D C Motor Armature Constructional Details

D C Motor Armature Constructional Details

D C Motor armature is consist of armature core, winding, commutator and shaft etc. The core is made  up of  silicon steel laminations of 0.35 to 0.5 mm thickness.These laminations are stacked and pressed in hydraulic press and riveted to make armature core. There are slots on the periphery of armature core to hold armature winding coils. No of slots (N) are generally 12, 24, 36 fully divisible by number of poles (P). Number of poles are always in multiple of 2, like 4, 6, 8 etc. Number of coils are equal to half the number of slots in simplex winding, each slot holds only one coil side. Number of coils are equal to the number of slots in duplex winding here each slot holds two coil sides. Each coils has two coils side with number of turns T.

Armature winding:-

Lap winding:- lap winding is used for high current low voltage machines. The number of parallel path (A) is equals to number of poles. Example welding generator.

Wave winding:- Wave winding is used for high voltage  low current  machines. The number of parallel path (A) is equals to 2. D C Motor voltage is generally limited 400 volt due to commutator size becomes large.

Commutator:- the commutator is made of copper segments fixed on periphery of insulating material bush. number of segments are equals to number of coils in armature.
Shaft:- Armature core with winding and commutator are rigidly fixed on the shaft. Two bearings are also fixed on both side of shaft to provide free rotation of armature within field poles of motor.