nuckollsr(at)cox.net
Guest
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 Posted: Fri Nov 24, 2006 6:26 pm Post subject: To ground loop . . . or not, that IS the question. |
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At 08:42 AM 11/24/2006 -0500, you wrote:
| Quote: | In a message dated 11/23/2006 10:31:05 PM Eastern Standard Time,
nuckollsr(at)cox.net writes:
"There is no such
thing as a DC system." Even a battery generates some
"wiggles" in output voltage as electrons within the chemistry
jump from ion to ion.
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Hi Bob:
I do live on my own planet, but unfortunately I have to share it; I would
even accept a planetoid.
GREAT statement above Bob. That is what I learned also. We must have
read the same books at one time or another.
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Then you agree with Eric's assertion that once a DC
system "wiggles" that it has now morphed into an AC
system?
| Quote: |
But, why in your GROUND explaination/seranio (your post explaining ground
loops) did you pick thermocouples and group them under the DC Ground
umbrella?
If you recall thermocouples when first produced were done so as a floating
(non-grounded) device. And in many cases as a non-shieled device. This
led to may erroneous reading on the gages ESPECIALLY when digital
read-outs with low voltage sensing circuits came into play. So the method
of correcting and stabilizing became a GROUNDED thermocouple.
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Yup, you do live on a different planet. I've never had to
shield a thermocouple. Digital instruments intended to
read thermocouple voltages came with specifications as
to what kind and amount of common mode voltages they would
tolerate. I've worked with all of them. If one understands
the performance and limits of the hardware at hand, one
may expect reliable results.
So, assuming you're using equipment that is NOT tolerant
of whatever common mode noises are present and assuming further
that you DO ground the thermocouple at the sense end and
your measurement equipment is also grounded at some other
point in the system, then yes . . . one should not be surprised
that the GROUND LOOP so generated produces poor results.
| Quote: | But, in this case you are talking Fruit Salad ... You know ... Apples &
Oranges. They are close, but throwing them into the same bowl, I feel
does not truly explain the issue. I think it is only confusing to many
out there. Too much Tech-Know-Babble, sounding too much like Professor
Irwin Cory.
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Okay, how about use of remote sensing in power generation
control systems . . . or the case I cited where we fixed
an instrumentation interference problem by making eliminating
a ground loop in the airplane's DC power sysrem?
| Quote: | The topic is DC GROUNDS. And you know me I keep things SIMPLE ...
K.I.S.S. M.E. SIMPLE.
And for those that just might still be interested in the basics and how to
eliminate about 98% of your electronical issues and NOISE issues here is
the short version of the basics:
GROUND at the SOURCE (Alternators, Batteries, Avionics and the like).
CLEAN YOUR GROUNDS
ADD MORE GROUNDS to DC Circuits - Battery to Engine, Battery to Firewall,
Firewall (after additional grounds have been added) to Panel and YES I
strongly believe in a nice heavy gage Ground Terminal Block. Or at least
a Brass Nut & Bolt.
[I believe my above statement is what started this debate - MORE Grounds
do HELP]
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No, you said:
"There is NO SUCH FREEKEN thing as a GROUND LOOP in a DC circuit."
| Quote: | AC Circuits Ground at BOTH ENDS
AF (Audio Frequencies) Ground ONLY at the Source
RF (Radio Frequencies) Ground at BOTH ends
Crazy thing here ... Alternators produce BOTH AF & RF, so what do you
do? GROUND at BOTH Ends. YES! GROUND!
After you do the grounding THEN you can start playing with Inductors &
Capacitors and Transient Suppressors.
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| Quote: |
This is the short list. I very seldom need to do more than that to prevent
or remove a problem.
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Now that's an illuminating dissertation. If it's "babble"
one is striving for, you've achieved it. I'm sure every new
builder on the List now knows exactly what you're describing but
the fact that you're finding issue with my words suggests that
that chapters on grounding, noise combined with architecture drawings
in appendix Z in the 'Connection are are now in doubt. Barry, I just don't
have the time or energy to discuss this with you. If you have
a goal of being helpful, it's just not coming through.
Tell you what. Write up a critical review of the work you find
in the 'Connection. Be specific. Use clear words and syntax that
brings to light anything I've written that leads anyone astray. If you
want to be a teacher in this venue, you'll have to act like one.
Ship me the document and I'll publish it on the website.
Here's an example of the format:
http://aeroelectric.com/articles/rules/review.html
You've demeaned my honor and my intelligence. Now back it
up with simple-ideas and illuminating anecdotes from your
experience. But if all you're going to do is sit on the
edge and throw in mud balls, then go away. You're not
entertaining or helpful.
Bob . . .
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