Question is ⇒ The effect of increasing the load on a synchronous motor running with normal excitation is to, Options are ⇒ (A) decrease both arrnature current and power factor, (B) decrease armature current but increase power factor, (C) increase armature current but decrease power factor, (D) increase both its armature current and power factor, (E) , Leave your comments or Download question paper.

Question is ⇒ The effect of increasing the load on a synchronous motor running with normal excitation is to, Options are ⇒ (A) decrease both arrnature current and power factor, (B) decrease armature current but increase power factor, (C) increase armature current but decrease power factor, (D) increase both its armature current and power factor, (E) , Leave your comments or Download question paper. Previous question Next question


Q1.	The effect of increasing the load on a synchronous motor running with normal excitation is to
A.	decrease both arrnature current and power factor [Wrong Answer]
B.	decrease armature current but increase power factor [Wrong Answer]
C.	increase armature current but decrease power factor [Correct Answer]
D.	increase both its armature current and power factor [Wrong Answer]
View Answer 15 -3 Explanation:- Answer : C 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 :

⇒ 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

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

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

⇒ The maximum power developed in a synchronous motor will depend on
the rotor excitation only
the supply voltage only
the rotor excitation and supply voltage both
the rotor excitation, supply voltage and maximum value of coupling angle (90°)

⇒ If one-phase of a 3-phase synchronous motor is short-circuited, motor
will refuse to start
will overheat in spots
will not come upto speed
will fail to pull into step

⇒ When V is the applied voltage, then the breakdown torque of a synchronous motor varies as
V
V^3/2
V²
1/V

⇒ If the field winding of an unloaded salient pole synchronous motor is open circuited, the motor will
stop
run as induction motor
function as static condenser
burn with dense smoke

⇒ Which of the following motors will be used in electric clocks ?
D.C. shunt motor
D.C. series motor
A.C. induction motor
A.C. synchronous motor

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

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

⇒ A rotory converter can also be run as a
d.c. shunt motor
d.c. series motor
d.c. compound motor
induction motor

⇒ When V is the supply voltage and R is the rotor resistance per phase, the mechanical power developed by the synchronous motor will be proportional to

V²

R²

⇒ An important advantage of a synchronous motor over wound round induction motor is that
its power factor may be varied at will
its speed is independent of supply frequency
its speed may be controlled more easily
none of the above

⇒ VVhen the voltage applied to a synchronous motor is increased, which of the following will reduce ?
Stator flux
Pull in torque
Both (a) and (b)
None of the above

⇒ If excitation of a synchronous motor running with a constant load is decreased from its normal value, ignoring effects of armature reaction, it leads to
increase in both armature current and power factor angle
increase in back e.m.f. but decrease in armature current
increase in both armature current and power factor which is lagging
increase in torque angle but decrease in back e.m.f.

⇒ The armature current of the synchronous motor
has large values for low excitation only
has large values for high excitation only
has large values for low and high excitation
any of the above

⇒ The speed regulation of a synchronous motor is always
0.01
0.005
positive
zero

⇒ The duration of sudden snort-circuit test on a synchronous motor is usually about
one hour
one minute
one second
none of the above

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

⇒ 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
none of the above

⇒ The speed of the synchronous motor
increases with increase in load
decreases as load increases
varies with power factor
always remains constant

⇒ While starting a synchronous motor by induction motor action, field winding is usually
connected to D.C. supply
short-circuited by low resistance
kept open-circuited
none of the above

⇒ In a synchronous motor running with fixed excitation, when the load is increased three times, its torque angle becomes approximately
one-third
twice
thrice
six times

⇒ VVhen the rotor speed, in a synchronous machine, becomes more than the synchronous speed during hunting, the damper bars develop
inductor motor torque
induction generator torque
synchronous motor torque
d.c. motor toque

⇒ 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

⇒ Which of the following resistances can be measured by conducting insulation resistance test on a synchronous motor?
Phase to phase winding resistance
Stator winding to earthed frame
Rotor winding to earthed shaft
All of the above

⇒ When a 3-phase synchionous generator is supplying a zero power factor lagging load, the armature field affects the main field in the following way
augments it directly
directly opposes it
cross-magnetises it
none of the above

⇒ A synchronous motor has better power factor as compared to that of an equivalent induction motor. This is mainly because
synchronous motor has no slip
stator supply is not required to produce magnetic field
mechanical load on the rotor remains constant
synchronous motor has large airgap

⇒ Synchronsizing power of a synchronous machine is
direcly proportional to the synchronous reactance
inversely proportional to the synchronous reactance
equal to the synchronous reactance
none of the above

⇒ The efficiency of a properly designed synchronous motor will usually fall in range
60 to 70%
75 to 80%
85 to 95%
99 to 99.5%