EMF Equation of DC Machine

 EMF Equation

Related terms :-

ⲫ→ flux / pole (Wb)
P→ number of poles
Z→ total number of conductors
N→ rotor speed (rpm)
A→ number of parallel paths
A→ 2 for wave winding
A→ P for lap winding

Flux cut by conductor in one revolution = Pⲫ  (wb)

Time for one revolution = 60 / N  (sec)

e = dⲫ/dt = Pⲫ/(60 / N) = PNⲫ / 60  volts

Number of conductors in series per parallel path = Z / A

Average induced emf in armature of DC machine,
 Ea = e.(Z / A) = NPⲫZ / 60A

 Ea = (ⲫZN / 60).(P / A)  volts


Other form,

N = 60⍵m / 2𝜋         ⍵m → mechanical rad/sec
                                                            
Ea = (ⲫZ / 60)*(60⍵m / 2𝜋)*(P / A)

Ea = (PZ / 2𝜋A)ⲫ⍵m

Ea = Kⲫ⍵m               ; Where K = PZ / 2𝜋A = machine constant