UKPSC AE 2023: Uttarakhand Combined State Engineering Service Examination, Electrical Engineering Second
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Electrical Engineering – II
1. The cyclo-converter frequency in the cyclo-converter speed control of induction motor will be
(a) Equal to supply frequency.
(b) Higher than supply frequency.
(c) Either higher or lower than 3 times supply frequency.
(d) Lower than supply frequency and about its 1/3 times.
2. A single phase half wave converter with free wheeling diode drives a separately excited DC
motor at 900 rpm, with firing angle of 60. When this motor is fed from single phase semi-
converter with = 60, the motor speed will be
(a) 1800 rpm (b) 1500 rpm (c) 1200 rpm (d) 900 rpm
3. A 415 V, 3 phase, 50 Hz, 2850 rpm induction motor is driven on an inverter with constant,
v/f control, at 40 Hz frequency and half the rated slip. The speed of the motor will be
(a) 2480 rpm (b) 2400 rpm (c) 2340 rpm (d) 2280 rpm
4. A separately excited DC motor armature is fed by a 3-phase semi-converter supplies non-
zero torque. Under steady state condition, what will be the value of voltage when the
armature current drops to zero at a certain instants ?
(a) Equal to instantaneous value of AC phase voltage.
(b) Equal to the instantaneous value of the motor back emf.
(c) Equal to the instantaneous value of field voltage of the motor.
(d) Zero
5. The ripple content of the load current in phase controlled converters feeding RL load is
decided by
(a) load resistance only
(b) load inductance only
(c) both load inductance and load resistance
(d) neither load inductance nor resistance
6. The six SCRs in a three phase full converter are fired at an interval of
(a) 30 (b) 60 (c) 90 (d) 120
7. The role of a free wheeling diode at the output of a rectifier is to
(a) trigger SCR properly. (b) turn off SCR at the end of half cycle.
(c) protect SCR against over voltages. (d) protect SCR against high current.
8. The overlap in a phase controlled converter under continuous conduction does not depend
upon
(a) Frequency (b) Applied voltage (c) Load current (d) Load inductance
9. Turn On Time (TON) of an SCR in series with an RL circuit can be reduced by
(a) increasing resistance (R) (b) decreasing resistance (R)
(c) increasing inductance (L) (d) decreasing inductance (L)
10. The maximum conduction of each thyristor in a 3-phase controlled bridge rectifier is for
which of the following options :
(a) 60 (b) 90 (c) 120 (d) 150
11. How many stable operating zones exist in the forward bias portion of a thyristor’s I-V
characteristics ?
(a) 1 (b) 2 (c) 3 (d) Zero
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– II
1. ( ) - -
(a)
(b)
(c)
(d)
2. () ( ) () ..
900 ... 60 = 60
,
(a) 1800 ... (b) 1500 ... (c) 1200 ... (d) 900 ...
3. 415 V, 3 , 50 Hz, 2850 ... v/f 40 Hz
?
(a) 2480 ... (b) 2400 ... (c) 2340 ... (d) 2280 ...
4. 3- - () ..
()
?
(a) ..
(b) ...
(c)
(d) ()
5. RL
(a) () (b) ()
(c) (d)
6. 3- 6 ... ?
(a) 30 (b) 60 (c) 90 (d) 120
7.
(a) ...
(b) ...
(c) ...
(d) ...
8. () ?
(a) (b) (c) (d)
9. RL ... (TON)
(a) (R) (b) (R)
(c) (L) (d) (L)
10. 3- ?
(a) 60 (b) 90 (c) 120 (d) 150
11. I-V () ?
(a) 1 (b) 2 (c) 3 (d)
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12. What will be the displacement factor of a single phase fully controlled rectifier feeding
constant dc current into the load with a firing angle of 30 ?
3
(a) 1 (b) 1/2 (c) 3 (d)
2
13. An ideal voltage regulator will have a voltage regulation of
(a) 0 (b) 1 (c) 50 (d) 100
14. The waveform of the current flowing through the diode in a buck boost converter is
(a) Square (b) Sinusoidal (c) Triangular (d) Trapezoidal
15. A semi-converter feeding on RLE load operates in which quadrant ?
(a) First quadrant only (b) First & second quadrant
(c) First & third quadrant (d) First and fourth quadrant
16. Schmitt Trigger can be used as which of the following ?
(a) Comparator (b) Square wave generator
(c) Flip Flop (d) All of these
17. The output of the circuit shown in the figure below will be
– –– –– –– – –
(a) A + BC (b) A + BC (c) AB + AC (d) AC + BC
18. If negative logic is used, the circuit shown in figure below represents the
(a) AND Gate (b) OR Gate (c) NOR Gate (d) NAND Gate
19. A DAC has a ladder of +10 V full scale output. The number of bits required at its input for
the resolution of 5 mV will be
(a) 7 (b) 8 (c) 9 (d) 11
20. The output expression of the Karnaugh map shown in the figure below is
BC
A 00 01 11 10
0 1 0 0 1
1 1 1 1 1
– – – – –
(a) A + B (b) A + C (c) A + C (d) A + C
21. Totem pole output stage is used in standard TTL gates, primarily to
(a) increase the noise margin of gate.
(b) decrease the output switching delay.
(c) facilitate a wired OR logic connection.
(d) increase the output impedance of the circuit.
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12. 30
?
3
(a) 1 (b) 1/2 (c) 3 (d)
2
13.
(a) 0 (b) 1 (c) 50 (d) 100
14. - ?
(a) (b) (c) (d)
15. RLE - ?
(a) (b)
(c) (d)
16. (Schmitt) ?
(a) (b) (c) - (d)
17.
– –– –– –– – –
(a) A + BC (b) A + BC (c) AB + AC (d) AC + BC
18. ( ) ,
?
(a) AND (b) OR (c) NOR (d) NAND
19. DAC +10 V 5 mV
(a) 7 (b) 8 (c) 9 (d) 11
20. :
BC
A 00 01 11 10
0 1 0 0 1
1 1 1 1 1
– – – – –
(a) A + B (b) A + C (c) A + C (d) A + C
21. TTL
(a) ()
(b)
(c) .. (OR)
(d) ()
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22. If the input voltage is higher than the reference voltage in a positive clipper then the output
will be equal to
(a) Input voltage (b) Reference voltage
(c) DC positive voltage (d) Zero
23. The expression for Absorption law is
–
(a) AB + AA = A (b) A + B = B + A (c) A + AB = B (d) A + AB = A
24. Simplification of Y = (A + B) (A + C) is
(a) A (B + C) (b) A + B C (c) B + A C (d) (A + B) C
– –
25. (A + B) (A + B) is equal to which of the following when both input are A = B = 1 ?
–
(a) AB (b) 1 (c) 0 (d) AB
26. Which among the following is the basic building block of the Arithmetic and logic unit of
Digital Computers ?
(a) Attenuator (b) Subtractor (c) Adder (d) Demultiplexor
27. In a positive clipper, the diode conducts when
(a) Vin > Vref (b) Vin < Vref (c) Vin Vref (d) None of these
28. A Hexadecimal Odometer displays F52F. The next reading will be
(a) G52F (b) F53O (c) F52E (d) F53F
29. A Debouncing Circuit is equivalent to
(a) An Astable Multivibrator (b) A latch
(c) A Bistable Multivibrator (d) A Monostable Multivibrator
30. Excess-3 Code is also known as
(a) Cyclic Redundancy Code (b) Self Complementing Code
(c) Algebraic Code (d) Weighted Code
31. Which of the following three binary additions are correct ?
1. 1011 + 1010 = 10101
2. 1010 + 1101 = 10111
3. 1011 + 1101 = 11111
(a) 1 and 3 (b) 1 and 2 (c) 2 and 3 (d) Only 3
32. How many NOR gates will be required to realise AND logic function ?
(a) 3 (b) 4 (c) 5 (d) 6
33. Which of the following is used for producing delay in a circuit ?
(a) Astable Multivibrator (b) Bistable Multivibrator
(c) Monostable Multivibrator (d) Schmitt Trigger
34. The result of Binary Division (11000)2 (100)2 will be equal to
(a) 110 (b) 1100 (c) 11 (d) 101
35. The minimum number of JK flip flops required to construct a BCD counter is
(a) 2 (b) 3 (c) 4 (d) 5
36. Which of the following flip flops can be used as a latch ?
(a) JK Flip Flop (b) RS Flip Flop (c) T Flip Flop (d) D Flip Flop
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22. ?
(a) (b)
(c) .. (d)
23.
–
(a) AB + AA = A (b) A + B = B + A (c) A + AB = B (d) A + AB = A
24. Y = (A + B) (A + C)
(a) A (B + C) (b) A + B C (c) B + A C (d) (A + B) C
– –
25. (A + B) (A + B) A = B = 1?
–
(a) AB (b) 1 (c) 0 (d) AB
26. ?
(a) (b) (c) (d)
27.
(a) Vin > Vref (b) Vin < Vref (c) Vin Vref (d)
28. F52F
(a) G52F (b) F53O (c) F52E (d) F53F
29. ?
(a) (b)
(c) (d)
30. -3 (Excess 3)
(a) (b)
(c) (d)
31. () ?
1. 1011 + 1010 = 10101
2. 1010 + 1101 = 10111
3. 1011 + 1101 = 11111
(a) 1 3 (b) 1 2 (c) 2 3 (d) 3
32. AND NOR ?
(a) 3 (b) 4 (c) 5 (d) 6
33. ?
(a) (b)
(c) (d)
34. (11000)2 (100)2
(a) 110 (b) 1100 (c) 11 (d) 101
35. BCD JK
(a) 2 (b) 3 (c) 4 (d) 5
36. ?
(a) JK (b) RS (c) T (d) D
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37. Which among the following is the decimal equivalent of the Hexadecimal Number 2AOF ?
(a) 17670 (b) 17607 (c) 17067 (d) 10767
38. Which among the following is not a sequential circuit ?
(a) Counter (b) Shift Register (c) Full Adder (d) JK Flip Flop
39. The circuit shown in the figure represents
(a) Clamper (b) Clipper (c) Log Amplifier (d) Anti log Amplifier
40. A logical expression in form of Sum Of Products (SOP) is suitable for implementation using
which of these logic gates ?
(a) AND Gates (b) NOR Gates (c) NAND Gates (d) EX-OR Gates
41. A 4-bit DAC gives an output voltage of 4.5 V for an input code of 1001. If the input code is
0110, what will be the output voltage ?
(a) 1.5 V (b) 2.0 V (c) 3.0 V (d) 4.5 V
42. The minimum number of memory elements required for the design of a sequential circuit
with nine (9) states
(a) 9 (b) 5 (c) 4 (d) 3
–
43. The Boolean Function A + AC can be realised by using only this one gate
(a) NAND Gate (b) AND Gate (c) OR Gate (d) EX-OR Gate
44. How many (2 4) decoders are required to implement a (4 16) decoder circuit ?
(a) 4 (b) 5 (c) 6 (d) 3
45. Assuming ideal diode, and input of VI = 5 sin t, the circuit shown below will behave as and
deliver the following output
(a) Clipper with sinewave clipped at –2V.
(b) Clamper with sinewave clamped at –2V.
(c) Clamper with sinewave clamped at zero volt.
(d) Clipper with sinewave clipped at 2V.
46. A circular loop has one turn and its radiation resistance is 0.01 Ohm. What will be the
radiation resistance of five such loops ?
(a) 0.002 (b) 0.5 (c) 0.05 (d) 0.25
47. Above which frequency do radio waves fade away due to rainfall ?
(a) 100 MHz (b) 1 GHz (c) 10 GHz (d) 100 GHz
48. At what position is the input signal inserted into a travelling wave tube ?
(a) At the controller end of the helix. (b) At the control grid.
(c) At the collector. (d) At the cathode end of the helix.
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49. Which among the following is not true for modulation ?
(a) It allows use of practical antennas.
(b) It ensures transmission over long distances.
(c) It reduces bandwidth.
(d) It separates different transmissions.
50. In a super heterodyne receiver, the IF stage has better selectivity than HF stage because
(a) frequency has been increased. (b) frequency has been lowered.
(c) constant pass band is possible. (d) The circuit has high L/C ratio.
51. In FM wave, the modulating frequency is 2 kHz and maximum frequency deviation is
10 kHz. If the number of significant pairs of side band is 8, the theoretical bandwidth
required will be
(a) 8 kHz (b) 16 kHz (c) 32 kHz (d) 64 kHz
52. The frequency for satellite communication should be
(a) less than the critical frequency of Ionosphere.
(b) equal to the critical frequency of Ionosphere.
(c) more than the critical frequency of Ionosphere.
(d) None of these
53. The channel capacity of a communication system is given by the formula (commonly used
notation to be considered)
(a) B log2 (S/N) (b) log2 (1 + S/N) (c) B log2 (S/N – 1) (d) B log2 (1 + S/N)
54. A geostationary satellite is placed in equatorial orbit at a height of approximately
(a) 900 km (b) 16000 km (c) 2000 km (d) 36000 km
55. A communication channel has bandwidth of 5 kHz and signal to noise ratio is 7. The
corresponding channel capacity will be
(a) 1800 bits/sec (b) 4000 bits/sec (c) 15000 bits/sec (d) 1000 bits/sec
56. A communication channel with a bandwidth of 75 kHz has been allocated for binary data of
100 kbps. What additional bandwidth will be required to transmit inter symbol interference
free data ?
(a) 18.65 kHz (b) 18.75 kHz (c) 17.85 kHz (d) 17.65 kHz
57. In order to suppress the ground reflected wave, the angle between the direct ray and reflected
wave should be
(a) small (b) large (c) moderate (d) zero
58. The cut off wavelength of the guided wave, when a = b and m = n will be (consider standard
notations)
2a m a a
(a) c = (b) c = (c) c = (d) c =
m 2a 2m 2m
59. The cut off frequency of waveguide depends upon which of the following ?
(a) Dimensions of waveguide
(b) Dielectric property of the medium in waveguide
(c) Wave mode
(d) All of these
60. Which of the following is the basic principle of operation of Klystrons ?
(a) Resonance (b) Degenerative feedback
(c) Velocity modulation (d) Negative resistance
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61. The functioning of Gunn devices is based on which of the following ?
(a) Transfer electron effect (b) Avalanche transit effect
(c) Trapped plasma (d) Impact ionisation
62. The capacitance used in varactor diode is
(a) Diffusion capacitance (b) Transition capacitance
(c) Both (a) and (b) (d) None of these
63. The bandwidth of AM transmitter with carrier frequency 100 kHz and modulating frequency
5 kHz is
(a) 5 kHz (b) 10 kHz (c) 20 kHz (d) 100 kHz
64. The amplitude of the modulating signal in FM transmission determines which of the
following ?
(a) Rate of frequency variation (b) Amount of frequency deviation
(c) Modulation Index (d) Distance of Broadcast
65. The bit rate of a 7 bit binary PCM system is 50 Mbps. What will be the maximum value of
bandwidth of the message signal ?
(a) 2.57 MHz (b) 3.20 MHz (c) 3.50 MHz (d) 3.57 MHz
66. A modern FM receiver uses De-emphasis circuit for
(a) Reducing high frequency noise.
(b) Limited line of sight range.
(c) Reducing amplitude of high frequency audio signal.
(d) Increasing amplitude of higher modulating frequencies signal.
67. Which among the following is commercial FM Broadcasting range ?
(a) 635 to 1065 kHz (b) 88 to 108 kHz
(c) 88 to 108 MHz (d) 635 to 1065 MHz
68. Which among the following modulation technique is used for Television transmission ?
(a) AM (b) FM (c) DSB-SC (d) VSB
69. In an FM circuit, the modulation index is 10 and the highest modulating frequency is
20 kHz. The bandwidth of the FM signal will be
(a) 220 kHz (b) 220 MHz (c) 440 kHz (d) 440 MHz
70. What will be the percent modulation efficiency of an AM single tone modulation, when the
modulation index = 0.5 ?
(a) 11% (b) 12% (c) 11.11% (d) 12.12%
71. A DC shunt generator supplies a load of 7.5 kW at 200 V. If the armature resistance is
0.6 and field resistance is 80 , what will be its induced emf ?
(a) 224 V (b) 218 V (c) 212 V (d) 204 V
72. The compensating winding in a DC generator is
(a) series connected for aiding armature reaction.
(b) shunt connected for cancelling armature reaction.
(c) series connected for cancelling armature reaction.
(d) shunt connected for aiding armature reaction.
73. A synchronous motor is operated from a bus voltage of 1.0 pu and draws 1.0 pu zero power
factor leading current. If the synchronous reactance is 0.5 pu, what will be its excitation e.m.f. ?
(a) 2.0 pu (b) 1.5 pu (c) 1.0 pu (d) 0.5 pu
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74. The number of poles in a Turbo Alternator are usually
(a) 2 (b) 10 (c) 6 (d) 8
75. Which of the following motors can be used for unity power factor operation ?
(a) Capacitor motor (b) Schrage motor
(c) Hysteresis motor (d) Split phase motor
76. Metadyne has ________ feedback with respect to main ________.
(a) positive, current (b) negative, current
(c) positive, voltage (d) negative, voltage
77. What will be the resultant axis flux in Amplidyne ?
(a) Cross magnetising flux (b) Sum of field flux and main flux
(c) Difference of field flux and main flux (d) Field flux
78. An ordinary DC machine is not preferable for use as amplidyne due to which of the following ?
(a) Poor gain (b) Low stability
(c) Sluggish transient response (d) High steady state error
79. What will be the effect of wave excitation of a stepper motor ?
(a) Increased step angle (b) Reduced resolution
(c) Micro stepping (d) Half stepping
80. How does a servo motor differ from an ordinary standard two phase induction motor ?
(a) Higher rotor resistance (b) Greater inertia
(c) Higher power rating (d) Motor stator windings’ design
81. The torque speed characteristics of a repulsion motor resembles which of the following DC
motor characteristics ?
(a) Separately excited (b) Shunt
(c) Series (d) Compound
82. The ratio of gross power to air gap power in an Induction Motor at slip ‘s’ is equal to which
of the following ?
(a) (1 – s)2 (b) (1 – s) (c) (1 – s) (d) 1 – s
83. A 1.8 step, 4-phase stepper motor has 40 teeth in total on 8 poles of stator. What will be the
total number of rotor teeth for this motor ?
(a) 40 (b) 50 (c) 80 (d) 100
84. What will be the decrease in maximum torque, if the supply voltage to a 3-phase squirrel
cage induction motor is reduced by 20% ?
(a) 10% (b) 25% (c) 36% (d) 48%
85. A three phase induction motor drives a constant torque load at a slip of 4% at rated voltage.
If the voltage is reduced by 10%, the change in slip will be
(a) Increases by 25% (b) Increases by 33%
(c) Decreases by 25% (d) Decreases by 67%
86. At what load angle in electrical degree does the developed reluctance torque attain its
maximum value in a salient pole synchronous motor ?
(a) 90 (b) 60 (c) 45 (d) 0
87. The purpose of having a high resistance rotor in a single phase fan induction motor is to achieve
(a) Reduced size (b) High efficiency
(c) Quick acceleration (d) Low starting torque
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74. () ?
(a) 2 (b) 10 (c) 6 (d) 8
75. (...) ?
(a) () (b) /
(c) (d)
76. ______ , ______
(a) , (b) , (c) , (d) ,
77. ( ) ?
(a) (b)
(c) (d)
78. ?
(a) (b)
(c) (d) ( )
79. ?
(a) (b)
(c) (d)
80. ( ) ( ) ?
(a) (b)
(c) (d)
81. - (-) ..
?
(a) ( ) (b)
(c) (d)
82. ‘s’ ?
(a) (1 – s)2 (b) (1 – s) (c) (1 – s) (d) 1 – s
83. 1.8 , 4- 8 40
?
(a) 40 (b) 50 (c) 80 (d) 100
84. 3- 20%
?
(a) 10% (b) 25% (c) 36% (d) 48%
85. 4% 3-
10% ?
(a) 25% (b) 33% (c) 25% (d) 67%
86. ()
?
(a) 90 (b) 60 (c) 45 (d) 0
87.
(a) (b) (c) (d)
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88. If a synchronous motor is running at leading power, its excitation induced voltage (E f) is
(a) Equal to terminal voltage (Vt) (b) Higher than terminal voltage (Vt)
(c) Less than terminal voltage (Vt) (d) Dependent upon supply voltage
89. While starting a three phase synchronous motor, its field winding should be kept
(a) open (b) short circuited
(c) connected to DC source (d) None of these
90. The stator of a 3-phase, 6-pole, slip ring induction motor is connected to 50 Hz supply and
its rotor to 20 Hz supply. It will run at what speed ?
1. 1600 rpm 2. 600 rpm 3. 1400 rpm 4. 400 rpm
(a) 1, 3 (b) 1, 4 (c) 2, 3 (d) 2, 4
91. The diameter of the circle diagram for a three phase induction motor is given by (consider
standard notations with 1 = Stator, 2 = Rotor)
(a) V1/X1 (b) V1/(R1 + R2) (c) V1/(X1 + X2) (d) V1/X2
92. The approximate value of efficiency of a three phase induction motor running at slip ‘s’ is
given by
(a) 1/(1 + s) (b) s/(1 + s) (c) (1 – s)/(1 + s) (d) s/(1 – s)
93. The rotor of a stepper motor does not have
1. Windings 2. Commutator 3. Brushes
(a) 1 and 2 only (b) 2 and 3 only (c) 1 and 3 only (d) 1, 2 and 3
94. Which of the following motors is the most suitable for signalling devices and timers ?
(a) AC series motor (b) DC series motor
(c) Reluctance motor (d) Induction motor
95. If a DC series motor is operated on AC supply, it will have the following result :
(a) poor efficiency (b) poor power factor (c) excessive sparking (d) All of these
96. Universal Motors are used in which of the following ?
1. Mixers 2. Portable Drills 3. Sewing Machines
(a) 1 and 2 (b) 2 and 3 (c) 1 and 3 (d) 1, 2 and 3
97. The damping bars of a synchronous machine under hunting conditions develop what, when
rotor speed is more than synchronous speed ?
(a) DC motor torque (b) Synchronous motor torque
(c) Induction generator torque (d) Induction motor torque
98. If a 3-phase squirrel cage induction motor operates at a slip of –0.05, then it will
1. Draw mechanical power from shaft.
2. Draw electrical power from mains.
3. Deliver electrical power to mains.
Which of these statements are correct ?
(a) 1 and 2 (b) 1 and 3 (c) 2 and 3 (d) 1, 2 and 3
99. A synchronous generator, connected to infinite bus, is supplying half of the maximum power
which is 1 pu. Its synchronizing power coefficient is
(a) 0.5 pu (b) 1 pu (c) 0 pu (d) 0.866 pu
100. The purpose of compensating winding in an AC series motor is to
(a) improve commutation (b) provide starting torque
(c) reduce reactance of armature winding (d) increase speed
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101. If the centrifugal switch of a split phase motor fails to open, then
(a) the motor will stop. (b) main winding will get overheated.
(c) auxiliary winding will get overheated. (d) rotor will get overheated.
102. Which among these motors is relatively free from mechanical and magnetic vibrations ?
(a) Universal motor (b) Hysteresis motor
(c) Shaded pole motor (d) Reluctance motor
103. A three stack variable reluctance stepper motor has 20 poles on each rotor and stator stack.
Its step angle will be
(a) 6 (b) 18 (c) 30 (d) 36
104. A single stack 8 phase (stator) multiple step motor has 6 rotor teeth. The poles are excited
one at a time at excitation frequency of 120 Hz. The speed of the motor will be
(a) 3 rps (b) 5 rps (c) 10 rps (d) 15 rps
105. A synchronous generator is feeding a zero power factor (lagging) load at rated current. The
nature of armature reaction is
(a) magnetising (b) demagnetising (c) cross-magnetising (d) ineffective
106. The characteristics of an impedance relay in R-X plane is represented by
(a) a parabola (b) a circle (c) a straight line (d) a hyperbola
107. Time graded over-current relays facilitate
(a) Faster protection (b) Accurate protection
(c) Back up protection (d) Primary protection
108. Which of the following relays is inherently directional ?
(a) Impedance Relay (b) Reactance Relay
(c) Mho Relay (d) Differential Relay
109. Standard voltage ratings of an electromagnetic relay are
(a) 110 V, 63.5 V (L – N) (b) 220 V, 110 V (L – N)
(c) 230 V, 154 V (L – N) (d) 400 V, 230 V (L – N)
110. The problem of high transient over-voltages occurs while interrupting which of the following ?
(a) Inductive current (b) Capacitive current
(c) Heavy short circuit current (d) Resistive current
111. In a biased differential relay, the bias is defined as the ratio of
(a) No. of turns of restraining and operating coil.
(b) Current of operating and restraining coil.
(c) Fault current and operating coil current.
(d) Fault current and restraining coil current.
112. Resistance switching is normally employed in
(a) All breakers (b) Bulk oil breakers
(c) Minimum oil breakers (d) Air blast circuit breakers
113. A 100 : 5 current transformer has secondary winding and lead resistance of 0.2 and
secondary burden is 5 VA. The output VA is
(a) 2.5 VA (b) 5 VA (c) 7.5 VA (d) 10 VA
114. The current chopping phenomenon occurs in Air Blast Circuit Breakers when
(a) A transformer at no load is switched off.
(b) A capacitor bank is switched off.
(c) A long transmission line is switched off.
(d) A heavy load is switched off.
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115. An over-current relay having a current setting of 125% is connected to a supply circuit
through CT ratio 400/5. The pick up value of current will be
(a) 5 A (b) 5.25 A (c) 6.25 A (d) 10 A
116. The purpose of harmonic restraint in a protection transformer is to protect against
(a) Lightening (b) Unbalance operation
(c) Switching over voltages (d) Magnetising inrush current
117. Which of the following combination of statements are incorrect ?
1. Mho relays are affected by arcing resistance.
2. Mho relays are affected by power swings.
3. Reactance relays are affected by power swings.
4. Mho relays are not affected by power swings.
(a) 1, 3 and 4 (b) 1, 2 and 3 (c) 1 and 3 (d) 1 and 4
118. Carrier current protection is normally used to protect
(a) HV cables (b) LV distribution lines
(c) HV transmission lines (d) Transformers
119. In circuit breakers, the rate of rise of restriking voltage depends upon
(a) the type of circuit breaker.
(b) the resistance of the circuit only.
(c) the inductance of the circuit only.
(d) the inductance and capacitance of the circuit.
120. When a 3-phase alternator is suddenly short circuited at its terminals, the initial value of
short circuit current is limited by which of the following ?
(a) Sub-transient Reactance (b) Transient Reactance
(c) Synchronous Reactance (d) Summation of all above
121. Which of the following is used to obtain the desired output waveform in an Op-Amp ?
(a) Clamper (b) Clipper (c) Peak Amplifier (d) Sample and Hold
122. The final corrector of the Fourth Order Runga Kutta method uses which of the following ?
(a) Backward Euler method (b) Simpson’s method
(c) Midpoint Rule (d) Trapezoidal Rule
123. Which of the following methods is used by Second Order Runga Kutta method as predictor ?
(a) Forward Euler method (b) Backward Euler method
(c) Multipoint Rule (d) Midpoint Rule
124. How many Op-Amp are needed to implement the equation ?
Rf Rf Rf
V0 = – V1 +
R3 3
V2 + V
R1 R2
(a) 1 (b) 2 (c) 3 (d) 4
125. When a step signal is given to Op-Amp integrator, the output will be ?
(a) Rectangular (b) Ramp
(c) Sinusoidal (d) Triangular wave with dc bias
126. Which of the following Amplifiers is used in a Digital to Analog Converter ?
(a) Voltage Follower (b) Non-invertor
(c) Difference Amplifier (d) Summer
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115. 125% 400/5 (CT)
( )
(a) 5 A (b) 5.25 A (c) 6.25 A (d) 10 A
116. ?
(a) (b) (c) (d)
117. ?
1.
2.
3.
4.
(a) 1, 3 4 (b) 1, 2 3 (c) 1 3 (d) 1 4
118. ?
(a) .. (b) ..
(c) .. (d)
119. ?
(a) (b)
(c) (d)
120. 3- ,
?
(a) (b)
(c) (d)
121. (Op-Amp)
?
(a) (b) (c) (d)
122. () - ()
?
(a) () (b)
(c) (d)
123. () - ?
(a) () (b) ()
(c) (d)
124. - (Op-Amp) ?
Rf Rf Rf
V0 = – V1 +
R3 3
V2 + V
R1 R2
(a) 1 (b) 2 (c) 3 (d) 4
125. - (Op-Amp)
(a) (b)
(c) (d) ..
126. ?
(a) (b) (c) (d) ()
EEN-02 21 Series-A
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127. The method of least squares finds the best fit line so that the error between the observed and
the estimated point on the line is
(a) maximised (b) minimized
(c) reduced to zero (d) approaches infinity
128. Interpolation provides a means for estimating functions at which of the following ?
(a) Initial point (b) End point (c) Intermediate point (d) Outside point
dx
129. The ordinary differential equation = –3x + 2 with x(0) = 1 is to be solved by Forward Euler
dt
method. The largest time step that can be used without making the solution unstable is
(a) 0.54 (b) 0.44 (c) 0.64 (d) 0.66
130. An Op-Amp has differential gain of 103 and CMRR of 100, what will be its output voltage
with inputs of 120 V and 80 V ?
(a) 26 mV (b) 41 mV (c) 100 mV (d) 200 mV
131. An Op-Amp has Common Mode Gain of 0.01 and Differential Mode Gain of 10 5. Its
common mode rejection ratio will be
(a) 107 (b) 10–7 (c) 103 (d) 10–3
132. The gain and distortion of an Amplifier are 150 and 5% respectively. What will be the %
distortion if it is used with 10% negative feedback ?
(a) 6 (b) 9/16 (c) 5/16 (d) 8
133. Find the value of I0 in the following circuit :
RL 1 1
(a) VS/RS (b) VS/RL (c) VS (d) VS +
RS(RS + RL) RS RL
134. A two stage amplifier with negative feedback
(a) can become unstable for large values of .
(b) will always be stable.
(c) will always be unstable.
(d) can become unstable when pole frequencies become complex.
135. The zero level detector is an application of which of the following ?
(a) Summing Amplifier (b) Differentiator
(c) Comparator (d) Integrator
136. What is the voltage gain of an ideal voltage follower ?
(a) 0 (b) 1 (c) <1 (d)
137. The purpose of phase lag compensation is to
(a) make Op-Amp stable at very low gain.
(b) make Op-Amp stable at very high gain.
(c) reduce unity gain frequency.
(d) increase bandwidth.
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138. The Boolean expression for the output F in terms of A & B for the 2 to 1 multiplexer shown
in the figure is
––––– –––––
(a) A B (b) A + B (c) A + B (d) A B
139. What will be the Eigen values of the matrix shown below :
5 0 1
0 –2 0
1 0 5
(a) –1, 5 and 6 (b) –1, 3 and 8 (c) –3, 5 and 8 (d) –2, 4 and 6
140. The output of an ideal differential amplifier is 300 mV for inputs of 5 mV and 3 mV. What
will be the output for the inputs of 153 mV and 155 mV ?
(a) 100 mV (b) 200 mV (c) 300 mV (d) 400 mV
141. A sinusoidal voltage of peak value 5 mV and frequency 1 kHz is applied to the differentiator
circuit in the figure shown below. What will be the output ?
(a) –2000 cos 2000 t mV (b) –1000 cos 1000 t mV
(c) –2000 cos 1000 t mV (d) –1000 cos 2000 t mV
142. The Op-Amp comparator circuit uses which of the following ?
(a) Positive Feedback (b) Negative Feedback
(c) Regenerative Feedback (d) No Feedback
143. What will be the overall modulus of a cascade of three identical Modulo-5 counters ?
(a) 5 (b) 15 (c) 125 (d) 625
144. A temperature in the range of – 40 C to 55 C is to be measured with a resolution of 0.1 C.
The minimum number of ADC bits required to get a matching dynamic range of temperature
sensor will be
(a) 8 (b) 10 (c) 12 (d) 14
145. Determine y(x) using Lagrange’s interpolation formula from the table given below :
x 0 1 3 4
y –12 0 12 24
2
(a) (x – 1) (x – 5x + 12) (b) (x + 1) (x2 – 5x + 12)
2
(c) (x – 1) (x + 5x – 12) (d) (x + 1) (x2 + 5x – 12)
146. A non-singular 2 2 square matrix A has trace (A) = 4 and trace (A2) = 5 respectively. The
approximate value of determinant of A will be
(a) 4.5 (b) 5.5 (c) 6.5 (d) 7.5
Series-A 24 EEN-02
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147. The set of values of P for which the roots of the equation
3x2 + 2x + P(P – 1) = 0 will have opposite signs is
(a) (– , 0) (b) (0, 1) (c) (1, ) (d) (0, )
148. What is the correct solution of the following equations ?
3x + y + 2z = 3
2x – 3y – z = –3
x + 2y + z = 4
(a) x = 2, y = 1, z = 1 (b) x = 1, y = 2, z = –1
(c) x = –1, y = 1, z = –1 (d) x = –1, y = –2, z = 1
b
.
149. Physically integrating .f(x) dx means finding the area
a
(a) under the curve from a to b (b) to the left of point a
(c) to the right of point b (d) above the curve from a to b
150. The technique of computing the value of a function inside the given argument is called
(a) Interpolation (b) Extrapolation
(c) Partial fraction (d) Inverse interpolation
151. What is stored in Microprocessor ROM chip ?
(a) Control function (b) Arithmetic functions
(c) Instructions to execute data (d) Memory functions design
152. CALL in microprocessor means
(a) to execute a part of the main program.
(b) to call a subprogram within main program.
(c) to transfer control to specified subroutine.
(d) to return to main program from subroutine.
153. What does programmable logic array (PLA) use ?
(a) ROM matrices (b) PROM matrices (c) RAM matrices (d) SILO memory
154. After the execution of the instruction XRA A in 8085 microprocessor
(a) the carry flag is set.
(b) the accumulator contains FF.
(c) the zero flag is set.
(d) the accumulator contents shift left by one bit.
155. Which of the following is not a vectored interrupt in 8085 microprocessor ?
(a) TRAP (b) INTR (c) RST 7.5 (d) RST 5.5
156. The number of control and status signals in microprocessor 8085 are respectively
(a) 2, 4 (b) 3, 3 (c) 3, 4 (d) 4, 5
157. The number of address and data lines required to address 8 kB of memory are respectively
(a) 13, 8 (b) 8, 13 (c) 4, 13 (d) 13, 4
158. A 8085 microprocessor uses 5 MHz crystal oscillator. The duration of its T-state will be
(a) 0.2 s (b) 0.8 s (c) 0.6 s (d) 0.4 s
159. A microprocessor can be brought out of the WAIT state by
(a) Pressing RESET key (b) Giving interrupt
(c) Both (a) and (b) (d) None of the above
Series-A 26 EEN-02
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147. P
3x2 + 2x + P(P – 1) = 0 ?
(a) (– , 0) (b) (0, 1) (c) (1, ) (d) (0, )
148. ?
3x + y + 2z = 3
2x – 3y – z = –3
x + 2y + z = 4
(a) x = 2, y = 1, z = 1 (b) x = 1, y = 2, z = –1
(c) x = –1, y = 1, z = –1 (d) x = –1, y = –2, z = 1
b
.
149. .f(x) dx
a
(a) a b (b) a
(c) b (d) a b
150.
(a) (b) (c) (d)
151. ROM ?
(a) (b) (c) (d)
152. CALL
(a)
(b)
(c) ()
(d)
153. (PLA) ?
(a) ROM (b) PROM (c) RAM (d) SILO
154. 8085 XRA A
(a)
(b) () FF
(c)
(d)
155. 8085 ?
(a) TRAP (b) INTR (c) RST 7.5 (d) RST 5.5
156. 8085
(a) 2, 4 (b) 3, 3 (c) 3, 4 (d) 4, 5
157. 8 kB ?
(a) 13, 8 (b) 8, 13 (c) 4, 13 (d) 13, 4
158. 8085 5 MHz T-
(a) 0.2 s (b) 0.8 s (c) 0.6 s (d) 0.4 s
159. WAIT
(a) RESET (key) (b)
(c) (a) (b) (d)
EEN-02 27 Series-A
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160. What will be the contents of carry flag and AL after the execution of the following program
in 8086 microprocessor ?
MOV AL, 7E
MOV BL, 8C
ADD AL, BL
(a) OA, carry is reset (b) OA, carry is set
(c) FA, carry is reset (d) FA, carry is set
161. The number of memory chips of size 1 k 4 bits required to build a memory bank of size
16 k 8 bits is
(a) 8 (b) 16 (c) 32 (d) 64
162. A microprocessor uses 3 MHz clock and has 3 T-states in each machine cycle. What will be
the time required to complete the instruction that needs 4 machine cycles ?
(a) 2 s (b) 4s (c) 6s (d) 8s
163. The flags of microprocessor 8085 are
(a) S, OV, Z, P, AC (b) S, Z, OV, P, AC
(c) S, Z, CY, P, OV (d) S, Z, AC, P, CY
164. Three devices A, B, C (in decreasing order of priority, A being the highest) are connected to
microprocessor 8085. The correct assignment of interrupts for them will be
(a) A RST 7.5, B RST 6.5, C RST 5.5
(b) A RST 9.5, B RST 8.5, C RST 7.5
(c) A RST 6.5, B RST 7.5, C RST 5.5
(d) A RST 6.5, B RST 5.5, C RST 4.5
165. The smallest valid signed integer that can be stored in a memory location of 4 k 8 bit RAM
is
(a) –128 (b) –256 (c) –2048 (d) –4096
166. The OPCODE for the instruction to add the data in the next byte to the Accumulator along
with carry in 8085 microprocessor is given by
(a) ADC (b) ADI (c) ACI (d) ADD
167. The DAA instruction in microprocessor 8085 is used for
(a) Decimal Adjust Accumulator (b) Direct Access Accumulator
(c) Direct Address Accumulator (d) Direct Add Accumulator
168. When microprocessor 8086 executes an INT type instruction, it
(a) Resets both IF and TF (b) Sets both IF and TF
(c) Sets all flags (d) Resets all flags
169. In which T-state does a CPU send the address to memory or I/O and the ALE signal for
demultiplexing ?
(a) T4 (b) T1 (c) T2 (d) T3
170. How does the data get transferred in a DMA Write operation ?
(a) From memory to I/O (b) From I/O to memory
(c) From I/O to CPU (d) From CPU to I/O
Series-A 28 EEN-02
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160. 8086 AL ?
MOV AL, 7E
MOV BL, 8C
ADD AL, BL
(a) OA, (b) OA, (c) FA, (d) FA,
161. 16 k 8 bits 1 k 4 bits ?
(a) 8 (b) 16 (c) 32 (d) 64
162. 3 MHz 3 T-
4 () ?
(a) 2 s (b) 4s (c) 6s (d) 8s
163. 8085
(a) S, OV, Z, P, AC (b) S, Z, OV, P, AC
(c) S, Z, CY, P, OV (d) S, Z, AC, P, CY
164. 8085 3 A, B, C ( , A )
:
(a) A RST 7.5, B RST 6.5, C RST 5.5
(b) A RST 9.5, B RST 8.5, C RST 7.5
(c) A RST 6.5, B RST 7.5, C RST 5.5
(d) A RST 6.5, B RST 5.5, C RST 4.5
165. 4 k 8 RAM () ?
(a) –128 (b) –256 (c) –2048 (d) –4096
166. 8085
OPCODE
(a) ADC (b) ADI (c) ACI (d) ADD
167. 8085 DAA ?
(a) (b)
(c) (d)
168. 8085 INT ,
(a) IF TF (b) IF TF
(c) (d)
169. CPU T- I/O ALE ?
(a) T4 (b) T1 (c) T2 (d) T3
170. DMA Write ?
(a) I/O (b) I/O (c) I/O CPU (d) CPU I/O
EEN-02 29 Series-A
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171. The power output for DC component of a full wave rectifier with maximum value of 10A
AC current and load resistance of 10 is approximately
(a) 225 W (b) 405 W (c) 150 W (d) 320 W
172. The main reason for connecting a pulse transformer at the output stage of a thyristor
triggering circuit is to
(a) Amplify the power of the triggering pulse.
(b) Provide electrical isolation.
(c) Reduce the turn on time of thyristor.
(d) Avoid spurious triggering of the thyristor due to noise.
173. A single phase full bridge converter supplies a load drawing constant and ripple free load
current. If the triggering angle is 45, the input power factor will be
(a) 0.866 (b) 0.707 (c) 0.636 (d) 0.368
174. Which among the following is the most suitable power device for high frequency switching
applications above 100 kHz ?
(a) SCR (b) Power MOSFET (c) GTO (d) BJT
175. The snubber circuit is used in thyristor circuits for the following action :
dV di
(a) Triggering (b) protection only (c) protection only (d) None of the above
dt dt
176. In comparison with a single phase half bridge inverter, the power output of a single phase
full bridge inverter is higher by a factor of
(a) 2 (b) 4 (c) 6 (d) 8
177. A thyristor controlled reactor is used to obtain which of the following ?
(a) Variable resistance (b) Variable capacitance
(c) Variable inductance (d) Improved reactor power factor
178. A step down chopper shown in the figure is switched at 2 kHz with a duty ratio of 0.75. The
peak to peak ripple in load current will be
(a) 0.125 A (b) 0.25 A (c) 0.5 A (d) 1 A
179. A 6 pulse, 415 V, 3 phase semi-converter controls a 440 V DC motor. If the total drop in the
circuit is limited to 10%, then the converter must be locked at an angle of
(a) 30 (b) 45 (c) 60 (d) 90
180. The chopper shown in figure operates with a duty ratio of 0.8. The load is sufficiently
inductive to keep the load current ripple free. The average current through the diode under
steady state condition is
(a) 1.6 A (b) 6.4 A (c) 8.0 A (d) 10.0 A
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Space For Rough Work / Series-A 32 EEN-02
Page 1 of 32
Source: Uttarakhand Public Service Commission. Question paper published by Uttarakhand Public Service Commission.