In message <1369188828.49145.yahoomail...@web160402.mail.bf1.yahoo.com>,
dated Tue, 21 May 2013, Bill Owsley writes:
It is the definition of zero impedance since there can be none lower.
I think that is the point; it's NOT zero. It may be the lowest
obtainable but it is still finite and the
A few decades ago when an intern, called co-op back then, a customer complaint
came in that they had been shocked by the power plug after pulling it from the
wall. No way said the engineers! Hey co-op go test this. We it
turns out there can be the peak voltage left on the pins of the
So the Safety engineer said the single fault condition was an open ground...
Now what?
A surge into a 300 volt SPD transfers that surge voltage to the open ground
(chassis) and there is now a hazard !!!
Thus the position, I've been told while sticking my fingers in my ears, The
SPD's have to als
Ahh... the common convolted and complex analysis discussing the issue with
complicated explanationsand rationalizations.
I may be way off in this, but it seems to work.
So take a unit square of ground plane, or power plane, or reference plane, or
whatever plane you'd like to call the intended re
dang you beat me too it. I thought this would evolve over several notes, but
no... you had to go all the way at once.
I was going to go from single point, expanded to a single edge, expended to a
plane, which can again be expanded to a chassis, and with care on cable shield
terminations, to sin
Hi Scott:
Your explanation makes sense but it presumes the SPD shunts the current
to ground.
It would appear to me that the SPD is allowed to simply bridge the
isolation barrier. That is the aspect that seems contradictory to
me.
In 60950-1 clauses 6.1.2 and 6.2 (the ones I work with most fr
Throwing in my 2 cents:
Hipot test values are based on expected transients. The concern with the
transient overvoltages is that they could punch through insulation needed for
safety and subsequently hazardous voltages can be allowed to reach areas where
they should not. The function of an SPD i
Rich -
Notwithstanding your statements about the safety insulation needing to
meet the testing, I have always viewed the testing with the SPC removed or
disabled to be an allowance, since in almost every instance, will cause a
false indication of breakdown of the safety insulation by means of
fulf
Hi Rich:
The apparent contradiction that I was trying to describe can be
summarized as follows:
a) The safety insulation barrier must withstand a hipot test of, say,
1500 VRMS
b) It is permissible to bridge this safety insulation barrier with a SPD
that breaks down at, say, 300 VRMS
In other word
What we call the Capacitor Discharge Test in the IEC 61010-1 standard section
6.10.3 says that voltage across the pins of the power cord must not be
Hazardous Live 5 seconds after disconnection from the supply. Most labs simply
check to see if the voltage across the pins are 60 volts or less at
Rich,
Given your rational that surge protective components
(SPCs), such as MOVs or GDTs, can have a fault mode anywhere
between a short-circuit and an open-circuit, looks like
there is a disconnect in the test levels.
In the open-circuit situation, the SPC does not divert
current and t
In message ,
dated Tue, 21 May 2013, "ce-test, qualified testing bv - Gert Gremmen"
writes:
In RF technology it is very common to use a plane as a single grounding
point.
It isn't a single point; it may be a close approach to a single point
but I have seen trouble even at audio frequencies
In message <1369105334.30674.yahoomail...@web160401.mail.bf1.yahoo.com>,
dated Mon, 20 May 2013, Bill Owsley writes:
Dr. Tom Van Doren demonstrates that single point grounding is not
possible above the audio frequencies.
Thus the lower cutoff in the "regulations" of 9 kHz. And that is
reall
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