ELECTRICIAN (THEORY) SEMESTER-III JULY 2018
Which of the following is not a
part of the
Alternator's specification plate
?
(a) Voltage
(a) Voltage
(b) Phase
(c)KVA
(d) Type of winding
Answer: (d) Type of
winding
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A single phase Hysteresis motor
can run at.......
(a) Synchronous speed only
(b) Sub synchronous speed only
(c) Synchronous and super
synchronous speed
(d) Synchronous and sub
synchronous speed
Answer: (a) Synchronous
speed only
The direction of rotation of
Hysteresis motor
is reversed by............
(a) Reversing supply leads
(b) Shift shaded pole with
respect to main pole
(c) Both (a) & (b)
(d) None of these
Answer: (b) Shift shaded
pole with respect to main pole
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The motor used in domestic mixer
grinder is................
(a) DC motor
(b) Induction motor
(c) Universal motor
(d) Synchronous motor
Answer: (c) Universal motor
A Stepper motor is a.....
(a) DC motor
(b) Two phase motor
(c) Single phase motor
(c) Single phase motor
(d) Multi phase motor
Answer:
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The slip ring induction motors
have..............rotor.
(a) Phase wound
(b) Squirrel cage
(c) Squirrel cage with winding
(d) Diamond coil wound
Answer: (a) Phase wound
The difference between the speed
of a rotating
magnetic field and the associated
rotor is called .............
(a) Split
(b) Salient pole
(c) Slip
(d) Pul1 out tor(lue •
Answer: (c) Slip
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If the voltage is reduced to
half, the torque
developed by an induction motor
will be
reduced to..................
reduced to..................
(a) 1/4 of original torque
(b) 1/2 of original torque
(c) 1/8 of original torque
(d) 2/3 of original torque
Answer:
In a three phase induction motor, the cage bars
of the rotor are arranged in an
offset
pattern to the axis of rotation
in order to prevent ...............
(a) Torque fluctuation
(b) Over heating
(c) Speed variation
(d) Voltage drop on load
Answer: (a) Torque
fluctuation
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The variation of power factor
with respect to the field
current is called ...............
(a) V curve
(b) Inverted curve
(c) Hysteresis curve
(d) Circle diagram
Answer: (b) Inverted
curve
When asynchronous motor is
running at
synchronous speed, the damper
winding
produces.................
(a) Damping torque
(b) Eddy current torque
(c) Torque aiding the developed
torque
(d) No torque
Answer: (d) No torque
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A motor which can conveniently be
operated
at lagging as well as leading
power factor is
the...................
the...................
(a) Squirrel cage induction motor
(b) Wound rotor induction motor
(c) Synchronous motor
(d) DC shunt motor
Answer: (c) Synchronous
motor
A synchronous motor is operating
on no load
at unity power factor. If the
field current is
increased, power factor will become............
increased, power factor will become............
(a) Leading and current will
decrease
(b) Leading and current will
increase
(c) Lagging and current will
decrease
(d) Lagging and current will
increase
Answer: (a) Leading and
current will decrease
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The frequency of ripple in the
output voltage of a
three phase Half controlled
bridge rectifier
depends on the................
(a) Firing angle
(b) Load inductance
(c) Load resistance
(d) Supply frequency
Answer: (d) Supply
frequency
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A PWM switching scheme is used in
a three phase inverter to........
(a) Reduce total harmonic
distortion with modest filtering
(b) Reduce low order harmonics
and increase high order harmonics
(c) Minimize the load on DC side
(d) Increase the life of the
batteries
Answer: (b) Reduce low
order harmonics and increase
high order harmonics
Which of the following is a Shell
type of transformer lamination?
(a) T & I type
(a) T & I type
(b) E & T type
(c) U & I type
(d) T & U type
Answer: (d) T & U
type
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For a given number of poles(2)
and armature conductors,
a hp winding will
carry.............a wave winding.
(a) More current than
(b) Same current as
(c) Less current than
(d) Half the current than
Answer: (a) More current than
An Eight pole duplex lap winding
will have ......... parallel paths.
(a) 8
(b) 12
(c) 32
(d) 16
Answer: (d) 16
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In a simplex wave winding the
number of
parallel paths is equal to
(a) Number of poles in the machine
(a) Number of poles in the machine
(b) Two
(c) Number of pair poles
(d) One
Answer: (b) Two
The number of parallel paths in
simplex lap
winding is equal to...
(a) Two
(a) Two
(b) Number of poles
(c) Number of pair poles
(d) One
Answer: (c) Number of
pair poles
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In a lap winding, the number of
brushes required
is equal to............
(a) Number of coils
(b) Number of pairs of poles
(c) Number of poles
(d) Commutator pitch
Answer: (c) Number of
poles
In a wave winding, the commutator
pitch is
approximately equal
to..................
(a) Twice the pole pitch
(b) Thrice the pole pitch
(c) Half the pole pitch
(d) Pole pitch
Answer: (a) Twice the
pole pitch
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The AC armature winding of an
alternator
operates at........the field
winding.
(a) The same voltage as
(b) Much higher voltage than
(c) Much less voltage than
(d) Half the voltage than
Answer: (b) Much higher
voltage than
The stator of an alternator is
wound for..........on the stator.
(a) A more number of poles than
(b) Less number of poles than
(c) The same number of poles as
(d) Twice the number of poles
Answer: (c) The same
number of poles as
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The Damper windings are used in
the alternators to ……
(a) Reduce eddy current loss
(b) Achieve synchronism
(c) Reduce winding losses
(d) Prevent hunting
Answer: (d) Prevent
hunting
The AC armature winding of an
alternator is.................
(a) Always star connected .
(b) Star delta connected
(c) Generally delta connected
(d) Pi connected
Answer: (a) Always star connected
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While testing a Fluorescent tube starter with series
While testing a Fluorescent tube starter with series
testing board, the starter is
considered good if the lamp................
(a) Glows continuously
(b) Does not glow at all
(c) Continuously flickers
(d) Glows initially then turns
off permanently
Answer: (c) Continuously
flickers
The illurnination power of a
lighting source is measured in.
(a) Lumen
(b) Candela
(c) Foot candle
(d) Candle power
Answer: (d) Candle power
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As per IE rules, the lighting
load in a sub-circuit
of the house wiring should not be
than.........watts.
(a) 1500W
(b) 1200W
(c) 1000W
(d) 800W
Answer: (d) 800W
As per IE rules, the load in a
power sub-circuit in
house wiring is normally
restricted to........watt
and number of outlets to.........
(a) 5000, two
(b) 3000, two
(c) 4000, three
(d) 4500, four
Answer: (b) 3000, two
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In a Fluorescent tube fixture, if
the tube does
not strike a glow but both
filaments glow
red, the possible defect is............
red, the possible defect is............
(a) Opened choke coil
(b) Short circuited choke coil
(c) Starter contacts permanently
opened
(d) Starter contacts permanently
shorted
Answer: (d) Starter
contacts permanently shorted
The electrical wiring in
factories and industries
is done by.........,.
(a) Cleats
(b) Casing capping
(c) Surface metal conduit
(d) Surface PVC conduit
Answer: (c) Surface
metal conduit
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The magnetic operating limit of
C-type of
MCB’s is..........times of the
rated current.
(a) 5 to 10
(b) 20 to 30
(c) 3 to 5
(d) 10 to 20
Answer: (a) 5 to 10
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Which one of the following lamps
has the
longest operating life?
(a) LED lamp
(a) LED lamp
(b) Fluorescent tube light
(c) CFL
(d) Incandescent lamp
Answer: (a) LED lamp
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When the Growler is connected with 230 V,
When the Growler is connected with 230 V,
AC supply and armature is placed
over it,
the arrangement behaves like a....................
the arrangement behaves like a....................
(a) Potential Divider
(b) AC Motor
(c) Transformer .
(d) DC Bridge
Answer: (c) Transformer
A motor normally fitted to a domestic
vacuum cleaner
is.............motor.
(a) Universal
(b) Cage Induction
(c) Wound rotor
(d) Shunt Wound
Answer: (a) Universal
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The type of single-phase
induction motor
having the highest power factor at full load
is....:..............
(a) Shaded pole type
(b) Split-phase type
(c) Capacitor-start type
(d) Capacitor-run type
Answer: (d)
Capacitor-run type
The method of braking an
induction motor by
interchanging the supply to two
of the
stator phase windings is
called..................
(a) Plugging
(b) Stopping
(c) Commutation
(d) Retarding
Answer: (a) Plugging
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If a three phase induction motor
is switched on with
one phase disconnected, the motor
will ................
(a) Run at low speed
(b) Burn Out
(c) Run at High Speed
(d) Not Run
Answer: (b) Burn Out
The running of induction motors
at slow and
steady speed much less than the
actual
speed is known as.
(a) Crawling
(a) Crawling
(b) Damping,
(c) Sinking
(d) Ageing
Answer: (a) Crawling
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The distribution of load between two alternators
The distribution of load between two alternators
operating in parallel can be
changed by
changing...............
(a) Phase sequence .
(b) Field excitation of
alternators
(c) Current direction
(d) Driving torques of prime
movers
Answer: (d) Driving
torques of prime movers
A 3-phase synchronous motor
connected to
AC mains is running at full load
and unity
power factor. If its shaft load is reduced by half,
power factor. If its shaft load is reduced by half,
with field current held constant,
its new
power factor will be.........
(a) Unity
(b) Leading
(c) Lagging
(d) Dependent upon motor
parameters
Answer: (b) Leading
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The starting torque of slip-ring
induction motor
can be increased by inserting a
suitable ……..
in series with the rotor circuit of the motor,
(a) Capacitor
in series with the rotor circuit of the motor,
(a) Capacitor
(b) Resistance
(c) Inductor
(d) Overload relay
Answer: (b) Resistance
The Growler instrument is made in
...............
type of iron core.
(a) E & I
(b) Shell
(c) T&U
(d) H
Answer: (d) H
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The voltage regulation of an
alternator with power
factor of 0.8 lagging is ……. at
unity power factor.
(a) Greater than
(b) The same as
(b) The same as
(c) Smaller than
(d) 100%
Answer: (a) Greater than
A ceiling fan uses.......
(a) Capacitor start motor
(b) Universal motor
(c) Capacitor start and capacitor
run motor
(d) Split-phase motor
Answer: (a) Capacitor
start motor
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The voltage regulation of an
alternator is larger
than that of a DC generator
because of ..................
(a) Large armature resistance
(b) Large leakage reactance
(c) Complex effects of armature
reaction
(d) Small armature resistance
Answer: (c) Complex
effects of armature reaction
[f the excitation an alternator
operating in
parallel with other alternators,
is increased
above the normal value of excitation, its .........
above the normal value of excitation, its .........
(a) Output current decreases
(b) Power factor becomes more
lagging
(c) Power factor becomes more
leading
(d) Output KW decreases
Answer: (b) Power factor
becomes more lagging
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