I bought a small vertical/horizontal mill about a month ago and got it into
my garage without too much excitement. It has a 2 hp, 3-phase motor for the
drive, and I bought it knowing I'd likely buy a VFD to drive it from my 220
volt service. (Buying a static converter doesn't make a lot of sense given
the loss of HP, and building/balancing a rotary phase converter isn't quite
up my alley and is going to take more space than a VFD. Also, VFD prices are
generally competitive with commercial phase converters.)

I've been primarily looking at the Teco FM100 unit at Dealers Electric,
having seen it mentioned on r.c.m. a number of times. However, my garage is
detached and isn't likely to be heated in this century. All the VFDs I've
seen specs for say that the ambient temperature shouldn't be lower than
about 10-15F (-10C). Well, that's true anytime between late May and early
October in my area (St. Paul, Minnesota).

I'd really like to use my tools year 'round (weekends mostly), and I'll be
installing radiant heaters over the lathe and mill for the cold periods, but
I don't want to keep them on all the time. (I may install contact heaters on
the mill and lathe and cover them with insulation to prevent rust.)

So I've been thinking about installing the VFD in an insulated box with a
thermostat-controlled heater to keep it at least within the spec'd range.
I'd think an insulated steel box for the VFD with a separate power-kill box
upstream would provide the safe and highly-visible way to turn off the VFD's
power supply.

Any suggestions for improving on this scheme? Any pitfalls that you can
think of?

Thanks,
Pete Bergstrom