We know that in a synchronous generator or alternator when the conductors of the rotor cuts the alternating magnetic flux lines produced by the stator or field winding an EMF will induce in the rotor conductors (according to the faraday's law). Eventually, this emf circulates currents through the rotor conductors. Let us see the expression for induced emf in the rotor conductors.

## EMF Equation of Synchronous Generator :

#### Let,- Z
_{ph} = Number of conductors in series per phase = 2T (T = Number of turns per phase). - P = Number of poles.
- Φ = Useful flux per pole in weber.
- f = Frequency of the induced emf equal to NP/120 Hz.
- N = Rotational speed in rpm.
- K
_{c} or K _{p} = Pitch or chrding or coil span factor = Cos α/2. - K
_{d} or K_{b} = Distribution factor/breadth factor
- K
_{f} = Form factor = 1.11 for sinusoidal emf.

_{ph}= Number of conductors in series per phase = 2T (T = Number of turns per phase)._{c}or K_{p}= Pitch or chrding or coil span factor = Cos α/2._{d}or K_{b}= Distribution factor/breadth factor_{f}= Form factor = 1.11 for sinusoidal emf.#### Total flux cut to complete one revolution is given by,
= P Φ weber
Time taken to complete one revolution is,
= 60/N sec
According to faraday's law of electromagnetic induction average emf induced per conductor,

#### Average emf induced per phase is given by,
= 2 f Φ Z_{ph} volts
= 4 f Φ T volts
RMS value of emf induced per phase is given by,
= Average value of emf per phase * Form factor
= 1.11 × 4 f Φ T
= 4.44 f Φ T volt
If pitch factor K_{c} and distribution factor K_{d} are considered then the actual emf induced will reduce. Actually induced emf per phase is given by,
= 4.44 K_{c} K_{d} f Φ T volts
E_{ph} = 4 K_{f} K_{c} K_{d} f Φ T volts

_{ph}volts

_{c}K

_{d}f Φ T volts

_{ph}= 4 K

_{f}K

_{c}K

_{d}f Φ T volts