I can't believe so few get my point. Frequency input to induction motor, as *separate* single parameter is under *your* control independent of other variables (voltages) you apply to the motor because commutator is external (solid state).
Not the case for brushed DC motor - *you* don't apply frequency to them. they take care of it with commutator. This is the difference. I get impression that instead of delivering useful information to the list some people almost waiting to catch errors and prove others wrong or inaccurate. I know it's not an intent but makes me to want to post less and less. Victor Lee Hart wrote: > > Victor Tikhonov wrote: > > > Fine. All these details are obscuring my point that there is > > a variable - frequency - applicable to AC motors only. > > How about a "brushless DC" motor, like a computer fan? They are actually > AC motors, with an electronic commutator. There is no frequency input, > and they run at a speed determined by load and the voltage applied. > > How about the induction motors in your furnace, window fan, or ceiling > fan? They all run on fixed 60 Hz AC (no frequency control), yet are > variable speed just by varying the voltage to them. > > Frequency applies to DC motors, too. The coils all have AC or pulsating > DC flowing in them, produced by the commutator (mechanical or > electronic). Higher frequencies = higher speeds. Unipolar stepper > motors, for example; coil current is pulsating DC (one polarity), and > the repetition rate determines speed. > -- > Lee A. Hart Ring the bells that still can ring > 814 8th Ave. N. Forget your perfect offering > Sartell, MN 56377 USA There is a crack in everything > leeahart_at_earthlink.net That's how the light gets in - Leonard Cohen
