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Distributed winding is a type of winding in electrical machines where all the winding turns are arranged in a number of full pitches or fractional pitches. These coils are then placed in phase form or the commutator winding in slots spread around the periphery of the air gap. This type of winding used in

Distributed winding is a type of winding in electrical machines where all the winding turns are arranged in a number of full pitches or fractional pitches. These coils are then placed in phase form or the commutator winding in slots spread around the periphery of the air gap. This type of winding used in Correct Answer <span style="">the </span>stator and rotor of induction machines

Distributed winding is a type of winding in electrical machines where all the winding turns are arranged in a number of full pitches or fractional pitches. These coils are then placed in phase form or the commutator winding in slots spread around the periphery of the air gap. This type of winding is used in the stator and rotor of induction machines.

Explanation:

The windings used in rotating electrical machines can be classified as

Concentrated Windings

All the winding turns are wound together in series to form one multi-turn coil

All the turns have the same magnetic axis

Examples of concentrated winding are

  • field windings for salient-pole synchronous machines
  • D.C. machines
  • Primary and secondary windings of a transformer

Distributed Windings

All the winding turns are arranged in several full-pitch or fractional-pitch coils

These coils are then housed in the slots spread around the air-gap periphery to form phase or commutator winding

Examples of distributed winding are

  • Stator and rotor of induction machines
  • The armatures of both synchronous and D.C. machines

Armature windings, in general, are classified as

Closed Windings

There is a closed path in the sense that if one starts from any point on the winding and traverses it, one again reaches the starting point from where one had started

Used only for D.C. machines and A.C. commutator machines

Open Windings

Open windings terminate at the suitable number of slip-rings or terminals

Used only for A.C. machines, like synchronous machines, induction machines

Important Terms :

Conductor: A length of wire which takes an active part in the energy-conversion process is called a conductor.

Turn: One turn consists of two conductors.

Coil: One coil may consist of any number of turns.

Coil–side: One coil with any number of turns has two coil-sides

The number of conductors(C) in any coil-side is equal to the number of turns (N) in that coil.

Single-layer winding

  • One coil-side occupies the total slot area
  • Used only in small ac machines

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Double-layer winding

  • The slot contains an even number (maybe 2,4,6 etc.) of coil-sides in two layers
  • Double-layer winding is more common above about 5kW machines

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The advantages of double-layer winding over single-layer winding are as follows:

  • Easier to manufacture and lower cost of the coils
  • Fractional-slot winding can be used
  • Chorded-winding is possible
  • Lower-leakage reactance and therefore, better performance of the machine
  • Better emf waveform in case of generators

Pole–pitch: A pole pitch is defined as the peripheral distance between identical points on two adjacent poles. Pole pitch is always equal to 180o

Coil–span or coil-pitch: The distance between the two coil-sides of a coil is called coil-span or coil-pitch. It is usually measured in terms of teeth, slots or electrical degrees.

Chorded-coil.

  • If the coil-span (or coil-pitch) is equal to the pole-pitch, then the coil is termed a full-pitch coil.
  • in case the coil-pitch is less, then it is called chorded, short-pitch or fractional-pitch coil

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