Don,
I have referred to VFD-s in an early posting as "RF
Weapons of Mass-Destruction". Still, they are useful and I
got one in my house.
As the contractor in your description did, I installed a
line filter on the input side. I also installed a three
wire common mode choke on the three phase output (6 turns
on a large #31 core) very close to the output terminals. I
also added three 3.3 nF high voltage mica caps on the load
side between each phase wire and ground. I used a wide
braid strap for grounding. My RX antenna is about 200 feet
from the drive but its noise is now well below my noise
floor and I can not tell when the drive is running.
Good luck getting rid of the rest of noise.
Unfortunately, for all of us, we will increasingly see
more of these drives residential buildings.
GW
On Wed, 13 May 2015 11:41:28 -0700
Jim Brown <jim@audiosystemsgroup.com> wrote:
On Wed,5/13/2015 11:14 AM, Don Kirk wrote:
The local technician is now planning on additional
changes since the input
line filters have not totally mitigated the problem (but
they sure helped),
and will provide an update when I have new information
to share.
Hi Don,
You might want to refer the people working on the
problem to this Power Point for a tutorial workshop that
I've taught to pro audio and video people. The principles
are no different when the interference is at RF.
http://k9yc.com/InfoComm-Grounding2012.pdf
Henry Ott's excellent text on EMC includes a sub-chapter
on these very nasty RFI sources. His book is widely used
as an EE text, and considered "the EMC bible."
http://www.amazon.com/Electromagnetic-Compatibility-Engineering-Henry-Ott/dp/0470189304
73, Jim K9YC
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