On Sun, 20 Mar 2005 14:54:37 -0800, Tim Wescott
wrote:

Wayne wrote:

Hi,

I want to mount a VFD over the headstock of my lathe,
on the wall. This VFD comes with 1/2 knockouts so I
can cable directly to the VFD. My question is this
a safe place to mount the VFD as far as getting
splattered by any oil from the lathe?
VFD is rated @ IP20 (which I believe is about nothing).

Is there any RF issues that I should be concerned
about that makes mounting the VFD in an enclosure
desirable? I would assume the motor radiates more
noise than VFD would.

If I can mount it there without an enclosure,
then I don't need to remote the display.

Picture in the dropbox:
http://www.metalworking.com/dropbox/VFD_placement.jpg

Thanks,
Wayne D.

An induction motor is totally contactless (at least a 3-phase one is)
and contains no rectifying elements: it'll be about as RF free as
anything could be on an AC line. If the VFD generates RF and lets it
loose on the motor lines then the motor'll radiate -- but only because
of the VFD, not as a fault of the motor.

And some VFDs generate considerable amounts of RFI..I as a service
technician can sometimes find new customers by listening to my AM
radio in the truck and driving through industrial strips until I get
to the maximum noise. Shrug.. They dont seem to bother TV, FM
etc..but AM radio is pretty common. And Ive seen some older units put
interference into Ethernet networks, though its very very rare.

The manufactures are getting better at making quieter devices.
Btw...shielding them in an enclosure seldom helps, as it radiates via
the motor wiring.

Gunner

Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats.
H. L. Mencken