diagram ingram

Armature Windings

Armature Windings :Drum-type armatures are wound with either of two types of windings - the Lap Winding or the Wave Winding. The difference beween the two is merely due to the different arrangement of the end connections at the front or commutator end of armature.Each winding can be arranged progressively or retrogressively and connected in simplex,duplex and triplex.The following rules,however,apply to both types of the windings:

(i)The front and back pitch are each approximately equal to the pole-pitch i.e windings should be full-pitched.This results in increased e.m.f round the coils.For special purposes,fractional-pitched windings are deliberately used.
(ii)Both pitches should be odd, otherwise it would be difficult to place the coils properly on the armature.For example if YB and YF were both even,then all the coil sides and conductors would lie either in the upper half of slots or in the lower half.Hence, it would become impossible for one side of the coil to lie in the upper half of one slot and the other side of the same coil to lie in the lower half of some other slot.
(iii) The number of commutator segments is equa to the number of slots or coils because the front ends of conductors are joined to the segments in pairs.
(iv) The winding must close upon itself i.e if we start from agiven point and move from one coil to another,then all conuctors should be traversed and we should reach the same point again without a break or discontinuty in betwen.