On 13 Oct 2005 06:24:06 GMT, (DoN. Nichols)
wrote:

According to william_b_noble :

"JB" wrote in message
...
Hi Guys,

Once again I am here with my hat in hand humbly requesting your
assistance. As some of you know, I am in the process of purchasing a
Colchester Circa 1960's MK 1 1/2 lathe. It has a two speed 5hp 3 phase
motor. Will I be able to run it successfully on a static phase converter?

you may find that a VFD costs about the same as a static converter (unless
you happen to have the parts and plan on building it yourself) - look for a
used one

Hmm ... a VFD is not likely to work well with a two-speed
three-phase motor -- unless you do all speed switching with the VFD.
You're not supposed to put the switch between the VFD and the motor, as
the voltage spikes from the switching can zap the output transistors of
the VFD.

Here is a place where I feel that a rotary converter
(build-it-yourself) would be the better choice. Or -- you could limit
yourself to one set of windings on the motor, and do all speed changing
with the VFD. For extreme cases (where you *really* need the higher
torque of the low speed, or the higher speed of the high speed), you can
stop the motor entirely (using the VFD's controls), switch to the other
speed at the lathe's switches, and then start the motor back up with the
VFD.

Good Luck,
DoN.

Absoutly correct Don. Bad things MAY happen when switching the lathe
controls when operating via a VFD.

I pulled all my lathes off the several VFDs and run them all on a 5hp
RPC for this reason.

The sole exception is that 9-18 Rivett that I wound up with several
months ago. It has a two speed motor..but last weekend, for the first
time I pulled the tarps and shrink wrap off of it..and discovered the
damned thing is 480vts....(Im not happy camper with a certain
Vietnamese charector because of this)

I could stick in one of the very very expensive 2 speed Hardnge motors
I have on hand...but I can sell them for more than the lathe is
worth..so will likely put in a single speed 3ph motor and run it off a
VFD. Its only a second ops lathe..so its no big deal.


Gunner

"Pax Americana is a philosophy. Hardly an empire.
Making sure other people play nice and dont kill each other (and us)
off in job lots is hardly empire building, particularly when you give
them self determination under "play nice" rules.

Think of it as having your older brother knock the **** out of you
for torturing the cat." Gunner