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Electrical Engineering Objective Questions { Synchronous Motors }

120. The maximum power developed in a synchronous motor will depend on
A. the rotor excitation only
B. the supply voltage only
C. the rotor excitation and supply voltage both
D. the rotor excitation, supply' voltage and maximum value of coupling angle
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121. A synchronous motor which works on a leading power factor and does not drive a mechanical load is called as
A. static condenser
B. condenser
C. synchronous condenser
D. none of the above
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122.  A synchronous motor develops maximum power when load agle is
A. 450?
B. 60?
D. 120?
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123.  A cylindrical rotor synchronous motor is switched on the supply with its field windings shorted on themselves. It will
A. not start
B. start but not run at synchronous speed
C. start as an induction motor and then run as synchronous motor
D. start and run as a synchronous motor
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124.  During hunting of synchronous motor
A. negative phase sequence currents are generated
B. harmonics are developed in the armature circuit
C. damper bar develops torque
D. field excitation increases
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125.  A salient pole synchronous motor is running with normal excitation. If the excitation is reduced to zero
A. it becomes an induction motor
B. it becomes a reluctance motor
C. it remains a synchronous motor
D. the motor would stop
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126. Which of the following will change in a three-phase synchronous motor, as a consequence of excitation variations? 1. Pull-out torque2. Torque angle3. Magnitude and power factor of stator current4. Output power Select the correct answer using the codes given below :Codes :
A. 1 and 3
B. 2 and 4
C. 2, 3 and 4
D. 1, 2 and 3
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