Re: [CAD_CAM_EDM_DRO] 3 Phase/VFD question

Hi Jan;

Not sure what I did with that catalog at the moment, but I do have another.
According to the Airgas/Rutland Tool catalog, there are several models, and
the RPMs listed at 60 Hz input are, 1710, 1725, 1740, and 1750. and are rated
at 1 to 3 horsepower.

I'm looking at the two one horse models, and the first is a TEFC-NEMA 56,
weighing in at 31 lbs., and the other is a TEFC-IEC B3 foot mount D80, weighing
about 13 lbs. Those are shipping weights. They are rated at 1725, and 1710
RPMs, respectively. Sounds like the second one might be better for the Z axis
spindle on a vertical mill, whereas either should workfor a lathe spindle, yes?

Bill

On Tue Jun 1 16:31:17 2004 JanRwl@... wrote:

>In a message dated 6/1/2004 1:31:00 PM Central Standard Time,
>ccq@... writes:
>motor that was rated, if I remember correctly, at 1792 RPM. A VFD I've
>looked at has a frequency rating of .5 to 360 Hz. If combined, what would be the
>output range of RPMs
>from the motor? Do I divide 1792 by 60, and then multiply that by 360, or
>what?
>
>Bill: I may be wrong, but I THINK this strange number, 1792, is the result
>of taking the 1800 RPM "sync. speed" and deducting some (theoretical quantity?)
>value "speed derating". You absolutely sure you have the number exactly
>correct? Because 1782 = 99% of 1800 RPM. If you run a standard "1750 RPM" motor
>on 60 Hz. with no load, or VERY little load, it will run at exactly 1800 RPM.
>Same for a "3450 RPM" motor: 3600 RPM. ANYway, you would get the correct
>result with your algorithm, but the CORRECT proceedure would be to divide the
>VFD's output-f by 60 (or 50, if in almost anywhere in the rest of the world),
>and then multiply the 1792 or 1750 or 3450 or whatever "name-plate RPM" by the
>result. (I understand that 360 Hz. is generally the highest f you can get "in
>the U.S." (60 Hz. mains), but in Europe with 50 Hz, you can get up to 400 Hz.
>Has something to do with the "explosion speed" of motors or some-such
>old-wives' tale spec. I dealt with a rotary f-converter I installed in England,
>once, and I PROMISE, though "all went well, and worked, and I was paid", I don't
>EVER wanna hafta mess with such again! Whew! TOO Much iron and copper for ME!
> Jan Rowland
>
>
>[Non-text portions of this message have been removed]
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