Related Questions

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
A remain same
B go down
C improve
D none of the above
In an actual transformer the iron loss remains practically constant from noload to fullload because
A value of transformation ratio remains constant
B permeability of transformer core remains constant
C core flux remains practically constant
D primary voltage remains constant
A,B,C,D,E,G and I are seven friends who study in three different standards namely 5th, 6th and 7th such that not less than two friends study in the same standard. Each friend also has a different favorite subject namely History, Civics, English, Bangla, Science , Maths , and Economics but not necessarily in the same order. A likes Maths and studies in the 5th standard with only one other friend who likes Bangla. I studies with tow other friends . Both the friends who study with I like languages (Here languages include only Science , English and Bangla ) . D studies in the 6th standard with only one person and does not like Civics . E studies with only one friend . The one who likes history does not study in 5th or 6th standard . E does not like languages. C does not like English , Science or Civics. Which combination represents E's favorite subject and the standard in which he studies?
A Civics and 7th
B Economics and 5th
C Civics and 6th
D History and 7th
If in a synchronous motor, driving a given mechanical load and drawing current at a leading power factor from constant voltage supply its field excitation is increased, its power factor
A will become more
B will become less
C will remain unchanged
D none of the above.
If in a synchronous motor, driving mechanical load and drawing current at lagging power factor from constant voltage supply, its field excitation is increased, then its power factor
A become more
B become less
C remain constant
D none of the above
Which one of the following is not necessarily the advantage of D.C. motors over A.C. motors?
A Low cost
B Wide speed range
C Stability
D High starting torque
The mechanical displacement of the rotor with respect to the stator, in polyphase multipolar synchronous motors running at full load, is of the order of
A zero degree
B two degrees
C five degrees
D ten degrees
Synchronous motors are generally not self-starting because
A the direction of rotation is not fixed
B the direction of instantaneous torque reverses after half cycle
C startes cannot be used on these machines
D starting winding is not provided on the machines
Synchronous motors are
A Not-self starting
B Self-starting
C Essentially self-starting
D None of the above
Mostly, synchronous motors are of
A alternator type machines
B induction type machines
C salient pole type machines
D smooth cylindrical type machines

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