If we change the excitation of synchronous machine will it affect on motor speed?

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asked Mar 18, 2018 by anonymous

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asked Mar 18, 2018 by anonymous

If we change the excitation of synchronous machine will it affect on power factor?

Last answer: Yes, If we change the excitation of synchronous machine it will affect on power factor. If the synchronous motor is overexcited then it will have leading power factor and if the motor is underexcited then it will have lagging power factor.

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asked Mar 18, 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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asked Mar 6, 2018 by anonymous

Can we make power factor of synchronous motor leading by adjusting its excitation?

Last answer: Yes, we can make the power factor of synchronous motor leading by adjusting its excitation.

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asked Mar 20, 2018 by anonymous

A synchronous motor running with normal excitation adjusts to load increases essentially by increase in?

Last answer: A synchronous motor running with normal excitation adjusts to load increases essentially by increase in armature current.

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asked Apr 28, 2018 by anonymous

The effect of increasing load on a synchronous motor running with normal excitation is

The effect of increasing load on a synchronous motor running with normal excitation is (A) Increase both its Ia and power factor. (B) Decrease Ia, but increase power factor. (C) Increase Ia, but decrease power factor (D) Decrease both Ia and power factor.

Last answer: The effect of increasing load on a synchronous motor running with normal excitation is Increase Ia, but decrease power factor

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asked Mar 20, 2018 by anonymous

In case of a reluctance motor, when the load is increased so that it cannot maintain synchronous speed the motor will?

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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6

asked Mar 20, 2018 by anonymous

If the centrifugal switch does not open at 70 to 80 percent of synchronous speed of motor, it would result in?

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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asked Mar 20, 2018 by anonymous

The operating speed of a synchronous motor can be changed to new fixed value by?

Last answer: The operating speed of a synchronous motor can be changed to new fixed value by changing frequency.

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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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asked Dec 31, 2017 by anonymous

The synchronous speed of an 8 pole induction motor supplied power from a 50 Hz source will be ?

Last answer: Ns equals f/pair pole 50/4 - 12.5

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asked Mar 20, 2018 by anonymous

Centrifugal switch disconnects the auxiliary winding of the motor at about what percent of synchronous speed?

Last answer: Centrifugal switch disconnects the auxiliary winding of the motor at about 70 to 80 percent of synchronous speed.

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138 views 1 answer

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asked Mar 15, 2018 by anonymous

Why the speed of synchronous motor is constant?

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asked Apr 29, 2018 by anonymous

In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load

In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load (A) The armature current increases and the power factor decreases (B) The armature current decreases and the power factor also decreases (C) The armature current decreases and the power factor increases but is lagging (D) The armature current decreases and the power factor increases and is leading

Last answer: In a synchronous generator if the excitation increased from a low value to normal value, with a fixed load The armature current decreases and the power factor increases and is leading

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13

asked Mar 20, 2018 by anonymous

If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will?

Last answer: If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will stop.

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asked Mar 18, 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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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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16

asked Mar 18, 2018 by anonymous

V - curve of synchronous machine shows the relation between?

Last answer: V - curve of synchronous machine shows the relation between AC armature current and DC field current.

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asked Mar 18, 2018 by anonymous

Which machine is the exciter of synchronous machine?

Last answer: DC shunt machine is the exciter of synchronous machine.

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asked Mar 20, 2018 by anonymous

Synchronsizing power of a synchronous machine is?

Last answer: Synchronsizing power of a synchronous machine is inversely proportional to the synchronous reactance.

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19

asked Mar 20, 2018 by anonymous

A synchronous machine with low value of short-circuit ratio has?

Last answer: A synchronous machine with low value of short-circuit ratio has lower stability limit.

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20

asked Mar 20, 2018 by anonymous

If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then?

Last answer: If the synchronous motor, properly synchronised to the supply is running on no load and is having negligible loss then the stator current will be zero.

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21

asked Mar 18, 2018 by anonymous

Why synchronous machine is called doubly excited machine?

Last answer: Armature windings of synchronous machines either deliver 3 phase AC or absorb 3 phase AC source, whereas field windings are energized from DC source. Thus due to presence of AC on armature and DC on field windings, synchronous machines are often referred as doubly excited machines.

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22

asked Mar 18, 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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183 views 1 answer

23

asked Mar 18, 2018 by anonymous

Can we use the synchronous motor as the synchronous capacitor?

Last answer: Yes, we can use the synchronous motor as the synchronous capacitor when the synchrnous motor is overexcited.

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76 views 1 answer

24

asked Mar 20, 2018 by anonymous

For a D.C. shunt motor if the excitation is changed?

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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117 views 1 answer

25

asked Apr 29, 2018 by anonymous

The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole)

The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole) (A) has q -axis current only (B) has d -axis current only (C) has both d and q axis currents (D) cannot be divided between q and d axis currents

Last answer: The armature current on symmetrical 3 phase short circuit of a synchronous machine (salient pole) has d -axis current only

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112 views 1 answer

26

asked May 1, 2018 by anonymous

In a synchronous machine, if the field flux axis ahead of the armature field axis in the direction of rotation,

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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310 views 1 answer

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asked Mar 20, 2018 by anonymous

The efficiency of a properly designed synchronous motor will usually fall in range?

Last answer: The efficiency of a properly designed synchronous motor will usually fall in range 85 to 95%.

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asked Mar 20, 2018 by anonymous

In case one phase of a three-phase synchronous motor is short-circuited the motor will?

Last answer: In case one phase of a three-phase synchronous motor is short-circuited the motor will not start.

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171 views 1 answer

29

asked Mar 20, 2018 by anonymous

The maximum torque which a synchronous motor will develop at rest for any angular position of the rotor...

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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86 views 0 answers

30

asked Apr 29, 2018 by anonymous

During a disturbance on a synchronous machine, the rotor swings form A to B before finally setting down to

During a disturbance on a synchronous machine, the rotor swings form A to B before finally setting down to steady state at point C on the power angle curve. The speed of the machine during oscillation is synchronous at point(s)

Last answer: During a disturbance on a synchronous machine, the rotor swings form A to B before finally setting down to steady state at point C on the power angle curve. The speed of the machine during oscillation is synchronous at point(s) only at C

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151 views 1 answer

31

asked Mar 20, 2018 by anonymous

The maximum constant load torque under which a synchronous motor will pull into synchronism...

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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213 views 1 answer

32

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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80 views 1 answer

33

asked Mar 20, 2018 by anonymous

The duration of sudden short-circuit test on a synchronous motor is usually about?

Last answer: The duration of sudden short-circuit test on a synchronous motor is usually about one second.

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asked Mar 18, 2018 by anonymous

The back emf of synchronous motor depends on?

Last answer: The back emf of synchronous motor depends on load angle.

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asked Mar 18, 2018 by anonymous

Three phase synchronous motor will have how many sliprings?

Last answer: Three phase synchronous motor will have two sliprings.

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63 views 1 answer

36

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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69 views 1 answer

37

asked Mar 20, 2018 by anonymous

If the speed of a D.C. shunt motor is increased, the back e.m.f. of the motor will?

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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111 views 1 answer

38

asked Apr 30, 2018 by anonymous

The 'Equal area criterion' for the determination of transient stability of a synchronous machine connected to

The 'Equal area criterion' for the determination of transient stability of a synchronous machine connected to an infinite bus (1) ignores line as well as synchronous machine resistance and shunt capacitances. (2) assumes accelerating power acting on the rotor as constant. (3) ignores the effect of voltage ... inherent damping present in the machine. (4) takes into consideration the possibility of machine losing synchronism after it has survived during the first swing.

Last answer: 1

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39

asked May 7, 2020 by anonymous

Define Feed and speed in shaping machine

Last answer: 1) Feed: Feed (S) is the relative movement of the work or tool in a direction perpendicular to the axis of reciprocation of the ram per double stroke. It is expressed in mm per stroke. 2) Speed: ... speed is the speed at which the metal is removed by the cutting tool in a period of one minute.

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40

asked Apr 28, 2018 by anonymous

Torque angle for the synchronous machine is the angle between

Torque angle for the synchronous machine is the angle between (A) stator magnetic field and rotor magnetic field (B) stator magnetic field and net magnetic field in the air gap (C) rotor magnetic field and net magnetic field in the air gap (D) excitation voltage and impedance voltage drop

Last answer: Torque angle for the synchronous machine is the angle between rotor magnetic field and net magnetic field in the air gap

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71 views 1 answer

41

asked Mar 20, 2018 by anonymous

The size of a synchronous motor decreases with the increase in?

Last answer: The size of a synchronous motor decreases with the increase in flux density.

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132 views 1 answer

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asked Mar 20, 2018 by anonymous

The construction of a synchronous motor resembles?

Last answer: The construction of a synchronous motor resembles an alternator.

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asked Mar 20, 2018 by anonymous

The coupling angle or load angle of synchronous motor is defined as the angle between the?

Last answer: The coupling angle or load angle of synchronous motor is defined as the angle between the rotor and the stator poles of opposite polarity.

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135 views 1 answer

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asked Mar 20, 2018 by anonymous

The armature current of the synchronous motor?

Last answer: The armature current of the synchronous motor has large values for low and high excitation.

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asked Mar 18, 2018 by anonymous

What is the maximum value of torque angle in synchronous motor?

Last answer: The maximum value of torque angle in synchronous motor is 90 degrees electrical.

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46

asked Mar 20, 2018 by anonymous

The wattage of motor for driving domestic sewing machine will be around?

Last answer: The wattage of motor for driving domestic sewing machine will be around 100 to 150 W.

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75 views 1 answer

47

asked Mar 18, 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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91 views 1 answer

48

asked Mar 20, 2018 by anonymous

A synchronous motor has better power factor as compared to that of an equivalent induction motor...

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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asked Mar 20, 2018 by anonymous

In a synchronous motor, the armature current has large values for?

Last answer: In a synchronous motor, the armature current has large values for high and low excitation.

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anonymous · Answer 1 · 2018-03-18T03:34:52+0000

No, If we change the excitation of synchronous machine it will not affect on motor speed.

If we change the excitation of synchronous machine will it affect on motor speed?

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