Saved Bookmarks
| 1. |
How are the different emfs generated in a three-plane AC generator? Show the graphical representation of theses emfs. |
|
Answer» Solution :i. In some AC generators, there are three separate COILS, which would give three-phase AC generators. ii.In the simplified construction of three-phase AC generator, the armature core has 6 slots, cut on its inner rim. Each slot is `60^(@)` away from one another. Six armature conductors are mounted in these slots. The conductor 1 and 4 are joined in series TOFORM coil 1. The conductors 3 and 6 from coil 2 while the coil are retangular in shape and are `120^(@)` apart from one another (Figure).  iii. The initial position of the field magnet is HORIZONTAL and field direction is perpendicular to the plane of the coil 1. As it is seen in single phase AC generator, when field magnet is ROTATED from that position in clockwise direction, alternating emf `omega1` in coil 1 begin a cycle from origin O. This is show in Figure.  iv. The corresponding cycle for alternating emf `omega_(2)` in coil 2 starts at point A after field magnet has rotated through `120^(@).` Therefore, the phase difference between `omega_(1)andomega_(2)" is "120^(@).` Similarly, emf `omega_(3)` in coil 3 would begin its cycle at point B after `240^(@)` rotation of field magnet from initial position. Thus these emf produced in the difference between one another. |
|