.25
MFcalculated (1.65) < MFlimit (2.25)
Hence the technical criterion is satisfied, so we select the voltage level of 220 KV.
Voltage Level for given Power Transmission =220 KV
Number of Circuit
=1
Power Factor ( cosØ )
= 0.96
2 | P a gLength
e
of Transmission Line (L)
= 160 Km
Calculation of Insulation Discs
For all the calculations of number of insulator discs, we considered following value of different
factor:
FOWR = Flashover Withstand Ratio
=1.15
NACF = Non Atmospheric Condition Factor = 1.1
FS = Factor of Safety
=1.2
1) Number of Insulator Discs Required for the temporary O/V
Temporary O/V
Equivalent Voltage (Veq)
Equivalent Voltage (Veq)
= Earth Factor (EF) * Maximum system voltage
= 1 * (220* 1.1)
= 242 KV
= Temporary O/V *√2 * FOWR *NACF * FS
= 242* √2 *1.15 * 1.1 *1.2
= 519.51 KV
From standard table number of insulator discs required to withstand above equivalent
voltage (Na) = 13
2) Number of Insulator Discs Required to withstand continuous operating voltage:
a) Voltage Level for dry condition = Equiv dry 1 min. voltage*FOWR*NACF * FS
Where,
Equivalent dry 1 min voltage is taken from standard table = 435 KV
Equivalent Voltage Level = 435 * 1.15 * 1.1 *1.2
= 660.33 kV
From Standard Table number of discs required to withstand above equivalent voltage level
(Nb1) =12
b) Voltage Level for Wet condition = Equiv dry 1 min. voltage*FOWR*NACF * FS
Where,
3|Page
Equivalent wet 1 min voltage is taken from standard table = 350 KV
Equivalent Voltage Level = 350* 1.15 * 1.1 *1.2
= 531.3 KV
From Standard Table number of discs required to withstand the above equivalent voltage level
(Nb2) =14
3) Number of Insulator Discs required for switching over voltage:
Voltage Level = switching o/v * Switching to impulse ratio * FOWR *NACF* FS
Where,
Switching to impulse ratio (SIR) = 1.15
Switching O/V = ( 2 / 3 )*242*SSR
SSR = Switching Surge Ratio =2.8
So Switching O/V = 553.25 KV
Voltage Level = 553.25*1.15*1.15*1.1*1.2
= 965.8 KV
From Standard Table number of discs required to withstand the above voltage level
(Nc) = 11.
3) Number of Insulator Discs required for over voltage due to Lightning:
From standard table Equivalent voltage level for the given system voltage =900 KV
Voltage Level = 900* FOWR *NACF* FS
= 900*1.15*1.1*1.2
= 1366.2
From Standard Table number of discs required to withstand the above voltage level
4|Page
(N d) = 16.
SN
Voltage Level Description
Voltage Level Number
of
Discs
1)
Temporary O/V appearing across the insulator
2)
Continuous voltage
i) Continuous operating Voltage in Dry condition
ii)
Continuous
operating
Voltage
in
519.15 KV
13
660.33 KV
12
Wet 531.3 KV
14
3)
condition
965.8 KV
11
4)
Switching Over voltage
1366.2 KV
16
O/V due to lightning
Hence from above table the required number of insulator discs to withstand all types voltage
level in all condition for given system voltage = 16
Required Number of Insulator Discs =16
Air Clearance Calculation
Air clearance parameters calculation for single circuit tower configuration:
a = minimum distance (clearance requirement) from a line conductor to any earthed
object, and is given by the following relation:
a=
v * 6.5
3 *10
9 =
245 * 6.5
3 *10
 9 =100.94 inch
=2.564 m
Now String Length (l) = 2 a =3.626 m
Tower width (b) = 1.5*a = 3.846 m
Cross arm length = 2*a = 5.128 m
5|Page
Vertical distance between two adjacent line conductor (y) =
(l  a)
2
 x l a
1    

 y   2a 
2
Where 0.25 < x/y< 0.333
=
(3.626  2.564)
 3.626  2.564 
1  0.25 

 2 * 2.564 
2
2
= 6.49 m
Horizontal distance between adj. conductor
Height of earth wire from top (d)
=5.5 a = 5.5*2.564 =14.1 m
b

= 3 *   2a  -l
2

 1.5a

 2a  -l
= 3 *
 2

= 8.58 m
Air clearance from earthed object (a)
String Length (l)
Tower Width (b)
Cross Arm Length
Vertical distance between two adjacent line conductor (y)
Horizontal distance between two adj. line conductor
Height of Earth wire from top cross arm (d)
= 2.564 m
= 3.626 m
= 3.846 m
= 5.128 m
= 6.49 m
= 14.1 m
= 8.58 m
Conductor and Tower Selection
Line current is calculated as:
Line current (I) =
P
3 * Vll * cos 
=
200 *1000
3 * 220 * 0.96
= 546.75 amp
Comparing this value of the current with the current carrying capacity from the given standard
ASCR conductor table, Conductor “Lion” is selected.
For Lion conductor, From ASCR conductor table,
Resistance at 200C (R20) = 0.1223 Ώ/Km
6|Page
Coefficient of Resistivity (α20) =0.004
So Resistance at 650C (R65) = R20 (1 + α20(65-20))
= 0.1223 (1+.004*45)
= 0.1443 Ώ/Km
Transmission Efficiency Criterion
Power Loss for single conductor = I2*R*L
= (546.75)2*0.1443 *160
= 6.90 MW/conductor
Transmission Efficiency (ή) = 200 / (200+3*6.90)
= 0.90620
= 90.62 %
Transmission Efficiency<94 %. So this conductor cannot be used .To get higher efficiency we
proceed in same way and calculate efficiency finally we got the conductor “Sheep” which has
efficiency greater than 94 %.
Voltage Regulation Criterion
For Conductor Sheep,
This conductor has 37 strands 30 Aluminum strands and 7 steel strands.
Diameter of each strands = 3.99 mm
With 1-6-12-18 configuration, GMR for inductance (GMRi)
=3.5*3.99 *0.75
= 10.47 mm
GMR for capacitance (GMRc) =13.965 mm
GMD for single ckt configuration = 11081.7 mm
Resistance of the whole line (R) = 13.67 Ώ
Inductance of Whole length (L) =2 * 10-04 ln (GMD/GMRi)*L
=2e-04*ln(11081.7/10.47)*160
=0.2136 H
7|Page
Capacitance of whole Length(C) =
2
* L * e3
 GMD 
ln 

 GMR 
= 1.33*e-6 μF
Now Impedance of the Line (Z) = R + j 314.15 *L
= 13.67 +j67.10
= 68.47<78.48
Susceptance of the Line (Y)
= j314.15*C
= j4.17 * e-04
= (4.17 * e-04) <90
A, B, C, D parameters calculation
A = 1 + ZY/2 = 0.9860<0.1656
B = Z= 68.47<78.48
C= Y(1+ZY/4)
D=A
Now, Sending end Voltage (Vs) = A*Vr +B*Ir
= 0.972<0.3361 * 220/√3<0 + 68.47<78.48 * 546.75*e-03<-16.26
= 123.46<0.3361 +37.43<62.22
= 144.90<13.5
Now Voltage Regulation = (|Vs|/A -|Vr| )/|Vr|
= 0.1701
= 17.01%
Voltage regulation > 12% so this conductor can not be used. To get lower voltage regulation we
proceed in same way and calculate the voltage regulation, finally we cannot get the conductor
for which voltage regulation less than 12 % (voltage regulation criterion) for a single conductor
for the given system voltage i.e.220 KV. So to obtain Voltage Regulation criterion we go for
bundle conductor.
8|Page
Design with Bundle (2) conductor
Current (I) = 546.75 amp
I/2 = 273.375 amp
Comparing this value of the current with the current carrying capacity from the given standard
ASCR conductor table, Conductor “Otter” is selected.
For Otter conductor, From ASCR conductor table,
Resistance at 200C (R20) = 0.3434 Ώ/Km
Coefficient of Resistivity (α20) =0.004
So Resistance at 650C (R65) = R20 (1 + α20(65-20))
= 0.3434 (1+.004*45)
= 0.4052 Ώ/Km
Transmission Efficiency Criterion
Power Loss (Pl)
= I2*R*L*6
= (273.375)2*0.4052 *160*6
= 29 MW
Transmission Efficiency (ή) = 200 / (200+29)
= 0.873
= 87.3%
Transmission Efficiency < 94 % so this conductor cannot be used .To get higher efficiency we
proceed in same way and calculate efficiency finally we got the conductor “Bear” which has
efficiency greater than 94 %.
Voltage Regulation Criterion
For Conductor Bear,
This conductor has 37 strands 30 Aluminum strands and 7 steel strands.
Diameter of each strands = 3.35 mm
With 1-6-12-18 configuration,
GMR for inductance (GMRi) = 51.36 mm
GMR for capacitance (GMRc) =59.30 mm
GMD for single ckt (bundle conductor) configuration =11171.9 mm
Resistance of the whole line (R) = 10.4Ώ
9|Page
Inductance of Whole length (L) =2 * 10-04 ln (GMD/GMRi)*L
=2e-04*ln (11171.9/51.36)*160
=0.17216 H
Capacitance of whole Length(C) =
2
* L * e3
 GMD 
ln 

 GMR 
= 1.696*e-6 μF
Now Impedance of the Line (Z) = 10.4 + j 314.15 *L
= 10.4 +j54
= 54.99<79.1
Susceptance of the Line (Y) = j314.15*C
= j5.32*e-04 siemen
= (5.32 * e-04) <90
A, B, C, D parameters calculation
A = 1 + ZY/2
=0.985<0.16
B = Z= 54.99<79.1
C = 5.28*e-04<90.07
D=A
Now, Sending end Voltage
(Vs)
= A*Vr +B*Ir
= 0.985<0.16 * 220/√3<0 + 54.99<79.1 * 546.75*e-03<-16.26
= 141.44<11.04 Kv
Now Voltage Regulation = (|Vs|/A -|Vr| )/|Vr|
= 0.1306
= 13.06%
Voltage regulation > 12% so this conductor can not be used. To get lower voltage regulation we
proceed in same way and calculate the voltage regulation, finally we got the conductor “Sheep”
for which voltage regulation less than 12 %. Voltage regulation for bundle (2) conductor
“Sheep” is calculated 11.64% in the same way as above.
10 | P a g e
Each Sheep conductor has 37 strands with 7 Steel strands and 30 Aluminum strands.
Diameter of each strands = 3.99 mm
With 1-6-12-18 configuration ,
GMR for inductance (GMRi)
GMR for capacitance (GMRc)
GMD for single ckt ( bundle conductor )
Resistance of the whole line (R)
Inductance of Whole length (L)
Capacitance of whole Length(C)
Now Impedance of the Line (Z)
Succeptance of the Line (Y)
= 56.05mm
=64.72 mm
=11171.9 mm
= 7.328Ώ
=0.168 H
= 1.712 μF
= 53.25<82.
= j5.37*e-04 siemen
= 5.37*e-04<90
A, B, C, D parameters calculation
A = 1 + ZY/2 = 0.985<0.11
B = Z= 53.25<82.1
C = 5.33*e-04<90.05
D = A=0.985<0.11
Now, Sending end Voltage
(Vs) = A*Vr +B*Ir
= 0.985<0.11 * 220/√3<0 + 53.25<79.1 * 546.75*e-03<-16.26
= 139.67<11.06 KV
Now Voltage Regulation = (|Vs|/A -|Vr| )/|Vr|
= 0.1164
= 11.64%
The voltage regulation is less than 12%.and hence the conductor is found to fulfill the voltage
regulation criteria.
Corona Inception Voltage Criterion
Corona Inception voltage (Vci)
=21.1*GMR*m*δ*ln(GMD/GMR)
Where, m = factor of roughness =0.72
δ = relative density of air =1
Vci = 21.1 * 5.605*1*0.72* ln (11171.9/56.05)
= 450.86 KV
Here Vci > Vs so Corona Inception Voltage criterion is met. So we can use conductor Sheep with
2nos of this conductor per phase.
11 | P a g e
Tension Calculation for Different Conductors with Different Span in
Different Condition
Four Different conductors below conductor Sheep in ASCR conductor table is chosen. Hence
Tension calculation will be done for conductor “Sheep, Deer, Zebra, Elk, and Moose” with Span
length 250 m, 275 m, 300 m, 325 m, and 350 m. Tensions for Toughest, Stringing and Easiest
condition are calculated and tabulated below. Sample calculation is also shown.
Sample calculation; Conductor 1: Sheep
Area of conductor = 462.6 mm2
Linear expansion coefficient = 17.73 e-6 per 0C
Modulus of elasticity (E) = 0.787 e+6 kg/cm2
Tension at toughest condition (T1) =
=
= 7955 Kg.
Weight of conductor (wc)
= 1726 Kg/Km
Wind pressure
= 100 kg/m2
Weight due to wind force (ww) = 100*1000*27.93e-3*2/3 = 1862 kg
Weight of ice (wice) = 0
Weight for toughest condition (w1) =
= 2538.92 kg
Weight for the stringing and easiest condition (w2) = 1726 kg.
Then, the tension at stringing (T2) and the easiest condition (T3) is calculated using the following
equation known as STRINGING EQUATION.
T22 [T2+k1] - k2 = 0 ………………………………….. (1)
Where,
2


W1 L2
K 1   T 1    2   1AE 
AE
 and,
2


24T1
2
W2 L2
AE .
K2=
24
From the above data, the values of K1 and K2 for the span of 250m are given by:
K1 = -5250.22;
K2 = 2.82e+10;
Using the stringing equation, the value of T2 is found to be,
12 | P a g e
T2 = 6027.62 kg.
Similarly, T3 is calculated by the similar procedure as above. For the calculation of T3 the value
of K1 and K2 for 250 m of length are given by:
K1 = -2797.36;
K2 = 2.82e+10;
Using the stringing equation, we get the value of T3 as:
T3 = 4314.59 kg.
In the similar manner, the values of tensions of different conductor for different span length is
calculated and presented in the table below:
13 | P a g e
T2 Calculation
A(cm2)
E(kg/cm2) Α (/0c) ø1(0c)
ø2(0c)
T1(kg)
Sheep
4.63E+00 7.87E+05 1.77E0.00
27 7955.00
05
4.63E+00 7.87E+05 1.77E0.00
27 7955.00
05
4.63E+00 7.87E+05 1.77E0.00
27 7955.00
05
4.63E+00 7.87E+05 1.77E0.00
27 7955.00
05
4.63E+00 7.87E+05 1.77E0.00
27 7955.00
05
4.63E+00 7.87E+05 1.77E0.00
27 7955.00
05
4.63E+00 7.87E+05 1.77E0.00
27 7955.00
05
Deer
5.30E+00 7.87E+05 1.77E0.00
27 9115.00
05
5.30E+00 7.87E+05 1.77E0.00
27 9115.00
05
5.30E+00 7.87E+05 1.77E0.00
27 9115.00
05
5.30E+00 7.87E+05 1.77E0.00
27 9115.00
05
5.30E+00 7.87E+05 1.77E0.00
27 9115.00
05
5.30E+00 7.87E+05 1.77E0.00
27 9115.00
14 | P a g e
W1(kg)
L (km)
W2(kg)
K1
K2
T2(kg)
2533.92
0.25 1726.00
-5250.22 2.82E+10
6027.62
2533.92
0.28 1726.00
-5048.21 3.42E+10
5998.13
2533.92
0.30 1726.00
-4826.96 4.07E+10
5968.64
2533.92
0.33 1726.00
-4586.48 4.77E+10
5939.53
2533.92
0.35 1726.00
-4326.75 5.54E+10
5911.10
2533.92
0.38 1726.00
-4047.78 6.35E+10
5883.59
2533.92
0.40 1726.00
-3749.57 7.23E+10
5857.19
2807.00
0.250 1977.00
-6089.27 4.24E+10
6964.28
2807.00
0.275 1977.00
-5873.02 5.14E+10
6939.40
2807.00
0.300 1977.00
-5636.18 6.11E+10
6914.44
2807.00
0.325 1977.00
-5378.75 7.17E+10
6889.71
2807.00
0.350 1977.00
-5100.72 8.32E+10
6865.47
2807.00
0.375 1977.00
-4802.09 9.55E+10
6841.93
5.30E+00 7.87E+05
Zebra
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
Elk
5.88E+00 7.87E+05
5.88E+00 7.87E+05
5.88E+00 7.87E+05
5.88E+00 7.87E+05
5.88E+00 7.87E+05
15 | P a g e
05
1.77E05
0.00
27
9115.00 2807.00
0.400 1977.00
-4482.88 1.09E+11
6819.23
1.94E05
1.94E05
1.94E05
1.94E05
1.94E05
1.94E05
1.94E05
0.00
27
6658.00 2504.90
0.25 1623.00
-3696.43 2.28E+10
4719.87
0.00
27
6658.00 2504.90
0.28 1623.00
-3439.15 2.76E+10
4692.18
0.00
27
6658.00 2504.90
0.30 1623.00
-3157.37 3.28E+10
4665.61
0.00
27
6658.00 2504.90
0.33 1623.00
-2851.09 3.85E+10
4640.43
0.00
27
6658.00 2504.90
0.35 1623.00
-2520.31 4.47E+10
4616.81
0.00
27
6658.00 2504.90
0.38 1623.00
-2165.02 5.13E+10
4594.82
0.00
27
6658.00 2504.90
0.40 1623.00
-1785.23 5.84E+10
4574.46
1.77E05
1.77E05
1.77E05
1.77E05
1.77E-
0.00
27 10120.00 3038.48
0.25 2196.00
-6816.14 5.82E+10
7777.52
0.00
27 10120.00 3038.48
0.28 2196.00
-6587.85 7.04E+10
7757.22
0.00
27 10120.00 3038.48
0.30 2196.00
-6337.82 8.37E+10
7736.82
0.00
27 10120.00 3038.48
0.33 2196.00
-6066.04 9.83E+10
7716.56
0.00
27 10120.00 3038.48
0.35 2196.00
-5772.53 1.14E+11
7696.65
5.88E+00 7.87E+05
5.88E+00 7.87E+05
Moose
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
16 | P a g e
05
1.77E05
1.77E05
1.95E05
1.95E05
1.95E05
1.95E05
1.95E05
1.95E05
1.95E05
0.00
27 10120.00 3038.48
0.38 2196.00
-5457.27 1.31E+11
7677.26
0.00
27 10120.00 3038.48
0.40 2196.00
-5120.27 1.49E+11
7658.51
0.00
27
8125.00 2914.43
0.25 2002.00
-4593.21 4.27E+10
5844.59
0.00
27
8125.00 2914.43
0.28 2002.00
-4305.04 5.17E+10
5827.89
0.00
27
8125.00 2914.43
0.30 2002.00
-3989.43 6.16E+10
5811.80
0.00
27
8125.00 2914.43
0.33 2002.00
-3646.37 7.22E+10
5796.46
0.00
27
8125.00 2914.43
0.35 2002.00
-3275.87 8.38E+10
5781.97
0.00
27
8125.00 2914.43
0.38 2002.00
-2877.92 9.62E+10
5768.39
0.00
27
8125.00 2914.43
0.40 2002.00
-2452.53 1.09E+11
5755.73
T3 Calculation
A(cm2)
E(kg/cm2) Α (/0c) ø1(0c)
ø2(0c)
T1(kg)
W1(kg) L (km) W2(kg) K1
K2
T3(kg)
Sheep
4.63E+00 7.87E+05 1.77E27.00
65 6027.62 1726.00
0.25 1726.00
-2797.36 2.82E+10
4314.59
05
4.63E+00 7.87E+05 1.77E27.00
65 5998.13 1726.00
0.28 1726.00
-2595.35 3.42E+10
4378.23
05
4.63E+00 7.87E+05 1.77E27.00
65 5968.64 1726.00
0.30 1726.00
-2374.10 4.07E+10
4438.57
05
4.63E+00 7.87E+05 1.77E27.00
65 5939.53 1726.00
0.33 1726.00
-2133.62 4.77E+10
4495.51
05
4.63E+00 7.87E+05 1.77E27.00
65 5911.10 1726.00
0.35 1726.00
-1873.89 5.54E+10
4549.04
05
4.63E+00 7.87E+05 1.77E27.00
65 5883.59 1726.00
0.38 1726.00
-1594.92 6.35E+10
4599.23
05
4.63E+00 7.87E+05 1.77E27.00
65 5857.19 1726.00
0.40 1726.00
-1296.72 7.23E+10
4646.19
05
Deer
5.30E+00 7.87E+05 1.77E27.00
65 6964.28 1977.00
0.250 1977.00
-3280.09 4.24E+10
4986.72
05
5.30E+00 7.87E+05 1.77E27.00
65 6939.40 1977.00
0.275 1977.00
-3063.85 5.14E+10
5065.30
05
5.30E+00 7.87E+05 1.77E27.00
65 6914.44 1977.00
0.300 1977.00
-2827.01 6.11E+10
5140.09
05
5.30E+00 7.87E+05 1.77E27.00
65 6889.71 1977.00
0.325 1977.00
-2569.57 7.17E+10
5210.92
05
5.30E+00 7.87E+05 1.77E27.00
65 6865.47 1977.00
0.350 1977.00
-2291.54 8.32E+10
5277.77
17 | P a g e
5.30E+00 7.87E+05
5.30E+00 7.87E+05
Zebra
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
4.85E+00 6.86E+05
Elk
5.88E+00 7.87E+05
5.88E+00 7.87E+05
5.88E+00 7.87E+05
5.88E+00 7.87E+05
18 | P a g e
05
1.77E05
1.77E05
27.00
65 6841.93 1977.00
0.375 1977.00
-1992.92 9.55E+10
5340.69
27.00
65 6819.23 1977.00
0.400 1977.00
-1673.70 1.09E+11
5399.80
1.94E05
1.94E05
1.94E05
1.94E05
1.94E05
1.94E05
1.94E05
27.00
65 4719.87 1623.00
0.25 1623.00
-1252.53 2.28E+10
3320.44
27.00
65 4692.18 1623.00
0.28 1623.00
-995.25 2.76E+10
3392.40
27.00
65 4665.61 1623.00
0.30 1623.00
-713.48 3.28E+10
3458.41
27.00
65 4640.43 1623.00
0.33 1623.00
-407.20 3.85E+10
3518.90
27.00
65 4616.81 1623.00
0.35 1623.00
-76.41 4.47E+10
3574.28
27.00
65 4594.82 1623.00
0.38 1623.00
278.87 5.13E+10
3624.98
27.00
65 4574.46 1623.00
0.40 1623.00
658.66 5.84E+10
3671.42
1.77E05
1.77E05
1.77E05
1.77E-
27.00
65 7777.52 2196.00
0.25 2196.00
-3696.24 5.82E+10
5570.41
27.00
65 7757.22 2196.00
0.28 2196.00
-3467.95 7.04E+10
5662.51
27.00
65 7736.82 2196.00
0.30 2196.00
-3217.92 8.37E+10
5750.40
27.00
65 7716.56 2196.00
0.33 2196.00
-2946.15 9.83E+10
5833.87
5.88E+00 7.87E+05
5.88E+00 7.87E+05
5.88E+00 7.87E+05
Moose
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
5.97E+00 6.86E+05
05
1.77E05
1.77E05
1.77E05
1.95E05
1.95E05
1.95E05
1.95E05
1.95E05
1.95E05
5.97E+00 6.86E+05 1.95Es5505
19 | P a g e
27.00
65 7696.65 2196.00
0.35 2196.00
-2652.63 1.14E+11
5912.84
27.00
65 7677.26 2196.00
0.38 2196.00
-2337.37 1.31E+11
5987.37
27.00
65 7658.51 2196.00
0.40 2196.00
-2000.37 1.49E+11
6057.56
27.00
65 5844.59 2002.00
0.25 2002.00
-1553.84 4.27E+10
4098.54
27.00
65 5827.89 2002.00
0.28 2002.00
-1265.67 5.17E+10
4199.08
27.00
65 5811.80 2002.00
0.30 2002.00
-950.05 6.16E+10
4291.82
27.00
65 5796.46 2002.00
0.33 2002.00
-607.00 7.22E+10
4377.28
27.00
65 5781.97 2002.00
0.35 2002.00
-236.49 8.38E+10
4456.00
27.00
65 5768.39 2002.00
0.375 2002.00
161.45 9.62E+10
4528.50
27.00
65 5755.73 2002.00
0.40 2002.00
586.85 1.09E+11
4595.29
Sag and height of tower calculation
We have the relation,
Maximum sag (Dmax) = (W L2)/ (8*T3);
Where,
W = weight of conductor.
L = length of span.
T3 = tension at easiest condition.
Sample calculation:
For sheep, W = 1726 kg/km.
L = 0.25 Km.
T3 =4314.59 Kg.
Using the above equation, Dmax = 3.12m.
Let the minimum ground clearance (hg) = 8m.
Height of lower conductor (H1) = hg+ Dmax =8+3.12 =11.12m.
Height of middle conductor (H2) = H1+y/2 = 14.366m.
Height of top most conductor (H3) = H1+y = 17.61m.
Total height of tower (Ht) = H3+l+d = 29.827m.
Similarly, the maximum sag, H1, H2, H3 and the total height of the tower are calculated and
presented in the table below:
Conductor span(Km) Dmax(m) h1(m)
h2(m)
h3(m)
Ht(m)
Sheep
0.25
3.12
11.12
14.366
17.61
29.827
0.275
3.72
11.72
14.966
18.21
30.427
0.3
4.37
12.37
15.616
18.86
31.077
0.325
5.06
13.06
16.306
19.55
31.767
0.35
5.8
13.8
17.046
20.29
32.507
0.375
6.59
14.59
17.836
21.08
33.297
0.4
7.42
15.42
18.666
21.91
34.127
Deer
0.25
0.275
0.3
0.325
0.35
0.375
0.4
3.09
3.63
4.32
5
5.73
6.5
7.3
11.09
11.63
12.32
13
13.73
14.5
15.3
14.336
14.876
15.566
16.246
16.976
17.746
18.546
17.58
18.12
18.81
19.49
20.22
20.99
21.79
29.797
30.337
31.027
31.707
32.437
33.207
34.007
Zebra
0.25
0.275
0.3
3.81
4.52
5.27
11.81
12.52
13.27
15.056
15.766
16.516
18.3
19.01
19.76
30.517
31.227
31.977
20 | P a g e
0.325
0.35
0.375
0.4
6.08
6.95
7.87
8.84
14.08
14.95
15.87
16.84
17.326
18.196
19.116
20.086
20.57
21.44
22.36
23.33
32.787
33.657
34.577
35.547
Elk
0.25
0.275
0.3
0.325
0.35
0.375
0.4
3.07
3.66
4.29
4.96
5.68
6.44
7.25
11.07
11.66
12.29
12.96
13.68
14.44
15.25
14.316
14.906
15.536
16.206
16.926
17.686
18.496
17.56
18.15
18.78
19.45
20.17
20.93
21.74
29.777
30.367
30.997
31.667
32.387
33.147
33.957
Moose
0.25
0.275
0.3
0.325
0.35
0.375
0.4
3.81
4.5
5.24
6.03
6.87
7.77
8.71
11.81
12.5
13.24
14.03
14.87
15.77
16.71
15.056
15.746
16.486
17.276
18.116
19.016
19.956
18.3
18.99
19.73
20.52
21.36
22.26
23.2
30.517
31.207
31.947
32.737
33.577
34.477
35.417
Earth wire selection
From earth wire table, earth wire is chosen as follows:
No of strands = 19; diameter of a strand = 3.15mm;
weight per meter = 1.163 kg/m;
Conductor diameter = 15.75mm;
conductor area = 148.09mm2;
Ultimate tensile strength = 10041 kg;
Hence, maximum tension (Te) = 10041/2 = 5020.5 kg.
Bending moment and tower weight calculation
Sample calculation: for sheep, Ht=29.827m, 250m span
Taking 85% for tower A; 10% for tower B; and 5% for tower C
Due to Earth wire
1) Bending moment acting on tower due to E/W considering wind force:
BMe1 = Fwe*Ht
= (100*15.73e-3*250*2/3)*29.827
= 7823.55 kg-m.
21 | P a g e
2) Bending moment due to turning of the E/W
BMe2 = 2*Te*(sin10*0.85 + sin7.50*0.1 + sin150*.05)*Ht
=2*5020.5*(0.040828)*29.827
= 12227.58 Kg-m
Due to power conductor
1) Bending moment acting on tower due to power conductor considering wind force
BMpw = Fw*(H1+H2+H3)*2
= (100*27.93e-3*250*2/3)*(10.12+13.336+16.61)*2
= 40142.44 kg-m
2) Bending moment due to turning of the power conductor
BMpt = 2*T1*(sin10*0.85 + sin7.50*0.1 + sin150*.05) *(H1+H2+H3)*2
= 55983.92 kg-m
Then the total bending moment is calculated as;
BMtotal = BMe1 + BMe2 + BMpw +BMpt
=116187.3 kg-m
Weight of tower
Weight of tower (Wt) =
=0.000631*Ht*
;
;
Where, Ht is in Ft; BM is in lb-ft.
where, Ht is in m; Bm is in kg-m.
The bending moment of different conductors at different length of span and weight of tower are
calculated and shown in the tabulated form below:
22 | P a g e
Bending moment
table
Conductor
sheep
deer
zebra
Elk
23 | P a g e
Ht(m)
span(m)
29.827
250
Fwe1
(kg)
262.63
BMe1
(kg-m)
7833.316
BMe2
(kg-m)
12227.58
h1
(m)
11.12
h2
(m)
14.366
h3
(m)
17.61
30.427
275
288.89
8789.98
12473.55
11.72
14.966
18.21
Dia
(m)
2.793E02
2.79E-02
BMpw
(kg-m)
40142.44
T1
(kg)
7955
BMpt
(kg-m)
55983.92
BMt(kgm)
116187.3
Wt
(tonnes)
6.415318
46000.98
7955
58322.22
125586.7
6.803938
31.077
300
315.15
9793.917
12740.02
12.37
15.616
18.86
2.79E-02
52362.52
7955
60855.37
135751.8
7.225057
31.767
325
341.41
10845.65
13022.88
13.06
16.306
19.55
2.79E-02
59232.64
7955
63544.4
146645.6
7.67609
32.507
350
367.68
11952.01
13326.24
13.8
17.046
20.29
2.79E-02
66683.99
7955
66428.3
158390.5
8.163396
33.297
375
393.94
13116.94
13650.11
14.59
17.836
21.08
2.79E-02
74758.49
7955
69507.05
171032.6
8.689082
34.127
400
420.2
14340.17
13990.36
15.42
18.666
21.91
2.79E-02
83453.35
7955
72741.69
184525.6
9.250298
29.797
250
262.63
7825.437
12215.28
11.09
14.336
17.58
2.99E-02
42869.74
9115
64013.55
126924
6.698442
30.337
275
288.89
8763.98
12436.65
11.63
14.876
18.12
2.99E-02
48933.06
9115
66424.89
136558.6
7.073942
31.027
300
315.15
9778.159
12719.52
12.32
15.566
18.81
2.99E-02
55857.65
9115
69506.04
147861.4
7.528293
31.707
325
341.41
10825.17
12998.28
13
16.246
19.49
2.99E-02
63156.05
9115
72542.54
159522
7.990885
32.437
350
367.68
11926.27
13297.55
13.73
16.976
20.22
2.99E-02
71070.5
9115
75802.31
172096.6
8.490949
33.207
375
393.94
13081.48
13613.21
14.5
17.746
20.99
2.99E-02
79600.98
9115
79240.69
185536.4
9.025547
34.007
400
420.2
14289.74
13941.17
15.3
18.546
21.79
2.99E-02
88735.55
9115
82813.05
199779.5
9.591204
30.517
250
262.63
8014.527
12510.44
11.81
15.056
18.3
2.86E-02
43109.91
6658
49106.8
112741.7
6.465669
31.227
275
288.89
9021.09
12801.51
12.52
15.766
19.01
2.86E-02
49657.24
6658
51422.64
122902.5
6.907803
31.977
300
315.15
10077.55
13108.97
13.27
16.516
19.76
2.86E-02
56748.62
6658
53868.96
133804.1
7.380772
32.787
325
341.41
11193.89
13441.03
14.08
17.326
20.57
2.86E-02
64492.87
6658
56510.98
145638.8
7.895316
33.657
350
367.68
12374.84
13797.69
14.95
18.196
21.44
2.86E-02
72941.51
6658
59348.7
158462.7
8.454119
34.577
375
393.94
13621.18
14174.84
15.87
19.116
22.36
2.86E-02
82103.16
6658
62349.52
172248.7
9.055129
35.547
400
420.2
14936.85
14572.49
16.84
20.086
23.33
2.86E-02
92020.75
6658
65513.42
187043.5
9.700712
29.777
250
262.63
7820.185
12207.08
11.07
14.316
17.56
3.15E-02
45115.85
10120
70972.39
136115.5
6.932088
Moose
178830.9
8.959681
24 | P a g e
30.367
275
288.89
8772.647
12448.95
11.66
14.906
18.15
3.15E-02
51672.8
10120
73897.48
146791.9
7.341457
30.997
300
315.15
9768.705
12707.22
12.29
15.536
18.78
3.15E-02
58752.92
10120
77020.89
158249.7
7.780733
31.667
325
341.41
10811.51
12981.89
12.96
16.206
19.45
3.15E-02
66394.02
10120
80342.61
170530
8.251572
32.387
350
367.68
11907.89
13277.05
13.68
16.926
20.17
3.15E-02
74678.04
10120
83912.21
183775.2
8.760795
33.147
375
393.94
13057.85
13588.61
14.44
17.686
20.93
3.15E-02
83604.98
10120
87680.13
197931.6
9.305316
33.957
400
420.2
14268.73
13920.67
15.25
18.496
21.74
3.15E-02
93263.09
10120
91695.94
213148.4
9.892356
30.517
250
262.63
8014.527
12510.44
11.81
15.056
18.3
3.18E-02
47854.71
8125
59926.81
128306.5
6.89756
31.207
275
288.89
9015.312
12793.31
12.5
15.746
18.99
3.18E-02
55052.73
8125
62673.32
139534.7
7.355673
31.947
300
315.15
10068.1
13096.67
13.24
16.486
19.73
3.18E-02
62880.11
8125
65618.84
151663.7
7.850554
32.737
325
341.41
11176.82
13420.53
14.03
17.276
20.52
3.18E-02
71384.53
8125
68763.38
164745.3
8.384453
33.577
350
367.68
12345.42
13764.89
14.87
18.116
21.36
3.18E-02
80613.67
8125
72106.95
178830.9
8.959681
34.477
375
393.94
13581.78
14133.85
15.77
19.016
22.26
3.18E-02
90662.88
8125
75689.35
194067.9
9.583753
35.417
400
420.2
14882.22
14519.2
16.71
19.956
23.2
3.18E-02
101487.7
8125
79430.96
210320
10.249
Cost per unit length calculation
Assumptions: Cost of the steel used in tower = Rs.150000 per tonne
Number of towers (Nt) = ((total length)/(length of span))+1
Cost of tower per unit length = (cost per tower*Nt)/length of transmission
Sample calculation:
For sheep; 250m; weight of tower= 6.4153 tonne
Number of tower = (160/.25 ) +1= 641 nos
Cost per tower = cost per tone* weight of tower
= Rs.150000*6.4153
= Rs. 962297.7
Cost of tower per unit length = (962295*641)/160
= Rs.3855205
Similarly the cost of tower per unit length of different conductor and different span are
shown in table below:
Conducto
r
sheep
span(Km)
0.25
0.275
0.3
0.325
0.35
weight(tonne) cost/tower
Nt (Nos)
(Rs.)
6.415318
962297.7
641
6.803938
1020590.7
583
7.225057
1083758.55
535
7.67609
1151413.5
494
8.163396
1224509.4
459
cost/Length
(Rs.)
3855205.161
3718777.363
3623817.652
3554989.181
3512811.341
deer
0.25
0.275
0.3
0.325
0.35
6.698442
7.073942
7.528293
7.990885
8.490949
1004766.3
1061091.3
1129243.95
1198632.75
1273642.35
641
583
535
494
459
4025344.989
3866351.424
3775909.458
3700778.616
3653761.492
zebra
0.25
0.275
0.3
0.325
0.35
6.465669
6.907803
7.380772
7.895316
8.454119
969850.35
1036170.45
1107115.8
1184297.4
1268117.85
641
583
535
494
459
3885462.965
3775546.077
3701918.456
3656518.223
3637913.082
25
Elk
0.25
0.275
0.3
0.325
0.35
6.932088
7.341457
7.780733
8.251572
8.760795
1039813.2
1101218.55
1167109.95
1237735.8
1314119.25
641
583
535
494
459
4165751.633
4012565.092
3902523.895
3821509.283
3769879.598
Moose
0.25
0.275
0.3
0.325
0.35
6.89756
7.355673
7.850554
8.384453
8.959681
1034634
1103350.95
1177583.1
1257667.95
1343952.15
641
583
535
494
459
4145002.463
4020335.024
3937543.491
3883049.796
3855462.73
Most economical span and conductor selection
From the above table,
The most economical span = 350m for all conductors
Data available;
Cost of aluminum per tonne = Rs.20150
Cost of steel per tonne = Rs. 150000
Sample calculation:
For sheep; span =350m; aluminum weight per Km = 1036 kg; steel weight
per km = 690 kg
Cost of power conductor
Cost of aluminum per km = Rs. 20150*1.036 = Rs.20875.4
Cost of steel per km = Rs 150000*.69 = Rs. 103500
Total Cost of power conductor = (Rs. 20875.4 + Rs. 103500)*6 = Rs.746252.4/km
From table above,
Tower cost per unit length = Rs. 3512811.341
Capital cost/length = conductor cost/km + tower cost/km
= Rs.746252.4 + Rs. 3512811.341
(P) =Rs. 429063.7
Annual capital cost (A) is calculated as:
A=
*P
This gives annual capital cost (A) = Rs. 500226.9494
26
Power loss per Km PL= 41.11 Kw;
load loss factor (LLf)=0.13;
Cost of Energy loss/Km = PL *LLf * time* rate per Kwh
=41.11*0.13*365*24*7.5
=Rs. 351120.51
Total annual cost
= Rs. 500226.9494 + Rs. 351120.51
=Rs. 851347.4594
The total annual cost calculation is shown in table below:
conductor
M.E.Span(Km)
tower
cost/L (Rs.)
cost of
cond/L
(Rs.)
capital
cost/L (Rs.)
annual
cost/L (Rs.)
power
loss/L
(Kw)
annual E L
cost/L
(Rs.)
sheep
0.35
3512811.00
746252.00
4259063.00
500226.95
41.11
351120.51
851347.46
Deer
0.35
3653761.00
853729.00
4507490.00
529404.70
35.86
306280.26
835684.96
Zebra
0.35
3637913.00
537466.00
4175379.00
490398.26
35.97
307219.77
797618.03
Elk
0.35
3769880.00
947988.00
4717868.00
554113.60
32.28
275703.48
829817.08
Moose
0.35
3855463.00
596746.20
4452209.20
522911.97
29.14
248884.74
771796.71
From the above table,
The minimum total annual cost is acquired by the conductor Moose. Hence we
go for the conductor Moose for the transmission line of 200 Mw and 160Km.
Transmission line characteristics of the conductor Moose
Electrical characteristics

61 strands with 7 Steel strands and 54 Aluminum strands.
Diameter of each strands = 3.53 mm
With 1-6-12-18-24 configuration ,
GMR for inductance (GMRi)
GMR for capacitance (GMRc)
GMD for single ckt ( bundle conductor )
Resistance of the whole line per phase(R)
Inductance of Whole length (L)
Capacitance of whole Length(C)
Now Impedance of the Line (Z)
Susceptance of the Line (Y)
= 59.78mm
=69.02 mm
=11171.9 mm
= 5.205Ώ
=0.167 H
= 1.7488 μF
= 52.78<84.3 Ώ
=j5.494*e-04 siemen
= 5.494*e-04<90
27
total annual
cost
(Rs.)
A, B, C, D parameters calculation
A = 1 + ZY/2 = 0.985<0.083
B = Z= 52.78<84.3
C = 5.454*e-04<90.04
D = A=0.985<0.083
Now, Sending end Voltage
(Vs) = A*Vr +B*Ir
= 0.985<0.083* 220/√3<0 + 52.78<84.3* 546.75*e-03<-16.26
= 138.54<11.12 KV
Sending end current(Is) = C*Vr +D*Ir
= 523.7<8.88 A
Now Voltage Regulation = (|Vs|/A -|Vr| )/|Vr|
= 0.1164
= 10.68%
Corona Inception Voltage Criterion
Corona Inception voltage (Vci)
=21.1*GMR*m*δ*ln(GMD/GMR)
Where, m = factor of roughness =0.72
δ = relative density of air =1
Vci = 21.1 * 5.978*1*0.72* ln (11171.9/59.78)
= 475.02 KV
28
Mechanical characteristics
Length of span =350m.
Tension at toughest condition = 8125kg
Tension at stringing condition = 5781.97 kg
Tension at easiest condition = 4456.00 kg
Heights:
Maximum sag =6.87 m; H1=14.87m; H2=18.116m; H3=21.36m; Ht=33.577m
Bending moment =178830.9kg-m
Tower weight=8.959681 tonne
Tower Cost per unit length=Rs.3855462.73 /Km
Total annual cost =Rs. 771796.71/km
29