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

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
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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
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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
asked
Mar 20, 2018
by
anonymous
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Last Answer : In a D.C. shunt motor, speed is independent of armature current.
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87 views
1 answer
asked
Mar 20, 2018
by
anonymous

What are the speed control methods of dc motor?
Last Answer : Field control of DC motor Armature control of DC motor
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252 views
2 answers
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Dec 16, 2017
by
anonymous

Why does the speed of a DC shunt motor decrease as the load increases?
Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.
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2.7k views
1 answer
asked
Jul 5, 2019
by
anonymous

The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) ... proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α
Last Answer : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ
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150 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will increase.
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201 views
1 answer
asked
Mar 20, 2018
by
anonymous

The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque (1) Decreases (2) Increases (3) Remains constant (4) None of the above
Last Answer : The speed of a three-phase induction motor is controlled by variable voltage variable frequency control (i.e. keeping V/f constant). As the frequency is reduced, the slip at maximum torque Increases
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227 views
1 answer
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May 1, 2018
by
anonymous

The speed of a 2-pole, 3-phase stepper motor operated by 1200 pulses/min (A) 100 rpm (B) 200 rpm (C) 400 rpm (D) 800 rpm
Last Answer : The speed of a 2-pole, 3-phase stepper motor operated by 1200 pulses/min 200 rpm
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151 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : In variable speed motor a weaker commutating field is needed at low speed than at high speed.
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61 views
1 answer
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Mar 20, 2018
by
anonymous
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Last Answer : Series motor has the poorest speed control.
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103 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : For the same H.P. rating and full load speed, following motor has poor starting torque differentially compounded.
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164 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The speed of a universal motor is usually reduced by using gearing.
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114 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Speed control of a universal motor is achieved by varying field flux with tapped field windings, connecting rheostat in series, applying variable voltage by means of silicon controlled rectifier, applying variable voltage by means of variable auto-transformer.
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100 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will run as induction motor.
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111 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : Centrifugal switch disconnects the auxiliary winding of the motor at about 70 to 80 percent of synchronous speed.
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222 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : The speed/load characteristics of a universal motor is same as that of D.C. series motor.
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175 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : Speed torque characteristic of a repulsion induction motor is similar to that of a D.C. compound motor.
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164 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in damage to the starting winding.
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129 views
1 answer
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Mar 20, 2018
by
anonymous

Last Answer : The speed control of universal motor used for sewing machines is by varying the resistance.
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105 views
1 answer
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Mar 20, 2018
by
anonymous
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Why the speed of synchronous motor is constant?
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67 views
0 answers
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Mar 15, 2018
by
anonymous
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speed control methods of three phase induction motor?
Last Answer : Speed control of three phase induction motor
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363 views
2 answers
asked
Aug 9, 2017
by
anonymous

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 more than its full-load speed can be obtained by decreasing the field current.
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146 views
1 answer
asked
Mar 20, 2018
by
anonymous

The fall in speed of a dc generator due to increase in load can be corrected by (1) cooling the armature.. (2) increasing the excitation. (3) reducing the load voltage. (4) increasing the input to the prime mover
Last Answer : It can be corrected by increasing the input to the prime mover.
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355 views
2 answers
asked
May 1, 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
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

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

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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329 views
1 answer
asked
May 3, 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
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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

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

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

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

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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91 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 : 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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352 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
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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
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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
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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

Last Answer : Differentially compounded D.C. motor has got maximum self loading property.
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77 views
1 answer
asked
Mar 20, 2018
by
anonymous
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Last Answer : The current drawn by the armature of D.C. motor is directly proportional to the torque required.
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582 views
1 answer
asked
Mar 20, 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
