>... BB conducted emissions from a battery charger...
>
The last product that I cert'ed was a PC based product,
its ATX supply was a special model which contained a UPS.
During product certification I "discovered" the our product's
worst conducted emissions occured when our product was "off"
and the UPS was trickle charging its batteries. I don't like
surprises like this that end up add "extra modes of operation"
for product testing.
dave garnier
David Garnier
e GE Medical Systems
___________________________________________
David S. Garnier
Senior Technician
PET Engineering
3000 N. Grandview Ave - M/S W-1250
Waukesha, Wi. 53188
Tel: 262.312.7246
From: Doug Smith [mailto:d...@emcesd.com]
Sent: Wednesday, March 26, 2003 12:38 AM
To: Grasso, Charles
Cc: 'lfresea...@aol.com'; emc-p...@majordomo.ieee.org
Subject: Re: OK, what's going on?
Hi All,
Just wanted to put my 2 cents worth in. The same thing may be
happening in Mil-spec testing. Recently, I was at a client's site for
a purpose unrelated to this story.
I noticed interference to the measurement I was trying to make on a
piece of equipment. The equipment had enough common mode current on
its leads to fail emissions, even though it was turned off! There was
a military battery charger for small batteries on their bench so I
connected my current probe to its power cord and noticed enough common
mode current to cause a 30 dB+ failure of emissions over a broad
frequency range. I would suppose the battery charger had been tested
to mil-specs. If so there is a problem here, even accounting for the
repeatability problems in mil-spec testing.
Doug
Grasso, Charles wrote:
> Hi Derek - Go Reds!!
>
> This is not a surprise to me. I have railed at much length a couple
> of years ago as to the latest FCC changes to the emissions
> qualification. I am sure you are familiar with it so I won't
> belabour the point. Fundementally the FCC PC emissions procedure
> has rendered the EMC discipline almost irrelevent. The new procedures
> coupled with the lack of enfocement makes it difficult to justify
> the increased costs of EMC design & test. It also makes the
> whole measurement uncertainty push ridiculous. After all
> if the procedures allow for prodcut that 20dB out of spec why
> bother with a couple of dB of error??
>
> Lets give the emissions standards some teeth or eliminate it
> all together.
>
> Best Regards
> Charles Grasso
> Senior Compliance Engineer
> Echostar Communications Corp.
> Tel: 303-706-5467
> Fax: 303-799-6222
> Cell: 303-204-2974
> Email: charles.gra...@echostar.com;
<mailto:charles.gra...@echostar.com; >
> Email Alternate: chasgra...@ieee.org <mailto:chasgra...@ieee.org>
>
>
> -----Original Message-----
> From: lfresea...@aol.com [mailto:lfresea...@aol.com]
> Sent: Tuesday, March 25, 2003 1:05 PM
> To: emc-p...@majordomo.ieee.org
> Subject: OK, what's going on?
>
> Hi all,
>
> This e-mail has been prompted because of a number of things that
> have all come together. This may take a little reading, but please
> stick with it.
>
> Last note... this is not intended to pick on any individuals, or
> organization, but I do want to stir the pot.
>
......
--
___ _ Doug Smith
\ / ) P.O. Box 1457
========= Los Gatos, CA 95031-1457
_ / \ / \ _ TEL/FAX: 408-356-4186/358-3799
/ /\ \ ] / /\ \ Mobile: 408-858-4528
| q-----( ) | o | Email: d...@dsmith.org
\ _ / ] \ _ / Website: http://www.dsmith.org
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