An alternator has 9 slots/pole. What is the value of the pitch factor if each coil spans 8 slot pitches

• A. Cos 10°
• B. Cos 45°
• C. Cos 30°
• D. Cos 60°

Answer: (A)

Coil Span = 8
Pole Pitch = 9 slots/pole
Slot angle (α) = 180° / Pole Pitch = 180°/9 = 20°
Pitch Factor = cos(α/2) = cos (20/2)
Pitch Factor = cos 10°