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Re: [femm] AC Solenoid example
bdearl65 wrote:
I am trying
to model an AC solenoid. I do not understand how to
drive the coil. For DC I already know the resistance of the coil so
it is simple to determine what the coil current will be. I enter
this either as a current density in the material properties dialog
box or as a current in the circuit dialog box.
For AC, the inductive reactance depends not only on the coil, which I
can compute, but also on the configuration of the solenoid
components, which is not easy to compute. I would assume this is one
of the reasons you would use FEMM anyway! How do I apply current to
the model when I don't yet know what the inductive reactance is?
Just apply an arbitrarily chosen current and evaluate the problem. Once
you solve the problem, you can then back out the inductive reactance using
the methods described in the example at
http://femm.berlios.de/induct1/induct1.htm For AC problems, it's best
to use the A.J method. Then, using this inductance, you can figure out how
much current should be there for a given source voltage.
Dave.