Quiz's for General Studies(GK) for Civil Service Exams 17 12

## June 20, 2013

### SOME TECHNICAL QUESTIONS FOR APGENCO APTRANSCO AEE EXAMS PART 3

APGENCO/APTRANSCO
Assistant Engineer Electrical Previous Question Papers
Q.1 The two windings of a transformer is

Q.2 A salient pole synchronous motor is running at no load. Its field current is switched off. The motor
will
come to stop.
continue to run at synchronous speed.
continue to run at a speed slightly more than the synchronous speed.
continue to run at a speed slightly less than the synchronous speed.
Q.3 The d.c. series motor should always be started with load because
at no load, it will rotate at dangerously high speed.
it will fail to start.
it will not develop high starting torque.
all are true.
Q.4 The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is
50 Hz.
20 Hz.
2 Hz.
Zero.
Q.5 In a stepper motor the angular displacement
can be precisely controlled.
it cannot be readily interfaced with micro computer based controller.
the angular displacement cannot be precisely controlled.
it cannot be used for positioning of work tables and tools in NC machines.
Q.6 The power factor of a squirrel cage induction motor is
low at light and heavy load both.
Q.7 The generation voltage is usually
between 11 KV and 33 KV.
between 132 KV and 400 KV.
between 400 KV and 700 KV.
None of the above.
Q.8 When a synchronous motor is running at synchronous speed, the damper winding produces
damping torque.
eddy current torque.
torque aiding the developed torque.
no torque.
Q.9 If a transformer primary is energised from a square wave voltage source, its output voltage will be
A square wave.
A sine wave.
A triangular wave.
A pulse wave.
Q.10 In a d.c. series motor the electromagnetic torque developed is proportional to
Ia
(Ia)2
1/Ia
1/(Ia)2
Q.11 In a 3 – phase induction motor running at slip ‘s’ the mechanical power developed in terms of air
gap power
(s-1)Pg
( B) Pg/(1-s)
(1-s)Pg
s.Pg
Q.12 In a 3 – phase induction motor the maximum torque
is proportional to rotor resistance r2
does not depend on r2
is proportional to sqrt(r2)
is proportional to (r2)2
Q.13 In a d.c. machine, the armature mmf is
stationary w.r.t. armature.
rotating w.r.t. field.
stationary w.r.t. field.
rotating w.r.t. brushes.
Q.14 In a transformer the voltage regulation will be zero when it operates at
unity p.f.
lagging p.f.
Q.15 The maximum power in cylindrical and salient pole machines is obtained respectively at load
angles of
900,900
<900,900
900,>900
900,<900
Q.16 The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The
secondary output voltage will be
3.6 V.
2.5 V.
3.0 V.
6.0 V.
Q.17 The emf induced in the primary of a transformer
is in phase with the flux.
lags behind the flux by 90 degree.
leads the flux by 90 degree.
is in phase opposition to that of flux.
Q.18 The relative speed between the magnetic fields of stator and rotor under steady state operation is
zero for a
dc machine.
3 phase induction machine.
synchronous machine.
single phase induction machine.
Ans: all options are correct
Q.19 The current from the stator of an alternator is taken out to the external load circuit through
slip rings.
commutator segments.
solid connections.
carbon brushes.
Q.20 A motor which can conveniently be operated at lagging as well as leading power factors is the
squirrel cage induction motor.
wound rotor induction motor.
synchronous motor.
DC shunt motor.
Q.21 A hysteresis motor
is not a self-starting motor.
is a constant speed motor.
needs dc excitation.
can not be run in reverse speed.
Q.22 The most suitable servomotor for low power applications is
a dc series motor.
a dc shunt motor.
an ac two-phase induction motor.
an ac series motor.
Q.23 The size of a conductor used in power cables depends on the
operating voltage.
power factor.
current to be carried.
type of insulation used.
Q.24 Out of the following methods of heating the one which is independent of supply frequency is
electric arc heating
induction heating
electric resistance heating
dielectric heating
Q.25 A two-winding single phase transformer has a voltage regulation of 4.5% at full-load and unity
power-factor. At full-load and 0.80 power-factor lagging load the voltage regulation will be
4.5%.
less than 4.5%.
more than 4.5%.
4.5% or more than 4.5%.
Q.26 In a dc shunt motor the terminal voltage is halved while the torque is kept constant. The resulting
approximate variation in speed ” ω” and armature current “Ia‘” will be
Both ω and Ia are doubled.
ω is constant and Ia is doubled
w is doubled while Ia is halved
w is constant but Ia is halved
Q.27 A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the
motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to
the rotor structure is
1500 r.p.m.
1425 r.p.m.
25 r.p.m.
75 r.p.m.
Q.28 An alternator is delivering rated current at rated voltage and 0.8 power-factor lagging case. If it is
required to deliver rated current at rated voltage and 0.8 power-factor leading, the required excitation
will be
less.
more.
more or less.
the same.
Q.29 A ceiling fan uses
split-phase motor.
capacitor start and capacitor run motor.
universal motor.
capacitor start motor.
Q.30 A stepper motor is
a dc motor.
a single-phase ac motor.
a multi-phase motor.
a two phase motor.
Q.31 The ‘sheath’ is used in cable to
provide strength to the cable.
provide proper insulation.
prevent the moisture from entering the cable.
avoid chances of rust on strands.
Q.32 The drive motor used in a mixer-grinder is a
dc motor.
induction motor.
synchronous motor.
universal motor.
Q.33 A 1:5 step-up transformer has 120V across the primary and 600 ohms resistance across the
secondary. Assuming 100% efficiency, the primary current equals
0.2 Amp.
5 Amps.
10 Amps.
20 Amps.
Q.34 A dc shunt generator has a speed of 800 rpm when delivering 20 A to the load at the terminal
voltage of 220V. If the same machine is run as a motor it takes a line current of 20A from 220V supply.
The speed of the machine as a motor will be
800 rpm.
more than 800 rpm.
less than 800 rpm.
both higher or lower than 800 rpm.
Q.35 A 50 Hz, 3-phase induction motor has a full load speed of 1440 r.p.m. The number of poles of the
motor are
4.
6.
12.
8.
36. In a dc shunt motor the terminal voltage is halved while the torque is kept constant. The resulting
approximate variation in speed ” ω” and armature current “Ia‘” will be
Both ω and Iaare doubled.
ω is constant and Ia is doubled
w is doubled while Ia is halved
w is constant but Ia is halved
37.The current from the stator of an alternator is taken out to the external load circuit through
slip rings.
commutator segments.
solid connections.
carbon brushes.
38.A motor which can conveniently be operated at lagging as well as leading power factors is the
squirrel cage induction motor.
wound rotor induction motor.
synchronous motor.
DC shunt motor.
39. The frequency of the rotor current in a 3 phase 50 Hz, 4 pole induction motor at full load speed is
50 Hz.
20 Hz.
2 Hz.
Zero.
40.The size of a conductor used in power cables depends on the
operating voltage.
power factor.
current to be carried.
type of insulation used.
41. The most suitable servomotor for low power applications is
a dc series motor.
a dc shunt motor.
an ac two-phase induction motor.
an ac series motor.
42.A two-winding single phase transformer has a voltage regulation of 4.5% at full-load and unity
power-factor. At full-load and 0.80 power-factor lagging load the voltage regulation will be
4.5%.
less than 4.5%.
more than 4.5%.
4.5% or more than 4.5%.
43. When a synchronous motor is running at synchronous speed, the damper winding produces
damping torque.
eddy current torque.
torque aiding the developed torque.
no torque.
44. If a transformer primary is energised from a square wave voltage source, its output voltage will be
A square wave.
A sine wave.
A triangular wave.
A pulse wave.
45. In a d.c. series motor the electromagnetic torque developed is proportional to
Ia
(Ia)2
1/Ia
1/(Ia)2
46.The two windings of a transformer is
47.In a 3 – phase induction motor running at slip ‘s’ the mechanical power developed in terms of air gap
power
(s-1)Pg
( B) Pg/(1-s)
(1-s)Pg
s.Pg
48. In a 3 – phase induction motor the maximum torque
is proportional to rotor resistance r2
does not depend on r2
is proportional to sqrt(r2)
is proportional to (r2)2
49 In a d.c. machine, the armature mmf is
stationary w.r.t. armature.
rotating w.r.t. field.
stationary w.r.t. field.
rotating w.r.t. brushes.
50. In a transformer the voltage regulation will be zero when it operates at
unity p.f.
lagging p.f.
51.. A salient pole synchronous motor is running at no load. Its field current is switched off. The motor
will
come to stop.
continue to run at synchronous speed.
continue to run at a speed slightly more than the synchronous speed.
continue to run at a speed slightly less than the synchronous speed.
52.The maximum power in cylindrical and salient pole machines is obtained respectively at load angles
of
900,900
<900,900
900,>900
900,<900
53. A stepper motor is
a dc motor.
a single-phase ac motor.
a multi-phase motor.
a two phase motor.
54.The primary winding of a 220/6 V, 50 Hz transformer is energised from 110 V, 60 Hz supply. The
secondary output voltage will be
3.6 V.
2.5 V.
3.0 V.
6.0 V.
55.In a stepper motor the angular displacement
can be precisely controlled.
it cannot be readily interfaced with micro computer based controller.
the angular displacement cannot be precisely controlled.
it cannot be used for positioning of work tables and tools in NC machines.
56.The emf induced in the primary of a transformer
is in phase with the flux.
lags behind the flux by 90 degree.
leads the flux by 90 degree.
is in phase opposition to that of flux.
57.The d.c. series motor should always be started with load because
at no load, it will rotate at dangerously high speed.
it will fail to start.
it will not develop high starting torque.
all are true.
58.The relative speed between the magnetic fields of stator and rotor under steady state operation is
zero for a
dc machine.
3 phase induction machine.
synchronous machine.
single phase induction machine.
Ans: all options are correct
59.The power factor of a squirrel cage induction motor is
low at light and heavy load both.
60. A hysteresis motor
is not a self-starting motor.
is a constant speed motor.
needs dc excitation.
can not be run in reverse speed.
61.Out of the following methods of heating the one which is independent of supply frequency is
electric arc heating
induction heating
electric resistance heating
dielectric heating
62. A balanced three-phase, 50 Hz voltage is applied to a 3 phase, 4 pole, induction motor. When the
motor is delivering rated output, the slip is found to be 0.05. The speed of the rotor m.m.f. relative to
the rotor structure is
1500 r.p.m.
1425 r.p.m.
25 r.p.m.
75 r.p.m.
63.An alternator is delivering rated current at rated voltage and 0.8 power-factor lagging case. If it is
required to deliver rated current at rated voltage and 0.8 power-factor leading, the required excitation
will be
less.
more.
more or less.
the same.
64.The generation voltage is usually
between 11 KV and 33 KV.
between 132 KV and 400 KV.
between 400 KV and 700 KV.
None of the above.
65. A ceiling fan uses
split-phase motor.
capacitor start and capacitor run motor.
universal motor.

capacitor start motor.
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