Determine the pitch factor for winding: 36 stator slots, 4-poles,
Determine the pitch factor for winding: 36 stator slots, 4-poles, coil spans 1 to 8.
A. <p>cos 20<span style="position: relative; font-size: 10.5px; line-height: 0; vertical-align: baseline; top: -0.5em;">0</span></p>
B. cos 40<span style="position: relative; font-size: 10.5px; line-height: 0; vertical-align: baseline; top: -0.5em;">0</span>
C. <p>cos 30<span style="position: relative; font-size: 10.5px; line-height: 0; vertical-align: baseline; top: -0.5em;">0</span></p>
D. cos 80<span style="position: relative; font-size: 10.5px; line-height: 0; vertical-align: baseline; top: -0.5em;">0</span>
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Right Answer is: A
SOLUTION
Concept:
Pitch factor for nth harmonic is given by,
\({k_c} = \cos \frac{{n\alpha }}{2}\)
Where α is short pitch angle in degrees
Calculation:
Given-
Total slots = 36,
Number of poles = 4
Coil span = 1 to 8 = 8 - 1 = 7 slots
Now, Slots per pole = 36 / 4 = 9
Number of empty slots = 9 – 7 = 2 slots
\(\therefore \alpha = 180^\circ \times \frac{2}{{9}} = 40^\circ\)
Hence pitch factor can be calculated as
Kc = cos 20°