E.M.F. Equation of an Alternator : Part4
Considering full pitch, concentrated winding.
Considering full pitch, concentrated winding.
E_{ph } = 4.44 f Φ T_{ph } Volts.
But due to short pitch, distributed winding used in practice, this will reduce by factors and . So generlised expression for e.m.f. equation can be written as
For full pitch coil, K_{c }= 1.
For concentrated winding K_{d }= 1.
Note : For short pitch and distributed winding K_{c } and K_{d }are always less than unity.
Example 1 : An armature of a three phase alternators has 120 slots. The alternators has 8 poles. Calculate its distribution factor.
Solution :
n = Slots/Pole = 120/8 = 15
m = slots/pole/phase = n/3 = 15/3 = 5
β = 180^{o}/n = 180^{o}/5 = 12^{o}
= 0.957
Example 2: In a 4 pole, 3 phase alternator, armature has 36 slots. It is using an armature winding which is short pitched by one slot. Calculate its coil span factor.
Solution :
n = Slots/pole = 36/4 = 9
β = 180^{o}/ = 20^{o}
Now coil is shorted by 1 slot i.e. by 20^{o }to full pitch distance.
.^{.}. α = Angle of short pitch = 20^{o}
.^{.}. K_{c }= cos (α/2) = cos (10)
= 0.9848
Related Articles
- E.M.F. Equation of an Alternator
- Pitch Factor or Coil Span Factor (Kc)
- Distribution Factor (Kd)
- Line Value of Induced E.M.F
Related Articles
- E.M.F. Equation of an Alternator
- Pitch Factor or Coil Span Factor (Kc)
- Distribution Factor (Kd)
- Line Value of Induced E.M.F
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