"Don Foreman" wrote in message
...
On 21 Jan 2006 11:51:23 -0800, "Mark Main" wrote:


Am I wrong with my understanding? Is there a better way to adjust the
RPM for the full range of the Monarch 10EE without severe torque
impact?

Bear in mind that when you change pulleys or gear ratios, you
increase available torque when you reduce output speed. A VFD does
not do this. The torque an induction motor can deliver does not
increase when speed is reduced by reducing drive frequency.


A proven design for the 10EE is to use a VFD and 10 HP motor. No need for
backgear (lower gear) if you go this route. You can run a VFD off single
phase if you oversize it. In this case a 15 hp. VFD would run your 10 hp.
motor. Belt your unit so that you get max RPM at two times motor nominal
speed. For example a 1750 motor will go 3500 RPM top end with a VFD. You'll
need to step it up a bit if you want 5000 at the spindle for example.

You have to be careful that you don't buy a VFD that senses for all three
phases present. I bought a Hitachi S300 and found out I couldn't use it. But
the Hitachi S100 doesn't test for three phase. I'm using a 10 hp unit to run
my 7 1/2 hp. lathe. I bought from Automation Direct web site.

I used the back gear on my Monarch 10 EE. I already had it on the machine.
Then I could use a 5 hp motor and 7 1/2 hp. VFD. WAY LESS BUCKS!

For your other queries. look up a web site "Metal Web News" There's a huge
section on 3 phase build your own converters.

Karl