Last Answer : The direction of rotation of universal motor can be reversed the by reversing the flow of current through either armature winding or field winding.
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249 views
1 answer
asked
Mar 20, 2018
by
anonymous

The direction of rotation of an inverter fed 3-phase ac motor is reversed by (A) a mechanical reversing switch (B) reversing the input dc link voltage (C) operating the inverter as a rectifier (D) changing the sequence of switching
Last Answer : The direction of rotation of an inverter fed 3-phase ac motor is reversed by changing the sequence of switching
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153 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : In case of a shaded pole motor the direction of rotation of the motor is from main pole to shaded pole.
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338 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Direction of rotation of a split phase motor can be reversed by reversing the connection of either running winding or starting winding.
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357 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The direction of rotation of an hysteresis motor is determined by position of shaded pole with respect to main pole.
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230 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In repulsion motor direction of rotation of motor is the same as that of brush shift.
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116 views
1 answer
asked
Mar 20, 2018
by
anonymous

How can we reverse the direction of rotation of synchronous motor?
Last Answer : By reversing supply phase sequence we can reverse the direction of rotation of synchronous motor.
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305 views
1 answer
asked
Mar 18, 2018
by
anonymous

In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as (1) synchronous motor (2) synchronous generator (3) asynchronous motor (4) asynchronous generator
Last Answer : In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation, the machine is operating as synchronous generator
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601 views
1 answer
asked
May 1, 2018
by
anonymous
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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
asked
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
asked
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
asked
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
asked
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
asked
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
asked
Mar 20, 2018
by
anonymous

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
asked
Mar 20, 2018
by
anonymous
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Last Answer : To reverse the direction of rotation of a capacitor start motor while it is running we should disconnect motor from the supply till it stops then reconnect it to supply with reversed connection of main or auxiliary winding.
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131 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

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

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
asked
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

how can we reverse the direction of rotation of three phase induction motor ?
Last Answer : The direction of rotation of three phase induction motor can be reversed by plugging i.e by changing any two out of three phases of the supply to the stator of the Induction motor terminal.
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137 views
1 answer
asked
Oct 4, 2017
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

In a single-phase induction motor, the operating direction is determined by the ________ A) Rotor B) Stator C) Starting circuit D) None of these
Last Answer : In a single-phase induction motor, the operating direction is determined by the Starting circuit
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128 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

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 : For a D.C. shunt motor if the excitation is changed torque will change but power will remain constant.
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168 views
1 answer
asked
Mar 20, 2018
by
anonymous

Write two applications of D.C. series motor.
Last Answer : The applications of D.C. series motor: 1. Cranes 2. Hoists 3. Trolley and cars 4. Conveyors 5. For traction work i.e. electric locomotives 6. Elevator 7. Air compressor
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117 views
1 answer
asked
Apr 27, 2020
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

A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be
Last Answer : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V
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481 views
1 answer
asked
May 8, 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

The function of a brush and commutator arrangement in a dc motor is to (1) produce unidirectional torque (2) produce unidirectional current in the armature (3) help in changing the direction of rotation of the armature (4) reduce sparking
Last Answer : The function of a brush and commutator arrangement in a dc motor is to produce unidirectional torque
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2.5k views
1 answer
asked
Apr 29, 2018
by
anonymous
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Last Answer : If a D.C. motor designed for 40°C ambient temperature is to be used for 50°C ambient temperature, then the motor is to be derated by a factor recommended by manufacturer and select the next higher H.P. motor.
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97 views
1 answer
asked
Mar 20, 2018
by
anonymous
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The speed of a D.C. motor can be controlled by varying 1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above
Last Answer : The speed of a D.C. motor can be controlled by varying 1. Its flux per pole 2. Resistance of armature circuit 3. Applied voltage 4. All of the above
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389 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : At the instant of starting when a D.C. motor is put on supply, it behaves like a low resistance circuit.
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130 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : In case the back e.m.f. and the speed of a D.C. motor are doubled, the torque developed by the motor will remain unchanged.
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228 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The speed of a D.C. shunt motor can be increased by increasing the resistance in field circuit.
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134 views
1 answer
asked
Mar 20, 2018
by
anonymous

As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit?
Last Answer : As there is no back e.m.f. at the instant of starting a D.C. motor, in order to prevent a heavy current from flowing though the armature circuit a resistance is connected in series with armature.
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187 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The armature voltage control of D.C. motor provides constant torque drive.
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92 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The armature torque of the D.C. shunt motor is proportional to armature current.
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210 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : As the load is increased the speed of D.C. shunt motor will reduce slightly.
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142 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : In a differentially compounded D.C. motor, if shunt field suddenly opens the motor will first stop and then run in opposite direction as series motor.
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94 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Flywheel is used with D.C. compound motor to reduce the peak demand by the motor, compound motor will have to be cumulatively compounded.
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353 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Sparking, is discouraged in a D.C. motor because commutator gets damaged.
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159 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : D.C. Series motor is generally preferred for cranes and hoists.
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120 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : (b) Clostridium butylicum Lipase Removal of oil stains
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107 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : Sparking at the commutator of a D.C. motor may result in damage to commutator segments, damage to commutator insulation, increased power consumption.
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228 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : If a D.C. shunt motor is working at no load and if shunt field circuit suddenly opens this will result in excessive speed, possibly destroying armature due to excessive centrifugal stresses.
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122 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Cumulatively compounded D.C. motor will be suitable along with flywheel for intermittent light and heavy loads.
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175 views
1 answer
asked
Mar 20, 2018
by
anonymous
