Hunting in a synchronous motor cannot be due to
variable supply voltage
windage friction
variable load
variable frequency
windage friction
In a synchronous motor V-curves represent relation between
armature current and field current
power factor and speed
field current and speed
field current and power factor
armature current and field current
A synchronous motor connected to infinite bus-bars has at constant full load 100% excitation and unity power factor. On changing the excitation only the armature current will have
leading power factor with under-excitation
lagging power factor with over-excitation
no change of power factor
leading power factor with over-excitation
leading power factor with over-excitation
By which of the following methods the constant speed of a synchronous motor can be changed to new fixed value ?
By interchanging any two phases
By changing the applied voltage
By changing the supply frequency
By changing the load.
By changing the supply frequency
In a synchronous motor it the back e.m.f. generated in the armature at noload is approximately equal to the applied voltage then
the excitation is said to be hundred per cent
the excitation is said to be zero per cent
the torque generated is maximum
the motor is said to be fully loaded
the excitation is said to be hundred per cent
If the field of a synchronous motor is underexcited the power factor will be
lagging
unity
zero
leading
lagging
Which of the following motors is non-self starting ?
Wound round induction motor
synchronous motor
D.C. series motor
Squirrel cage induction motor
synchronous motor
The back e.m.f. in the stator of a synchronous motor depends on
rotor excitation
number of poles
flux density
rotor speed
rotor excitation
The maximum value of torque that a synchronous motor can develop without losing its synchronism is known as
breaking torque
pull-out torque
slip torque
synchronising torque
synchronising torque
Which of the following losses in a synchronous motor does not vary with load?
Copper losses
Any of the above
Windage loss
None of the above
Windage loss
पोस्ट अच्छी लगी हो तो प्लीज नीचे दिए गए लिंक पर क्लिक कर शेयर जरुर करें
0 Comments