Design of electric machine

1. Distribution Factor.
Concentrated Windings.
Distributed Windings.
Submitted To:
Mr. Ahsan ul Haq
Subject:
Design of electric
machine.
Submitted By:
M. Abdullah
(2014-EE-469)
Dated:
(21-12-2017)

2. Distribution Factor

3. Definition:
 As per definition, distribution factor, is measure of resultant emf of a distributed
winding in compared to a concentrated winding.
 It is expressed as ratio of the phasor sum of the emfs induced in all the coils
distributed in a number of slots under one pole to the arithmetic sum of the emfs
induced. Distribution factor is,
Kd= phasor sum of the emfs induced / arithmetic sum of the emfs induced
Kd=
cos mβ/2
mcosβ/2

4. Bisector to Find β :

5. Bisector to Find β :
 As pitch factor, distribution factor is also always less than unity.
 Let number of slots per pole is n.
β=
180
𝑛
The emfs induced in different coils of one phase under one pole are represented by
AC, DC, DE, EF and so on. They are equal in magnitude but differ from each other by
an angle β.

6. Cocentrated Windings

7. Concentrated Windings:

8. Concentrated Windings:
 Concentrated winding is employed where number of slots on the armature is
equal to number of poles in the machine.
 This armature winding of alternator gives maximum output voltage but not exactly
sinusoidal.
 The most simple single phase winding, is shown below in the figure-1.
 In the figure-1, number poles = number of slots = number of coil sides.
 One coil side is inside one slot under one pole and other coil side inside other slot
under next pole.
 Clearly the emf induced in one coil side is added to that of adjacent coil side.

9. Concentrated Windings:
 This arrangement of armature winding of alternator, is known as skelton wave
winding.
 As per the fig-1, coil side-1 under N-pole is connected to coil side-2 under S-pole at
the back and coil side-3 at the front and so on.
 The direction of induced emf of coil side-1 is upward and emf induced in coil side-2 is
downward as shown in fig 1.
 Again as coil side-3 is under N-pole, it will have emf in upward direction and so on.
Hence total emf is summation of emf of all coil sides.
 In order to get higher emf, the multi turn half coiled winding is used, for this we have
to use double layer windings as shown in fig2
 Same process will run thoroughly as for single layer windngs.

10. Concentrated Windings:

11. Distributed Windings:
 For obtaining smooth sinusoidal emf wave from, conductors are placed is several
slots under single pole we used distributed windings.
 Although distributed armature winding of alternator, reduces emf but still it very
much usable due to following reasons:
1. It also reduces harmonic emf and so wave form is improved.
2. It also diminishes armature reaction.
3. Even distribution of conductors, helps for better cooling.
4. The core is fully utilized as the conductors are distributed over the slots on the
armature periphery.

12. Distributed Windings:

13. THANKS FOR WATCHING