[SI-LIST] Re: Troubleshooting Technique for System Cables for high frequency noise (such as ESD)
- From: Doug Smith <doug@xxxxxxxxxx>
- To: Paul Levin <levinpa@xxxxxxxxxxxxx>
- Date: Wed, 31 Dec 2008 09:28:39 -0800
Hi Paul,
The currents I have measured are well in excess of 2 Amps. The peak current
of the contact discharge is about 4 Amps/kV into a metal plate, less into
some other structures. We could think of the 4 Amps as a short circuit
current. This current is not delivered by the power supply or even a
discretecapacitor, but rather a structural capacitance in the simulator and
lasts for a nanosecond or two with a 700 ps rising edge. The power supply
supplies a relatively small current over a longer time to charge up both the
capacitor (most of the current) and the structural capacitance of the
simulator. So a 4 kV setting has about a 15 Amp short circuit current, a
goodamount of which will couple into the wires, certainly a few Amps.
Doug
Paul Levin wrote: Dear Doug, The math in your Tidbit is impeccable, but I
wonder if the voltage doesn't drop considerably when the load is not an open
circuit. If truly 2 amps is delivered, the 2 amps would have to come from
your generator's power supply and through the output circuit. What are the
ratings for those parts? The few generators I've seen had quite a hefty
source impedance. Regards, Paul Levin Senior Principal Engineer Xyratex
________________ Doug Smith wrote: Hi Everyone, Just finished and posted my
latest Technical Tidbit, for January 2009. As always, the picture of the
testsetup at the bottom of the page at http://emcesd.com[1][1] is the link
tothe article. The direct link is:
http://emcesd.com/tt2009/tt010109.htm[2][2] Technical Tidbit - January 2009
Injection of ESD Current Into Cables Using Capacitance (a useful ESD
troubleshooting tool) Abstract: When a piece of equipment is subjected to
ESD, the cause of the resulting system response can be difficult to find
because the ESD event couples to many parts of the system, not just the
placewhere the event happened. A technique is described that allows ESD
energy to be coupled onto system cables, one at a time. Doing so can
identifysensitive cables that maybe contributing to an ESD problem. Also, I
am trying a new way (for me) to deliver a seminar on ESD, combining aday of
my material with a day presented by a noted expert in the materials field,
Bob Vermillion. If interested the URL is:
http://emcesd.com/pdf/NewportESD.pdf[3][3] or look for the picture of the
Newport, CA (Orange County) sunset on my website[4]. Have a Happy New Year!
Doug -- ------------------------------------------------------- ___ _ 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: doug@xxxxxxxxxx[4][5] \ _ / ] \ _ / Website:
http://www.dsmith.org[5][6]
------------------------------------------------------- --- Links --- 1
http://emcesd.com[6] 2 http://emcesd.com/tt2009/tt010109.htm[7] 3
http://emcesd.com/pdf/NewportESD.pdf[8] 4 http://emcesd.com[9] 5
mailto:doug@xxxxxxxxxx[10] 6 http://www.dsmith.org[11]
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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: doug@xxxxxxxxxx[26] \ _ / ] \ _ / Website: http://www.dsmith.org[27]
-------------------------------------------------------
--- Links ---
1 http://emcesd.com
2 http://emcesd.com/tt2009/tt010109.htm
3 http://emcesd.com/pdf/NewportESD.pdf
4 mailto:doug@xxxxxxxxxx
5 http://www.dsmith.org
6 http://emcesd.com
7 http://emcesd.com/tt2009/tt010109.htm
8 http://emcesd.com/pdf/NewportESD.pdf
9 http://emcesd.com
10 mailto:doug@xxxxxxxxxx
11 http://www.dsmith.org
12 mailto:si-list-request@xxxxxxxxxxxxx
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27 http://www.dsmith.org
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