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

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Description :

If the load of the normally excited synchronous motor is increased the power factor will?

Answer :

If the load of the normally excited synchronous motor is increased the power factor will become lagging.

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Description :

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

Answer :

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

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245 views 1 answer
Description :

Why synchronous machine is called doubly excited machine?

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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Description :

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

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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199 views 1 answer
Description :

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

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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131 views 1 answer
Description :

Separately Excited DC motor

Answer :

Separately Excited DC motor

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311 views 2 answers
Description :

A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because?

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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94 views 1 answer
Description :

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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148 views 1 answer
Description :

Can we use the synchronous motor as the synchronous capacitor?

Answer :

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

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82 views 1 answer
Description :

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.

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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Description :

Answer :

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

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Description :

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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Description :

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

Answer :

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

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81 views 1 answer
Description :

The synchronous motor which works on leading power factor and does not drive any mechanical load is called?

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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86 views 1 answer
Description :

The back emf of synchronous motor depends on?

Answer :

The back emf of synchronous motor depends on load angle.

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54 views 1 answer
Description :

Answer :

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

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133 views 1 answer
Description :

An unexcited single phase synchronous motor is ?

Answer :

An unexcited single-phase synchronous motor is reluctance motor.

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Description :

what will happen when excitation of an unloaded salient pole synchronous motor suddenly gets disconnected?

Answer :

When excitation of an unloaded salient pole synchronous motor suddenly gets disconnected the motor will stop.

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305 views 1 answer
Description :

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

Answer :

Ns         equals        f/pair pole 50/4      - 12.5

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139 views 2 answers
Description :

List different starting methods of three phase synchronous motor. Explain any one of them.

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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84 views 1 answer
Description :

Draw and explain V and inverted V curves for synchronous motor.

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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310 views 1 answer
Description :

List different torques in synchronous motor. 

Answer :

Different Torques in Synchronous Motor: 1) Starting torque 2) Running torque 3) Pull-in torque 4) Pull-out torque

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61 views 1 answer
Description :

Damper winding in a synchronous motor

Answer :

Damper winding in a synchronous motor Serves to start the motor.

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Description :

In a self-controlled synchronous motor fed from a variable frequency inverter  (1) the rotor poles invariably have damper windings  (2) there are stability problems  (3) the speed of the rotor decides stator frequency  (4) the frequency of the stator decides the rotor speed

Answer :

In a self-controlled synchronous motor fed from a variable frequency inverter the frequency of the stator decides the rotor speed

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457 views 1 answer
Description :

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

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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85 views 1 answer
Description :

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

Answer :

Leading

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516 views 2 answers
Description :

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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Description :

Answer :

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

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166 views 1 answer
Description :

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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Description :

Answer :

Slip-rings in a synchronous motor carry direct current.

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Description :

Answer :

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

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Description :

Answer :

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

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Description :

Answer :

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

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Description :

Answer :

A synchronous motor can develop synchronous torque at synchronous speed.

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Description :

Answer :

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

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222 views 1 answer
Description :

Answer :

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

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Description :

Answer :

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

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183 views 1 answer
Description :

The maximum constant load torque under which a synchronous motor will pull into synchronism at rated rotor supply voltage and frequency is known as?

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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244 views 1 answer
Description :

Answer :

The construction of a synchronous motor resembles an alternator.

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66 views 1 answer
Description :

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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Description :

Answer :

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

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Description :

Which motor have more efficiency, synchronous motor or induction motor?

Answer :

Synchronous motor has more efficiency.

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70 views 1 answer
Description :

How can we reverse the direction of rotation of synchronous motor?

Answer :

By reversing supply phase sequence we can reverse the direction of rotation of synchronous motor.

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241 views 1 answer
Description :

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

Answer :

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

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1.0k views 1 answer
Description :

Hunting in synchronous motor cannot be due to?

Answer :

Hunting in synchronous motor cannot be due to windage friction.

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Description :

The damping winding in synchronous motor is generally used to?

Answer :

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

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137 views 1 answer
Description :

A synchronous motor can be made self starting by providing?

Answer :

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

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115 views 1 answer
Description :

In a synchronous motor which losses varies with load?

Answer :

In a synchronous motor, copper losses varies with load.

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Description :

Synchronous motor always runs at which speed?

Answer :

Synchronous motor always runs at synchronous speed.

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Description :

The synchronous motor will develop maximum power when the load angle is?

Answer :

The synchronous motor will develop maximum power when the load angle is 900.

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