I am running an alternator with an electric motor (variable speed), but I do not know the shaft speed. I would like to calculate it from voltage frequency.
The rotor of the alternator has 12 poles (6 south + 6 north >> http://www.tb-training.co.uk/images/poles.gif). The stator winding is connected as Delta. If a connect a multimeter (Fluke 87V) across one of the three windings, I get 100Hz. Following formula:
Nshaft = 120*frequency/poles
I get rotation speed of 1000 rpm. Is my calculation correct?
Best Answer
You are correct. The number of poles is the sum of the north plus south poles. Speed(RPM) = Frequency(Hz) X 120 / Poles = 100 X 120 / 12 = 1000 RPM. I think Andy must have read your question too fast.