USA - Armature For Electrlc Machines - Google Patents
Pole Pitch Definition of Pole Pitch The pole pitch is defined as peripheral distance between center of two adjacent poles in DC machine.
We can overcome this problem, some extent by using multi turns coil. An armature for electric machines, consisting of a laminated core formed with diverging slots for receiving the Wires, said slots leaving intervening webs, and coils of wire wound in said slots.
If the coil is made up of single turn or a single loop of conductor, it is called single turn coil. Whatever may number of armature slots the number of conductors per side of the coil, each coil side is placed inside one armature slot only.
This armature winding is known as distributed winding. A single turn coil will have one conductor per side of the coil whereas, in multi turns coil, there will be multiple conductors per side of the coil.
This arrangement of an armature winding in an alternator is known as skeleton wave winding. Hence resultant terminal voltage of the coil is vector sum of these two emfs and it is less than that of full-pitched coil.
An armature-core for electric machines, consisting of plates of magnetizable material separated by insulation, having radial openings at intervals, slots diverging from said openings for receiving armature-coils, and windingblocks or clips at the ends of the core. Here, one coil side is inside one slot under one pole and the other coil side inside other slots under next pole.
Say red phase winding starts at slot no 1 and ends over slot no If the coil is made up of more than one turn of a conductor, we refer it as a multi-turn coil. If the coil span is less than the pole pitch, then the winding is referred as fractional pitched. The phase difference of induced emfs, in red phase and yellow, yellow phase and blue phase and blue phase and red phase winding respectively by 60 degrees, 60 degree and degrees electrical respectively.
Single Phase Armature Winding Single phase armature winding can be either concentrated or distributed type. Balanced Winding If under each pole face, there are an equal number of coils of different phases, then the winding is said to be balanced winding.
The invention relates to the construction of armatures for electric generators and motors, and the object is to provide an electricallyeffioient armature, the construction of which is simple and economical, and in which the coilsfof insulated conducting wire or ribbon may be conveniently Wound or formed into bobbins so located with reference to the body of the number of armature slots as to afford as good results as possible.
Definition of Coil Span Coil span is defined as the peripheral distance between two sides of a coil, measured in term of the number number of armature slots armature slots between them. Figure - 2 shows this. The outer coil pitch is 5, the middle coil pitch is 3, and inner coil pitch is one.
The induced emfs on two opposite side of coil differ by degrees electrical. In this winding, the coils are of different pitches. Fractional pitched windings are purposely used to effect substantial saving in copper of the end connection and for improving commutation.
This winding has 12 slots per pole per phase.
Armature Winding | Pole Pitch Coil Span Commutator Pitch