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  ARMATURE WINDINGSFUNCTION OF THE ARMATURE WINDING The armature is the heart of the d-c machine; it is where the electric power srcinates in the generator and where the torque is developed in motor.Current passes to and from the armature winding across brush contacts—moving contacts;  TYPES OF ARMATURE WINDING: The two types of armature winding used on modern dc machines are LAP  and WAVE . They can be distinguished from each other in two general ways: 1 from the stand point of construction they differ only by the manner in which the coil ends are connected to the commutator bars. ! from the standpoint of an electrical circuit they differ in the number of parallel paths between positive and negative brushes. The simplest armature windings are called simplex ( simplex lap a! simplex  wave. ther modification of lap and wave types are called m l#iplex( m l#iplex$lap a! m l#iplex$%a&e' these windings differ from those of simple# construction by having more parallel paths between plus and minus brushes.The only difference between LAP  nad WAVE is the manner in which the coils ends are brought out. 1.$n lap coils the ends usually emerge midway between the sides so that connections can be readily made to commutator segments that are close together.!.$n wave coils the ends are brought out at the sides so that they may easily be  bent outward for connection to commutator bars about %&' electrical degrees apart.  COIL CONSTRUCTION :  COIL PITCH: Two important aspects of a coil for d-c- armature windings1its coil pitch !its commutator pitch Cil Pi#)*  refers to the distance between the two sides of the individual coils.(easured in terms of slots) it is determined in e#actly the same way for all windings whether lap or wave) simple# or multiple#) generator or motor. *here:+ ,(/: 0 s   2 - 3 0 s  coil pitch) slots 4 2  total number of armature slots 4  number of main poles 3  any part of 254 that is subtracted to ma3e 0 s  an integer  6#ample: 1 Calculate the coil pitches 0 s  and indicate the slot numbers for the first elements) for windings with the following slot and pole combination:a 278) 48)  b2&!) 48 c 2&&) 4 & d 2 181) 4  &) e 2  1%!) 4  9 2olution:a 0 s   78 - 1  1% slots 1 to 18 8 ! b 0 s  &!  1  17 slots 1 to 1& 8 !c 0 s   &&  '  1! slots 1 to 1! &C ((T/T , 4$TC: Commutator pitch refers to the distance on the commutator between the two ends of a coil element. (easured in terms of commutator segments) its value is determined in a different way for lap and wave windings.a Cmm #a#+ Pi#)* ,+ Lap Wi!i-s : <esignated the commutator pitch by 0 c  )its value is equal to the degree of multiplicity---the ple#—of a lap winding. Thus 0 c  equals 1)!)%)8) etc) for simple#) duple#) triple#) quadruple#) etc.) lap windings respectively. These numbers indicate that the coil ends are =oined to segments 1 and !) 1 and %) 1 and 8) etc. b Cmm #a#+ Pi#)* ,+ %a&e %i!i-s : the ends of each coil element of a wave winding are bent outward from the coil sides and are connected to commutator segments ea+l.  %&' electrical degrees apart. +or simple# wave: +or multiple# wave 0 c   C >- 1 0 c   C >- m 45! 45! *here: 0 c   commutator pitch C  total number of commutator segments 4  number of poles 6?/(46: Calculate the commutator pitches 0 c  and indicate the commutator segment numbers for the first coil elements) for simple#-wave windings with the following segment and pole combination. / C  &@) 48 b C  187) 4  8; c C  !!A) 4  & dC  !&@ ) 4  9 e C  %!& ) 4  1'
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