Page 157 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Ex. For duplex 2x2 = 4 conductors.
For triplex 2x3 = 6 conductors and so on.
The average pitch should be as given by the formula
Commutator pitch should be
Y = ± 1 for simplex
C
= ± 2 for duplex
= ± 3 for triplex and so on.
• The number of parallel paths `A’ in the armature will be the multiple of the number of poles. A = P, in the case
of simplex lap winding, i.e 2-pole armature winding will have 2 parallel paths, 4-pole armature winding will have
4 parallel paths and so on. However, the number of parallel paths for multiplex winding will be equal to A = P
x No. of `plex’.
• There must be as many brushes as there are poles.
• The brushes must be wide enough to cover atleast m segments, where ‘m ‘ is the ‘plex’ (multiplicity) of the
winding.

Progressive winding
Z
Back pitchY B 1
P
Front pitch Y = Y 2 x plex
B
F
Reprogressive winding
Z
Front pitchY F P 1

Back pitch Y = Y 2 x plex
B
F
To make the winding possible as lap-winding, Z/P must be an even number.
Considering the above points, only the armature having the designated slots can be wound for lap
winding.

Calculations : The following calculations are made for finding out winding pitches and coil connections with
commutator segments for simplex lap winding.
Example

No. of commutator segments 6
No. of slots 6
No. of poles 2
Type of winding simple lap.
As pointed out earlier the winding should be in double layer only.

Solution
No. of coils = No. of commutator segments = 6 coils
No. of conductors or coil sides = No. of coils x 2
= 6 x 2 = 12 conductors.

No. of slots
Pole pitchY P No. of poles 6/2 3 slots

No. of conductors
Also Y P in terms of conductors
No. of poles
12/2 6 conductors

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