Ignoramus8727 wrote:
What would you say, can one run a 230/440v motor that is 45 years old,
from a VFD.

I ran a Bridgeport M-head motor off a VFD. The
crummy less-than first
generation VFD eventually smoked when I tried plug
reversing the motor.
That motor worked SO MUCH better off a VFD than a
static phase converter it
was amazing. The motor was, I'm sure, the
original 1938 motor on that
mill.
I had a bad experience running a 230v only motor of a similar vintage,
due to current leakage. The 440v motors, though, have better
insulation.
Yes, the motor I mention above was a 230/460 V
unit. I am also running
a 1950's vintage J-head motor on a VFD now, and it
also works fine. So, it
also pretty much qualifies for your 45 year old
question. I have run it
for well over 10 years on a VFD with no problems.
This is the Bridgeport
"pancake" motor on 1 Hp step-pulley mills,
single-speed 230/460 V.

Jon