Say I'm trying to connect an AC generator to a circuit containing an inductor and a resistor, powered by a steam turbine. I understand that because of the resistor, I'll be dissipating energy and therefore I'll need to drive the generator with a certain torque. But what about the inductor? Obviously there's no dissipation of energy. Rather it is given and taken from the inductor. So does this mean that I'll get pulses of torque in the generator shaft? I mean, sometimes the inductor will pose a torque that opposes the rotation of the shaft, then the next moment it will produce a torque in the same direction. Have I understood this correctly?

  • $\begingroup$ @StainlessSteelRat The average torque depends on the average real power. The OP is asking about the change in torque during each cycle of the AC current. $\endgroup$
    – alephzero
    Apr 29 '21 at 23:01
  • $\begingroup$ You are right, and this is an important criterion for generator design. Note that for a 3-phase generator, there can also be torque variations at twice the AC frequency caused by unbalanced load in the phases. See energiforskmedia.blob.core.windows.net/media/25107/… for details, and also ISO 22266-1. $\endgroup$
    – alephzero
    Apr 29 '21 at 23:21
  • $\begingroup$ So it's true then, that reactive power does result in periodic torque variations, right? $\endgroup$
    – Nacho
    May 1 '21 at 21:18

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