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
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Mar 20, 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
asked
Mar 20, 2018
by
anonymous
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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
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Mar 20, 2018
by
anonymous

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
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Mar 20, 2018
by
anonymous
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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
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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
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Mar 20, 2018
by
anonymous

Last Answer : Differentially compound D.C. motors can find applications requiring low starting torque.
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125 views
1 answer
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Mar 20, 2018
by
anonymous

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

Describe the reason of using dc series motor for electric trains.
Last Answer : Electric trains require an inverse torque speed characteristics for proper operation. That is a higher torque is required at start (when speed is nil or low) and as the train picks up ... torque - speed characteristics of DC series motors match, these motors are suitable for electric trains
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142 views
1 answer
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Sep 18, 2018
by
anonymous

In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is :
Last Answer : In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is : 0.075
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109 views
1 answer
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Apr 29, 2018
by
anonymous

Last Answer : In a D.C. series motor, if the armature current is reduced by 50%, the torque of the motor will be equal to 25% of the previous value.
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503 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The speed of a D.C. series motor is inversely proportional to the armature current.
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114 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : A D.C. series motor is that which has its field winding consisting of thick wire and less turns.
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82 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The direction of rotation of a D.C. series motor can be changed by interchanging field terminals.
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185 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : A.C. series motor as compared to D.C. series motor has smaller brush width, less number of field turns, more number of armature turns, less air gap.
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136 views
1 answer
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Mar 20, 2018
by
anonymous
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Last Answer : If a D.C. series motor is operated on A.C. supply, it will spark excessively, have poor efficiency, have poor power factor.
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91 views
1 answer
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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
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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
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Last Answer : D.C. shunt motors are used for driving machine tools.
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85 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The D.C. motors preferred for traction applications beacuse the speed is inversely proportional to the torque and the torque is proportional to square of armature current.
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159 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In A.C. series motor compensating winding is employed to reduce sparking at the brushes.
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145 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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381 views
1 answer
asked
May 7, 2020
by
anonymous

Brake test on DC series motor
Last Answer : .embed-container { position: relative; padding-bottom: 56.25%; height: 0; overflow: hidden; max-width: 100%; } .embed-container iframe, .embed-container object, .embed-container embed { position: absolute; top: 0; left: 0; width: 100%; height: 100%; }
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298 views
2 answers
asked
Apr 21, 2020
by
anonymous

We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be
Last Answer : We connected a 35V dc supply to a resistance of 600 Ohm in series with an unknown resistance R.A. voltmeter having a resistance of 1.2 kOhm is connected across 600 Ohm resistance and read 5v. The value of resistance R will be 2.4 kOhm
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149 views
1 answer
asked
May 8, 2018
by
anonymous

A DC voltage source is connected across a series RLC circuit. Under steady-state conditions, the applied DC voltage drops entirely across the
Last Answer : A DC voltage source is connected across a series RLC circuit. Under steady-state conditions, the applied DC voltage drops entirely across the C only
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2.0k views
1 answer
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Apr 29, 2018
by
anonymous

Last Answer : If equalising bar is connected to the 2 DC generators the current will be equal in 2 generators irrespective of parallel connection so that we connect equaliser bar
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165 views
2 answers
asked
Mar 21, 2018
by
anonymous

Last Answer : When a D.C. series motor is connected to A.C. supply, the power factor will be low because of high inductance of field and armature circuits.
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119 views
1 answer
asked
Mar 20, 2018
by
anonymous

What are the advantages of DC series motor?
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92 views
0 answers
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Mar 15, 2018
by
anonymous

Why dc series motor should not be started at no load?
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629 views
0 answers
asked
Mar 15, 2018
by
anonymous

Why a dc series motor has a high starting torque?
Last Answer : motor
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86 views
1 answer
asked
Mar 15, 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
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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
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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

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

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

Last Answer : In case of a 4-pole D.C. generator provided with a two layer lap winding with sixteen coils, the pole pitch will be 8.
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258 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : In a A.C. series motor armature coils are usually connected to commutator through resistance.
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161 views
1 answer
asked
Mar 20, 2018
by
anonymous

A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is
Last Answer : A 200 V dc shunt motor is running at 1000 rpm and drawing a current of 10 A. Its armature winding resistance is 2 Ohm. It. is braked by plugging. The resistance to be connected in series with armature to restrict armature current to 10 A, is 36 Ohm
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331 views
1 answer
asked
May 3, 2018
by
anonymous

A 36 slot, 4 -pole, dc machine has a simplex lap winding with two conductors per slot. The back pitch and front pitch adopted could be respectively
Last Answer : A 36 slot, 4 -pole, dc machine has a simplex lap winding with two conductors per slot. The back pitch and front pitch adopted could be respectively 19,17
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588 views
1 answer
asked
May 3, 2018
by
anonymous

Aluminium is not used as winding wire for the armature of a dc machine because (1) aluminium has low resistivity (2) a large winding space is taken by aluminium conductors and creates ... ) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper
Last Answer : Aluminium is not used as winding wire for the armature of a dc machine because (2) a large winding space is taken by aluminium conductors and creates jointing problems (3) the thermal conductivity of aluminium is low (4) aluminium has low conductivity as compared to copper
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621 views
1 answer
asked
Apr 29, 2018
by
anonymous

Last Answer : In D.C. machines fractional pitch winding is used to reduce the sparking.
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355 views
1 answer
asked
Mar 20, 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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19 views
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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22 views
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
