APGENCO/APTRANSCO
Assistant Engineer Electrical Previous Question
Papers
Q.1
The two windings of a transformer is
conductively
linked.
inductively
linked.
not
linked at all.
electrically
linked.
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
about
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 load only.
low
at heavy load only.
low
at light and heavy load both.
low
at rated load only.
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.
leading
p.f.
lagging
p.f.
zero
p.f. leading.
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
about
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
conductively
linked.
inductively
linked.
not
linked at all.
electrically
linked.
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.
leading
p.f.
lagging
p.f.
zero
p.f. leading.
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 load only.
low
at heavy load only.
low
at light and heavy load both.
low
at rated load only.
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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