[TheForge] Frequency Converters

[Chuck Robinson]

Hey Steve,
 Wrong company.
The motor I'm looking at is at
http://www.surpluscenter.com
The motor would be used to drive a variable speed 2" x 72" heavy duty belt
grinder for hogging out hammer billets.
All ready using a 2 hp dc motor and speed controller, But it stalls under hi
load conditions.
Chuck

----- Original Message -----
From: "Steve Smith" <sos at alum.mit.edu>
To: "Sponsored by ABANA" <theforge at mailman.qth.net>
Sent: Tuesday, September 21, 2004 7:35 PM
Subject: Re: [TheForge] Frequency Converters


>
>
> Chuck Robinson wrote:
> > Hey Folks,
> > I don't know my ass from my elbow about frequency converters, but the
latest
> > Surplus Center  flyer has  a Leeson 3 phase 3450 rpm motor advertised
for
> > $150. Item # 10-2041.
> > Is this a good candidate for FC controller?
> > If so what is a good source for the FC and approximate price?
> > Chuck
>
> Chuck, I'm not finding your motor on the Surplus Center's web page (I
> assume you mean http://www.surplussales.com/ ), so I can't help you
> there. It looks like their web page isn't fully cooperating with
> Mozilla. Note that used three phase motors (scrapyard, auctions) often
> go cheap.
>
> I think you're talking about a Variable Frequency Drive (VFD); a box of
> electronics which produces three phase (variable frequency) out of
> single phase or three phase. A good source is:
> http://www.dealerselectric.com/
> Note that they sell a package deal on a VFD and a motor. To see their
> VFD's, click on "Browse our Inventory" then "Variable Freq. Drives".
> They are very helpful on the telephone. I bought an FM100 from them for
> my mill (which of course I haven't had time to put in yet...). A couple
> of things to note about VFD's:
> 1. You can't hook the VFD output up to a bunch of wiring with different
> machines on it. The VFD must drive your machine directly, not even using
> the switch on the machine (there are ways to work this, just not
> directly). Otherwise, the VFD can be damaged by a no-load condition.
> 2. You can get units up to 3HP that will take single phase input and put
> out three phase output. Above 3HP, you need to derate by one step if you
> have single phase in. For instance, if you want to run a 5HP, 3 phase
> motor off single phase, you need to use a 7.5HP VFD.
>
> If you don't already have a three phase motor, it may make more sense to
> buy a single phase motor. This is probably cheaper than buying both a
> three phase motor and a VFD.
>
> Steve Smith
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