Page 153 - Electrician - TT (Volume 2)

ELECTRICIAN - CITS

Example: Back and front end connections. (Fig 3)

Fig 3

Leads of coil : The ends coming out from a coil are known as leads of a coil. Every coil has got two leads.
Pole-pitch(Yp) : It may be variously defined as:

• the periphery of the armature divided by the number of poles of the machine i.e. the distance between two
adjacent poles. It is denoted by Yp.
• it is equal to the number of armature conductors (or armature slots) per pole. For example, if there are 48
conductors, 24 coils, 24 slots and 4 poles, then the pole pitch is

Number of slots 24
Y P Number of poles 4 in 6 terms of slots
or
No. of conductors 48
Y P 12 in terms of conductors
No. of poles 4

Coil-span or coil-pitch(YS) : The coil-span or coil-pitch is the distance, measured in terms of armature slots or
armature conductors between two sides of a coil. It is in fact the periphery of the armature measured in terms of
slots or conductors spanned by the two sides of the coil. It is denoted by YS as shown in Fig 4.

Fig 4

Coil-pitch YS is calculated in the same way as is done for Pole pitch.
Hence the modified calculation will be

No. of slots S
Y S No. of poles - K P - K (in terms of slots)

No. of conductors C
- K - K (in terms of conductors )
No. of poles P

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