Winding factor

In power engineering, winding factor is what makes the rms generated voltage in a three-phase AC electrical generator become lesser. This is because the armature winding of each phase is distributed in a number of slots. Since the emf induced in different slots are not in phase, their phasor sum is less than their numerical sum. This reduction factor is called distribution factor K_d. Another factor that can reduce the winding factor is when the slot pitch is smaller than the pole pitch, called pitch factor K_p. The winding factor can be calculated as K_w = K_d * K_p.

Most of the three-phase machines have winding factor values between 0.85 and 0.95.

With the free online winding editor in Emetor, it is possible to determine the fundamental winding factor as well as the winding factor space harmonics for different winding arrangements as a function of the number of slots and number of poles of the winding.

See also

• Electrical machine

References

• Saadat, Hadi. 2004. Power Systems Analysis. 2nd Ed. McGraw Hill. International Edition.
• "Emetor winding editor", December 18, 2010, Emetor AB