ITI Electrician Mock Test - Semester 3

Module 3 – AC. Three Phase Motor
Module 4 – AC Single Phase Motor
Module 5 – Alternator
Module 6 – Synchronous Motor and MG Set

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Created on August 14, 2022
Electrician

ITI Electrician Mock Test - Semester 3

Semester : 3
Module 3 - AC. Three Phase Motor
Module 4 - AC Single Phase Motor
Module 5 - Alternator
Module 6 - Synchronous Motor and MG Set

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Category: Electrician Sem 3 Module 4

How the direction of rotation of a capacitor start induction run motor is reversed?

A) By changing the supply terminals

B) By changing the capacitor connections

C) By interchanging main winding terminals

D) By interchanging both main and auxiliary winding terminals

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Category: Electrician Sem 3 Module 3

What is the phase displacement between windings in 3 phase motor?

A) 90°

B) 120°

C) 180°

D) 360°

3 / 171

Category: Electrician Sem 3 Module 6

What is the name of the converter?

A) Metal rectifier

B) Rotary converter

C) Mercury arc rectifier

D) Silicon controlled rectifier

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Category: Electrician Sem 3 Module 3

Which type of motor is used to provide high starting torque at variable speed?

A) Universal motor

B) Permanent capacitor motor

C) 3 Phase slip ring induction motor

D) 3 Phase single squirrel cage induction motor

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Category: Electrician Sem 3 Module 5

How alternators are rated?

A) KVA

B) KW

C) MW

D) KV

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Category: Electrician Sem 3 Module 5

What is the effect in increasing the field excitation current in alternator?

A) Prevents demagnetizing

B) Over voltage protection

C) Dead short circuit protection

D) Alternator will be over loaded

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Category: Electrician Sem 3 Module 4

Where the capacitor is connected in a single phase permanent capacitor motor?

A) In series with starting winding

B) In series with running winding

C) In parallel with starting winding

D) In parallel with running winding

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Category: Electrician Sem 3 Module 3

Which method is used to control the speed of 3 phase induction motor from stator side?

A) By cascade operation

B) By rotor rheostat control

C) By injecting emf in rotor circuit

D) By changing the applied frequency

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Category: Electrician Sem 3 Module 6

Why the synchronous motor fails to run at synchronous speed?

A) Short in damper winding

B) Insufficient excitation

C) Defective pony motor

D) Open in damper winding

10 / 171

Category: Electrician Sem 3 Module 6

Which converter is having high efficiency?

A) SCR converter

B) Rotary converter

C) Motor generator set

D) Mercury arc rectifier

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Category: Electrician Sem 3 Module 4

Which method is adopted to start the single phase induction motor?

A) Split phase method

B) Varying supply voltage method

C) Reversal of input supply terminals

D) Reversal of running coil connection

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Category: Electrician Sem 3 Module 3

What is the speed control method of 3 phase induction motor?

A) Cascade operation method

B) Rotor rheostat control method

C) Changing applied voltage method

D) Injecting emf in rotor circuit method

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Category: Electrician Sem 3 Module 3

What is the effect of open circuit in rotor of an induction motor?

A) Motor does not start

B) Over heating in motor

C) Excess vibration of shaft

D) Motor runs with very low speed

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Category: Electrician Sem 3 Module 5

What is the speed of an alternator connected with a supply frequency of 50 Hz at rated voltage having 4 poles?

A) 1000 rpm

B) 1500 rpm

C) 3000 rpm

D) 4500 rpm

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Category: Electrician Sem 3 Module 5

What is the use of synchroscope?

A) Adjust the output voltage

B) Adjust the phase sequence

C) Adjust the supply frequency

D) Indicate the correct instant for paralleling

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Category: Electrician Sem 3 Module 3

What is the type of rewinding process?

A) Hand winding

B) Skein winding

C) Former winding

D) Machine winding

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Category: Electrician Sem 3 Module 3

What is the electrical degree of 6 pole stator of motor?

A) 360°

B) 720°

C) 1080°

D) 1440°

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Category: Electrician Sem 3 Module 4

Which type of winding wire is used for rewinding submersible pumps?

A) PVC covered copper wire

B) Super enamelled copper wire

C) Single cotton covered copper wire

D) Double cotton covered copper wire

19 / 171

Category: Electrician Sem 3 Module 6

Why D.C supply is necessary for
synchronous motor operation?

A) Reduce the losses

B) Start the motor initially

C) Run the motor with over load

D) Run the motor at synchronous speed

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Category: Electrician Sem 3 Module 4

Which type of A.C single phase motor is classified under commutator motor type?

A) Stepper motor

B) Repulsion motor

C) Shaded pole motor

D) Permanent capacitor motor

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Category: Electrician Sem 3 Module 3

What is the formula to find synchronous speed of a A.C 3 phase induction motor?

A) Synchronous speed = 120F/P

B) Synchronous speed = 120P/F

C) Synchronous speed = 120/PF

D) Synchronous speed = PF/120

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Category: Electrician Sem 3 Module 3

Calculate the number of coils per phase per pair of poles of 3 phase motor having 2 pole, 24 slots,12 coils?

A) 1

B) 2

C) 3

D) 4

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Category: Electrician Sem 3 Module 4

Which type of AC single phase motor having low starting torque?

A) Induction start induction run motor

B) Capacitor start induction run motor

C) Capacitor start capacitor run motor

D) Resistance start induction run motor

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Category: Electrician Sem 3 Module 4

What is the effect, if some slots in a split phase motor left out without winding after completion of concentric winding?

A) Works normally

B) Reduction in speed

C) Reduction in torque

D) Runs with very high speed

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Category: Electrician Sem 3 Module 3

What is the name of the starter symbol?

A) D.O.L starter

B) Auto transformer starter

C) Automatic star/delta starter

D) Semi automatic star/delta starter

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Category: Electrician Sem 3 Module 3

What is the name of the part marked as ‘X’?

A) Shaft

B) Brushes

C) Bearings

D) Slip rings

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Category: Electrician Sem 3 Module 3

Where the panel boards are used?

A) Industrial motor drives

B) Domestic wiring circuits

C) 3 phase domestic wiring

D) Load distribution for AC & DC supply

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Category: Electrician Sem 3 Module 5

What causes the terminal voltage of an alternator reduces, if the load increases?

A) Field resistance

B) Armature reaction

C) Inductive reactance

D) Armature resistance

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Category: Electrician Sem 3 Module 4

What is the working principle of split phase motor?

A) Lenz’s law

B) Joule’s law

C) Faraday’s laws of electrolysis

D) Faraday’s laws of electromagnetic induction

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Category: Electrician Sem 3 Module 5

Which formula is used to calculate the percentage voltage regulation in alternator?

A) .

B) .

C) .

D) .

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Category: Electrician Sem 3 Module 4

Which motor is having half coil winding?

A) Mixer

B) Grinder

C) Ceiling fan

D) Washing machine

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Category: Electrician Sem 3 Module 6

Which is the main application of synchronous motor?

A) Elevators

B) Paper rolling mills

C) AC to DC converter

D) Power factor correction device

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Category: Electrician Sem 3 Module 4

What is the relation between running winding and starting winding of a single phase induction motor with respect to resistance?

A) Both resistances will be equal

B) Running winding is less, starting winding more

C) Running winding is more, starting winding less

D) Running winding is less, starting winding infinity

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Category: Electrician Sem 3 Module 3

What is the rotor frequency of a 3 phase squirrel cage induction motor at the time of starting?

A) Equal to supply frequency

B) 3 times less than supply frequency

C) 3 times more than supply frequency

D) √3 times less than supply frequency

35 / 171

Category: Electrician Sem 3 Module 3

Calculate the number of coils /phase/ pole for a 3 phase double layer distributed winding for a motor having 36 slots, 36 coils and 4 poles.

A) 3 coils /phase/ pole

B) 6 coils / phase/pole

C) 9 coils / phase/pole

D) 12 coils/ phase/ pole

36 / 171

Category: Electrician Sem 3 Module 4

What is the effect in a repulsion motor, if the magnetic axis shifted to another side?

A) Direction of rotation will change

B) Direction of rotation remains same

C) Motor speed increases from rated speed

D) Motor speed will reduce from rated speed

37 / 171

Category: Electrician Sem 3 Module 4

Which single phase motor is fitted with wound rotor?

A) Repulsion motor

B) Shaded pole motor

C) Permanent capacitor motor

D) Capacitor start capacitor run motor

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Category: Electrician Sem 3 Module 3

Which method is applied to control the speed of 3 phase squirrel cage induction motor from its rotor side?

A) Cascade operation

B) Changing applied voltage

C) Changing applied frequency

D) Changing the number of poles

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Category: Electrician Sem 3 Module 3

What is the relation between torque and slip in an A.C induction motor?

A) Slip increases torque decreases

B) Slip increases torque increases

C) Slip decreases torque increases

D) Slip decreases torque decreases

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Category: Electrician Sem 3 Module 3

What is the effect of motor, if the rotor windings in slipring induction motor is open circuited at starting?

A) Will not run

B) Runs at slow speed

C) Runs at very high speed

D) Runs but not able to pull load

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Category: Electrician Sem 3 Module 3

Which operation the control circuit is used?

A) Remote control

B) Inching

C) Sequential control

D) Forward and reverse

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Category: Electrician Sem 3 Module 3

Which test in winding is illustrated?

A) Polarity test

B) Ground test

C) Continuity test

D) Short circuit test

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Category: Electrician Sem 3 Module 3

Which type of winding has more space for cooling?

A) Between overhanging coils

B) Between overhanging coil and rotor

C) Between overhanging coils and yoke

D) Between overhanging coil and wedge

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Category: Electrician Sem 3 Module 4

What is the function of centrifugal switch used in capacitor start, capacitor run induction motor?

A) Disconnect the running winding after reached 75% to 80% speed

B) Disconnect the starting winding after reached 75% to 80% speed

C) Disconnect the starting capacitor after reached 75% to 80% speed

D) Disconnect the starting and running winding after reached 75% to 80% speed

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Category: Electrician Sem 3 Module 5

What is the supply frequency of an alternator having 6 poles runs at 1000 rpm?

A) 25Hz

B) 40Hz

C) 50Hz

D) 60Hz

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Category: Electrician Sem 3 Module 5

What is the purpose of damper winding in alternator?

A) Reduces the copper loss

B) Reduces windage losses

C) Reduces the hunting effect

D) Improves the voltage regulation

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Category: Electrician Sem 3 Module 3

Which type of AC motor winding having the number of coil/pole/phase is more than one arranged in different slots?

A) Basket winding

B) Concentric winding

C) Distributed winding

D) Concentrated winding

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Category: Electrician Sem 3 Module 3

What is the name of the diagram used for 3phase motor winding?

A) Ring diagram

B) Development diagram

C) Coil connection diagram

D) End connection diagram

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Category: Electrician Sem 3 Module 3

What is effect of A.C induction motor if rotor bar is in open circuit?

A) Vibration of shaft

B) Motor will not start

C) Runs in slow speed

D) Over heating of motor

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Category: Electrician Sem 3 Module 3

Which type of starter is used to start and run the 3 phase slip ring induction motor?

A) Direct on-line starter

B) Rotor rheostat starter

C) Auto transformer starter

D) Manual star-delta starter

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Category: Electrician Sem 3 Module 3

What happens to a 3 phase induction motor if one phase fails during running?

A) Motor runs normally

B) Motor stop instantaneously

C) Motor runs slowly, finally it burns

D) Motor runs with irregular speed

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Category: Electrician Sem 3 Module 3

Which method of speed control is only applicable for 3 phase slipring induction motor?

A) Cascade operation method

B) Rotor rheostat speed control

C) Changing the applied frequency method

D) Changing the number of stator poles method

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Category: Electrician Sem 3 Module 3

What is the formula to calculate the slip speed (Nslip) of 3 phase squirrel cage induction motor?

A) .

B) .

C) .

D) .

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Category: Electrician Sem 3 Module 3

What is the name of the contact marked as ‘X’?

A) Star contact

B) Delta contact

C) Auxiliary contact

D) Over load relay contact

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Category: Electrician Sem 3 Module 5

Calculate the speed in r.p.s of the 2 pole, 50Hz
alternator?

A) 50 rps

B) 100 rps

C) 1500 rps

D) 3000 rps

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Category: Electrician Sem 3 Module 3

Why pre heating is necessary for motors before varnishing in rewinding process?

A) To dry the varnish quickly in winding

B) To easy flow of varnish in the winding

C) To increase the insulation resistance value

D) To drive out the moisture in between winding layers

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Category: Electrician Sem 3 Module 3

What is the reason for frequent blowing of fuse after motor running some time?

A) Improper earthing

B) Over loading of motor

C) Heavy voltage fluctuation

D) Poor insulation in winding

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Category: Electrician Sem 3 Module 5

Which formula is used to calculate EMF/phase in a ideal alternator?

A) .

B) .

C) .

D) .

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Category: Electrician Sem 3 Module 6

Which acts as both inverter and converter?

A) Metal rectifier

B) Mercury arc rectifier

C) Semi conductor diode

D) Synchronous converter

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Category: Electrician Sem 3 Module 3

Which type of insulating material is selected for binding the coils and over hangs?

A) Cotton sleeves

B) Empire sleeves

C) Terylene thread

D) Fibre glass tape

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Category: Electrician Sem 3 Module 4

Which single phase motor tapped field speed control method is employed?

A) Universal motor

B) Shaded pole motor

C) Capacitor start induction run motor

D) Capacitor start capacitor run motor

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Category: Electrician Sem 3 Module 3

What happens to the rotor of a 3 phase induction motor if its speed attains to synchronous speed?

A) Rotor speed reduces

B) Rotor speed increases

C) Rotor speed remains same

D) Rotor bars get damaged

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Category: Electrician Sem 3 Module 3

Which is the cause for the 3 phase motor starter with single phase preventer trips frequently?

A) Incorrect fuse ratings

B) Unbalanced line voltage

C) Incorrect settings of OLR

D) Improper phase sequence

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Category: Electrician Sem 3 Module 3

Calculate the phase displacement in terms of slots for a 3 phase, 36 slots, 12 coils, 4 pole stator winding?

A) 3 slots

B) 4 slots

C) 6 slots

D) 8 slots

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Category: Electrician Sem 3 Module 4

What is the angular displacement between starting and running winding of a single phase induction motor?

A) 45 electrical degree

B) 60 electrical degree

C) 90 electrical degree

D) 120 electrical degree

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Category: Electrician Sem 3 Module 4

Why running winding is placed in the bottom of the core?

A) To get low resistance

B) To get low inductance

C) To get high resistance

D) To get high inductance

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Category: Electrician Sem 3 Module 4

Which type of single phase motor is illustrated?

A) Universal motor

B) Permanent capacitor motor

C) Capacitor start induction run motor

D) Capacitor start capacitor run motor

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Category: Electrician Sem 3 Module 4

Which is the application of universal motor?

A) Jet pump

B) Food mixer

C) Teleprinter

D) Compressor

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Category: Electrician Sem 3 Module 4

Calculate the slot distance for a ceiling fan having 28 slots, 14 poles, 14 coils in half coil connection?

A) 90°

B) 120°

C) 180°

D) 240°

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Category: Electrician Sem 3 Module 3

Which type of handle design of rotary switch is illustrated?

A) Knob

B) Lever

C) Coin slot

D) Key operation

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Category: Electrician Sem 3 Module 3

What are the two functional circuits incorporated with a three phase motor starter?

A) Open circuit and short circuit

B) Closed circuit and open circuit

C) Short circuit and closed circuit

D) Control circuit and power circuit

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Category: Electrician Sem 3 Module 6

Which converting device can be over
loaded?

A) Rectifier unit

B) Rotary converter

C) Motor generator set

D) Mercury arc rectifier

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Category: Electrician Sem 3 Module 4

What is the function of centrifugal switch in split phase motor?

A) Protects from over current

B) Maintains constant speed

C) Protect the motor from over loading

D) Make and break the starting winding from supply

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Category: Electrician Sem 3 Module 3

Which instrument is used to measure insulation resistance of a 3 phase induction motor?

A) Megger

B) Multimeter

C) Shunt type ohmmeter

D) Series type ohmmeter

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Category: Electrician Sem 3 Module 3

What is the purpose of using thermal cutout in addition to fuse in A.C motor circuit?

A) Protect from heavy load

B) Protect against high voltage

C) Allow for continuous over loading

D) Protect against dead short circuit

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Category: Electrician Sem 3 Module 5

Calculate the pitch factor (KP) for a winding having 36 stator slots 4 pole with angle (α) is 30° in alternator.

A) 0.942

B) 0.965

C) 0.978

D) 0.985

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Category: Electrician Sem 3 Module 3

Which loss of 3 phase induction motor is determined by blocked rotor test?

A) Copper loss

B) Friction loss

C) Hysteresis loss

D) Eddy current loss

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Category: Electrician Sem 3 Module 3

What is the function of collar?

A) Provides insulation around field

B) Provides insulation for coil tapping

C) Helps tightening material for flange

D) Provides insulation for heat transfer from coil

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Category: Electrician Sem 3 Module 4

How the direction of rotation of repulsion motors is to be reversed?

A) By shifting the brush axis

B) By interchanging the supply terminals

C) By changing the main winding terminals

D) By changing the compensating winding terminals

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Category: Electrician Sem 3 Module 5

What is the purpose of using damper winding in AC generator?

A) Prevents heating

B) Reduces copper loss

C) Reduces windage loss

D) Prevents the hunting effect

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Category: Electrician Sem 3 Module 3

What is the name of the A.C motor starter?

A) DOL starter

B) Auto transformer starter

C) Semi automatic star delta starter

D) Fully automatic star delta starter

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Category: Electrician Sem 3 Module 3

What is the name of the starter symbol?

A) Star delta starter

B) Rheostatic starter

C) Direct on-line starter

D) Autotransformer starter

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Category: Electrician Sem 3 Module 4

Why a capacitor is connected across centrifugal switch in the centrifugal switch speed control method?

A) To maintain constant speed

B) To protect from over loading

C) To improve the power factor

D) To reduce the spark in contacts

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Category: Electrician Sem 3 Module 6

What is the advantage of motor generator set?

A) Noiseless

B) High efficiency

C) Low maintenance required

D) DC output voltage can be easily controlled

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Category: Electrician Sem 3 Module 6

What is the function of inverter?

A) Convert A.C to D.C

B) Convert D.C to A.C

C) Smoothening A.C sine wave

D) Convert pulsating DC into pure D.C

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Category: Electrician Sem 3 Module 3

Which device is used to test stator winding short and open fault?

A) Tong Tester

B) Internal Growler

C) External Growler

D) Digital multimeter

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Category: Electrician Sem 3 Module 3

Why external resistance is included in the rotor circuit at starting through 3 phase slipring induction motor starter?

A) To get high running torque

B) To get high starting torque

C) To reduce the load current

D) To get increased speed at starting

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Category: Electrician Sem 3 Module 5

What is the formula to calculate emf equation of an alternator?

A) E = 4.44 Kd Kc T ɸm

B) E = 2.22 Kd Kc Fɸm

C) E = 4.44 Kd Kc FT ɸm

D) E = 1.11 Kd Kc F ɸm

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Category: Electrician Sem 3 Module 3

What is the synchronous speed of a A.C 3 phase induction motor having 6 poles at a frequency of 50 Hertz?

A) 800 rpm

B) 1000 rpm

C) 1200 rpm

D) 1440 rpm

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Category: Electrician Sem 3 Module 3

Which is the main property of leatheroid paper insulation?

A) Non moisturized material

B) Highly non-hygroscopic

C) Very good for class F insulation

D) Better ageing and dielectric strength

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Category: Electrician Sem 3 Module 3

Which formula is used to calculate the total electrical degree in stator of an A.C motor?

A) Total electrical degree = 180° / No. of slots

B) Total electrical degree = 180° x No. of slots

C) Total electrical degree = 180° / No. of poles

D) Total electrical degree = 180° x No. of poles

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Category: Electrician Sem 3 Module 3

Which fault condition thermal overload relay protects A.C induction motor?

A) Short circuit

B) Open circuit

C) Over current

D) Under voltage

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Category: Electrician Sem 3 Module 6

What is the function of damper windings in synchronous motor?

A) Maintain power factor

B) Excite the field winding

C) Maintain constant speed

D) Start the synchronous motor

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Category: Electrician Sem 3 Module 5

Calculate the speed of an alternator having 2 poles at a frequency of 50 Hz.

A) 1500 rpm

B) 2500 rpm

C) 3000 rpm

D) 6000 rpm

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Category: Electrician Sem 3 Module 3

What is the name of the winding?

A) Skew winding

B) Skein winding

C) Involute coil winding

D) Diamond coil winding

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Category: Electrician Sem 3 Module 5

What is the type of alternator?

A) Brushless alternator

B) Three phase alternator

C) Single phase alternator

D) Salient pole type alternator

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Category: Electrician Sem 3 Module 6

What is the purpose of damper winding in a synchronous motor at starting?

A) Produce high voltage to initiate the rotation

B) Produce high current to start rotate the motor

C) Produces torque and runs near in synchronous speed

D) Produce a high magnetic-field to maintain a constant speed

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Category: Electrician Sem 3 Module 4

What is the effect, if coil group connection is wrongly connected in a single phase motor rewinding?

A) Motor runs slowly

B) Motor will not run

C) Motor runs in very high speed

D) Motor runs and takes more current at no load

99 / 171

Category: Electrician Sem 3 Module 6

What is the name of the converter?

A) Metal rectifier

B) Rotary converter

C) Mercury arc rectifier

D) Motor-Generator set

100 / 171

Category: Electrician Sem 3 Module 4

What is the function of centrifugal switch in single phase motors?

A) Maintain constant speed

B) Break the starting winding

C) Break the running winding

D) Protect the motor from over loading

101 / 171

Category: Electrician Sem 3 Module 3

Determine the torque in newton metres produced by a 7.5 HP squirrel cage motor rotating at 1440 rpm?

A) 21.63 Nm

B) 24.4 Nm

C) 33.05 Nm

D) 36.6 Nm

102 / 171

Category: Electrician Sem 3 Module 3

Which speed is called as synchronous speed in 3 phase induction motor?

A) No load speed

B) Full load speed

C) Rotating magnetic field speed

D) Relative speed between stator and rotor

103 / 171

Category: Electrician Sem 3 Module 3

Which type of testing of winding is illustrated?

A) Polarity test

B) Resistance test

C) Short circuit test

D) Voltage drop test

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Category: Electrician Sem 3 Module 3

What is the defect, if starter with single phasing preventer does not switch ‘ON’?

A) Improper phase sequence

B) Fluctuations in line voltage

C) Loose contact in supply lines

D) Wrong terminal connections at motor

105 / 171

Category: Electrician Sem 3 Module 6

Which application requires only DC?

A) Electroplating

B) Stepping up of voltage

C) Operating induction motor

D) Operating repulsion motor

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Category: Electrician Sem 3 Module 5

What is the name of the equipment that provides D.C to the rotor of alternator?

A) Exciter

B) Inverter

C) Converter

D) Synchroniser

107 / 171

Category: Electrician Sem 3 Module 3

Which type of winding wire is used to wind submersible pump motors?

A) PVC covered type

B) Terylene thread type

C) Super enamelled type

D) Double cotton covered type

108 / 171

Category: Electrician Sem 3 Module 4

What is the purpose of the capacitor (C) in centrifugal switch speed control method of universal motor?

A) Maintain constant speed

B) Improve the power factor

C) Protect from the over loading

D) Reduce the sparks on the contacts

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Category: Electrician Sem 3 Module 6

How synchronous motor works as a power factor corrector?

A) Varying the line voltage

B) Varying the field excitation

C) Increasing the speed of motor

D) Decreasing the speed of motor

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Category: Electrician Sem 3 Module 4

Why the hysteresis motor is suitable for sound recording instruments?

A) Small in size

B) High efficiency

C) Noiseless operation

D) Less error operation

111 / 171

Category: Electrician Sem 3 Module 5

What condition the two lamps become bright and one lamp dark during paralleling of two alternators?

A) Terminal voltages are equal

B) Voltages and frequencies are equal

C) Voltages and phase sequence are equal

D) Both the alternators receive same frequency

112 / 171

Category: Electrician Sem 3 Module 4

What is the type of A.C single phase motor?

A) Permanent capacitor motor

B) Capacitor start capacitor run motor

C) Induction start induction run motor

D) Capacitor start induction run motor

113 / 171

Category: Electrician Sem 3 Module 3

What is the formula to calculate pitch factor?

A) Pitch Factor = Pole pitch / Winding pitch

B) Pitch Factor =Winding pitch / Pole pitch

C) Pitch Factor =Number of slots / Number of poles

D) Pitch Factor = Number of Poles / Number of Slots

114 / 171

Category: Electrician Sem 3 Module 3

What is the type of control circuit?

A) Inching control

B) ON remote control

C) OFF remote control

D) Forward & reverse control

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Category: Electrician Sem 3 Module 5

What condition the lamps become dark in dark lamp method of parallel operation of two alternators?

A) Terminal voltages are equal

B) Voltage and frequency are equal

C) Voltage and power rating are equal

D) Frequency are same in both alternator

116 / 171

Category: Electrician Sem 3 Module 4

What is the function of the part marked as ‘x’ in shaded pole motor?

A) Strengthen the magnetic field

B) Increase the efficiency

C) Maintain constant speed

D) Initiate the rotor movement

117 / 171

Category: Electrician Sem 3 Module 4

What is the application of shaded pole motor?

A) Hair dryer

B) Ceiling fan

C) Wet grinder

D) Washing machine

118 / 171

Category: Electrician Sem 3 Module 3

What is the starting current of an A.C 3 phase induction motor?

A) 1 to 2 times of full load current

B) 2 to 3 times of full load current

C) 4 to 5 times of full load current

D) 5 to 6 times of full load current

119 / 171

Category: Electrician Sem 3 Module 3

What happens to a 3 phase induction motor, if one phase fails during starting?

A) Motor runs and stop immediately

B) Motor runs in slow speed continuously

C) Motor runs and draws more current

D) Motor continues to run with irregular speed

120 / 171

Category: Electrician Sem 3 Module 4

How the radio interference can be suppressed in centrifugal switch method of speed control of universal motor?

A) By connecting capacitor across centrifugal switch

B) By connecting capacitor in series with centrifugal switch

C) By adding compensating winding with armature

D) By connecting an inductor in series with centrifugal switch

121 / 171

Category: Electrician Sem 3 Module 3

Which type of AC winding the number of coil/pole/phase is more than one at different pitches?

A) Involute coil winding

B) Diamond coil winding

C) Flat loop over lapped winding

D) Flat loop non-over lapped winding

122 / 171

Category: Electrician Sem 3 Module 3

What is the reason of long chord winding is avoided in AC motors?

A) Low efficiency

B) Low starting torque

C) More winding wire required

D) Less heat dissipation

123 / 171

Category: Electrician Sem 3 Module 3

How pole pitch is measured in terms of slots in AC winding?

A) Total electrical degree / Number of slots

B) Number of slots / Total electrical degree

C) No. of slots in the stator / No. of poles

D) No. of poles / No. of slots in the stator

124 / 171

Category: Electrician Sem 3 Module 6

How the synchronous motor is used as a synchronous condenser?

A) Varying the motor load

B) Varying the rotor excitation

C) Varying stator voltage in motor

D) Varying stator current in motor

125 / 171

Category: Electrician Sem 3 Module 3

Which test in winding is essential before giving supply?

A) Ground test

B) Polarity test

C) Open circuit test

D) Short circuit test

126 / 171

Category: Electrician Sem 3 Module 3

What is the purpose of using rotor resistance starter to start 3 phase slip ring induction motor?

A) Reduce rotor voltage

B) Reduce rotor current

C) Increase the torque

D) Reduce the power loss

127 / 171

Category: Electrician Sem 3 Module 4

What is the reason to use a permanent capacitor in fan motor circuit?

A) Speed regulation

B) Lower power consumption

C) Splitting of phase for torque

D) Controlling electrical interference

128 / 171

Category: Electrician Sem 3 Module 3

Which loss is determined by no load test of 3 phase induction motor?

A) Iron loss

B) Copper loss

C) Friction loss

D) Windage loss

129 / 171

Category: Electrician Sem 3 Module 3

What is the function of timer in automatic star delta starter?

A) Trip at over load

B) Switch ON at pre set time

C) Change from star to delta

D) Switch OFF at pre set time

130 / 171

Category: Electrician Sem 3 Module 4

What is the effect if the centrifugal switch is not disconnected after the motor starts?

A) Motor will run normally

B) Motor will stop immediately

C) Starting winding will burn out

D) Motor will run very slow speed

131 / 171

Category: Electrician Sem 3 Module 3

What is the name of AC coil winding?

A) Half coil winding

B) Whole coil winding

C) Single layer winding

D) Double layer winding

132 / 171

Category: Electrician Sem 3 Module 5

What is the name of the part of alternator?

A) Stator

B) Exciter

C) Salient pole rotor

D) Smooth cylindrical rotor

133 / 171

Category: Electrician Sem 3 Module 4

Which type of single phase motor is used for hard disk drives?

A) Stepper motor

B) Repulsion motor

C) Hysteresis motor

D) Reluctance motor

134 / 171

Category: Electrician Sem 3 Module 4

How to produce starting torque in a shaded pole fan motor?

A) Using rings on poles

B) Using capacitor on winding circuits

C) Interchanging cage rotor windings by switch

D) Interchanging the field coil windings by switch

135 / 171

Category: Electrician Sem 3 Module 3

What is the formula to calculate the mean circumference of the coil?

A) .

B) .

C) .

D) .

136 / 171

Category: Electrician Sem 3 Module 5

How to compensate de-magnetizing effect due to armature reaction in an alternator?

A) Reducing the speed of alternator

B) Reducing field excitation current

C) Increasing field excitation current

D) Increasing the speed of alternator

137 / 171

Category: Electrician Sem 3 Module 3

What is the defect in AC 3 phase induction motor runs at low speed if loaded?

A) Wrong motor connection

B) Wrong starter connection

C) Open circuit in rotor winding

D) Partially shorted stator winding

138 / 171

Category: Electrician Sem 3 Module 5

What is the cause for hunting effect in alternators?

A) Due to over load

B) Running without load

C) Running with fluctuation of speed

D) Due to continuous fluctuation in load

139 / 171

Category: Electrician Sem 3 Module 3

Which insulation is used for cuffing in AC winding?

A) Fibre glass tape

B) Leatheroid paper

C) Empire fiber glass tape

D) Fabric based adhesive tape

140 / 171

Category: Electrician Sem 3 Module 6

Why exciter is essential to run a synchronous motor?

A) Carry more load in motor

B) Improve the power factor

C) Reduce the losses in motor

D) Run the motor at synchronous speed

141 / 171

Category: Electrician Sem 3 Module 4

Which motor is used in table fan?

A) Universal motor

B) Shaded pole motor

C) Eddy current motor

D) Permanent capacitor motor

142 / 171

Category: Electrician Sem 3 Module 3

Which is the demerit of 3 phase concentric winding?

A) More space is required

B) A stepped former is required

C) More difficult to shape the coils uniformly

D) It is not easy to make the end connection

143 / 171

Category: Electrician Sem 3 Module 3

What is the fuse rate to run a 10 HP three phase induction motor at full load?

A) 10A

B) 15 A

C) 25 A

D) 30 A

144 / 171

Category: Electrician Sem 3 Module 3

What is the name of 3 phase motor winding, if the coil pitch is less than pole pitch?

A) Full pitch winding

B) Whole coil winding

C) Long chorded winding

D) Short chorded winding

145 / 171

Category: Electrician Sem 3 Module 3

Which formula is used to calculate percentage slip of an AC 3 phase induction motor

A) .

B) .

C) .

D) .

146 / 171

Category: Electrician Sem 3 Module 3

How the voltage is received in the rotor of induction motor?

A) Direct connection from stator

B) Due to back emf produced in stator

C) Direct connection to rotor from supply

D) By the transformer action of stator and rotor

147 / 171

Category: Electrician Sem 3 Module 3

What refers coil in AC winding?

A) Number of turns connected in series

B) Number of turns connected in parallel

C) Number of turns under two similar poles

D) Number of turns under two dissimilar poles

148 / 171

Category: Electrician Sem 3 Module 3

Why the rotor bars are mounted in a slightly skewed position in 3 phase motor?

A) Generate maximum flux

B) Reduce the stray losses

C) Maintain the rotor speed constant

D) Produce more uniform rotor field and torque

149 / 171

Category: Electrician Sem 3 Module 3

What is the name of the coil winding?

A) Concentric coil winding

B) Distributed coil winding

C) Mesh shaped coil winding

D) Diamond mesh shaped coil winding

150 / 171

Category: Electrician Sem 3 Module 3

Which material is used as wedges in winding process?

A) Terylene

B) Empire

C) Cotton

D) Bamboo

151 / 171

Category: Electrician Sem 3 Module 4

Which type of single phase induction motor is used in food mixer?

A) Universal motor

B) Repulsion motor

C) Shaded pole motor

D) Permanent capacitor motor

152 / 171

Category: Electrician Sem 3 Module 5

What is the advantage of using rotating field type alternator?

A) Easy to locate the faults in the field

B) Easy to connect the load with alternator

C) Easy to dissipate the heat during running

D) Two slip rings only required irrespective of No. of phases

153 / 171

Category: Electrician Sem 3 Module 5

Calculate the voltage regulation in percentage if the load is removed from an alternator, the voltage rises from 480V to 660V.

A) 27.20%

B) 32.50%

C) 37.50%

D) 38.50%

154 / 171

Category: Electrician Sem 3 Module 4

Which type of single phase motor is having very high starting torque than any other type of single phase motor?

A) Universal motor

B) Reluctance motor

C) Repulsion start induction run motor

D) Capacitor start induction run motor

155 / 171

Category: Electrician Sem 3 Module 3

Name the part marked as ‘X’ of the winding machine?

A) Mandrel

B) Wire feed

C) Wire guides

D) Spool carrier

156 / 171

Category: Electrician Sem 3 Module 3

Why slip ring induction motor is fitted with wound rotor?

A) To reduce the slip

B) To control the speed

C) To reduce the losses

D) To get high starting and running torque

157 / 171

Category: Electrician Sem 3 Module 3

5 Calculate the percentage slip in a 3 phase induction motor having 6 poles with a frequency of 50 Hertz rotating with actual speed of 960 rpm?

A) 2%

B) 3%

C) 4%

D) 5%

158 / 171

Category: Electrician Sem 3 Module 3

What is the type of A.C motor stator winding?

A) Single layer basket winding

B) Double layer basket winding

C) Involute coil winding

D) Diamond coil winding

159 / 171

Category: Electrician Sem 3 Module 3

What indication denotes the shorted coil defect in 3 phase motor stator winding while testing with internal growler by keeping hacksaw blade?

A) Hacksaw blade gets over heated

B) Rapid vibration of hacksaw blade

C) Hacksaw blade repels against the slots

D) Attracted by the winding turns on the slot

160 / 171

Category: Electrician Sem 3 Module 5

Which rule is used to find the direction of induced emf in an alternator?

A) Cork screw rule

B) Right hand palm rule

C) Fleming’s left hand rule

D) Fleming’s right hand rule

161 / 171

Category: Electrician Sem 3 Module 4

What is the working principle of single phase induction motor?

A) Lenz’s law

B) Joule’s law

C) Faraday’s laws of electrolysis

D) Faraday’s laws of electromagnetic induction

162 / 171

Category: Electrician Sem 3 Module 3

Which method of speed control two variable speeds only obtained in 3 phase motor?

A) By rotor rheostat control

B) By changing applied frequency

C) By changing the applied voltage

D) By changing the number of stator poles

163 / 171

Category: Electrician Sem 3 Module 5

Which condition is to be satisfied before parallel
operation of alternators?

A) Rating must be same

B) Phase sequence must be same

C) Rotor impedance must be same

D) Stator impedance must be same

164 / 171

Category: Electrician Sem 3 Module 4

Which motor is preferred for domestic water pumps?

A) Universal Motor

B) Repulsion motor

C) Shaded pole motor

D) Capacitor start motor

165 / 171

Category: Electrician Sem 3 Module 4

What is the name of single phase motor?

A) Permanent capacitor motor

B) Induction start capacitor run motor

C) Capacitor start capacitor run motor

D) Capacitor start induction run motor

166 / 171

Category: Electrician Sem 3 Module 3

Which type of test is conducted using internal growler in AC motor winding?

A) Ground test

B) Polarity test

C) Continuity test

D) Short circuit test

167 / 171

Category: Electrician Sem 3 Module 3

What is the effect on 3 phase induction motor if one phase is cut-off during running with load?

A) Motor stops at once

B) Motor will run normally

C) Motor runs with humming noise with slow speed

D) Motor will run slow speed but winding will be burnt out shortly

168 / 171

Category: Electrician Sem 3 Module 6

What is the function of the part marked as ‘X’ of the rotary converter?

A) Converts AC to DC

B) Reduces voltage drop

C) Helps to deliver without noise

D) Collects the delivered direct current

169 / 171

Category: Electrician Sem 3 Module 4

Which type of motor has relatively small starting torque?

A) Universal motor

B) Capacitor start capacitor run motor

C) Capacitor start induction run motor

D) Resistance start induction run motor

170 / 171

Category: Electrician Sem 3 Module 6

Why the LED’s are avoided as converters in rectifier diodes?

A) Heavily doped device

B) Very low power device

C) Designed for light emitting

D) Very sensitive to temperature

171 / 171

Category: Electrician Sem 3 Module 3

Which type of wire is used for rewinding of A.C 3 phase motors?

A) Super enamelled copper wire

B) PVC covered copper winding wire

C) Single cotton covered copper wire

D) Double cotton covered copper wire

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