Synchronous motors Archives - Page 7 of 10 - MCQ and Quiz for Exams

61. 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

Detailed SolutionThe torque angle, in a synchronous motor, is the angle between

62. For V-curves for a synchronous motor the graph is drawn between

field current and armature current

terminal voltage and load factor

power factor and field current

armature current and power factor

Detailed SolutionFor V-curves for a synchronous motor the graph is drawn between

63. Synchronsizingpower 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

Detailed SolutionSynchronsizingpower of a synchronous machine is

64. The armature current of the synchronous motor

has large values for low excitation i niy

has large values for high excitation only

has large values for low and high excitation

any of the above

Detailed SolutionThe armature current of the synchronous motor

65. The back e.m.f. of a synchronous motor depends on

speed

load

load angle

all of the above

Detailed SolutionThe back e.m.f. of a synchronous motor depends on

66. The standard full-load power factor ratings for synchronous motors are

zero or 0.8 leading

unity or 0.8 lagging

unity or 0.8 leading

unity or zero

Detailed SolutionThe standard full-load power factor ratings for synchronous motors are

67. Mostly, synchronous motors are of

alternator type machines

induction type machines

salient pole type machines

smooth cylindrical type machines

Detailed SolutionMostly, synchronous motors are of

68. A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as

static condenser

condenser

synchronous condenser

none of the above

Detailed SolutionA synchronous motor which works on a leading power factor and does not drive a mechanical load is called as

69. Armature of a synchronous machine is

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

Detailed SolutionArmature of a synchronous machine is

70. 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

Detailed SolutionWhich of the following losses, in a synchronous motor, does not vary with load?

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