If the field of synchronous motor is under excited, power factor will be?

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asked Mar 18, 2018 by anonymous

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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

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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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

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 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 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 15, 2018 by anonymous

How can we improve power factor using synchronous motor?

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asked Mar 20, 2018 by anonymous

An over excited synchronous motor on noload is known as?

Last answer: An over excited synchronous motor on noload is known as synchronous condenser.

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asked Mar 20, 2018 by anonymous

The standard full-load power factor ratings for synchronous motors are?

Last answer: The standard full-load power factor ratings for synchronous motors are unity or 0.8 leading.

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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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asked Mar 20, 2018 by anonymous

For power factor correction, synchronous motors operate at?

Last answer: For power factor correction, synchronous motors operate at no-load and greatly over-excited fields.

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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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asked Mar 20, 2018 by anonymous

When a D.C. series motor is connected to A.C. supply, the power factor will be low because of?

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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asked Apr 28, 2018 by anonymous

The power factor angle and torque angle of a salient pole synchronous generator drawing a current of 1.0 pu

The power factor angle and torque angle of a salient pole synchronous generator drawing a current of 1.0 pu from a lagging load are 45o and 15o, respectively. The direct axis and quadrature axis currents, respectively, are (A) 0.5 pu, 0.866 pu (B) 0.866 pu, 0.5 pu (C) 0.707 pu, 0.707 pu (D) 0.5 pu, 0.5 pu

Last answer: The power factor angle and torque angle of a salient pole synchronous generator drawing a current of 1.0 pu from a lagging load are 45o and 15o, respectively. The direct axis and quadrature axis currents, respectively, are 0.866 pu, 0.5 pu

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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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asked Mar 20, 2018 by anonymous

In a distribution system, in order to improve power factor, the synchronous capacitors are installed?

Last answer: In a distribution system, in order to improve power factor, the synchronous capacitors are installed at the receiving end.

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asked Apr 29, 2018 by anonymous

In a synchronous generator delivering lagging power factor load

In a synchronous generator delivering lagging power factor load (1) the excitation emf leads terminal voltage by the power angle (2) the excitation emf lags terminal voltage by the power angle (3) excitation emf leads the terminal voltage by the power factor angle (4) excitation emf lags the terminal voltage by the power factor angle

Last answer: In a synchronous generator delivering lagging power factor load the excitation emf leads terminal voltage by the power angle

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asked Mar 19, 2018 by anonymous

Can a synchronous condenser improve power factor?

Last answer: Yes, synchronous condenser can improve power factor.

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asked Mar 18, 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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asked Apr 28, 2018 by anonymous

The maximum reluctance power of a salient-pole synchronous motor having direct-axis reactance, 1.0 pu and

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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asked Mar 20, 2018 by anonymous

The power factor of a single-phase induction motor is usually?

Last answer: The power factor of a single-phase induction motor is usually lagging.

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asked Mar 3, 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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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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asked Mar 20, 2018 by anonymous

An induction motor has relatively high power factor at?

Last answer: An induction motor has relatively high power factor at near full load.

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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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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

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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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 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 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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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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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

Hunting in synchronous motor cannot be due to?

Last answer: Hunting in synchronous motor cannot be due to windage friction.

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asked Mar 18, 2018 by anonymous

A synchronous motor can be made self starting by providing?

Last answer: A synchronous motor can be made self-starting by providing damper bar.

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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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92 views 1 answer

asked Apr 30, 2018 by anonymous

A separately excited dc motor operating in first quadrant is fed from 3-phase semi -converter free -wheeling

A separately excited dc motor operating in first quadrant is fed from 3-phase semi -converter free -wheeling diode is open circuited, then the motor : (A) can be operated in first quadrant (B) can be operated in first & second quadrants (C) can be operated in first & fourth quadrants (D) cannot be operated

Last answer: A separately excited dc motor operating in first quadrant is fed from 3-phase semi -converter free -wheeling diode is open circuited, then the motor : can be operated in first & fourth quadrants

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168 views 1 answer

asked Apr 28, 2018 by anonymous

The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a

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) inversely proportional to α and Φ (C) directly 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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asked Aug 9, 2017 by anonymous

Separately Excited DC motor

Last answer: Separately Excited DC motor

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296 views 2 answers

asked Apr 28, 2018 by anonymous

A three-phase synchronous motor connected to ac mains is running at full load and unity power factor.

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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457 views 2 answers

asked Mar 20, 2018 by anonymous

In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be?

Last answer: In a D.C. shunt motor, under the conditions of maximum power, the current in the armature will be more than full-load current.

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173 views 1 answer

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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117 views 1 answer

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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136 views 1 answer

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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761 views 1 answer

asked Mar 18, 2018 by anonymous

The damping winding in synchronous motor is generally used to?

Last answer: The damping winding in synchronous motor is generally used to provide starting torque and prevent hunting.

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121 views 1 answer

asked Mar 18, 2018 by anonymous

An unexcited single phase synchronous motor is ?

Last answer: An unexcited single-phase synchronous motor is reluctance motor.

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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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137 views 1 answer

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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55 views 1 answer

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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67 views 1 answer

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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194 views 1 answer

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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47 views 1 answer

anonymous · Answer 1 · 2018-03-18T02:26:14+0000

answered Mar 18, 2018 by anonymous

If the field of synchronous motor is under excited, power factor will be lagging.

If the field of synchronous motor is under excited, power factor will be?

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