Synchronous Motor Multiple Choice Questions and Answers
1. The direction of rotation of a synchronous motor can be reversed by reversing
A.Current to the field winding
B.Supply phase sequence
C.Polarity of rotor poles
D.None of the above
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B.Supply phase sequence
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2. In a synchronous motor, the magnitude of stator back e.m.f. Eb depends on
A.Speed of the motor
B.Load of the motor
C.Both the speed and rotor flux
D.D.C. excitation only
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3. The maximum value of torque angle a in a synchronous motor is .......... degrees electrical
A.45
B.90
C.Between 45 and 90
D.Below 60
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4. If the field of a synchronous motor is under excited, the power factor will be
A.Lagging
B.Leading
C.Unity
D.More than unity
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5. The V-curves of a synchronous motor show relationship between
A.Excitation current and back e.m.f
B.Field current and p.f.
C.D.C. field current and A.C. armature current
D.Armature current and supply voltage
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