Synchronous motors

31. Which of the following motors is non-self starting ?

D.C. series motor
synchronous motor
series motor B. synchronous motor C. Squirrel cage induction motor
Wound round induction motor

Detailed SolutionWhich of the following motors is non-self starting ?

32. A synchronous motor can be started by

pony motor
D.
compound motor C. providing damper winding
any of the above

Detailed SolutionA synchronous motor can be started by

33. 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
none of the above

Detailed SolutionA 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

34. The speed regulation of a synchronous motor is always

1%
0.50%
positive
zero

Detailed SolutionThe speed regulation of a synchronous motor is always

35. A rotory converter can also be run as a

d.c. shunt motor
d.c. series motor
d.c. compound motor
induction motor E. synchronous motor

Detailed SolutionA rotory converter can also be run as a

36. 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

Detailed SolutionIf one-phase of a 3-phase synchronous motor is short-circuited, motor

37. The construction of a synchronous motor resembles

a series motor
an induction motor
an alternator
a rotary converter

Detailed SolutionThe construction of a synchronous motor resembles

38. As the load is applied to a synchronous motor, the motor takes more armature current because

The increased load has to take more current
The rotor by shifting its phase backward causes motor to take more current
The back e.m.f. decreases causing an increase in motor current
The rotor strengthens the rotating field causing more motor current

Detailed SolutionAs the load is applied to a synchronous motor, the motor takes more armature current because

39. In which of the following motors the stator and rotor fields rotate simultaneously ?

D.C. motor
Reluctance motor
motor B. Reluctance motor C. Universal motor
Synchronous motor

Detailed SolutionIn which of the following motors the stator and rotor fields rotate simultaneously ?

40. A synchronous motor will always stop when

supply voltage fluctuates
load in motor varies
excitation winding gets disconnected
supply voltage frequency changes

Detailed SolutionA synchronous motor will always stop when

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