Q. A 6 - pole, DC armature with 36 slots and 2 coil - slides/slot is to be wave wound (double layer). Calculate the back pitch, front - pitch and commentator pitch. How many dummy coils, if any are required?
Ans.
Given
C = 36
P = 6
C = P/2Y_{c }± 1
36 = 6/2 Y_{c }± 1
36 = 3Y_{c }± 1
Let Y = 12 then
C = 3 ×12-1
= 35
SO we choose C = 35 which actually 36 coils be accommodate
Y_{es} = S/P = 36/6 = 6
Y_{B} = 2Y_{CS} + 1
Y_{B} = 2 × 6 + 1
Y_{B} = 13
Y_{F} = 2Y - Y_{B} = 2 ×12 - 13 = 11