Power System Transmission & Distribution B.Tech Question Paper : vardhaman.org

College : Vardhaman College Of Engineering
Degree : B.Tech
Department : Electrical & Electronics Engineering
Semester : V
Subject :Power System Transmission & Distribution
Document type : Question Paper
Website : vardhaman.org

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Vardhaman Power System Transmission Question Paper

Four Year B. Tech V Semester Supplementary Examinations June – 2014
(Regulations : VCE-R11)
(Electrical and Electronics Engineering)
Date : 17 June, 2014 FN
Time: 3 hours
Max Marks: 75
Answer ONE question from each Unit
All Questions Carry Equal Marks

Related : Vardhaman College Of Engineering Geo Technical Engineering-I B.Tech Question Paper : www.pdfquestion.in/6362.html

All parts of the question must be answered in one place only :

Unit – I

1. a) Derive the expression for the capacitance per km of a single phase line without ground effect? 7M
b) Find the capacitance of a single phase transmission line 40kM long consisting of two parallel lies each 4mm in diameter and 2m apart. Determine the capacitance of the same line taking into account effect of ground. The height of conductors above ground is 5m? 8M

2. a) Explain the necessity of transposition in transmission lines? 8M
b) A single phase transmission line has two parallel conductors 3m apart. The radius of each conductor being 1cm. Calculate the loop inductance per km length of the line if the material of the conductor is i) copper ii) steel with µr = 100. 7M

Unit – II

3. a) Derive the ABCD constants for a medium transmission line which can be analyzed using Nominal p method?9M
b) Using a nominal p model find the sending end voltage and regulation of a 250 km three phase line delivering 50 MVA at 0.85 p.f lag, 132 kV, 50 Hz. The conductors are spaced 3m apart equilaterally. The conductor diameter is 1.6 cm and resistance is 0.11 O/km. 6M

4. a) Show that for a transmission line the receiving end voltage and current (Vr, Ir) are given in terms of sending end voltage and current (Vs, Is) and auxiliary constants (ABCD) as
Vr = DVs-BIs
Ir = – CVs+AIr 7M

b) A short three phase transmission line connected to a 33kV, 50Hz generating station at the sending end is required to supply a load of 10MW at 30kV, 0.8pf lagging at the receiving end. If the minimum transmission efficiency is to be limited to 96%, estimate the resistance and inductance values of the line. 8M

Unit – III

5. a) What is corona? Discuss the various factors affecting corona. 8M
b) Derive an expression for the sag when supports are at unequal levels? 7M
6. a) Distinguish between disruptive critical voltage and visual critical voltage. Give expressions for the same? 8M
b) Calculate the sag for a span of 200 m if the ultimate tensile strength of conductor is 5788 kg. Factor of safety is 2. Weight of conductor is 604 Kg/km. 7M

Unit – IV

7. a) Derive an expression for string efficiency. Why should shielding be provided to insulators? 8M
b) Obtain expressions for the voltages across 4 units of an insulator string in terms of voltage across its top most unit. 7M
8. a) Briefly describe the three main types of insulators highlighting their advantages. 9M
b) A string of 6 suspension insulators is to be graded to obtain uniform distribution of voltage across the string. If the pin to earth capacitances are equal to C, and the self capacitance of the top insulator is 10C. Find the mutual capacitance of each unit in terms of C. 6M

Unit – V

9. a) Distinguish between ring main and radial distribution systems. 8M
b) Prove that the volume of copper required for single phase 2 wire system is more than three phase 4 wire system. 7M
10. a) Briefly describe any three different types of DC distributors. 9M
b) Compare the DC 2 wire, AC 3-phase 3-wire on the basis of equal maximum potential difference between any two conductors? 8M