A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?
Last Answer : A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because stator supply is not required to produce magnetic field.
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1 answer
asked
Mar 20, 2018
by
anonymous

Which motor have more efficiency, synchronous motor or induction motor?
Last Answer : Synchronous motor has more efficiency.
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93 views
1 answer
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Mar 18, 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
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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
asked
Mar 20, 2018
by
anonymous

Last Answer : The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.
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119 views
1 answer
asked
Mar 20, 2018
by
anonymous

If we change the excitation of synchronous machine will it affect on motor speed?
Last Answer : No, If we change the excitation of synchronous machine it will not affect on motor speed.
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105 views
1 answer
asked
Mar 18, 2018
by
anonymous

Synchronous motor always runs at which speed?
Last Answer : Synchronous motor always runs at synchronous speed.
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90 views
1 answer
asked
Mar 18, 2018
by
anonymous

Why the speed of synchronous motor is constant?
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67 views
0 answers
asked
Mar 15, 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
asked
May 1, 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

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

What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these
Last Answer : What is the slip (as a percentage) when a 6 pole single phase induction motor operating on 220 V and 60 Hz is rotating at speed of 1140 rpm? A) 60% B) 5% C) 10% D) None of these
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125 views
1 answer
asked
Apr 29, 2018
by
anonymous

What will happen if the induction motor runs at synchronous speed ?
Last Answer : Since there is always slip present in rotor it cannot run at synchronous speed no current will be developed hence no torque will developed
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112 views
3 answers
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Aug 18, 2019
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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304 views
1 answer
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Apr 29, 2018
by
anonymous

The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be?
Last Answer : The number of poles in a phase induction motor at 50 Hz and running at 1500 rpm will be 4.
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143 views
1 answer
asked
Mar 26, 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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2.0k views
2 answers
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

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 : If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.
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257 views
1 answer
asked
Mar 20, 2018
by
anonymous

what will happen when excitation of an unloaded salient pole synchronous motor suddenly gets disconnected?
Last Answer : When excitation of an unloaded salient pole synchronous motor suddenly gets disconnected the motor will stop.
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367 views
1 answer
asked
Mar 18, 2018
by
anonymous

Basic electrical engineering
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12 views
0 answers

With a neat sketch give the working of shaded pole induction motor.
Last Answer : Explanation: It has squirrel cage rotor and salient pole stator. The stator poles are shaded partially by short circuited conductor band to create the phase difference between the fluxes emerging from shaded ... rotating magnetic field in the air-gap and torque is exerted on the squirrel cage rotor.
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264 views
2 answers
asked
Apr 27, 2020
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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361 views
1 answer
asked
Apr 29, 2018
by
anonymous
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What is back EMF of synchronous motor?
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77 views
0 answers
asked
Mar 15, 2018
by
anonymous

In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is (A) 0.2 Ω (B) 0.3 Ω (C) 0.4 Ω (D) 0.5 Ω
Last Answer : In a 3-phase slip-ring induction motor, the slip at some speed is 0.05. The speed is reduced by inserting an external resistance in the rotor circuit and the slip is 0.15. If the rotor winding resistance per phase is 0.2 Ω, the external resistance is 0.3 Ω
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165 views
1 answer
asked
Apr 28, 2018
by
anonymous

A three-phase synchronous motor connected to ac mains is running at full load and unity power factor. lf its shaft load is reduced by half and field current is held constant then its new power factor will be
Last Answer : Leading
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564 views
2 answers
asked
Apr 28, 2018
by
anonymous

If the load of the normally excited synchronous motor is increased the power factor will?
Last Answer : If the load of the normally excited synchronous motor is increased the power factor will become lagging.
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150 views
1 answer
asked
Mar 18, 2018
by
anonymous

The synchronous motor which works on leading power factor and does not drive any mechanical load is called?
Last Answer : The synchronous motor which works on leading power factor and does not drive any mechanical load is called synchronous condenser.
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162 views
1 answer
asked
Mar 18, 2018
by
anonymous

If the field of synchronous motor is under excited, power factor will be?
Last Answer : If the field of synchronous motor is under excited, power factor will be lagging.
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483 views
1 answer
asked
Mar 18, 2018
by
anonymous

The synchronous motor will develop maximum power when the load angle is?
Last Answer : The synchronous motor will develop maximum power when the load angle is 900.
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223 views
1 answer
asked
Mar 18, 2018
by
anonymous

How can we improve power factor using synchronous motor?
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78 views
0 answers
asked
Mar 15, 2018
by
anonymous

Last Answer : Yes, we can make the power factor of synchronous motor leading by adjusting its excitation.
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109 views
1 answer
asked
Mar 6, 2018
by
anonymous

Define Slip of Induction Motor.
Last Answer : Slip: It is the ratio of relative speed of rotor (difference between synchronous speed and rotor speed) to the synchronous speed of rotating magnetic field. Slip = (NS – N) / NS where , NS = synchronous speed, N = speed of rotor
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59 views
1 answer
asked
Aug 17, 2019
by
anonymous

Explain the working of a single phase capacitor start induction motor.
Last Answer : Single phase capacitor start induction motor https://youtu.be/31lvvzU5Puc
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393 views
2 answers
asked
Jul 30, 2019
by
anonymous

State any four advantages of three phase induction motor.
Last Answer : Advantages of three phase induction motor https://youtu.be/27OIOCKN05U
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136 views
2 answers
asked
Jul 30, 2019
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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127 views
1 answer
asked
Apr 29, 2018
by
anonymous

Why starter is required for starting an induction motor?
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114 views
0 answers
asked
Mar 15, 2018
by
anonymous

Why does induction motor have high starting current?
Last Answer : In induction motor , the flux produce is quadrature to the applied voltage. Since when we are going to start motor , there is no flux present inside . So in order to lets say compensate it ... times of current to further increase flux. So that is reason for high starting current in induction motor
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143 views
2 answers
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

The torque developed by any 3-phase induction motor at 0.8 p.u. slip is (A) Full-load torque (B) unstable torque (C) starting torque (D) break down
Last Answer : The torque developed by any 3-phase induction motor at 0.8 p.u. slip is unstable torque
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3.1k views
1 answer
asked
Apr 28, 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

Explain energy conservation technique “by improving power quality” for induction motor.
Last Answer : Energy conservation method in induction motor by improving power quality: Electrical energy can be conserved by improving the power quality. It can be achieved by avoiding voltage unbalance, maintaining ... losses can be minimized by using harmonic filter thus reducing the harmonics in the system.
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3.5k views
2 answers
asked
Sep 22, 2018
by
anonymous

Last Answer : The power factor of a single-phase induction motor is usually lagging.
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189 views
1 answer
asked
Mar 20, 2018
by
anonymous

Last Answer : An induction motor has relatively high power factor at near full load.
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91 views
1 answer
asked
Mar 20, 2018
by
anonymous

At which time power factor of the induction motor is low?
Last Answer : The power factor of the inducction motor is low at the time of starting as compare to while the induction motor is running.
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150 views
1 answer
asked
Mar 3, 2018
by
anonymous

List different starting methods of three phase synchronous motor. Explain any one of them.
Last Answer : Different Starting Methods of Three Phase Synchronous Motor: As synchronous motor is not self starting, different methods of starting are as follows: 1) By using an Induction (Pony) motor 2) ... . The rotor gets pulled into synchronism and starts running at constant speed as a synchronous motor.
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156 views
1 answer
asked
May 7, 2020
by
anonymous
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Draw and explain V and inverted V curves for synchronous motor.
Last Answer : V curves' and inverted V curves' for Synchronous Motor: V curve: V curve is a plot of the stator current versus field current for different constant loads. The graph is plotted ... Vcurves of synchronous motor. The highest point on each of these curves indicates unity power factor.
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498 views
1 answer
asked
May 7, 2020
by
anonymous

List different torques in synchronous motor.
Last Answer : Different Torques in Synchronous Motor: 1) Starting torque 2) Running torque 3) Pull-in torque 4) Pull-out torque
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115 views
1 answer
asked
May 7, 2020
by
anonymous

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
