Which of the following test is usually conducted to determine the efficiency of traction motors ? (A) Field’s test (B) Swinburne’s test (C) Hopkinson’s test (D) Retardation test.
Last Answer : Which of the following test is usually conducted to determine the efficiency of traction motors ? (A) Field’s test (B) Swinburne’s test (C) Hopkinson’s test (D) Retardation test.
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248 views
1 answer
asked
Apr 28, 2018
by
anonymous

Which of the following motors is being extensively used in servo applications ? A. AC motor B. Field controlled dc motor C. Armature controlled dc motor D. None of these
Last Answer : Which of the following motors is being extensively used in servo applications ? A. AC motor B. Field controlled dc motor C. Armature controlled dc motor D. None of these
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203 views
1 answer
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Apr 26, 2018
by
anonymous

Last Answer : During rheostat braking of D.C. series motors motor is run as a generator.
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85 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : D.C. shunt motors are used for driving machine tools.
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85 views
1 answer
asked
Mar 20, 2018
by
anonymous

Why DC motor is used for traction?
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81 views
0 answers
asked
Mar 11, 2018
by
anonymous
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Last Answer : Differentially compound D.C. motors can find applications requiring low starting torque.
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125 views
1 answer
asked
Mar 20, 2018
by
anonymous

Why are DC motors used in trains and not AC motors ?
Last Answer : The reason is torque. torque is inversely proportional to speed..i.e when th knowe train comes to rest position to motion.. initial speed is zero..so it requires high starting torque for ... current will flow through field and armature coils then maximum torque is available at the intial condition.
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161 views
1 answer
asked
Sep 3, 2019
by
anonymous

Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above
Last Answer : Which of the following motors can run on both AC and DC? A) Universal motor B) Dual wattage motor C) Flexible motor D) All the above
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179 views
1 answer
asked
Apr 29, 2018
by
anonymous

In case of conductively compensated D.C. series motors, the compensating winding is provided?
Last Answer : In case of conductively compensated D.C. series motors, the compensating winding is provided in series with armature winding.
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97 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : In case of D.C. shunt motors the speed is dependent on back e.m.f. only because flux is practically constant in D:C. shunt motors.
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250 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : When two D.C. series motors are connected in parallel, the resultant speed is normal speed.
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378 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In D.C. shunt motors as load is reduced the speed will remain almost constant.
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145 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Starters are used with D.C. motors because to restrict armature current as there is no back e.m.f. while starting.
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120 views
1 answer
asked
Mar 20, 2018
by
anonymous

State the modification to be done in dc series motor to work satisfactorily as ac series motor. State applications of ac series motor.
Last Answer : Modifications are necessary in a dc series motor so that it operates satisfactorily on ac supply. The modifications are as follows: 1) AC series motor is built with a few field turns as ... and grinders 5) High speed vacuum cleaners 6) Sewing machines 7) Food processors 8) Drilling machine
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380 views
1 answer
asked
May 7, 2020
by
anonymous

Suggest electric motors for i) traction ii) crane iii) lathe machine iv) domestic fan.
Last Answer : i) Traction :- DC Series motor ii) Crane :- DC Series motor iii) Lathe machine :- 3 phase Induction motor or DC shunt motor iv) Domestic fan :- 1 phase induction motor
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74 views
1 answer
asked
Aug 17, 2019
by
anonymous

The motor used for electric traction is (1) D.C. shunt motor (3) D.C. series motor (2) D.C. compound motor (4) Synchronous motor
Last Answer : The motor used for electric traction is D.C. series motor
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1.0k views
1 answer
asked
May 1, 2018
by
anonymous

In quadrilateral speed-time curve of electric traction system, the accelerations during successive time periods are ______ respectively. (A) positive, negative and negative (B) positive, zero and negative (C) positive, positive and negative (D) positive, negative and zero
Last Answer : In quadrilateral speed-time curve of electric traction system, the accelerations during successive time periods are positive, negative and negative respectively.
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142 views
1 answer
asked
Apr 30, 2018
by
anonymous
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In electric traction for a trapezoidal speed-time curve, the time period is (A) free running speed period = constant speed period (B) free running period = coasting period (C) free running period + coasting period = constant speed period (D) average speed period = scheduled speed period
Last Answer : In electric traction for a trapezoidal speed-time curve, the time period is free running period + coasting period = constant speed period
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328 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : An ideal traction system should have easy speed control, high starting tractive effort, equipment capable of with standing large temporary loads.
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90 views
1 answer
asked
Mar 22, 2018
by
anonymous

Which motor is used in traction system?
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76 views
0 answers
asked
Mar 11, 2018
by
anonymous

What is the traction system?
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105 views
0 answers
asked
Mar 11, 2018
by
anonymous

SYNCHRONOUS MOTORS MCQ
Last Answer : 101. In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage, then (a) the motor is said to be fully loaded (b) the torque ... square of the applied voltage (c) inversely proportional to applied voltage (d) none of the above Ans: a
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3 answers

SINGLE PHASE INDUCTION MOTORS MCQ
Last Answer : 101. After the starting winding of a single phase induction motor is disconnected from supply, it continues to run only on (a) running winding (b) rotor winding (c) field winding (d) compensating winding Ans: a ... motor is usually reduced by using (a) gearing (b) belts (c) brakes (d) chains Ans: a
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3 answers

THREE PHASE INDUCTION MOTORS MCQ
Last Answer : 101. Insertion of resistance in the stator of an induction motor (a) increases the load torque (b) decreases the starting torque (c) increases the starting torque (d) none of the above Ans: b
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323 views
3 answers

State which electric motors are generally used in electro agro systems with reason.
Last Answer : 1) 3 phase induction motor is used in electro agro system for water pumping from wells as 3 phase ac supply is easily available, cost of induction motor is less, maintenance free being rugged ... as 1 phase ac supply is easily available for domestic purpose, repair is simple and easily available.
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94 views
1 answer
asked
Aug 17, 2019
by
anonymous

State factors for selection of motors as drive.
Last Answer : Following Factors governing / or are considered while selecting electric drive (Motor) for particular application: Factors to be considered for selection of Electrical Drives: 1) Nature of Supply:- ... level, load equalization 7) Cost: - Capital, Running and maintenance cost should be less.
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1.9k views
2 answers
asked
Aug 17, 2019
by
anonymous

Compare variable reluctance and permanent magnet motors.
Last Answer : Variable reluctance Motor Permanent magnet motors The rotor is not magnetised The rotor is magnetised High torque to inertia ratio Low torque to inertia ratio ... rotor has salient pole construction The rotor has mostly smooth cylindrical type of construction.
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2.5k views
1 answer
asked
Jul 30, 2019
by
anonymous

What are the factors to be considered while selection of motors for different drives?
Last Answer : Following Factors are considered while selecting electric drive (Motor) for particular application: Factors to be considered for selection of Electrical Drives: 1) Nature of Supply:- Whether supply ... , load equalization 7) Cost: - Capital, Running and maintenance cost should be less.
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140 views
1 answer
asked
Jul 30, 2019
by
anonymous

3 phase motor 42 hp same ratting two motors but pole change 2 and 4 pole tell me difference amp of both motors
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2.6k views
0 answers
asked
Jul 24, 2019
by
ZAHID

A relay used for protection of motors against overload is : (A) Impedance relay (B) Electromagnetic attraction type (C) Thermal relay (D) Buchholz's relay
Last Answer : D
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547 views
2 answers
asked
May 8, 2018
by
anonymous
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Damper winding is provided in 3 phase synchronous motors to :
Last Answer : Damper winding is provided in 3 phase synchronous motors to : provide starting torque and prevent hunting
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93 views
1 answer
asked
Apr 29, 2018
by
anonymous

Stepper motors are used in (1) printers (2) lifts (3) amplifiers (4) oscillators
Last Answer : Stepper motors are used in printers
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68 views
1 answer
asked
Apr 29, 2018
by
anonymous

Slot harmonics are reduced in induction motors by using (A) fractional-pitch windings (B) fractional-slot windings (C) integral-slot windings (D) distributed windings
Last Answer : Slot harmonics are reduced in induction motors by using fractional-slot windings
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79 views
1 answer
asked
Apr 28, 2018
by
anonymous

Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as (A) One-third of their synchronous speed (B) One-fifth of their synchronous speed (C) One-seventh of their synchronous speed (D) One-ninth of their synchronous speed
Last Answer : Generally, Crawling in squirrel cage induction motors is tendency to run stably at speeds as low as One-seventh of their synchronous speed
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102 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : A direct online starter is used for starting motors up to 5 H.P.
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83 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The capacitors used in single-phase capacitor motors have no polarity marking.
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133 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Most of the fractional horsepower motors have either plain or sleeve bearings.
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92 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : As hysteresis motors are free from mechanical and magnetic vibrations therefore these are considered as suitable for sound equipment.
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115 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The range of efficiency for shaded pole motors is 5% to 35%.
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120 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a capacitor start and run motors the function of the running capacitor in series with the auxiliary winding is to improve power factor.
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710 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In capacitor start single-phase motors current in the starting winding leads the voltage.
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101 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The standard full-load power factor ratings for synchronous motors are unity or 0.8 leading.
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98 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Synchronous motors are generally not self-starting because the direction of instantaneous torque reverses after half cycle.
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93 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : For power factor correction, synchronous motors operate at no-load and greatly over-excited fields.
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110 views
1 answer
asked
Mar 20, 2018
by
anonymous

The efficiencies of transformers compared with that of electric motors of the same power are?
Last Answer : Transformers have high efficiency than the same ratted motors
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179 views
2 answers
asked
Mar 19, 2018
by
anonymous

What are the five types of single phase motors used in the industry?
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79 views
0 answers
asked
Mar 15, 2018
by
anonymous

What is the difference between synchronous and asynchronous motors?
Last Answer : The motor which rotates at constant speed is called synchronous motor. And that constant speed is called as synchronous speed. And the motor which does not rotates at constant speed are called asynchronous motor. Asynchronous motor is also called as Induction motor.
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143 views
1 answer
asked
Mar 15, 2018
by
anonymous

Do AC induction motors have back EMF?
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71 views
0 answers
asked
Mar 15, 2018
by
anonymous

The widely used series-parallel system of speed control of d.c. series motors in traction work gives a speed range of about (a) 1 : 2 (b) 1 : 3 (c) 1 : 4 (d) 1 : 6
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0 answers
asked
May 25, 2018
by
anonymous

Mini Lathe Applications
Last Answer : Don't Go Cutting Lathes more than just come in different shapes and sizes; they come with various features and functions too. Take the case of the woodworking lathe. As its name suggests, ... standard lathe, but mini lathes more than make up for it with their size, convenience and portability.
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1 answer
