Page 152 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Armature winding - terms - types - rewinding of mixer/

liquidizer

Objectives: At the end of this lesson you shall be able to:
• define the general terms used in DC armature winding
• explain the different types of DC armature winding.

DC armature winding : It is a closed coil winding, wherein the coil ends are connected through the commutator
segments to form the closed circuit.

Terms used in DC armature winding
Coil or winding element : Length of a wire lying in the magnetic field and in which an emf is induced is called
an active conductor.
Referring to Fig 1, we find the two active conductors AB and CD along with their end connections constitute one
coil or winding element of the armature winding. The coil may consist of a single turn only as shown in Fig 2 or
multi-turns as shown in Fig 3. A single-turn coil or winding element will have two conductors only. But a multi-turn
coil may have many conductors per coil side. In Fig 2 for example, each coil side has 3 conductors. The group of
conductors constituting a coil side of a multi-turn coil is tied together with a tape as a unit (Fig 3) and is placed in
the armature slot. It may be noted that each winding element has two connecting leads and each commutator bar
has two connecting leads brought from the winding. As such there are as many commutator bars as the number
of winding elements.

Fig 1 Fig 2

Active sides : These are the sides which lie within the slots. They are also known as coil sides. The induction
takes place only in the active sides of the coil while they move in the magnetic field. (Fig 3)
In winding calculation these active sides are considered as conductors. The coil has got two
conductors irrespective of the number of turns.
Inactive sides : That part of a coil which does not lie in the slot is known as the inactive side of a coil. No induction
takes place in the inactive sides.

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CITS : Power - Electrician & Wireman - Lesson 86-92