synchronous generator quiz

A.Frequency of synchronous generator is given by:

1. f = NP/120
2.  f = N/120

3.   f = P/120N
4.  f = 120/NP

Ans: 1

B.Pitch factor of Synchronous Generator is given by:

 1. Kp = cos 3θ/2
  2. Kp = cos 5θ/2
  3. Kp = 5cos θ/2
  4. Kp = cos θ/2

Ans: 4

C.The power factor of an alternator depends on

   1.  core losses
  2. Rotor speed
  .3.   load
  4.   Armature losses. 

Ans: 3

D.Rotor is most suitable for turbo alternators

  1.   Salient pole type
  2. Non-salient pole type
  3. Both (1) and (2) above
  4.  None of the above

Ans: 1

E.The frequency of voltage generated by an alternator having 8 poles and rotating at 750 rpm is

 1.    60 Hz
 2.  40 Hz
  3.  25 Hz
  4.   50Hz.

Ans: 4

F.Magnitude of Induced emf in alternators / phase:

   1. 4.44 Kp Kb φ f.T. volts
  2. 4Kp Kb φ f.T. volts
   3. 4.44 Kp Kb φ .T. volts
  4. 4.44 Kp Kb  f.T. volts

Ans: 1

G.For Parallel Operation of Synchronous Generators

  1. The terminal voltage of the incoming generator must be same as bus-bar voltage.
 2. The terminal voltage of the incoming generator must be greater than bus-bar voltage.
  3. The terminal voltage of the incoming generator must be less than bus-bar voltage.
   4. The terminal voltage of the incoming generator has nothing to do with bus-bar voltage.

Ans: 1

H. For low speed turbine such as in hydel power plant altrnator used are

                     1.Salient pole type
2. Smooth cylindrical type

         3. Both 

         4.  None of the above

I.  The direction of the induced current in a conductor can be determined by

1. Flemming's right hand rule
2. Flemming's left hand rule
3. Right hand thumb rule
4. None of the above

J. Generally in an alternator 

 1. Armature conductors are stationary and field magnets rotate between them
 2. Armature conductors are rotating and field magnets are stationary
 3. Both of them are common
4. None of them is used.

Ans: 1