Correct Answer - Option 3 : 36°
Pitch Factor or Coil Span Factor or Chording factor (Kp):
- It is defined as the ratio of emf generated in a short pitch coil to the emf generated in a full pitch coil.
- It is denoted by Kp and its value is always less than unity.
- It can also be defined as the ratio of the vector sum of induced emf per coil to the arithmetic sum of induced emf per coil
.
If α be the angle in electrical degrees, by which the span of the coil is less than a pole pitch in the alternator, then mathematically pitch factor is defined as
KP = resultant emf of short pitch coil/ resultant emf of full pitch coil = cos α/2
For nth harmonic
Kpn = cos nα/2
Where n is the nth harmonic
Calculation:
Kp5 = 0 will make fifth harmonic component to zero
cos (5α/2) = 0
(5α/2) = π/2
Chording angle
α = π/5 = 36°
