The coupling angle or load angle of a synchronous motor is defined as the space angle between __________
  • a) rotor and stator poles of opposite polarity
  • b) rotor and stator poles of same polarity
  • c) rotor and stator teeth
  • d) rotor and resultant magnetic field
What is Synchronizing power?
  • a) i,ii
  • b) ii, iii
  • c) iii, i
  • d) i, ii, iii
Large stiffness coefficient represents ____________
  • a) motor speed remains practically constant
  • b) large fluctuations due to mechanical load
  • c) motor speed is variable to changes
  • d) no such significance with speed
An over excited synchronous machine is more stable than under excited.
  • a) True
  • b) False
Consider the below remarks for an alternator.
  • a) (i) is True, (ii) is False
  • b) (i) is False, (ii) is True
  • c) (i) is True, (ii) is True
  • d) (i) is False, (ii) is False
As load angle is increased, degree of stability __________
  • a) reduces
  • b) increases
  • c) remains same
  • d) no change in stability
Synchronizing power is __________
  • a) transient in nature
  • b) steady state in nature
  • c) pulsating at small frequencies
  • d) constant for a machine
Which of the following makes synchronizing power to come to play in the machine?
  • a) Disturbance in power mover
  • b) Disturbance in field current
  • c) Disturbance in load
  • d) All of the mentioned
Which of the following is/are used in synchronous machines to maintain mechanical stability?
  • a) Damper winding
  • b) Interpole winding
  • c) Compensating winding
  • d) Equalizer rings
For a 4-pole 3 phase,alternator has synchronizing power ofunits. Then the synchronizing power per mechanical degree is?
  • a) 300
  • b) 1200
  • c) 900
  • d) 600
Electromagnetic torque is present in rotating machines when ____________
  • a) both stator and rotor windings carry current
  • b) rotor windings carry current
  • c) stator windings carry current
  • d) any of the mentioned
The operation of a synchronous motor operating on constant excitation across infinite bus will not be stable if power angle δ?
  • a) exceeds internal angle θ
  • b) is less than θ
  • c) is more than θ/2
  • d) is less than θ/2
In a synchronous motor the back emf peak set up in the stator depends on ___________
  • a) rotor excitation
  • b) supply voltage
  • c) rotor speed
  • d) load on the motor
Variation in the dc excitation of a synchronous motor causes variation in ___________
  • a) armature current and power factor
  • b) power factor
  • c) armature current
  • d) speed
Which motor can conveniently operate at lagging as well as leading power factor?
  • a) Synchronous motor
  • b) Slip ring induction motor
  • c) Squirrel cage induction motor
  • d) Stepper motor
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