Winding factor

In power engineering, winding factor is a technique that is employed to improve the rms generated voltage or electromotive force (EMF) in a three-phase AC electrical machine so that the output voltage and hence torque does not have any harmonics in it which may reduce efficiency. 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 Kd. Another factor that can reduce the winding factor is when the slot pitch is smaller than the pole pitch, called pitch factor Kp. In power engineering, winding factor is a technique that is employed to improve the rms generated voltage or electromotive force (EMF) in a three-phase AC electrical machine so that the output voltage and hence torque does not have any harmonics in it which may reduce efficiency. 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 Kd. Another factor that can reduce the winding factor is when the slot pitch is smaller than the pole pitch, called pitch factor Kp. The winding factor can be calculated as Kw = Kd * Kp To calculate the winding factor, Kw=Kd X Kp ----(1) Where Kd=~1 (point here to keep in mind is that all(three phase) motors are balanced systems. Kp=Cos(a/2) ----(2) where a is the value of by which the coil is short-pitched To calculate a, one needs to know and hence calculate the coil pitch and pole pitch of the motor. Coil pitch is 2pi/number of slots. It needs to be in electrical degrees so the answer has to be divided by 2.