The winding of a 4-pole alternator having 36 slots and a coil span of 1 to 8 is short-pitched by........ degrees.

The winding of a 4-pole alternator having 36 slots and a coil span of 1 to 8 is short-pitched by........ degrees.

A.140
B. 80
C. 20
D. 40

Explanatory answer:

Pole pitch:
                Centre to centre distance between two adjacent poles
                Pole picth= 180 deg electrical
                Pole pitch= slots/Pole= n

Coil span :
               The distance between two coil sides of acoil
               Expressed in electrical deg or by no. of slots
Given:
          P=4, S=36

Pole pitch,n= 36/4= 9 slots

i.e. 9 slots contributes one pole pitch(9 slots=180 deg)

therefore 1 slots = 180/9 = 20 deg

i.e 1 slots contributes 20 deg

given coil span (1 to 8 slots) i.e.8-1=7 slots

so the winding is short pitched by  = 2 slots ( pole pitch- actual coil span=9slots-7slots)

short pitch in deg = (deg for 1 slot * no of slots short pitched)

                          =  20 * 2
                          = 40 deg