harryagain wrote:
Why do you suppose that "iron losses" in AC motors and tranformers are
almost constant regardless of load.
Not for the reasons you suppose.

The iron losses are constant because the flux is constant.

The flux varies with the current. That's how a transformer works. The
current in the primary winding varies, which causes the magnetic flux in
the core to vary, which generates current in the secondary winding.

The losses in iron cores are due to hysteresis, which is a non-linearity
in magnetic response of the iron to changing magnetic fields,
particularly ones that reverse periodically. Entropy and quantum effects
are involved.

--
Tciao for Now!

John.