Transmission and Distribution
10EE53
Assignment Questions
Unit 1. Basics of Transmission and Distribution
1. Draw the line diagram of a typical power supply scheme indicating the standard voltages.
2. Write short note on advantages of HV transmission.
3. Write short note on H V D C transmission.
4. Write short note on feeders, distributors and service mains.
5. Write the comparison between Overhead and underground transmission system.
6. What are the advantages and limitations of high voltage a.c transmission?
Unit 2. Overhead Transmission Lines
1. Show that a transmission line conductor suspended between level support assumes the
shape of a catenory. Derive the expression for sag.
2. Explain what is sag and why it is inevitable in over head transmission lines? What are the
factors influencing it?
3. With usual notations derive an expression for maximum sag of a transmission Line where
the supports are at different levels?
4. Obtain the expression for sag in a freely suspended conductor when the supports are at
equal levels.
5. Explain the effects of sag in overhead transmission Line.
6. Obtain the expression for sag in a power conductor when the supports are at equal levels,
taking into the effect of wind and ice loading
7. Write short note on effect of ice load and wind effect on sag of transmission. Line.
8. From the first principles derive the expression for sag in a freely suspended conductor
when the supports are at unequal levels
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Transmission and Distribution
10EE53
Unit 3. Corona
1. What is corona? Derive expression for the disruptive critical voltage and visual critical
voltage.
2. What are the effects of corona?
3. Write short note on disruptive critical voltage.
4. Discuss the advantages and disadvantages of corona.
5. Explain the terms with reference to corona.
i) disruptive critical voltage ii) Power loss due to corona
6. Write short note on corona in transmission lines.
7. Write short note on factors affecting corona and methods of reducing corona effect.
6. 8. Explain the terms with reference to corona.
i) Visual critical voltage
ii) Power loss due to corona
Unit 4. Insulators
1 Explain the various tests conducted on insulators. With usual notations, derive the general
expression for the metal link of string to line capacitance, when guard ring is used for the string
of insulators.
2. What is string efficiency in the context of suspension insulators? Explain the methods of
improving the same.
3. Write short note on different types of O H line insulators.
4. Define string efficiency and hence calculate the mathematical expression for it.
5. Explain the methods of improving the string efficiency.
6. What are the insulators with O H Lines? Discuss the desirable properties of insulators and
name the types of insulators.
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Transmission and Distribution
10EE53
Unit 5. Under ground Cables
1. Draw the cross sectional view of a single core cable and explain the construction.
2. Compare the dielectric stress of a homogeneous cable with that of a capacitance graded
cable.
3. Write short notes on testing of cables.
4. Derive an expression for insulation resistance of a cable.
5. Explain capacitance grading of cables with appropriate derivation.
6. What is meant by grading of cables? Briefly explain the various methods of grading.
7. Write short note on thermal rating of cables.
8. Derive expressions for the maximum and minimum dielectric stress in a single core cable
and ontain the criterion for keeping the diectric stress to a minimum value.
9. Compare the merits and demerits of underground system overhead system.
10. State five advantages of using underground cables for power distribution.
11. Write short note on laying of UG Cables.
Unit 6. Transmission Line Parameters
1. Explain the terms self GMD and mutual GMD and prove that the inductance of a group of
parallel wires carrying current can be represented in terms of their geometric distances.
2. Derive an expression for the capacitance of a unsymmetrically spaced but
regularly transposed line.
3. Derive the expression for the inductance of a 3 phase transmission line with un
symmetrcal spacing without transposition. Use the Flux linkage concept.
4. Write short notes on transposition of transmn. Lines.
5. Derive the expression for the inductance of a 3 phase unsymmetrically spaced
but transmission line/km.
6. Derive the expression for the capacitance of a 3 phase single ckt. Line
with equilateral spacing
7. Show how the inductance of 3 phase transmission. Line with equilateral and
symmetrical spacing between conductors can be calculated.
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Transmission and Distribution
10EE53
8. Derive the expression for the capacitance of a 3 phase line with
unsymmetrical spacing.
9. What is skin effect? Which are the factors influencing skin effect?
10. Derive from first principles, an expression for the inductance per phase per km of a 3 phase
regularly transposed trn. Line. The conductors are of diamt. d mt. and placed at the corner of a
triangle of sides a, b, c.
11. Calculate the inductance of single phase two wire line starting from fundamentals
Unit 7. Performance of Transmission Line
1. Derive expressions for generalized ABCD constants for a long transmission line
using rigorous method of analysis.
2. Derive expressions for ABCD constants for a medium transmission line using
nominal T model. Hence prove AD-BC = 1.
3. Write short note on classification of transmission lines.
4. Write short note on Ferranti effect.
5. What are ABCD constants of a transmission Line? Determine the same for a a medium
transmission line using nominal TI model. Hence prove AD-BC = 1.
6. Derive the expressions for sending end voltage and current of a medium transmission Line
(Nominal T method) in terms of Y, Z, Vr and Ir.
8. Write short note on surge impedance loading.
9. Derive expressions for generalized ABCD constants for equivalent T representation
of long transmission line.
10. Discuss the terms voltage regulation and transmission efficiency as applied
to transmission line.
11. Write and explain the classification of overhead transmission. Lines.
12. Calculate the efficiency. And voltage regulation for medium transmission
Line assuming nominal T method.
13. Derive an expression for the efficiency. And voltage regulation for short
transmission Line giving the vector diagram.
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Transmission and Distribution
10EE53
Unit 8. Distribution Systems
1. Write short note on radial and ring main distributors.
2. What is meant by DC distribution? Explain with diagram different types of DC distribution and
discuss their merits and demerits.
3. Write short note on radial distribution system.
4. Show different types of distribution systems with single line diagrams and state the merits and
demerits of ring main and radial distribution. Systems.
5. Calculate the total voltage drop in uniformly loaded distributor, when it is fed at one end.
6. Write short note on ring main distributors.
7. Write short note on feeders, distributors and service mains.
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