Last Answer : The rotor of a hysteresis motor is made of chrome steel.
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56 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : Locked rotor current of a shaded pole motor is slightly more than full load current.
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85 views
1 answer
asked
Mar 20, 2018
by
anonymous

Describe with neat sketch working of hysteresis motor.
Last Answer : Working: When stator is energized with single phase ac supply, rotating magnetic field is produced because of starting (auxiliary) and main windings, which remain in circuit permanently. The ... the principle of magnetic locking this motor either rotates at synchronous speed or not at all.
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205 views
1 answer
asked
May 7, 2020
by
anonymous

Last Answer : A hysteresis motor works on the principle of hysteresis loss.
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121 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

Explain with neat circuit diagrams the procedures to perform no load and blocked rotor tests on three phase induction motor.
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133 views
0 answers
asked
Apr 16, 2020
by
anonymous

The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be
Last Answer : The rotor impedance of a slip ring induction motor is (0.1 + j0.6)Ohm/ ph . The resistance/ph to be inserted into rotor to get maximum torque at starting should be 0.5 Ohm
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165 views
1 answer
asked
May 3, 2018
by
anonymous

Ratio of the rotor reactance X to the rotor resistance R for a two-phase servo motor (A) is equal to that of a normal induction motor (B) is less than that of a normal induction motor (C) ... than that of a normal induction motor (D) may be less or greater than that of a normal induction motor
Last Answer : C
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582 views
2 answers
asked
Apr 28, 2018
by
anonymous

Last Answer : The rotor developed by a single-phase motor at starting is zero.
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90 views
1 answer
asked
Mar 20, 2018
by
anonymous

An electric motor in which both stator field and rotor rotates with same speed is called?
Last Answer : An electric motor in which both stator field and rotor rotates with same speed is called synchronous motor.
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177 views
1 answer
asked
Mar 18, 2018
by
anonymous

What is the rotor of a motor?
Last Answer : Rotor is the rotating or moving part in motor and generator.
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133 views
1 answer
asked
Dec 16, 2017
by
anonymous

The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?
Last Answer : The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as pull-in torque.
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302 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

In dc machines, the armature windings are placed on the rotor because of the necessity for (1) electromechanical energy conversion (2) generation of voltage (3) commutation (4) development of torque
Last Answer : 3 Commutation
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292 views
2 answers
asked
May 1, 2018
by
anonymous

What is magnetic hysteresis? What is the cause of hysteresis?
Last Answer : Magnetic hysteresis: When a magnetic material is subjected to cycle of magnetization, it is found that flux density (B) in the material lags behind applied magnetizing force (H). This ... the movement of orientation, due to which the flux density lags behind the magnetic field intensity.
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77 views
1 answer
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Sep 4, 2018
by
anonymous
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State the factors affecting hysteresis loss.
Last Answer : i) Flux density ii) Frequency iii) Volume of the magnetic material iv) Nature of magnetic material
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86 views
1 answer
asked
Sep 4, 2018
by
anonymous

Explain the hysteresis loop of a magnetic material with neat diagram.
Last Answer : Hysteresis loop of magnetic material: The circuit arrangement for plotting the hysteresis loop is shown in figure given below. The electromagnetic part consists of a coil wound on the iron ring ... one magnetic reversal is called hysteresis loop. Meaning of hysteresis is to lag behind.
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662 views
1 answer
asked
Aug 8, 2018
by
anonymous

Hysteresis is commonly found in ______ A) ferromagnetic materials B) ferroelectric materials C) both A and B D) none of these
Last Answer : Hysteresis is commonly found in ______ A) ferromagnetic materials B) ferroelectric materials C) both A and B D) none of these
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125 views
1 answer
asked
Apr 29, 2018
by
anonymous

The term hysteresis is associated with (A) On-Off control (B) P-I control (C) Feed forward control (D) Ratio control
Last Answer : The term hysteresis is associated with On-Off control
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74 views
1 answer
asked
Apr 26, 2018
by
anonymous

If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be?
Last Answer : If the area of hysteresis loop of a material is large, the hysteresis loss in this material will be large.
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623 views
1 answer
asked
Mar 25, 2018
by
anonymous

In a magnetic material hysteresis loss takes place primarily due to?
Last Answer : In a magnetic material hysteresis loss takes place primarily due to it high retentivity.
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410 views
1 answer
asked
Mar 25, 2018
by
anonymous

What is the difference between eddy current and hysteresis loss?
Last Answer : Loss occurred by magnetising and demagnetising process is called histerisis loss and the current flowed due to the magnetic field produced by the electric field applied is called eddy current losses
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3.0k views
1 answer
asked
Mar 15, 2018
by
anonymous

Explain hysteresis loss, eddy current loss and skin effect limitations with reference to magnetic material.
Last Answer : Hysteresis loss: Hysteresis loss is a loss which occurs due to the friction of magnetic domain due to the change in magnetic field in ferromagnetic material like iron. Hysteresis loss causes power loss ... loss in transformer is given by, We=Kef2Kf2Bm2watts Skin effect limitations:
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721 views
1 answer
asked
Feb 16, 2018
by
anonymous

Last Answer : The bearings used to support the rotor shafts are generally ball bearings.
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122 views
1 answer
asked
Mar 20, 2018
by
anonymous

Salient pole rotor is use for which speed?
Last Answer : Salient pole rotor is use for low and medium speed prime movers.
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100 views
1 answer
asked
Mar 18, 2018
by
anonymous

Which rotor is use for high speed in turbo alternators?
Last Answer : Non-salient pole rotor is used for high speed in turbo alternators.
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81 views
1 answer
asked
Mar 18, 2018
by
anonymous
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In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then (A) the flux is constant (B) the flux first decreases and then increases in ... increases and decreases in the opposite direction with the same magnitude (D) current flows through the rotor
Last Answer : In a single-phase induction motor when the rotor is stationary and voltage is applied to the stator, then the flux first decreases and then increases in the same direction
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95 views
1 answer
asked
Apr 28, 2018
by
anonymous

A 3-phase, 4-pole, 50Hz induction motor runs at a speed of 1440 rpm. The rotating field produced by the rotor rotates at a speed of ________ rpm with respect to stator field. (A) 1500 (B) 0 (C) 1440 (D) 60
Last Answer : 0
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2.1k views
2 answers
asked
Apr 28, 2018
by
anonymous

An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is (A) 5.06 kW (B) 0.3 kW (C) 100 kW (D) 83.33 kW
Last Answer : An 8-pole, 50Hz, three-phase induction motor is running at 705rpm and has a rotor copper loss of 5kW. Its rotor input is 83.33 kW
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179 views
1 answer
asked
Apr 28, 2018
by
anonymous

Last Answer : The rotor slots, in an induction motor, are usually not quite parallel to the shaft because it helps in reducing the tendency of the rotor teeth to remain under the stator teeth.
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146 views
1 answer
asked
Mar 20, 2018
by
anonymous

The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor, at rated stator supply voltage and frequency, is known as?
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106 views
0 answers
asked
Mar 20, 2018
by
anonymous
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Split phase induction motor
Last Answer : Split phase induction motor : There are two windings used in split phase induction motor. It is a type of single-phase induction motor. There are two winding one is called main winding and ... motor have low starting torque it is used for small fans, blowers, centrifugal pumps, grinders etc.
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230 views
1 answer
asked
Sep 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
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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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483 views
1 answer
asked
May 8, 2018
by
anonymous
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Damper winding in a synchronous motor
Last Answer : Damper winding in a synchronous motor Serves to start the motor.
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87 views
1 answer
asked
May 8, 2018
by
anonymous

In a double squirrel cage induction motor, good starting torque is produced as (A) Large current flows through the outer high resistance winding. (B) Large current flows through the inner high ... the outer high resistance winding. (D) Large current flows through the inner low resistance winding.
Last Answer : In a double squirrel cage induction motor, good starting torque is produced as Large current flows through the outer high resistance winding.
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136 views
1 answer
asked
May 8, 2018
by
anonymous
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A change of 4% in the supply voltage to an induction motor will produce a change of approximately
Last Answer : A change of 4% in the supply voltage to an induction motor will produce a change of approximately 8% in the rotor torque
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467 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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332 views
1 answer
asked
May 3, 2018
by
anonymous

In an induction motor if the flux density is reduced to one-half, of its normal value then the torque will (1) reduce to one-half (2) reduce to one-fourth (3) remain unchanged (4) increase four times
Last Answer : In an induction motor if the flux density is reduced.to one-half, of its normal value then the torque will reduce to one-fourth
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372 views
1 answer
asked
May 1, 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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235 views
1 answer
asked
May 1, 2018
by
anonymous

The number of poles of 8/6 stepper motor can be :
Last Answer : The number of poles of 8/6 stepper motor can be : 4
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267 views
1 answer
asked
Apr 30, 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

For using regenerative breaking, the most suitable motor is : (A) DC series motor (B) Slip ring induction motor (C) Squirrel cage induction motor (D) Synchronous motor
Last Answer : For using regenerative breaking, the most suitable motor is : Slip ring induction motor
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91 views
1 answer
asked
Apr 29, 2018
by
anonymous

Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be
Last Answer : Torque developed by a three-phase, 400V, induction motor is 100 N -m. If the applied voltage is reduced to 200-V, the d'veloped torque will be 25 N -m
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422 views
1 answer
asked
Apr 29, 2018
by
anonymous

The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is
Last Answer : The slip of 400 V, three phase, 4 -pole induction motor when rotating at 1440 rpm is 4 percent
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362 views
1 answer
asked
Apr 29, 2018
by
anonymous

A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for
Last Answer : A 400 V, 50 Hz three-phase induction motor rotates at 1440 rpm on full -load. The motor is wound for 4 poles
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305 views
1 answer
asked
Apr 29, 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

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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152 views
1 answer
asked
Apr 28, 2018
by
anonymous

In a split-phase induction motor, the resistance/reactance ratios of windings are such that (A) current in the auxiliary winding leads the current in the main winding (B) current in the ... (C) both windings develop the same starting torque (D) both windings develop high starting current
Last Answer : In a split-phase induction motor, the resistance/reactance ratios of windings are such that current in the auxiliary winding leads the current in the main winding
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106 views
1 answer
asked
Apr 28, 2018
by
anonymous

The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is (A) 0.25 pu (B) 0.5 pu (C) 1.0 pu (D) 1.5 pu
Last Answer : The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and quadrature-axis reactance, 0.5 pu, and input voltage, 1.0 pu is 0.5 pu
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98 views
1 answer
asked
Apr 28, 2018
by
anonymous
