E.M.F. Equation of an Alternator : Part4
Considering full pitch, concentrated winding.
Considering full pitch, concentrated winding.
Eph = 4.44 f Φ Tph 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, Kc = 1.
For concentrated winding Kd = 1.
Note : For short pitch and distributed winding Kc and Kd 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 = 180o/n = 180o/5 = 12o
= 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 = 180o/ = 20o
Now coil is shorted by 1 slot i.e. by 20o to full pitch distance.
... α = Angle of short pitch = 20o
... Kc = 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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