| Beachcomber 2006-04-15, 4:21 pm |
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>
>The problem with your arguement is that the current system, as applied to
>medium voltage distribution lines in the US, is NOT killing people. Some
>stray voltage problems exist, but they are usually localized problems.
>These stray voltages are not killing people. They do scare people but they
>don't kill them.
>
>In many of the stray voltage cases we have studied, the high levels of 3rd
>harmonic current in the neutral have been a major contributor. These
>currents are created by electronic loads and since they are triplens, they
>add, rather than cancel, in the neutral. I propose that the US adopt a
>European style regulation for all, and I mean ALL, electronic equipment
>requiring power factor corrected power supplies. Fewer harmonics, better
>power factor, everyone wins.
>
>Charles Perry P.E.
>
>
Thanks for the reply. Just to clarify, I'm not advocating either
point of view. I'm just interested in hearing from the experts in the
industry, like yourself, as to what the current state of this debate
is.
I will say this though, yes the stray voltages, where they exist, are
not killing people, but apparently there are serious consequences to
dairy farms, in particular, with the cows becoming sick, not producing
milk, etc. I'm not sure that all of these problems are solved, but it
does seem to be a good thing that utilities now pay attention to the
problem when it comes up, instead of issuing a summary dismissal as a
"customer wiring problem".
I don't think there is any best solution or design to an electrical
system. I think the systems evolved with the culture and the unique
characteristics of the region.
Here in the US, the formulative agency seemed to be the REA (Rural
Electrification Administration) that decided during the depths of the
depression that the new distribution system would be a grounded
system, single-phase to most residential users, and a 240/120 split
phase Edison 3-wire connection at the service entrance.
I'm sure they did this with the cost savings in mind (it does seem to
be the most economical system in terms of using the least amount of
copper wire). But that is logical as it was the depression, after
all.
I like to think that the appointed reps who issue changes to the
electrical codes should be open to new ideas and not just say "well
that's the way we've been doing it for fifty years... why do we need
to change it"?
Beachcomber
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