Hi Derek,
In this case, I have seen secondary discharges through various paper based
materials between the bottom of the EUT and the table. The peak current and
di/dt is mainly a function of arc length and this arc is very small and so
will be very severe at most voltages.
Doug
On 7/26/11 5:45 AM, Derek Walton wrote:
Hi Doug?
I'm lost: what secondary discharge?
Please don't include MU in ESD discussions, MU in EMC is a stupid idea
at
best. Leave that to Meteorologists.
Your idea of common sense, may not agree with others. Imagine what
havoc we
would unleash if we applied common sense to many of our standards.
If it's important, it MUST be specified, and be proceeded by a "SHALL".
Otherwise, it's open season.
Cheers,
Derek.
-----Original Message-----
From: Doug Smith <[email protected]> <mailto:[email protected]>
To: Derek Walton <[email protected]> <mailto:[email protected]>
Cc: Michael_Sundstrom <[email protected]>
<mailto:[email protected]> ; bstammerjohan
<[email protected]> <mailto:[email protected]> ; EMC-PSTC
<[email protected]> <mailto:[email protected]>
Sent: Tue, Jul 26, 2011 1:32 am
Subject: Re: [PSES] ESD Spacer
Hi Derek,
I disagree. Why would you knowingly allow secondary discharges that are
more intense than applied stress? In this case, the measurement
uncertainty of the setup would go up astronomically, dominating all
other factors, if the insulating layer can be penetrated by a spark.
The
EN may not specify this, but common sense must prevail.
Doug
On 7/25/11 7:27 PM, Derek Walton wrote:
> Hi All,
>
> I'd just like to point out here that the EN does not give any
criteria for
the
dielectric withstand nature of the spacer. So, while we can argue best
practice,
if a lab meets the thickness, all is permissible.
>
> I also disagree with Doug's statement on cables. You must test with
whats
supplied by the manufacturer, or with ones that he states you must use.
Why,
well because cables can make a huge difference in performance. I would
call
messing with cables like this part substitution and fraud.
>
>
>
>
> I also disagree about using new cables. The reason for this is that
cables
will degrade with some flexing and you should be assuring a product
meets the
EMC requirements for it's design lifetime, not on a good day in a lab,
with
the
wind behind it and rubber boots on.
>
> Just trying to keep the common sense hat on compliance testing
>
> Cheers,
>
> Derek Walton.
>
>
>
>
> -----Original Message-----
> From: Doug Smith<[email protected]>
> To: Sundstrom, Michael<[email protected]>
> Cc: Bryce Stammerjohan<[email protected]>;
EMC-PSTC<[email protected]>
> Sent: Mon, Jul 25, 2011 8:59 pm
> Subject: Re: [PSES] ESD Spacer
>
>
> If the poster board is 0.5 mm thick as required, you
may be
failing equipment that might otherwise pass, which I have seen
happen. A
spark through the poster board will likely be worse than the one you
supply
from the ESD simulator in terms of peak current and di/dt. In any
case,
unless the poster board in 0.5mm thick and you have confirmed
there is
no
spark through, than you cannot say you have tested to IEC 61000-4-2!
Maybe
OK
for a pretest but not for CE marking. It's hardly worth it to save a
few
cents on test materials (the insulating layer we are talking about,
USB
cables, Ethernet cables, and many other things) and waste thousands
of
dollars in the end. I see this happen a dozen times per year.
>
> I also recommend using new, high quality cables for any
performance
test. This is especially important for USB and Ethernet cables.
>
> Doug
>
> On 7/25/11 10:32 AM, Sundstrom, Michael wrote:
>
>
> Guys,
>
> I just use poster board, I get 20 sheets at a local office
supple
house for $5-$6 ?
>
> Am I missing something? Do you need plastic sheets?
>
>
>
>
>
>
> Michael Sundstrom
>
> OHD / TREQ Dallas
>
> Electronic Lab Analyst, EMC Lead
>
> 2170 French Settlement Rd, Suite B
>
> Dallas, Texas 75212
>
> (214) 579 6312
>
> (940) 390 3644c
>
> KB5UKT
>
>
>
> Albert Einstein once said, "The definition of insanity is
doing
the same thing over and over again and expecting different
results".
>
>
>
>
>
>
> From: Bryce Stammerjohan
[mailto:[email protected]
<mailto:[email protected]?> ]
> -
> ----------------------------------------------------------------
> This message is from the IEEE Product Safety Engineering Society
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>
> All emc-pstc postings are archived and searchable on the web at:
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> Graphics (in well-used formats), large files, etc. can be posted to
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>
> Website: http://www.ieee-pses.org/
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--
-------------------------------------------------------
___ _ 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: [email protected]
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-------------------------------------------------------
--
-------------------------------------------------------
___ _ 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: [email protected]
\ _ / ] \ _ / Website: http://www.dsmith.org
-------------------------------------------------------
-
----------------------------------------------------------------
This message is from the IEEE Product Safety Engineering Society emc-pstc
discussion list. To post a message to the list, send your e-mail to
<[email protected]>
All emc-pstc postings are archived and searchable on the web at
http://product-compliance.oc.ieee.org/
Graphics (in well-used formats), large files, etc. can be posted to that URL.
Website: http://www.ieee-pses.org/
Instructions: http://listserv.ieee.org/request/user-guide.html
List rules: http://www.ieee-pses.org/listrules.html
For help, send mail to the list administrators:
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Mike Cantwell <[email protected]>
For policy questions, send mail to:
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David Heald <[email protected]>
