ELECTRICIAN
(THEORY)
SEMESTER-III
JULY 2018
Which of the following is not a part of theAlternator's specification plate ?
(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
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
(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
If the voltage is reduced to half, the torque
developed by an induction motor will be
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:
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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
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...................
(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............
(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
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
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
(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
In a simplex wave winding the number of
parallel paths is equal to
(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
(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
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
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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
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
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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
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
In a Fluorescent tube fixture, if the tube does
not strike a glow but both filaments glow
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
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
(b) Fluorescent tube light
(c) CFL
(d) Incandescent lamp
Answer: (a) LED lamp
When the Growler is connected with 230 V,
AC supply and armature is placed over it,
the arrangement behaves like a....................
(a) Potential Divider
(b) AC Motor
(c) Transformer .
(d) DC Bridge
Answer: (c) Transformer
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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
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
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
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The running of induction motors at slow and
steady speed much less than the actual
speed is known as.
(a) Crawling
(b) Damping,
(c) Sinking
(d) Ageing
Answer: (a) Crawling
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,
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
(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
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
(c) Smaller than
(d) 100%
Answer: (a) Greater than
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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
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 .........
(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
ELECTRICIAN THEORY SEM 3 JAN 15 QUESTIONS
Small type transfomer core for shell type generally used.............
A E& I type of core. B F& F type of coro. C E& E type of core. D T& U type of core .
The distance measured in terms of armature slots or armature conductors between two sides of a coil is.................
A back pitch. B coil pitch. C front pitch.. D pole pitch.
The distance measured in terms of armature Conductors which a coil advances on back cf the armature is called as....................
A front pitch. B coil pitch. C back pitch. D pole pitch.
The end tead of coil 1 is connected to the beginning lead of adjacent coil (coi! 2)
inrough the commutator segments is.....................
A simple lap winding. B duplex lap winding. C simple wave winding. D duplex wave winding.
The end lead of the coil 1 is connected to the begining of a coil placed at a distance equal to one pole pitch is called................
A. simple lap winding, B. simple wave winding,
C. duplex lap winding, D. duplex wave winding.
Laying the coils clockwise .the connections to the commutator segment's will also proceed clock wise then this type of winding is called as......
A retrogressive lap or wave winding.
B progressive lap or wave winding.
C lap winding.
D wave winding.
Laying the coils clock wise, the connections to the commutator segments will proceed anti- Clock wise then this type of winding is called as...........
A. lap winding,
B. wave winding.
C. progressive lap or wave winding,
D. retrogressive lap or wave winding.
The motor suitable for loads where constant speed is requried is...............
A induction motor. B synchronous motor. C capacitor motor. D universal motor.
The magnetic field produced in the stator of a three phase induction motor travels at.......
A rotating speed. B asynchronous speed. C synchronous speed. D slip speed.
The syncthronous speed of an induction motor refers to the speed of the.............
A rotor B armature C rotating magnetic field D value marked on the name plate
It is advisable to avoid direct on line starting of induction motor having a capacity of more than 3HP because............
A the starting torque is very low
B the motor takes five to seven times of its full load current
C it will pick up very high speed
D it will tun in the reverse direction
On switching'ON'the starter the magnetic contactor vibrates heavily the causes may be............
A high voltage.
B dirt in the armature contact surface.
C low voltage and single phasing.
D low voltage and dirt on the armature contact surface.
For a small capacity induction motor the type of starter used is........
A star-delta starter. B DOL-starter. C Auto-transformer starter. D Rotor -resistance starter.
In a 3phase induction motor started by a DOL starter the short circuit current is protected by.............
A over load relay. B no-volt coil. C back -up fuses. D protective earth conductor.
In the manual star delta starter.the stop button connection is in series with the.........
A no-volt coil. B over load relay contacts.
C no volt coil and load relay contacts. D no-volt coil and start button.
In shaded pole single phase motor the revolving field is produced by.........
A capacitor B regulator C shading ring D winding
If the capacitor in a fan is shorted, then the fan will.............
A not run B run slowly C run fast D run with noise
in the motor generator set the type of AC motor used is.......
A squirrel cage induction motor B wound rotor induction motor
C AC commutator motor D synchronous motor
In which type of AC to DC converter, losses are less and efficiency is higher?
A Motor generator set B Rotary converter
C Mercury arc rectifier D Metal rectifier
In which of the following applications DC is essential?
A Electric traction motor B Electric home appliances C Machine shop motors D illumination
Motor used in electric traction is.................
A DC compound B DC shunt C DC series D DC long shunt compound
Cables are drawn through the pipe and terminated. The system of wiring is called........
A PVC casing capping wiring B conduit wiring C T.W batten wiring D T.W casing capping wiring
The radius of bends used in conduit wiring should not be (ess than........
A 3 cm B 5 cm C 6 cm D 7.5 cm
The thread on conduit pipes in all cases should have a length of range.........
A 10 to 20 mm B 11 to 27 mm C 12 to 25 mm D 15 to 35 mm
The fuse rating is expressed in terms of
A voltage B current C KVA D VAR
A delayed action cartridge fuse is used for...
A motor circuits B lighting circuits C fluorescent lamp circuits D heating circuits
As compared to rewirable fuses, HRC fuses have............
A high rupturing capacity B high speed of operation C no ageing effect D low rupturing effect
According to NE code the colour code for the neutral..........
A red B blue C black D green
Which type of relay is used to protect the
damage of equipment during under and over voltage fault?
A Current sensing relay B Undercurrent relay C Voltage sensing relay D Latching relay
The quick response type catridge fuse is used for.................
A lighting circuits B heating circuits C motor circuits D wiring circuit
A fuse in a circuit provides protection against...........
A open circuit B over load C short circuit and over load D open circuit and over load
Which type of wiring is suitable for multi- storey building?
A Tree-system
B Ring main system
C Distribution board system
D Ring main and distribution board system
Which type of looping method uses less cables in wiring ?
A looping out from switch and ceilling rose B looping out from switch
C looping out from 3 plate ceilling rose D looping out with junction box
While estimating in wiring for any contlgencies generally an additional amount of total cost is added...........
A 3 percent B 5 percent C 7 percent D 10 percent
The space in the back of switch board width should not be less than............
A 22.88 cm B 21.88 cm C 20.88 cm D 20.77 cm
Earth continuity conductors should run from the machine to the panel boards and to the main, no. of earth electrodes are..........
A 1 B 2 C 3 D 4
Height of the control panel installed from the ground level is..........
A 2.2 metres B 2.0 metres C 1.5 metres D 1 metre
Pumps can be classified mainly into
A 2 B 3 C 4 D 5
As per standard practice the circuit of different phases should be kept at...............
A 3.5 metres B 3.05 metres C 2.55 metres D 2.05 metres
Copper used in electric work should have a very high degree of purity say..............
A 90.9% B 95.9% C 96.9% D 99.9%
Operating temperature range of heating elements in hotplate is..............
A 550° to 700°C B 700° to 350°C C 750° to 900°C D 800°to850°C
To operate 6 volt bulb in a 24C volt supply no. of bulbs required is...........
A 30 B 32 C 40 D 42
A100 watts heater is connected to a 240v AC supply then the current drawn by the heater is...............
A 4.006 A B 4.106A C 4.160 A D 4.156 A
ELECTRICIAN THEORY SEM 3 JAN 18
Which type of pitch is commonly used due to its advantages during rewinding.........
a) Short pitch
b) Long pitch
c) Full pitch
d) None of these
Mostly field used in three phase stator rewinding is .......
a) Flat Loop
b) Basket
c) Chain
d) None of these
The Unit of luminous flux is-
a) Candale Power
b) Lux
c) Lumen
d) Meter Candle
The unit of luminous intensity is ..............
a) Candale Power
b) Lumen
c) Lume Flux
d) None of these
The unit of soild angle is ............
a) Degree b) Steradian
c) Radian d) Candale
Which lamp is generally used for lighting purpose .............?
a) Carbon filament Lamp
b) Arc lamp
c) Tungsten filament lamp
d) All of these
Carbon Filament Lamp is used for ........
a) Lighting
b) Battery Charging
c) Projectors
d) Indicating
Which Lamp is used in the cinema Projectors?
a) Carbon arc lamp
b) Carbon filament lamp
c) Neon larnp
d) Gas discharge lamp
In a mercury vapour lamp which gas is filled?
a) Hydrogen
b) Argon
c) Helium
d) Neon
The Function of auxiliary electrode in a Mercury vapour lamp is ............
a) Starting Purposes
b) To drop the voltage
c) To reduce the current
d) Gives more Light
Mercury vapour lamps are made in .........
a) M.A.T MA and A.B.T type
b) M.A M.B And M.A.T type
c) MtB.T B.C.T and A.B.T type
d) None of these
The working temperature of high pressure mercury vapour lamp is ..............
a) 6000. b) 6800
c) 8000 d) 12000
The sodium vapour lamp has
a) Neon gas
b) Helium
c) Hydrogen
d) Nitrogen
Sodium vapour has two electrodes ..........
a) Oxide coated tungsten
b) Oxide coated carbon
c) Oxide coated nichrome
d) Oxide coated eureka
The colour of sodium vapour lamp light is ..............
a) Blue b) Red c) Yellow d) White
The working temperature of sodium vapour is ..............
a) 250°C b) 300°C
c) 450°C d) 60°C
Which lamp takes more time for giving full light?
a) Sodium 'vapour lamp
b) Mercury vapour lamp
c) Tugsten filament lamp
d) Néon lamp
A sodium vapour lamp has ............
a) 20-30 lumen/watts
b) 40-50 lumen/watts
c) 55-75 lumen/watts
d) 85-105 lumen/watts
Sodium vapour lamp has how much ionisation potential ...........
a) 5.12 V b) 6.2 Vc) 6.76 v d) 7.2 V
The fluorescent tube has .........
a) Mercury vapour
b) Neon
c) Mercury & Argon
d) Helium& Mercury
The main function of Choke in a fluorescent tube is ...........
a) Induce surge voltage at the time of starting
b) To drop the voltage
c) To improve the P.F
d) To induce high voltage and
limit the current
In running condition, voltage across starter is ............
a) HO V b) 180 V c) 220 v d) Zero
The light efficiency of fluorescent tube is ............
a) 40 lumen/watls
b) 45 lumen/watts
c) 60 lumen/watts
d) 75 lumen/watts
lamp gives direct light when its filament is heated.
a) Incandescent lamp
b) Gas discharge lamp
c) Neon lamp
d) Arc lamp
The diameter of 40 Watt tube is ......
a) 12mm b) 25 mm
c) 30mm d) 38 mm
Gas filled in a tube starter is-
a) Argon
b) Helium
c) Neon
d) None of these
Condenser is used in tube circuit to .........
a) To improve the P.F
b) To improve the voltage
c) safeguard the tube
d) To give full light
The inner side colour of the Reflector is ............
a) Black
b) White
c) Any Dark
d) None of these
In a power house, Illuination should be approximately
a) 20-40 Lumen/M2
b) 80-90 Lumen/M2
c) 100-150 Lumen/M2
d) 200-250 Lumen/M2
In parking lots, illumination height should be approximately
a) 8 Lumen/M3
b) 10 Lumen/M3
c) 12 Lumen/M3
d) 80 Lumen/M3
When a rotating machine is observed under a gas discharge lamp, it appear to be either stationary or seams to be running in reverse direction. What is reason for it ...........?
a) Argon
b) Helium
c) Neon
d) None of these
The circuit of tube starter has condenser which
a) Reduce the spark
b) Improves power factor
c) Limit the current
d) Reduce the stroboscope effect
The diameter of electrode in a D.C arc lamp is ............
a) Positive electrode very thick
b) Negative electrode very thick
c) Positive electrode very thin
d) Both similar
Voltage used in D.C arc lamp is-
a) 40-60V b) 80-110 V
c) 180-210 v d) 220-250 V
The threaded portion on the outer side of the edison screw type lamp holder should be connected with
a) Neutral wire ofthe circuit
b) Half wire of the circuit
c) Phase wire of the circuit
d) Earth wire of the circuit
The working temperature of a gas filled tungsten filament lamp is
a) 1035%
b) 1200%
c) 1500%
d) 2300%
Rotary convertor is generally available in .............
a) Single phase
b) Three phase
c) Both (a) & (b)
d) Twelve phase
Mercury arc rectifier anodeis made up of.............
a) Carbon b) Graphite
c) Both (a) & (b) c) None of these
.............. is also known as hote cathode rectifier.
a) Copper oxide rectifier
b) Tunger bulb rectifier
c) Mercury arc rectifier
d) None ofthese
Machine which converts A-C into D.C is known as ..........
a) Convertet
b) Inverter
c) Both (a) & (b)
d) None of these
In a full wave rectifier, ripple frequency is equal to ...............
a) 2 F input
b) 3 F input
c) Both (a) & (b)
d) None of these
Which rnethod is used to make a full wave rectifier?
a) Bridge method
b) Center tap method
c) Both (a) & (b)
d) None ofthese
Rectification is of how many types ..........
a) One b) Two c) Three d) Four
The supply in Growler is ..........
a) DC b) AC
c) Both (a) & (b) d) None of these
The number of coils per group in balanced winding is.........
a) Same b) Un equal
c) Both (a) & (b) d) None or these
The mostly used winding for rewinding is ..........
a) Basket winding
b) Chain winding
c) Concentric winding
d) None of these
For earth with testing volt meter when connected to commutator segment and body of an amature, the growler is connected to A.C. supply. The milli voltmeter should read
a) No reading
b) Low reading
c) Infinity
d) More reading
The number of slots with respect of number of coils in double layer winding is .........
a) Same
b) Less
c) More than one
d) Half
Pitch factor in full pitch winding is ............
a) One
b) Less than one
c) More than one
d) None of these
The numbers of windings in double cage induction motors
a) One b) Two c) Three d) Four
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