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.
  1. Write short note on advantages of HV transmission.
  1. Write short note on H V D C transmission.
  1. Write short note on feeders, distributors and service mains.
  1. Write the comparison between Overhead and underground transmission system.
  1. 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.
  1. Explain what is sag and why it is inevitable in over head transmission lines? What are the factors influencing it?
  1. With usual notations derive an expression for maximum sag of a transmission Line where the supports are at different levels?
  1. Obtain the expression for sag in a freely suspended conductor when the supports are at equal levels.
  1. Explain the effects of sag in overhead transmission Line.
  1. 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
  1. Write short note on effect of ice load and wind effect on sag of transmission. Line.
  1. 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.
  1. What are the effects of corona?
  1. Write short note on disruptive critical voltage.
  1. Discuss the advantages and disadvantages of corona.
  1. Explain the terms with reference to corona.

i) disruptive critical voltage ii) Power loss due to corona

  1. Write short note on corona in transmission lines.
  1. Write short note on factors affecting corona and methods of reducing corona effect.
  1. 8. Explain the terms with reference to corona.

i) Visual critical voltageii) 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.

  1. Write short note on different types of O H line insulators.
  1. Define string efficiency and hence calculate the mathematical expression for it.
  1. Explain the methods of improving the string efficiency.
  1. 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.
  1. Compare the dielectric stress of a homogeneous cable with that of a capacitance graded cable.
  1. Write short notes on testing of cables.
  1. Derive an expression for insulation resistance of a cable.
  1. Explain capacitance grading of cables with appropriate derivation.
  1. What is meant by grading of cables? Briefly explain the various methods of grading.
  1. Write short note on thermal rating of cables.
  1. 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.
  1. Compare the merits and demerits of underground system overhead system.
  1. State five advantages of using underground cables for power distribution.
  1. 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.
  1. Derive an expression for the capacitance of aunsymmetrically spaced but regularly transposed line.
  1. Derive the expression for the inductance of a 3 phase transmission line with unsymmetrcal spacing without transposition. Use the Flux linkage concept.
  1. Write short notes on transposition of transmn. Lines.
  1. Derive the expression for the inductance of a 3 phase unsymmetrically spaced but transmission line/km.
  1. Derive the expression for the capacitance of a 3 phase single ckt. Line with equilateral spacing
  1. 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
  1. Derive the expression for the capacitance of a 3 phase line with unsymmetrical spacing.
  1. What is skin effect? Which are the factors influencing skin effect?
  1. 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. dmt. and placed at the corner of a triangle of sides a, b, c.
  1. 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.
  1. Derive expressions for ABCD constants for a medium transmission line using nominal T model. Hence prove AD-BC = 1.
  1. Write short note on classification of transmission lines.
  1. Write short note on Ferranti effect.
  1. What are ABCD constants of a transmission Line? Determine the same for aa medium transmission line using nominal TI model. Hence prove AD-BC = 1.
  1. 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.

  1. Write short note on surge impedance loading.
  1. Derive expressions for generalized ABCD constants for equivalent T representation of long transmission line.
  1. Discuss the terms voltage regulation and transmission efficiency as applied to transmission line.
  1. Write and explain the classification of overhead transmission. Lines.
  1. Calculate the efficiency. And voltage regulation for medium transmission Line assuming nominal T method.
  1. 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.
  1. What is meant by DC distribution? Explain with diagram different types of DC distribution and discuss their merits and demerits.
  1. Write short note on radial distribution system.
  1. Show different types of distribution systems with single line diagrams and state the merits and demerits of ring main and radial distribution. Systems.
  1. Calculate the total voltage drop in uniformly loaded distributor, when it is fed at one end.
  1. Write short note on ring main distributors.
  1. Write short note on feeders, distributors and service mains.

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