of winding is used in dc generators designed for high-current applications. The
windings are connected to provide several parallel paths for current in the
armature. For this reason, lap-wound armatures used in dc generators require
several pairs of poles and brushes.
winding, the finishing end of one coil is connected to a commutator segment and
to the starting end of the adjacent coil situated under the same pole an so
on,till all the coils have been connected.This type of winding derives its name
from the fact it doubles or laps back with its succeding coils.Following points
regarding simplex lap winding should be noted:
The back and front pitches are odd and of opposite
sign.But they can't be equal. They differ by 2 or some multiple thereof.
Both YB and YF shpuld be nearly equal to a pole
The average pitch YA = (YB + YF)/2.It equals pole
pitch = Z/P.
Commutator pitch YC = ±1.
Resultant pitch YR is even, being the arithmetical
difference of two odd numbers i.e YR = YB - YF.
The number of slots for a 2-layer winding is equal
to the number of coils.The number of commutator segments is also the same.
The number of parallel paths in the armature = mP
where 'm' is the multiplicity of the winding and 'P' the number of poles.Taking
the first condition, we have YB = YF ± 2m where m=1 fo simplex lap and m =2 for
duplex winding etc.
If YB > YF i.e YB = YF + 2, then we get a
progressive or right-handed winding i.e a winding which progresses in the
clockwise direction as seen from the comutator end.In this case YC = +1.
If YB < size="1">F i.e YB = YF -
2,then we get a retrogressive or left-handed winding i.e one which advances in
the anti-clockwise direction when seen from the commutator side.In this case YC
Hence, it is obvious that for