The value of slots per pole per phase decides the class of the winding.
m = slots / pole / phase
Note : When the value of m is integer, then the winding is called integral slot winding.
Consider 2 pole, 12 slots alternator hence,
n = slots / pole = 12/2 = 6
... Pole pitch = 180o = 6 slots
... m = n/3 = 6/3 = 2
As m is integer, the type of winding is integral slot winding.
This winding can be full pitch winding or short pitch winding.
Let, the winding is full pitch winding. For integral slot
winding, coils of one coil group lying under one pole pair are connected
in series. Thus the end of the first coil is connected to start of the
next coil lying to the right of the first coil. The alternate coil
groups must be reverse connected such that e.m.f. induced in them is
additive in nature. Any slot contains the coil sides which belong to the
same phase. Such a winding is shown in the Fig. 1.
 |
| Fig. 1 Double layer integral slot winding |
If the short pitch coils are used for integral slot winding then
in each group of the slots per pole phase, the coil sides of different
phases exist.
