[RFI] Washer RFI/EMI

Paul Christensen w9ac at arrl.net
Mon Sep 7 05:21:14 PDT 2009

> In other words, you do NOT want the chassis or "ground" to be part of the
> current path, either at the fundamental frequency or at the high harmonics
> (RF) that are causing us grief.

My thought is to isolate any existing cabinet shielding from the RFI 
abatement.  This would include using large #31 toroids on the VFD cabling 
close to the motor connect point, and also close to the serving VFD circuit 
point that connects the motor by wires.  But as you know Jim, trying to get 
ample turns to provide enough choking reactance oftentimes means extending 
the wires. -- and that can turn into a real project.  When I attack this, 
I'll try to document the inside changes if I'm successful.  The toroids are 
here -- it's just a matter of doing this when the XYL is away <g>.

I've also given consideration to the filing of a Petition for Rulemaking 
with the FCC to amend Part 15 to include "appliances" that are currently 
exempt from meeting RFI standards.  But that kind of filing needs the 
backing of interested organizations.  The EU nations have been more 
proactive on this front and my understanding is that their household 
appliances must meet the same strict RFI/EMI standards as is required of 
other electronic equipment.

This is an area ripe for organizations like the ARRL, NAB, SBE, AES, and the 
like to join forces.  It's interesting to note that in the most recent 
edition of RadioWorld, a well-read broadcast engineering publication, the 
front page story addressed the gradual increase in average noise floor over 
time from unintentional radiators.  The point the author was making, is that 
the rise in noise floor due to these devices is already having a devastating 
impact on analog AM and HD radio services in North America.  What the author 
did not address is the fact that the rise in noise floor is due in large 
part to exempt appliances that internally use computers, inverters, and 
switch-mode power supplies in everything from the clothes washer to the 
toaster.   These internal devises by themselves must meet technical 
standards, but as soon as that device is thrown into an "appliance," it is 
then exempt from meeting unintentional radiator standards.  Why?

We really need to get Part 15 current with the times.  As more consumers 
replace their household appliances with models that incorporate RFI/EMI 
emitting technology, the problem will only become worse.

 Paul, W9AC


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