Page 173 - Electrician - TT (Volume 2)

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Concentrated winding : If in any winding the number of coils/pole/phase is one, then the winding is known as
‘concentrated winding’. In this winding each coil side occupies one slot.
Distributed winding : In this winding the number of coil/pole/phase is more than one - arranged in different slots.
In this case each coil has the same pole pitch.

Fig 11

Partially distributed winding: In this winding the coil sides do not occupy all the slots, but some slots remain
empty and they are called dummy slots.
Fully distributed winding : It is a winding in which not a single slot remain empty.
Different types of AC Windings
The types of AC windings according to shape are as follows.

a Basket winding
b Concentric winding
c Skein winding
d Flat loop Non-overlapped winding
e Flat loop overlapped or chain winding
f Skew winding

g Diamond coil winding
h Involute coil winding
Basket winding : After the completion of the winding, the ends of the winding resemble the weaving of a basket
and hence it is known as basket winding. Basket winding is of two types. a) Single layer basket winding as shown
in Fig 12a, double layer basket winding as shown in Fig 12b.
Concentric (or box type) winding : This winding has two or more than two coils in a group, and the coils in each
group have the same centre. In each group, the coil pitch is not equal, and, therefore, do not overlap each other.
In this winding the coil pitches are not equal and each coil of the group has a difference of 2 slots in its pitch.
Though it requires more labour to insert coils due to different coil spans, the design allows more cooling space.
This winding is usually provided in single phase motor winding. This is shown in Fig 13.

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CITS : Power - Electrician & Wireman - Lesson 86-92