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.Management Sciences
A. the rotor excitation only
B. the supply voltage only
C. the rotor excitation and supply volt-age both
D. the rotor excitation, supply voltage and maximum value of coupling angle (90°)
E. none of the above
Related Mcqs:
- 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...
- The standard full-load power factor ratings for synchronous motors are___________?
- A. zero or 0.8 leading B. unity or 0.8 lagging C. unity or 0.8 leading D. unity or zero...
- A synchronous motor connected to infinite bus-bars has at constant full load, 100% excitation and unity power factor. On changing the excitation only, the armature current will have_____________?
- A. no change of power factor B. lagging power factor with over-excitation C. leading power factor with under-excitation D. leading power factor with over-excitation...
- The minimum armature current of the synchronous motor corresponds to operation at______________?
- A. zero power factor leading B. unity power factor C. 0.707 power factor lagging D. 0.707 power factor leading...
- In a 3-phase synchronous motor, the negative phase sequence exists when the motor is_______________?
- A. supplied with unbalanced voltage B. under-loaded C. over-loaded D. none of the above...
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