JT> A higher inductance might have something to do with it as
JT> well...

JB> ISTM that twice as many turns means twice the inductance
JB> therefore half the current

 Basically, inductance is proportional to the *square* of turns, but
iron running high flux will be saturated and increasing turns will
also increase the permeability so you'll get even more inductance
than that. With an electric motor, most of the current comes from the
load (the fan loads the motor considerably) so the actual current
won't drop by much.

JB> but since the half current is through twice as many turns you
JB> get exactly the same magnetic field.

The magnetic field halves - current drops 4-times. For a fixed mains
voltage, if you double the turns you halve the flux densisty, so the
current has to drop *four* times to give the same answer for flux on
ampere-turns. Otherwise, it doesn't make sense.

JB> what am I doing wrong?

 God was very clever when he designed electric fields. It all fits.
When you think it doesn't... it's you that doesn't fit.

Regards,
Bob







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