Birla Institute of Technology and Science, Pilani - Hyderabad Campus, Second Semester 2013-14
Course No: EEE C374/EEE F312
Course Name: Power Systems
Time: 45 Minutes
Max. Marks: 30 M
Compre Test (Part-A)
Date: 7th April, 2014
Note: 1.Write the answer in the tabular column provided at the back
Name :
ID.No.:
2.Overwritten answers will be treated as invalid. No negative marking
Answer the following:
1. The conductors of a 10 km long, single phase two wire line are
separated by a distance of 1.5 m. the diameter of each
conductor is 1 cm. if the conductors are of copper, the
inductance of the circuit is
a) 50 mH
b) 45.3 mH
c) 23.8 mH
d) 19.6 mH
2. An over current relay, having a current setting of 12.5% is
connected to a supply circuit through a current transformer of
ratio 400/5. The pick-up value is
a) 10 A
b) 6.25 A
c) 12.5 A
d)15.2 A
3. The p.u. impedance value of an alternator corresponding to base
values 13.2 kV and 30 MVA is 0.2 pu. The pu value for the base
values 13.8 kV and 50 MVA will be
a) 0.306
b) 0.33
c) 0.318
d) 0.328
4. The capacitance and inductance per unit length of a line
operating at 110 kV are 0. 01 F and 2 mH. The surge
impedance loading of the line is
a) 40 MVA
b) 30 MVA
c) 27 MVA
d) None of these
5. Two alternators each having 4% speed regulation are working
in parallel. Alternator 1 is rated for 12 MW and alternator 2 is
rated for 8 MW. When the total load is 10 MW, then loads
shared by alternators 1 and 2 would be respectively
a) 4 MW and 6 MW
b) 6 MW and 4 MW
c) 5 MW and 5 MW
d) 10 MW and above
6. The charging reactance of 50 km length of line is 1500 . The
charging reactance for 100 km length of line will be
a) 1500
b) 3000
c) 750
d) 600
7. If for a given alternator in economical operation mode, the
dPL
incremental cost is given by (0.012P+8)Rs/MW, dP
and plant
=0.2
= 25, then the power generation is
a) 1000 MW
b) 1250 MW
c) 750 MW
d) 1500 MW
8. A three phase breaker is rated at 2000 MVA, 33 kV its making
current will be
a) 35 kA
b) 49 kA
c) 70 kA
d) 89 kA
9. A voltage controlled bus is treated as a load bus in subsequent
iteration when its
a) Voltage limit is violated
b) Active power limit is violated
c) Reactive power limit is violated
d) Phase angle limit is violated
10. A star connected 3-phase, 11 kV, 25 MVA alternator with its
neutral grounded through a 0.033 pu reactance (based on
alternator rating) has positive, negative and zero sequence
reactances of 0.2 pu, 0.1 pu and 0.1 pu respectively. A single
line to ground fault on one of its terminals would result in a
fault current of
a) 4.35 pu
b) 3.25 pu
c) 5.02 pu
d) 6.01 pu
11. A 100 km long transmission line is loaded at 110 kV. If the loss
of the line is 5 MW and the load is 150 MVA, the resistance of
the line is
a) 8.06 ohms per phase b) 18.06 ohms per phase
c) 10.08ohms per phase d) 9.86 ohms per phase
12. An isolated synchronous generator with transient reactance
equal to 0.1 pu on a 100 MVA base is connected to the high
voltage bus through a step up transformer of reactance 0.1 pu
on a 100 MVA base. The fault level at the bus is
a) 10000 MVA
b) 500 MVA
c) 700 MVA
d) 800 MVA
13. A 500 MVA synchronous generator has H1 = 4.6MJ/MVA and a
1500 MVA machines has H2 = 3.0 MJ/MVA. The two machines
operate in parallel in a power station. The equivalent inertia
constant for the two, relative to a 100 MVA base is
a) 58 MJ/MVA
b) 580 MJ/MVA
c) 68 MJ/MVA
d) 680 MJ/MVA
14. A 60 Hz generator, connected to an infinite busbar operating at
a voltage of 1.0 pu has a synchronous reactance of 1.35 pu. The
generator no-load voltage is 1.1 pu and its inertia constant H is
4 MJ/MVA. The generator is suddenly loaded to 60% of its
maximum power limit; the frequency of the resulting natural
oscillations of the generator rotor is
a) 0.9 Hz
b) 1.20 Hz
c) 0.45 Hz
d) 0.88 Hz
15. A single phase overhead transmission line has its conductors
arranged at the corners of an equilateral triangle of 2m side; the
diameter of each conductor is 1.25 cm. The capacitance of each
line conductor per km is
a) 0.0125 F
b) 0.0096 F
c) 0.1203 F
d) 0.2056 F
16.
17.
S
18. Answer
19.
S.
20. Answer
21.
1
22. c
23.
9.
24. c
25.
2
26. b
27.
1
28. d
29.
3
30. a
31.
1
32. a
33.
4
34. c
35.
1
36. b
37.
5
38. b
39.
1
40. c
41.
6
42. c
43.
1
44. d
45.
7
46. a
47.
1
48. b
49.
8
50. d
53.
