[TheForge] Frequency Converters

[Steve Smith]

The missing piece...I hadn't realized you wanted variable speed. You are 
right on the mark.

Steve

Chuck Robinson wrote:
> I don't know how I could make one of those single phase AC motors variable
> speed, except by changing drive wheel diameter.  What am I missing?
> Variable speed control is paramount in my grinding operation.
> Chuck
> ----- Original Message -----
> From: "Steve Smith" <sos at alum.mit.edu>
> To: "Sponsored by ABANA" <theforge at mailman.qth.net>
> Sent: Wednesday, September 22, 2004 6:15 PM
> Subject: Re: [TheForge] Frequency Converters
> 
> 
> 
>>Well that explains a lot. Burden's is the place with all the good stuff.
>>I thought the other URL was Burden's. Thanks for the correct address.
>>
>>Why not go with one of the single phase motors? They've got some 5HP
> 
> motors:
> 
> http://www.surpluscenter.com/sort.asp?UID=2004092218080590&catname=electric&
> keyword=MBAL
> 
>>some of which are cheaper than your 3HP. Also, note that a VFD will cost
>>you more than any one of the motors.
>>
>>Steve
>>
>>Chuck Robinson wrote:
>>
>>>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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>>>>
>>>
>>>
>>>
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>>>
>>>
>>
>>_______________________________________________
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>>
> 
> 
> 
> _______________________________________________
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