| No. |
Question |
| 1 |
The RMS value of the voltage u(t) =3 + 4cos (3t)
is |
| Options |
| A)
V |
B) 5 V |
| C) 7 V |
D) (3 + 2
) V |
|
| Correct Answer |
A |
| |
| 2 |
The open loop transfer function of a unity feed
back control system is given as G(s) =
The value of �a� to give a phase margin of 45� is equal to |
| Options |
| A) 0.141 |
B) 0.441
|
| C) 0.841 |
D) 1.141 |
|
| Correct Answer |
C |
|
| |
| 3 |
The armature resistance of a permanent magnet dc
motor is 0.8 W. At no load, the motor draws 1.5 A from a supply voltage
of 25 V and runs at 1500 rpm. The efficiency of the motor while it is
operating on load at 1500 rpm drawing a current of 3.5 A from the same
source will be |
| Options |
| A) 48.0% |
B) 57.1%
|
| C) 59.2% |
D) 88.8% |
|
| Correct Answer |
A |
| |
| 4 |
The solution of the first order differential
equation x(t) = -3x(t), x (0) = x0 is
|
| Options |
| A) x (t) = x0 e-3t |
B) x (t) = x0 e-3
|
| C) x (t) = x0 e-1/3 |
D) x (t) = x0 e-1 |
|
| Correct Answer |
A |
| |
| 5 |
The unit impulse response of a second order
under-damped system starting from rest is given by
c(t) = 12.5 e-6t sin 8 t, t 
0
The steady-state value of the unit step response of the system is equal
to |
| Options |
| A) 0 |
B) 0.25 |
| C) 0.5 |
D) 1.0 |
|
| Correct Answer |
D |
| |
| 6 |
A single-phase, 230 V, 50 Hz, 4 pole,
capacitor-start induction motor has the following stand-still impedances
Main winding Zm = 6.0 + j4.0 W
Auxiliary winding Za = 8.0 + j6.0 W
The value of the starting capacitor required to produce 90� phase
difference between the currents in the main and auxiliary windings will
be |
| Options |
| A) 176.84 mF |
B) 187.24 mF |
| C) 265.26 mF |
D) 280.86 mF
|
|
| Correct Answer |
A |
| |
| 7 |
A single-phase half-controlled rectifier is
driving a separately excited dc motor. The dc motor has a back emf
constant of 0.5 V/rpm. The armature current is 5 A without any ripple.
The armature resistance is 2W. The converter
is working from a 280 V, single phase ac source with a firing angle of
80�. Under this operating condition, the speed of the motor will be |
| Options |
| A) 339 rpm |
B) 359 rpm |
| C) 366 rpm |
D) 386 rpm |
|
| Correct Answer |
C |
| |
| 8 |
The 8085 assembly language instruction that
stores the content of H and L registers into the memory locations 2050H
and 2051H, respectively, is
|
| Options |
| A) SPHL 2050H |
B) SPHL2051H |
| C) SHLD 2050H |
D) STAX 2050H
|
|
| Correct Answer |
C |
| |
| 9 |
A 50 Hz, 4-pole, 500 MVA, 22 kV turbo-generator
is delivering rated megavolt-amperes at 0.8 power factor. Suddenly a
fault occurs reducing is electric power output by 40%. Neglect losses
and assume constant power input to the shaft. The accelerating torque in
the generator in MNm at the time of the fault will be |
| Options |
| A) 1.528 |
B) 1.018 |
| C) 0.848 |
D) 0.509 |
|
| Correct Answer |
A |
| |
| 10 |
The Nyquist plot of loop transfer function G(s)
H(s) of a closed loop control system passes through the point (-1, j0)
in the G(s) H(s) plane. The phase margin of the system is |
| Options |
| A) 0� |
B) 45�
|
| C) 90� |
D) 180�
|
|
| Correct Answer |
D |
| |
| 11 |
A 50 kW dc shunt motor is loaded to draw rated
armature current at any given speed. When driven
(i) at half the rated speed by armature voltage control and
(ii) at 1.5 times the rated speed by field control, the respective
output powers delivered by the motor are approximately. |
| Options |
| A) 25kW in (i) and 75kW in (ii) |
B) 25kW in (i) and 50kW in (ii)
|
| C) 50kW in (i) and 75kW in (ii) |
D) 50kW in (i) and 50kW in (ii) |
|
| Correct Answer |
B |
| |
| 12 |
A hydraulic turbine having rated speed of 250 rpm
is connected to a synchronous generator. In order to produce power at 50
Hz, the number of poles required in the generator are |
| Options |
|
| Correct Answer |
D |
| |
| 13 |
For the equation x(t)+3 x(t) +2x(t) = 5, the
solution x (t) approaches which of the following values as t � � ? |
| Options |
|
| Correct Answer |
B |
| |
| 14 |
The following motor definitely has a permanent
magnet rotor |
| Options |
| A) DC commutator motor |
B) Brushless dc motor
|
| C) Stepper motor |
D) Reluctance motor |
|
| Correct Answer |
C |
| |
| 15 |
A110 kV, single core coaxial, XLPE insulated
power cable delivering power at 50Hz, has a capacitance of 125 nF/km. If
the dielectric loss tangent of XLPE is 2 x 10-4, the
dielectric power loss in this cable in W/km is |
| Options |
| A) 5.0 |
B) 31.7
|
| C) 37.8 |
D) 189.0 |
|
| Correct Answer |
D |
| |
| 16 |
The simultaneous application of signals x(t) and
y(t) to the horizontal and vertical plates, respectively, of an
oscilloscope, produces a vertical figure-of-8 display. If P and Q are
constants, and x(t) = P sin (4t + 30), then y(t) is equal to |
| Options |
| A) Q sin (4t - 30) |
B) Q sin (2t + 15)
|
| C) Q sin (8t + 60) |
D) Q sin (4t + 30) |
|
| Correct Answer |
B |
| |
| 17 |
A 500 MW 3-phase Y-connected synchronous
generator has a rated voltage of 21.5 kV at 0.85pf. The line current
when operating at full load rated conditions will be |
| Options |
| A) 13.43 kA |
B) 15.79 kA
|
| C) 23.25 kA |
D) 27.36 kA |
|
| Correct Answer |
B |
| |
| 18 |
Total instantaneous power supplied by a 3-phase
ac supply to a balanced R-L load is |
| Options |
| A) zero |
B) constant
|
| C) pulsating with zero average |
D) pulsating with non-zero average |
|
| Correct Answer |
B |
| |
| 19 |
The equivalent circuit of a transformer has
leakage reactances X1 , X |
| Options |
| A) X1>> X |
B) X1<< X |
| C) X1� X |
D) X1� X |
|
| Correct Answer |
D |
| |
| 20 |
If P and Q are two random events, then the
following is TRUE
|
| Options |
A) Independence of P and Q implies that probability
(P
Q ) = 0
|
B) Probability (P 
Q )
Probability (P) + Probability (Q)
|
C) If P and Q are mutually exclusive, then they must
be independent
|
D) Probability (P
Q ) 
Probability (P)
|
|
| Correct Answer |
D |
