Re: Serious EMI
Posted by
beer@s...
on 2001-02-21 09:17:23 UTC
On 21 Feb, CAD_CAM_EDM_DRO@yahoogroups.com wrote:
I didn't notice the problem right away, as for some time, only the
lathe had the VFD on it - the mill retained the standard motor for a
few months and it was the mill that I was using for CNC.
Then one day, I had a project to bore a BIG hole in a some round stock.
A job for a CNC lathe. Fired it up and .. what the heck is this jiggle?
I then spent some time trying to reduce the EMI going INTO the CPU and
controller - no success. Big suppressor on the AC line going into the
VFD. No luck.
Hmmm. Guess we bore this on the mill and figure it out later.
Next day, I moved things around in the shop, necessitating the
unplugging of the computer and the controller ( from the 110VAC ).
Fired up the lathe for something or other and noticed .. jiggle.
Double-checked that CPU and controller WERE unplugged and was left with
only one explanation - serious currents being directly induced.
Now, I agree with you, it could have been that more complex interaction
you describe, but in any case, a REAL lesson about RFI.
Alan
--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta
>No foolin' !
> WOW, that is some SERIOUS EMI! Moving a stepper motor with induced
> currents!
I didn't notice the problem right away, as for some time, only the
lathe had the VFD on it - the mill retained the standard motor for a
few months and it was the mill that I was using for CNC.
Then one day, I had a project to bore a BIG hole in a some round stock.
A job for a CNC lathe. Fired it up and .. what the heck is this jiggle?
I then spent some time trying to reduce the EMI going INTO the CPU and
controller - no success. Big suppressor on the AC line going into the
VFD. No luck.
Hmmm. Guess we bore this on the mill and figure it out later.
Next day, I moved things around in the shop, necessitating the
unplugging of the computer and the controller ( from the 110VAC ).
Fired up the lathe for something or other and noticed .. jiggle.
Double-checked that CPU and controller WERE unplugged and was left with
only one explanation - serious currents being directly induced.
Now, I agree with you, it could have been that more complex interaction
you describe, but in any case, a REAL lesson about RFI.
Alan
--
Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta