Doug,
Oh well, another unintended consequence from SMPSs.
And, of course, some of this energy will couple to ground and add to
the touch current for the product as well as interfere with proper operation
of downstream electronics in GFCI and AFCI units.
And these SMPSs are becoming ubiquitious in all installations - in
addition to electronic equipment, now VFD motor operated equipment from
kitchen blenders on up plus lighting circuits of every stripe.
And, of course, with pressure to eliminate mains wiring and run
everything from 100W USB these issues will expose more of the infrastructure
to fire.
All of this outside any EMC interactions.
The great society is moving forward; spread the word.
:>) br, Pete
Peter E Perkins, PE
Principal Product Safety Engineer
PO Box 23427
Tigard, ORe 97281-3427
503/452-1201 fone/fax
[email protected]
_ _ _ _ _
Hi All,
I was able to measure in my lab late tonight, a very important extension of
an effect I discovered earlier. That discovery describes how some power
supplies can take in a single ESD pulse and generate from it many ESD pulses
of both polarities with both human metal model and cable discharge current
waveforms embedded in corona discharges from the single original ESD pulse.
Tonight, I was able to create the same effect using EFT (electrical fast
transient) pulses. Some power supplies can take a single EFT pulse and a
microsecond to several microseconds later generate one or more EFT pulses,
some larger that the stimulus one, embedded in corona discharges!
This is very bad as EFT occurs much more than ESD and is not visible to
equipment operators. The EFT can be amplified and made worse by some power
supplies! This could easily the the cause of equipment failure either at
compliance testing or in the field.
This appears to be a new phenomena that I have not seen published. I have
been able to reproduce the ESD version at a NASA Ames laboratory, my own
laboratory, and at an ESD test site on the US East Coast using different ESD
simulators and equipment.
If you are interested in this, contact me privately at [email protected] or
call me.
Doug
--
University of Oxford Tutor
Department for Continuing Education
Oxford, Oxfordshire, United Kingdom
--------------------------------------------------------------
___ _ Doug Smith
\ / ) P.O. Box 60941
========= Boulder City, NV 89006-0941
_ / \ / \ _ TEL/FAX: 702-570-6108/570-6013
/ /\ \ ] / /\ \ Mobile: 408-858-4528
| q-----( ) | o | Email: [email protected]
\ _ / ] \ _ / Web: http://www.dsmith.org
--------------------------------------------------------------
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