Download GTU (Gujarat Technological University Ahmedabad) B.Tech/BE (Bachelor of Technology/ Bachelor of Engineering) 2020 Winter 5th Sem 3150911 Power System Ii Previous Question Paper
Enrolment No.___________
GUJARAT TECHNOLOGICAL UNIVERSITY
BE- SEMESTER?V (NEW) EXAMINATION ? WINTER 2020
Subject Code:3150911 Date:29/01/2021
Subject Name:Power System- II
Time:10:30 AM TO 12:30 PM Total Marks: 56
Instructions:
1. Attempt any FOUR questions out of EIGHT questions.
2. Make suitable assumptions wherever necessary.
3. Figures to the right indicate full marks.
MARKS
Q.1 (a) Explain Types of Transmission Line.
03
(b) Write a short note on
04
(I)
Ferranti effect
(II)
Tuned power lines
(c) Using Rigorous, Derive expressions for sending end voltage current
07
for long transmission line.
Q.2 (a) What is p.u. system? Give the advantages of p.u. system
03
(b) Explain power in single phase AC circuits briefly
04
(c) A synchronous generator is rated 645 MVA, 24 KV, 0.9 pf lagging. It
07
has a synchronous reactance 1.2 . The generator is feeding full load
at 0.9 pf lagging at rated voltage. Calculate:
(a) Excitation emf (Ef) and power angle
(b) Reactive power drawn by the load
Carry out calculations in pu form and convert the result to actual
values.
Q.3 (a) Give classification of faults. What is difference between steady state
03
reactance Xd, transient reactance Xd' and sub-transient reactance
Xd''?
(b) What is receiving end power circle diagram? Write down steps to
04
draw it.
(c) Explain factors deciding selection of circuit breaker.
07
Q.4 (a) Explain the performance of loaded Synchronous Machine.
03
(b) Why does a generator produce only positive sequence voltage?
04
(c) A 50 Hz transmission line 300 km long has a total series impedance
07
of 40 + j125 ohms and a total shunt admittance of 10-3 mho. The
receiving end load is 50MW at 220 KV with 0.8 lagging pf. Find the
sending end voltage, current, power and power factor using nominal ?
method.
Q.5 (a) What are symmetrical components and its need?
03
(b) Write and explain symmetrical component transformation
04
(c) Using appropriate interconnection of sequence networks, derive the
07
equation for a line to line fault in a power system with fault
impedance of Zf.
Q.6 (a) Differentiate symmetrical and unsymmetrical faults. List various
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unsymmetrical faults.
(b) Write equation of phase voltage in terms of symmetrical components
04
(c) Explain sequence impedances and networks of synchronous machine. 07
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Q.7 (a) Explain the phenomena of corona
03
(b) Explain overvoltage due to arcing ground with necessary vector
04
diagram.
(c) Derive the equation for attenuation of travelling waves
07
Q.8 (a) Write a brief note on capacitance switching.
03
(b) Give reasons for following: The disruptive critical voltage is less than
04
visual critical voltage.
(c) Explain travelling waves of a transmission line when the receiving
07
end is short circuited.
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This post was last modified on 04 March 2021