31. Armature winding in ac machines
- is always closed one
- is always open one
- may be either closed one giving delta connections or open
- one giving star connections
32. The stator of modern alternators are wound for _______ phase groups.
- 180 degrees
- 120 degrees
- 60 degrees
- 240 degrees
33. Concentrated winding has
- one coil per phase
- two coils per phase
- one coil per pole of poles per phase
- one coil side per pole pair per phase
34. For a two layer winding the number of stator slots is equal to the number of
- poles
- conductors
- coil sides
- coils
35. For a concentrated winding the polar group of each phase is ______ electrical degrees apart.
- 360
- 180
- 120
- 60
36. Distributed winding is preferred over concentrated winding as it
- reduces noise
- reduces the machine size
- reduces the amount of copper required
- improves the generated emf waveform and adds rigidity and mechanical strength to the winding.
37. In an synchronous alternator, which of the following coils will have emf closer to sine wave form?
- concentrated winding in full pitch coils
- concentrated winding in short pitch coils
- distributed winding in full pitch coils
- distributed winding in short pitch coils
38. If the space flux distribution is non-sinusoidal, emf induced in the distributed winding will be
- more sinusoidal in comparison to the flux distribution
- less sinusoidal in comparison to the flux distribution
- of the same shape as that of flux distribution
- none of the above
39. The short pitch winding is preferred over full pitch winding for an alternator because it
- gives improved waveform of the induced emf as the distorting harmonics can be reduced or totally eliminated
- reduces the inductance of the winding
- increases the total induced emf
- both (1) and (2)
40. Chording and distribution of armature windings for ac machines results in
- reduction in air gap mmf harmonics
- reduction in fundamental component or induced emf
- increase in fundamental component or induced emf
- both (1) and (2)