PU CET PG 2017 Question Paper M.E. Electrical Engg. _Instrumentation _ Control_

M.E. Electrical Engg. (Instrumentation & Control)

1. Three equal resistances of 5 ohms are connected in delta. What is the resistance in one of
the arms in an equivalent star circuit?
A) 5.0 ohm B) 1.33 ohm C) 15 ohm D) 10 ohm

2. When the superposition theorem is applied to any circuit, the dependent voltage source in
that circuit is always
A) Opened B) Shorted C) Active D) None of these

3. A single phase transformer has a maximum efficiency of 90% at full load and unity
power factor. Efficiency at half load at the same power factor is
A) 86.7% B) 88.26% C) 88.9% D) 87.8%

4. When an UJT is used for triggering an SCR, the wave shape of the voltage obtained from
UJT circuit is a
A) Sine wave B) Saw-tooth wave
C) Trapezoidal wave D) Square wave

5. If the velocity of a wind is doubled, then the power output will be increased by
A) 10 times B) 8 times C) 2 times D) 6 times

6. The cyclo-converters (CCs) require natural or forced commutation as under:
A) Natural commutation in both step-up and step-down CCs
B) Forced commutation in both step-up and step-down CCs
C) Forced commutation in step up CCs
D) Forced commutation in step-down CCs.

7. A440 V shunt motor has an armature resistance of 0.5 ohms and shunt field resistance of
650 ohms. If the no load current is 3A, then current in the armature will be
A) 2.32 A B) 3 A C) 0.68 A D) 880 A

8. In single-pulse modulation of PWM inverters, the pulse width is 1200. For an input
voltage of 220 V dc, the r.m.s. value of output voltage is
A) 179.63 V B) 254.04V C) 127.02 V D) 185.04 V

9. A single-phase full-bridge VSI operating in square-wave mode supplies a purely
inductiveload. If the inverter time period is T, then the time duration for which each of
thefeedback diodes conduct in a cycle is
A) T B) T/2 C) T/4 D) T/8

10. The rotor resistance and stand still reactance of 3-phase induction motor are respectively
0.015 and 0.09 ohms per phase.At a slip of 4%, the operating power factor of motor is
A) 0.164 B) 0.24 C) 0.974 D) 0.74

11. The power delivered to a star-connected load of R ohm per phase, from a 3-phase bridge
inverter fed from fixed dc source, is 10 kWfor 180o mode. For 120o mode, thepower
delivered to load would be
A) 10 kW B) 5 kW C) 6.667 kW D) 7.5 kW

12. Control of frequency and control of voltage in 3-phase inverters operating in 120o mode
or 180o mode of conduction is
A) Possible only through inverter control circuit
B) Possible through the control circuit of inverter and converter simultaneously
C) Possible through inverter control for frequency and through converter control for
voltage
D) Possible through converter control only

13. In a series resonant inverter
A) The load current has square waveform
B) Trigger frequency is higher than damped resonant frequency
C) Change of frequency does not alter transferred power
D) Output voltage depends upon damping factor of the load

14. In McMurray commutation circuit, the circuit turn-off time is
A) Dependent on load current and independent of operating frequency
B) Dependent on load current and also on load power factor
C) Independent of load current and dependent on operating frequency
D) Independent of load current and dependent on recovery period

15. Bulk power transmission over long HVDC lines are preferred on account of
A) Low cost of HVDC terminals B) No harmonic problems
C) Less line power losses D) Simple protection

16. A separately-excited dc motor, when fed from 1 phase full converter with firing angle 600
runs at 1000 rpm. If this motor is connected to 1-phase semi-converter with the same
firing angle of 600, the motor would now run at
A) 2000 rpm B) 1500 rpm C) 1450 rpm D) 1000 rpm

17. A separately-excited dc motor, when fed from 1-phase full converter, runs at a speed of
1200 rpm. Load current remains continuous. If one of the four SCRs gets open circuited,
the motor speed will reduce to
A) 900 rpm B) 800 rpm C) 600 rpm D) 400 rpm

18. The matrix

10 1 −2
P= = 1 4 −1@ is
−2 −1 1
A) Positive definite B) Negative definite
C) Positive semi definite D) Negative semi definite

19. Analysis of voltage waveform of single phase bridge converter shows that it contains x%
of 6th harmonic. The 6th harmonic content of the voltage waveform of a 3-phase bridge
converter would be
A) Less than x% due to an increase in the number of pulses
B) Equal to x% the same as that of a single phase converter
C) Greater than x% due to change in the input and output voltages of the converter
D) Difficult to predict as the analysis of converter is governed by any generalized
theory.

20. A single phase full-wave mid-point thyristor converter uses 230/200 V transformer with
center tap on the secondary side. The peak inverse voltage per thyristor is
A) 100V B) 141.4 V C) 200 V D) 282.8 V

21. A 220V, 1400 rpm, 40A. separately excited dc motor has an armature resistance of 0.4 Ω.
The motor is fed from a signal phase circulating current dual converter with an input ac
line voltage of 220V (rms). The approximate firing angles of the dual converter for
motoring operation at 50% of rated torque and 1000 rpm will be:
A) 43°, 137° B) 43°, 47° C) 39°, 141° D) 39°, 51°

22. When biasing JFET, if drain and source are interchanged, then
A) Device will work normally
B) Device will get damaged
C) Device will work but value of IDwill get affected
D) Device will not operate at all

23. The control of ALFC loop of a multi-area system is achieved by using ______
mathematical approach.
A) Root locus B) Bode plot C) State variable D) Nyquist plots

24. In the dynamic programming method, the cost function FN(X) represents minimum cost
in Rs/hour of generation of
A) N MW by X units B) X MW by N units
C) N MW by Xth units D) X MW by Nth units

25. In the priority list method of solving an optimal problem:
A) Most efficient unit is loaded first to be followed by less efficient unit in order as
load increases
B) Less efficient unit is loaded first to be followed by most efficient unit in order as
load increases
C) Most efficient unit is loaded first followed by less efficient unit in order as load
increases
D) Either A or B

26. To find the optimal trajectory for the first order system, A = − + 2u, with the given
boundary conditions and performance index as

J = 1( + 4B )CD,the Euler equation is given by

A) ẍ + 2(ẋ + x) = 0 B) ẍ + 2x = 0
C) ẍ - 2x = 0 D) ẍ - 2(ẋ + x) = 0

27. The conditions at the sliding surface are given by
A) σ = 0, σA = 0 B) σσA = 0 C) σσA < 0 D) σσA > 0

28. A dead beat control system has closed loop poles
A) On negative real axis B) On imaginary axis
C) Origin D) At infinity

29. Consider the system
A = 2E + u
with performance index

J= 1( + FB )CD
∞

The value of r such that the optimal closed loop system has pole at -3 is
A) B) 0 C) D) <
√0 √<

30. The invariant approximation, for sampling interval = 0.1 sec, to the following continuous
time transmittance

G(s) = (; is
G)

1. H0 1.H0 1. H0 1.H0
A) ( . 1.HI) B) ( . 1.HI) C) ( . 1.H I) D) ( . 1.H I)

31. The details of the system for t ≥ 0 with given input and initial conditions are
ẋ = -2x + u(t)
y = 10x
x(0_) = 3
u(t) = 4e5t

The output is
I1 G1
A. J . * + I J 0*
I
I1 G1
B. J . * + I J .0*
I
I1 G1
C. J . * + I J 0*
I
I1 G1
D.
I
J . * + I J 0*
32. In an microprocessor with PUSH operation the content of stackpointer is
A) Increased by 1 B) Decreased by 1
C) Increased by 2 D) Decreased by 2

33. If f1(t) and f2(t) have widths(duration) of T1 and T2 respectively , then width (duration) of
f1(t) *f2(t) is (* denotes convolution)

A) Larger than T1 and T2 B) Smaller than T1 and T2
C) T1 + T2 D) T1 - T2

34. In general in a squirrel cage induction motor as the load increases
A) Power factor decreases and efficiency decreases
B) Power factor decreases and efficiency increases
C) Power factor increases and efficiency decreases
D) Power factor increases and efficiency increases

35. It is given that G(s) = ; (K . This system in a closed loop with unity feedback. What is
)
order and type of the closed loop system?

A) 2 and 3 B) 3 and 2 C) 3 and 3 D) 2 and 2

36. In a synchronous generator, thechording angle for eliminating 5th harmonic should be
under excited and lagging power factor
A) 300 B) 340 C) 360 D) 350
37. The rotor resistance and stand still reactance of 3-phase induction motor are respectively
0.015 and 0.09 ohms per phase.At a slip of 4%, the operating power factor of motor is
A) 0.164 B) 0.24 C) 0.974 D) 0.74

38. The voltage at the two ends of a transmission line are 132 KV and its reactance is40 ohm.
The capacity of the line is
A) 435.6 MW B) 217.8 MW C) 251.8 MW D) 500 MW
39. A d’Arsonval meter measurement is rated at 100 µA.If only 50µA is passing through its
coil, the deflection will be

A) 100% of full scale B) 50% of full scale
C) 25% of full scale D) 5% of full scale
40. Number of comparator required to build a 5 bit analog to digital type of convertor is
A) 5 B) 11 C) 31 D) 21

41. The approximate rise time of an amplifier which has upper 3db frequency as 5MHz is
A) 350 ns B) 3.5 µs C) 700 ns D) 70 ns
B)
42. Which one of the following is equivalent to AND-OR realization?
A) NAND-NOR realization B) NOR-NOR realization
C) NOR-NAND realization D) NAND-NAND realization

43. ‘Cogging’ in Induction Motor occurs when
A) Number of stator teeth – number of rotor teeth = odd number
B) Number of stator teeth – number of rotor teeth = even number
C) Number of stator teeth – number of rotor teeth = zero
D) Number of stator teeth – number of rotor teeth = negative number

44. In which of the following, it is not desired to attain the condition of maximum power
transfer
A) Electronic circuits B) Communicational circuits
C) Computer circuits D) Electrical circuits
45. A 100 km long transmission line is loaded at 100 kV. If the loss of line is 5 MW and the
load 150 MVA, the resistance of the line is

A) 0.806 ohms/phase B) 8.06 ohms/phase
C) 0.0806 ohms/phase D) 80.6 ohms/phase
46. In a dual slope integrating type digital voltmeter. The first integration is carried out for 10
periods of the supply frequency of 50 Hz. If the reference voltage used is 2V, the total
conversion time for an input of 1V is
A) 0.01 s B) 0.05 s C) 0.1 s D) 1 s

47. Determine the output voltage of an op-amp for input voltages of 200 µV and 160 µV. The
differential gain of op-amp is 4000 and value of CMRR is 150
A) 16 V B) 164.8 mV C) 64 mV D) 76 mV

48. What is frequency of the output of the eight flip-flops when the input clock frequency is
512 kHz
A) 16 kHz B) 4 kHz C) 2 kHz D) 8 kHz

49. The yearly load duration curve of a power plant is a straight line. The maximum load is
750 MW and the minimum load is 600 MW. The rated plant capacity is 900 MW. The
capacity factor and utilization factor are
A) 0.56, 0.80 B) 0.75, 0.83 C) 0.78, 0.9 D) 0.83, 0.75

50. Match List 1 (Protective Schemes) with List 2 (Equipment) and select the correct answer
using codes given the lists.

List 1 List 2

P. Mho relays 1. Generators

Q. Inverse time over current relays 2. Transmission Lines

R. Differential Relays 3. Motors

Codes
P Q R
A) 2 1 3
B) 2 3 1
C) 3 2 1
D) 1 3 2

51. The circuit is driven by an unit impulse source, then the response equal to
A) Transfer function B) One
C) Zero D) Inverse of transfer function
52. If the input of a circuit is represented by series of impulse function, the response consists of
A) Sum of the series of uniformly delayed impulse responses
B) Sum of the series of responses
C) One
D) Zero
53. For physically realizable circuit, impulse response is
A) Zero for t<0 B) Zero for t>0 C) One for t<0 D) Infinite for t>0

54. The instantaneous current in an inductor when an impulse voltage V0 applied to the
terminals of an inductor
A) Zero
B) Unity
C) V0
L
D) V0δ(t)
L
55. The function is said to be having simple poles and zeros and only if
A) The poles are not repeated
B) The zeros are not repeated
C) Both poles and zeros are not repeated
D) None of the above
56. The necessary condition for a driving point function is

A) The real part of all poles and zeroes must not be zero or negative
B) The polynomials P(s) and Q(s) may not have any missing terms between the
highest and lowest degree unless all even or all odd terms are missing.
C) The degree of P(s) and Q(s) may differ by more than one
D) The lowest degree in P(s) and Q(s) may differ in degree by more than two.

57. The necessary condition for the transfer function is that
A) The coefficient in the polynomials P(s) and Q(s) must be real
B) Coefficients in Q(s) may be negative
C) Complex or imaginary poles and zeroes may not conjugate
D) If the real part of pole is zero, then that pole must be multiple

58. The system is said to be stable, if and only if
A) All the poles lie on right half of the s-plane
B) Some poles lie on the right half of the s-plane
C) All the poles does not lie on the right half of the s-plane
D) None of the above

59. If Z11 = 2Ω; Z12 = 1 Ω; Z21 = 1 Ω and Z22 = 3 Ω, what is the determinant of admittance
matrix.
A) 5 B) 1/5 C) 1 D) 2

60. For a symmetric lattice network the value of the series impedance is 3 Ω and that of the
diagonal impedance is 5 Ω, then the Z parameters of the network are given by
A) Z11= Z22= 2 Ω
Z12=Z21=1/2 Ω
B) Z11= Z22= 4 Ω
Z12=Z21=1 Ω
C) Z11= Z22= 8 Ω
Z12=Z21=2 Ω
D) None of the above

61. For a two-port network to be reciprocal
A) Z11= Z22 B) y21=y22 C) h21=-h12 D) AD-BC=0
62. The values of L and C for a low pass filter with cut-off frequency of 2.5 KHz to operate
with a terminated load resistance of 450 ohms are given by
A) 57.32 mH; 0.283µF B) 28.66 mH; 0.14µF
C) 114.64 µH; 0.566µF D) 0.283mH; 0.14µF
63. A voltage wave consists of two components, a 50 V dc component and a sinusoidal
component with a maximum value of 50 volts. The average value of the resultant will be
A) Zero B) 86.6V C) 50V D) 100 V

64. The power consumed in a circuit element will be least when the phase difference between
the current and the voltage is

A) 00 B) 300 C) 900 D) 1800

65. In the m-derived low pass filters, the resonant frequency is to be chosen so that it is
A) Above the cut-off frequency
B) Below the cut-off frequency
C) Equal to cut off frequency
D) None of the above

66. In the m-derived high pass filters, the resonant frequency is to be chosen so that it is
A) Above the cut-off frequency
B) Below the cut-off frequency
C) Equal to cut off frequency
D) None of the above

67. The Laplace transform of a unit step function is
A) 1/s B) 1 C) 1/s2 D) 1/ (s+a)

68. A band elimination filter is one
A) Which attenuates all frequencies less than lower cut-off frequency f1.
B) Which attenuates all frequencies greater than upper cut-off frequency f2.
C) Frequencies lying between f1 and f2 are attenuated and all other frequencies are
passed.
D) Frequencies lying between f1 and f2 are passed and all other frequencies are
attenuated.

69. Norton’s equivalent circuit consists of
A) Voltage source in parallel with resistance.
B) Voltage source in series with resistance
C) Current source in series with resistance
D) Current source in parallel with resistance.
70. The reciprocity theorem is applicable to
A) Linear networks only B) Bilateral networks only
C) Linear/bilateral networks D) Neither of the two

71. In a constant torque-angle control of a permanent magnet synchronous motor (PMSM),
the torque angle is maintained at:
A) Zero-degree B) 90-degree C) 180-degree D) 45-degree

72. In a single phase full converter if output voltage has peak and average value of 325 V,
133 V respectively, then the firing angle in degrees
A) 40 B) 140 C) 50 D) 130

73. Modern ac to dc converters employ GTOs instead of SCRs in order to have
A) Low reactive volt amp flow B) Reliable commutation
C) Low switching losses D) Smaller heat sink

74. Each diode of a 3 phase half wave diode rectifier conducts for
A) 600 B) 1200 C) 1800 D) 900

75. In a 3 phase full wave diode rectifier, the Peak Inverse Voltage in terms of average
output voltage is
A) 1.57 B) 0.955 C) 1.047 D) 2.094

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