Question is ⇒ When V is the applied voltage, then the breakdown torque of a synchronous motor varies as, Options are ⇒ (A) V, (B) V3/2, (C) V2, (D) 1/V, (E) , Leave your comments or Download question paper.

Question is ⇒ When V is the applied voltage, then the breakdown torque of a synchronous motor varies as, Options are ⇒ (A) V, (B) V3/2, (C) V2, (D) 1/V, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	When V is the applied voltage, then the breakdown torque of a synchronous motor varies as
A.	V [Correct Answer]
B.	V^3/2 [Wrong Answer]
C.	V² [Wrong Answer]
D.	1/V [Wrong Answer]
View Answer 8 -11 Explanation:- Answer : A Discuss it below : !! OOPS Login [Click here] is required to post your answer/result Help other students, write article, leave your comments

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⇒ The maximum speed variation in a 3- phase synchronous motor is
10 per cent
6 per cent
4 per cent
2 per cent

⇒ In a synchronous motor which loss varies with load ?
Windage loss
Bearing friction loss
Copper loss
Core loss

⇒ In a synchronous motor, the maximum power developed depends on all of the following except
rotor excitation
maximum value of coupling angle
direction of rotation
supply voltage

⇒ Mostly, synchronous motors are of
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induction type machines
salient pole type machines
smooth cylindrical type machines

⇒ Which of the following methods is used to start a synchronous motor ?
Damper winding
Star-delta starter
Damper winding in conjunction with star-delta starter
Resistance starter in the armature circuit

⇒ A synchronous motor can operate at
lagging power factor only
leading power factor only
unity power factor only
lagging, leading and unity power factors

⇒ A synchronous machine with large air gap has
a higher value of stability limit
a small value of inherent regulation
a higher synchronizing power which makes the Machine less sensitive to load variations
all of the above

⇒ In which of the following motors the stator and rotor magnetic field rotate at the same speed ?
Universal motor
Synchronous motor
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Reluctance motor

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⇒ Due to which of the following reasons a synchronous motor fails to pull into synchronism after applying D.C. field current ?
High field current
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⇒ In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately
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⇒ In a synchronous motor, the forced vibrations will be maximum when driving
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a centrifugal pump
a centrifugal blower
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⇒ A synchronous motor installed at the receiving end substation operates with such an excitation that it takes power at lagging power factor. Now if the applied voltage of the synchronous motor goes down, the power factor of the synchronous motor will
remain same
go down
improve
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⇒ The coupling angle or load angle of synchronous motor is defined as the angle between the
rotor and stator teeth
rotor and the stator poles of opposite polarity
rotor and the stator poles of the same polarity
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⇒ The speed of a synchronous motor
increases as the load increases
decreases as the load decreases
always remains constant
none of the above

⇒ Synchronsizing power of a synchronous machine is
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inversely proportional to the synchronous reactance
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⇒ The speed regulation of a synchronous motor is always
0.01
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⇒ A rotory converter can also be run as a
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d.c. series motor
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⇒ A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed
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the motor continue to run in the same direction
the winding of the motor will burn
the motor will run in the reverse direction

⇒ Higher the applied ____voltage will be the stator flux and____ will be the pullin torque
lower, lower
lower, greater
greater, lower
greater, greater

⇒ Synchronous motors are generally not self-starting because
the direction of rotation is not fixed
the direction of instantaneous torque reverses after half cycle
startes cannot be used on these machines
starting winding is not provided on the machines

⇒ A synchronous motor is running on a load with normal excitation. Now if the load on the motor is increased
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power factor as well as armature current will increase
power factor will increase but armature current will decrease
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⇒ The efficiency of a properly designed synchronous motor will usually fall in range
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⇒ A synchronous machine with low value of short-circuit ratio has
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⇒ Which of the following motors will be used in electric clocks ?
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its speed may be controlled more easily
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