Semester : Fall Year:2024 Course : Transmission Line Design The power conductor has maximum working of 6890 kg and

diameter of 25.97mm. The earth wire has maximum working

1a) Define substation. Explain the classification of substation. 7 tension of 2856 kg and diameter of 16.52mm. Assume 80% tower
b) Describe the di erent surveying technique in detail 8 are A type, 15% are of B type and 5% are of C type and the wind
2a) Di erentiate between feasibility study and detailed design of a 7 force is 100 kg/m².
transmission line project. 5a) In an experiment with suspension insulator unit comprising of 7
b) Select most economical and technically adequate voltage level 8 disc units, following results were obtained as:
and no. of circuits for transmission line to transmit 200 MW power Dry power frequency flashover voltage for each disc = 65 kV
over a distance of 200 km. Wet power frequency flashover voltage for each disc =43 kV
Length 80 160 240 320 Find out the safety factor if 4 units of disc are used in the string
MF 2.75 2.25 1.75 1.35 insulator to insulate at 110 kV system. Consider the ratio of pin to
3a) What do you mean by line compensation? Explain how 7 earth capacitance to the disc capacitance is 1/5.
synchronous compensator used to compensate reactive power in b) What is stringing chart? Derive the expression for stringing 8
transmission system during full load and no load or light load equation.
conditions. 6a) Explain the design consideration for EHV line. 8
b) What do you mean by Virtual Sag? Derive the Expression to obtain 8 b) A 400 kV 3-phase bundled conductor line with three sub- 7
ground clearance required for a conductor hanged at di erent conductors per phase has a horizontal configuration. The radius
height. of each sub-conductor is 1.6 cm. Spacing between sub-
4a) A double circuit transmission line is designed to transmit 90 MW 7 conductors in the bundle is 40 cm and phase separation is 12
power over 100 km. The most economical voltage is found to be meter.
132 kV. The minimum air clearance to be 6.5 inches per 10 kV with i. Find the inductance per phase per km of the line.
safety factor 8 inches and the maximum swing of insulator string ii. Compute the inductance of the line with only one conductor
to be 45º. Calculate: per phase (i.e without bundling), each conductor having the
i. Cross arm length cross-sectional are equal to total cross sectional area of the
ii. Insulator string length bundled conductor mentioned above.
iii. vertical separation of conductor iii. Comment on the results.
iv. Height of earth wire from the top most conductors. 7 Write short notes on: (Any two) 10
b) To transmit the given amount of power to a given distance a single 7 a) Conductor vibrations
earth wire is chosen for which the following design steps are b) E ect of topography and climate condition on transmission line
completed, compute the most economical span if the design c) Corona loss
transmission length is 200km.
Span(m) Dmax(m) H1(m) H2(m) H3(m) Ht(m)
250 3.14 10.245 13.555 16.865 28.815
275 3.69 10.801 14.111 17.421 29.371
300 4.27 11.383 14.693 18.003 29.953
325 4.88 11.965 15.298 18.608 30.558
350 5.50 12.548 15.923 19.233 31.183
Where H1 height of lower conductor from ground, H2 height of
middle conductor from ground. H3 height of top conductor from
ground. Ht total height of tower
Semester : Spring Year:2023 Course : Transmission Line Design 5a) Calculate the No. of Disc in a string required to withstand the 7
Temporary O/V, Lighting O/V and Continous O/V for a
1a) Why radial configuration is preferred over mesh configuration for 7 Transmission line at 132 KV voltage level.
distribution feeder line? Derive the expression for percentage FOWR-1.15. NACF-1.1 FS-1.2
voltage drop for substation service area with 'n' number of primary
b) List out the tests conducted on insulators? A line conductor is 8
feeders. Using the expression calculate percentage voltage drop
suspended from the cross-arm by a string of 4 disc insulators.
for square shaped service area having.
Calculate the conductor voltage with respect to the cross arm if
Load density 200 KVA/ sq km Length of feeder =1.5 KM
the voltages across the second and third units from the cross-arm
Constant K=0.0018%
are 13.2 kV and 18 kV respectively. What is the string e iciency it
b) Describe the various types of substation bus schemes. Briefly 8 leakage current is ignored?
describe the factor that a ect the site selection of a distribution
6a) 2024 Fall 6a 8
substation.
b) Why it is important to use bundled conductor for HV and EHV 7
2a) What are the issues related to 'Right of Way (RoW)' for 7
transmission line? How do bundled conductor. conductor
construction of transmission line in Nepal? What measures do
diameter and spacing between conductors a ect the power
you take to minimize the e ects of topographical features and
transfer capability of a transmission line? Explain.
climate conditions while designing a transmission line?
7 Write short notes on: (Any two) 10
b) What do you mean by line compensation? How does high voltage 8
a) Vibration and Damper in Transmission line.
transmission e ect on energy loss, conductor and insulator
b) E ects of Corona on performance of power system.
economy?
c) Earthing and Bounding.
3a) Derive the Expression to obtain ground clearance required for a 7
conductor hanged at di erent height. Data Tables
b) Show that the force acting on the tower due to horizontal turning 8 Table 1: Transmission line capability curve with assumption of
of the conductor by angle of a with the conductor tension T could single circuit transmission line surge impedance of 400 ohm
be expressed as 2Tsina/2.
4a) 2024 Fall 4a 7 Length (km) Multiplying factor (mf)
b) For a three phase power transmission line design. following 7 80 2.75
computation have been made for designing a 32 meter high tower: 160 2.25
Height of each conductor from ground in meter 240 1.75
H1=11 H2=17 H3=24 320 1.35
Span length in meter = 250 Diameter of conductor (mm) =22.26 480 1.00
Diameter of earth wire (mm)=14.6 Wind pressure (kg/sq m)=100 640 0.75
Maximum working Tension of Conductor (kg)=10210
Maximum working Tension of earth wire (kg)=6664
Number of circuit=2 Number of earth wire=2

Assume the line is straight throughout. Calculate bending

moment acting on the tower and weight of the tower
Semester : Fall Year:2022 Course : Transmission Line Design 91.4*103 N /mm2 find the sag and tension under erection
conditions.
1a) How do you analyze the distribution substation areas shaped as N 7
b) Calculate the No. of Disc in a string required to withstand the 7
sided polygonal? And find the % voltage drop in heptagon.
Temporary O/V, Lighting O/V and Continuous O/V for a
b) What is a distribution service area? Describe the di erent 8 Transmission line at 220 KV voltage level.
surveying technique: FOWR-1.15, NACF-1.1 FS-1.2
2a) How do environmental and cultural heritage a ects the route 7 5a) For a double circuit 400 kV line, suggest the dimension for the 7
selection of transmission line? Also list some factors to be following.
considered for transmission line design planning. (i) Cross-arm length (ii) Insulator string length (iii)No.of earth wire
b) A power of 2000 MW is required to be transmitted over a distance 8 (iv) Horizontal and vertical separation of conductor.
of 800Km at voltage levels of 400kV, 750 kV. Determine: (v) Height of earth wire from top most conductor (take maximum
(i) Possible number of circuits required with 50% series capacitor swing angle of insulator = 450)
compensation b) In an experiment with suspension insulator units comprising of 8
(ii) Total power loss (iii) Loss per km. discs units, the following results were obtained as
Assume the values of X and rohm/km are given as (i)Dry power frequency flashover voltage for each dist = 65kV
kV rohm/km X ohm/km(50HZ) (ii) Wet power frequency flashover voltage for each disc = 43 kV
400 0.031 0.327 No. of units in a string Dry power freq Wet power freq
750 0.0136 0.272 flash over voltage, kV flash over voltage, kV
3a) 2024 Fall 2b 7 4 210 150
b) For a three-phase power transmission line design. The following 8 8 385 285
computation have been made for designing a 32.65 meter high 10 460 345
tower: Find out (i) dry and wet string e iciency for each of the three
Height of each conductor from ground in meter strings (ii) factor of safety if the 8 string unit is used to insulate a
H1=11.24 H2=17.6 H3=23.96 110kV system. Consider the ratio of pin to earth capacitance and
Span length in meter = 250 Diameter of conductor (mm) =22.26 disc capacitance as 1/6.
Diameter of earth wire (mm)=14.6 Wind pressure (kg/sq m)=100 6a) Design a transmission line to transmit three phase 85000KW at 15
Maximum working Tension of Conductor (kg)=10210 0.85 power factor, over a distance of 160 km. the Regulation of the
Maximum working Tension of earth wire (kg)=6664 line should be within 10 percent of receiving end voltage, e icacy
Number of circuits=2 Number of earth wire=2 95% and corona loss not to exceed 0.6 KW/KM.
Calculate bending moment acting on the tower and weight of the a) Choose voltage, size of conductor and spacing between
tower. Take 80% are type A, 15% are type B, and remaining are conductors.
type C. b) Calculate the constant of the line and determine the regulation
4a) An overhead line having a span of 250m is to be erected at a 7 c) Find the e iciency on full load.
temperature of 40 deg C in still air condition. It is desired that a d) Predict corona loss per KM of the line and the total corona loss.
factor of safety of 2 should be maintained under bad weather 7 Write short notes on: (Any two) 10
conditions when the temperature is 10 deg c and wind load is a) Design Consideration of EHV Lines
378N / (m ^ 2) of projected area. The data for the ACSR conductor b) Advantage of Bundle Conductor
used for the line is as under: diameter 1.95 cm, area 2.25cm^2 , c) Line Compensation Techniques
weight is 8.31N / m breaking load 77900N, coe icient of linear
expansion 18.44*10-6 per degree C, young's modulus
Semester : Fall Year:2021 Course : Transmission Line Design Semester : Fall Year:2020 Course : Transmission Line Design

1a) How do you analyze the distribution substation areas shaped as n 7 1a) What are the major components of Distribution system? Briefly 7
sided polygonal? And also find the % voltage drop in Dodecagon explain advantages and disadvantages of Loop type Sub
feeder and Heptagon feeder. transmission system over Radial type Sub transmission system.
b) 2022 Fall 1b 8 b) 2023 Spring 1a 8
2a) Name the act and regulation for govern the permit and license 7 2a) How topographical features and climate condition a ect the route 7
requirement for construction of transmission line in Nepal? selection of transmission line?
b) Select most economical and technically adequate voltage level 8 b) 2024 Fall 2b 8
and no. of circuits for transmission line to transmit 100 MW power 3a) 2024 Fall 3a 7
over a distance of 180 km. b) A single circuit transmission line is designed to transmit 90 MW 8
Length 80 160 240 320 power over 100 km. The most economical voltage is found to be
MF 2.75 2.25 1.75 1.35 132 kV. The minimum air clearance to be 6.5 inches per 10 kV with
3a) 2023 Spring 3b 7 safety factor 8 inches and the maximum swing of insulator string
b) Why is compensation necessary in high voltage transmission 8 to be 45º. Calculate:
system? Di erentiate shunt compensation from series i. Cross arm length
compensation with their advantages. ii. Insulator string length
4a) 2023 Spring 5a 7 iii. vertical separation of conductor
b) For a three-phase power transmission line design. The following 7 iv. Height of earth wire from the top most conductors.
computation has been made for designing a 32.65 meter high 4a) To transmit 90 MW of power to 150 km distance a single circuit 7
tower: witch 8 single earth wire is chosen for which the following design
Height of each conductor from ground in meter steps and completed.
H1=10.26 H2=16 H3=20.11 Span (m) H1(m) H2(m) H3(m) Ht (m)
Span length in meter = 250 Diameter of conductor (mm) =21.65 300 11.5 14.5 18 30
Diameter of earth wire (mm)=15.65 Wind pressure (kg/sq m)=110 Where, H1, H2 and H3 are the height of lower, middle and top
Maximum working Tension of Conductor (kg)=10050 conductors from ground respectively; and Ht is the total height of
Maximum working Tension of earth wire (kg)=6660 the tower. The power conductor has maximum working tension of
Number of circuits=1 Number of earth wire=1 6890kg and diameter of 25.97 mm. The earth wire has maximum
Calculate bending moment acting on the tower and weight of the working tension of 2856 kg and diameter of 16.52 mm. Wind
tower. Take 85% are type A, 10% are type B, and 5% are type C. pressure is 981 N/m². Assume 80% towers are type A, 15% are
5a) 2022 Fall 6 15 type B and remaining are straight line towers. Calculate bending
moment acting on the tower, weight of the tower in each span and
6a) 2022 Fall 5a 8
total cost if the cost of steel used in tower is Rs 150,000 per ton.
b) 2024 Fall 6a 7
b) 2024 Fall 5b 7
7 Write short notes on: (Any two) 10
5a) 2022 Fall 6 7
a) Distribution Planning and its importance
b) ROW 6a) For a double circuits 132 KV Transmission line, suggest the 8
c) Corona loss and corona inception voltage dimension for the following
i. Cross arm length
ii. Insulator string length
 iii.Horizontal and vertical separation of conductor Assume: all towers are straight line towers. The air clearance is
iv. Height of earth wire from top most conductor shown in figure below. Minimum ground clearance is 10 m.
(Take maximum swing angle of insulator -45) neglect the e ect of ground wire
b) Explain how you can improve the string e iciency of an insulator? 7
7 Write short notes on: (Any two) 10
a) E ects intra group spacing on bundled conductor line
capability b) Conductor vibration c) String e iciency

b) 2022 Fall 3b 7
5a) What are the tests conducted on insulators? Briefly describe the 7
Semester : Fall Year:2019 Course : Transmission Line Design procedure for conducting each of these tests?
b) What do you mean by bundle spacing and bundle radius? How do 8
1a) 2021 Fall 1a 7 you calculate equivalent radius of bundle conductor having N-sub
b) A three phase 11 kV distribution line has 37/2.36 ACSR conductor 8 conductors?
with conductor spacing 0.8 meter in equilateral configuration. The 6a) 2022 Fall 5a 8
load 600 kVA is supplied at 0.8 power factor lagging. Determine
b) How does the size of the conductor and the spacing between 7
the constant K. What will be the percentage voltage drop in the
conductors a ect the line performance?
line when the line length is 1.5 km
7 Write short notes on: (Any two) 10
2a) How would plan and profile drawing assists in design of 7
a) AIS and GIS
transmission line?
b) Distribution Planning and its importance
b) How topographical features and climate condition a ect the 8 c) ROW
design of 8 a transmission line? Point out the conditions for
requirement of EIA or IEE for transmission line construction in
Nepal.
3a) 2022 Fall 2b 7
Semester : Spring Year:2018 Course : Transmission Line Design
b) 2021 Fall 3b 8
4a) For the design of most economical span of an extra high voltage 7 1a) What is a distribution service area? Describe about the factors 7
transmission line. Following data are available for a particular that a ect the site selection of a distribution substation.
conductor. Select the most economical span. b) Earthing and bonding is the first step in designing a substation, 8
Cross-sectional conductor area=346.36 mm², wind pressure =981 explain it. Also classify the types of substation.
N/m², UTS=20121.59 pound. 2a) Why surveying is important while designing the transmission line? 7
Span (m) Maximum sag in feets Describe the di erent surveying techniques.
250 14
b) 2022 Fall 2b 8
275 18
300 22 3a) Select the most economical and technically adequate voltage 7
325 25 level and 7 number of circuit to transmit 90MW of power over a
distance of 200Km
 b) For the voltage level and number of circuits selected in above 8 b) Show that the force acting on the tower due to horizontal turning 8
question no 3(a) the most economical span for di erent of conductor by an angle a with the conductor tension T is given
conductor are tabulated below: by expression 2T sin a/2. In a single circuit 220 kV transmission
Conductor Economical Span(m) Cost of tower per unit length(Rs) line, Maximum swing of insulator string is 45°,
SHEEP 350 3,698,198 Minimum air clearance: 6.5 inch per 10 kV (rms)
KUNDAH 300 3,810,451 Factor of safety = 8
DEER 275 3,891,120 Carryout the following design steps to find
ZEBRA 300 4,322,745 i) Cross arm length
4a) Determine the position of maximum sag from either supporting 7 ii) Insulator string length
towers of equal height at di erent elevation. Also explain the iii)Horizontal and vertical separation of conductor
condition of virtual sag. iv) Height of earth wire from the top most conductor
b) 2024 Fall 5b 7 4a) To transmit the given amount of power to a given distance ,double 15
5a) 2022 Fall 5b 7 circuit line with a double earth wire is chosen for which the
following design steps are completed, compute the most
b) Describe the e ect of conductor area and intra group spacing on 8
economical span.
bundled conductor line capability.
Span(m) Dmax(m) H1(m) H2(m) H3(m) Ht(m)
6a) 2022 Fall 6 8 250 5.27 12.178 14.998 17.818 28.444
7 Write short notes on: (Any two) 10 275 6.24 13.148 15.968 18.778 29.414
A) Right of Way B) Compensation Technique 300 7.30 14.208 17.028 19.848 30.474
C) Advantages of Extra High Voltage Transmission line 325 8.43 15.338 18.158 20.978 31.604
350 9.65 16.558 19.378 22.198 32.824
Where H1 height of lower conductor from ground, H2 height of
middle conductor from ground. H3 height of top conductor from
Semester : Fall Year:2018 Course : Transmission Line Design ground. Ht total height of tower
The power conductor has maximum working of 6000 kg and
1a) What do you mean by distribution system planning? Describe 7 diameter of 4cm. The earth wire has maximum working tension of
about short-term, long-term and dynamic planning with 2000 kg and diameter of 2cm. Assume 80% tower are A type, 15%
examples. are of B type and 5% are of C type and the wind force is 100 kg/m².
b) Describe about the various types of subtransmission network 8 5a) Why bundling of wire is necessary in EHV transmission system. 7
configuration. Derive the expression for the geometric mean radius GMR of the n
2a) How topographical features and climate condition a ect the 7 sub conductor bundle in an EHV transmission line.
design of a transmission line? Name the acts and regulations that b) 2023 Spring 5a 8
govern the legal permit and license requirements for construction 6a) Determine the horizontal position of maximum sag from either 8
of transmission line in Nepal. supporting towers of equal height at a di erent elevation from a
b) Find the most economical voltage and number of circuits for 8 common reference. Also explain the condition of virtual sag.
transmitting 180MW at 0.97 power factor lag to a distance of 150 b) For transmission line design following computation has been 7
km. made. Select the most economical conductor. All in 1000Rs
3a) Why compensation is necessary in high voltage transmission 7
system? Di erentiate shunt compensation and series Conductor Total tower Total conductor Annual Energy
compensation with their advantages. Cost/km Cost/km loss/km(1000Rs)
 Goat 890 1254 32 Semester : Fall Year:2017 Course : Transmission Line Design
Sheep 936 1450 27
Zebra 974 1585 24 1b) The consumer data for particular distribution transformer for a 8
Deer 964 1663 24 specified year is as shown as follows.
Elk 968 1847 21
Energy rate = Rs. 7.2 per unit Interest rate=105 Project life 20 yrs.
7 Write short notes on: (Any two) 10
a)Substation configuration
b) Design consideration of EHV line
c) Route Selection and Right of Way (ROW) for transmission line

Semester : Fall Year:2016 Course : Transmission Line Design Determine the following. For each class of consumer:
i. peak load ii. load factor (daily and annual)
1a) 2018 Fall 1a 7 iii. contribution factor iv. annual energy sell
b) Derive an expression for percentage voltage drop in the 8 3a) Explain about di erent types of compensation techniques used in 7
distribution substation for hexagonal shaped service area with 6 high voltage transmission line.
primary feeders.
2a) 2018 Fall 2a 7
b) 2022 Fall 2b 8
3a) 2018 Spring 3a 7
b) Why is grounding of tower needed? Describe di erent methods. 8
4a) 2022 Fall 3b 7
b) 2022 Fall 5b 7
5a) 2018 Spring 5b 7
b) 2022 Fall 4a 8
6a) 2022 Fall 6 15
7 Write short notes on: (Any two) 10
a) Configuration of EHV transmission
b) Compensation Technique c) Vibration of Conductor