Re: [CAD_CAM_EDM_DRO] VFD's - Variable Frequency Drive

When I was first exposed to analog VFD drives ~15 years ago, the rule of thumb was 50% of rated speed or 30hz. I was told that this was to ensure proper cooling of the TEFC motor. These motors were on industrial equipment operated 24/7 in a wastewater treatment plant. I never did monitor the temperature, but I did not have any temperature related motor failures using 30hz minimum speed.



Joe Fahy

----- Original Message -----
From: mayfieldtm
To: CAD_CAM_EDM_DRO@yahoogroups.com
Sent: Tuesday, March 18, 2003 7:33 PM
Subject: [CAD_CAM_EDM_DRO] VFD's - Variable Frequency Drive



When I inquired with the Lathe Sales Person on the
Amperage Rating of my Motor. He said that I should
never run the Motor under 40Hz, in that it could
damage the Motor.

Is this true?

I mean I would expect that very slow or fast speeds
are not desirable, but, 40Hz is only 67% of normal.

(I was planning to use a range of about 20Hz to 90Hz.)
(3 times slower to 50% faster)

After all the glowing comments that I've read by "happy"
VFD users, now I have doubts about my purchase.

Any one have a VFD, and any comments?

Tom M.



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