Page 797 - Basic Electrical Engineering

30. An eight-pole synchronous generator is running at 750 rpm. What is the frequency of induced
EMF? At what speed should the generator be run so that the EMF induced will have a frequency of
60 Hz?

[Ans 50 Hz, 900 rpm]

31. Calculate the distribution factor for a four-pole, three-phase alternator having 36 slots on the slator.

[Ans 0.96]

C. Multiple Choice Questions

1. In synchronous machines

a. Field system is stationary and the armature windings are made rotating
b. The armature windings are placed on stator slots and the field system is made
rotating
c. Both the field system and armature windings are rotating at synchronous speed
d. Both the field system and armature windings are rotating at synchronous speed but in
opposite directions.

2. In a synchronous machine the speed of rotation of the magnetic field N is
s

a.

b.

c.

d.

3. For a synchronous machine with concentrated winding with full-pitch coil, which of the
following is true?

a. Distribution factor, K < 1 and pitch factor, K < 1
p
d
b. K > 1 and K > 1
d
p