Question is ⇒ VVhen the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop, Options are ⇒ (A) inductor motor torque, (B) induction generator torque, (C) synchronous motor torque, (D) d.c. motor toque, (E) none of the above, Leave your comments or Download question paper.

Question is ⇒ VVhen the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop, Options are ⇒ (A) inductor motor torque, (B) induction generator torque, (C) synchronous motor torque, (D) d.c. motor toque, (E) none of the above, Leave your comments or Download question paper. Previous question Next question


Q1.	VVhen the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
A.	inductor motor torque [Wrong Answer]
B.	induction generator torque [Correct Answer]
C.	synchronous motor torque [Wrong Answer]
D.	d.c. motor toque [Wrong Answer]
E.	none of the above [Wrong Answer]
View Answer 11 -5 Explanation:- Answer : B 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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Also Read Similar Questions Below :

⇒ The angle between the rotor poles and stator poles, in a synchronous motor, is known as
power factor angle
torque angle
synchronizing angle
angle of retardation

⇒ Armature of a synchronous machine is kept fixed because
of reducing number of slip rings on the rotor
armature is associated with large power as compared to the field circuits
of difficulty of providing high voltage insulation on rotor
all of the above reasons

⇒ In a synchronous motor, damper windings are provided on
stator frame
rotor shaft
pole faces
none of the above

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

⇒ A 3-phase synchronous motor is running clockwise. If the direction of its field current is reversed
the motor will stop
the motor continue to run in the same direction
the winding of the motor will burn
the motor will run in the reverse direction

⇒ In a synchronous motor, the breakdown torque is
directly proportional to applied voltage
directly proportional to the square of the applied voltage
inversely proportional to applied voltage
none of the above

⇒ The torque angle, in a synchronous motor, is the angle between
the supply voltage and the back e.m.f.
magnetising current and back e.m.f.
the rotating stator flux and rotor poles
none of the above

⇒ The magnitude of field flux in a 3-phase synchronous motor
remains constant at all loads
varies with speed
varies with the load
varies with power factor

⇒ The speed of a synchronous motor
increases as the load increases
decreases as the load decreases
always remains constant
none of the above

⇒ The oscillations in a synchronous motor can be damped out by
maintaining constant excitation
running the motor on leading power factors
providing damper bars in the rotor pole faces
oscillations cannot be damped

⇒ The power factor of a synchronous motor is better than that of induction motor because
stator supply is relieved of responsibility of producing magnetic field
mechanical load on the motor can be adjusted
synchronous motor runs at synchronous speed
synchronous motor has large air gap

⇒ 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
the stator current will be very small
the stator current will be very high
the back e.m.f. will be more than the supply voltage

⇒ The construction of a synchronous motor resembles
a series motor
an induction motor
an alternator
a rotary converter

⇒ Slip rings are usually made of
carbon or graphite
brass or steel
silver or gold
copper or aluminium

⇒ A synchronous motor can be used as a synchronous capacitor when it is
under-loaded
over-loaded
under-excited
over-excited

⇒ An over-excited synchronous motor is used for
fluctuating loads
variable speed loads
low torque loads
power factor corrections

⇒ In case one phase of a three-phase synchronous motor is short-circuited the motor will
not start
run at 2/3 of synchronous speed
run with excessive vibrations
take less than the rated load

⇒ An over-excited synchronous motor takes
leading current
lagging current
both (a) and (b)
none of the above

⇒ Slip-rings in a synchronous motor carry
direct current
alternating current
no current
all of the above

⇒ If load (or torque) angle of a 4-pole synchronous motor is 6° electrical, its value in mechanical degrees is
2
3
4
6

⇒ Which of the following losses, in a synchronous motor, does not vary with load ?
Windage loss
Copper losses
Any of the above
None of the above

⇒ The ratio of starting torque to running torque in a synchronous motor is
zero
one
two
infinity

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

⇒ Synchronous motors are
not-self starting
self-starting
essentially self-starting
none of the above

⇒ While starting a salient pole synchronous motor by induction motor action and connecting field discharge resistance across field, starting and accelerting torque is produced by
induction motor torque in field winding
induction motor torque in damper winding
eddy current and hysteresis' torque in pole faces
reluctance motor torque due to saliency of the rotor

⇒ The angle between the rotating stator flux and rotor poles is called____ angle
torque
obtuse
synchronizing
power factor

⇒ The mechanical displacement of the rotor with respect to the stator, in polyphase multipolar synchronous motor running at full load, is of the order of
zero degree
two degrees
five degrees
ten degrees

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

⇒ For power factor correction, synchronous motors operate at
no-load and greatly over-excited fields
no-load and under-excited fields
normal load with minimum excitation
normal load with zero excitation

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