Let Z = No. of conductors or coil sides in series/phase
And, Z=2T, where T is the No. of coils or turns per phase (NOTE --one turn or coil has two sides)
P = No. of poles
f = frequency of induced e.m.f. in Hz
φ = flux/pole in webers
kd = distribution factor
kc or kp = pitch or coil span factor
kf = from factor = 1.11 , if e.m.f. is assumed sinusoidal
N = rotor r.p.m.
In one revolution of the rotor (i.e. in 60./N second) each stator conductor is cut by a flux of φ P Weber.
Now, we know that,
f = PN/120 or, N = 120 f/P
Substituting this value of N above, we get
If there are Z conductors in series/phase, then
This is the actual value of induced voltage if all coil in a phase This would have been the actual value of the induced voltage if all the coils in a phase were (i) full-pitched and (ii) concentrated.
The actually available voltage is reduced in the ratio of these two factors.
