| Author |
-48 volt DC Question
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| The Streets 2007-01-23, 1:25 pm |
| I know that most telco switch rooms run their equipment
from a common DC supply (at least in the US).
I understand the advantages of a common supply. But
what is the advantage of using a negative rather than
a positive supply voltage?
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| Palindrome 2007-01-23, 1:25 pm |
| The Streets wrote:
> I know that most telco switch rooms run their equipment
> from a common DC supply (at least in the US).
>
> I understand the advantages of a common supply. But
> what is the advantage of using a negative rather than
> a positive supply voltage?
>
>
A Hamlet*:
Galvanic corrosion takes place on the anodic surface. With a positive
supply voltage, this means that the any part of the wiring with leakage
to the ground plane will corrode. With a negative supply voltage, the
ground plane will become pitted and corroded, in the presence of a
leakage path and an electrolye. This is often less of a problem as there
is usually far more of it to corrode..
*Wild stab in the dark...
--
Sue
| |
|
| Bet you'll find more 24v than 48v now.
"Palindrome" <me9@privacy.net> wrote in message
news:ep5dam$q1u$1@aioe.org...
> The Streets wrote:
> A Hamlet*:
>
> Galvanic corrosion takes place on the anodic surface. With a positive
> supply voltage, this means that the any part of the wiring with leakage to
> the ground plane will corrode. With a negative supply voltage, the ground
> plane will become pitted and corroded, in the presence of a leakage path
> and an electrolye. This is often less of a problem as there is usually far
> more of it to corrode..
>
>
> *Wild stab in the dark...
>
> --
> Sue
>
>
>
>
>
>
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| Phillip Devoll 2007-01-23, 8:25 pm |
| Most larger switches (phone systems like sbc or att and ect use) are
negative 48 volts....
"Rack" <someone@aol.com> wrote in message
news:l9rth.26713$gS1.13133@trndny01...
> Bet you'll find more 24v than 48v now.
>
>
> "Palindrome" <me9@privacy.net> wrote in message
> news:ep5dam$q1u$1@aioe.org...
to[color=darkred]
ground[color=darkred]
far[color=darkred]
>
>
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| Floyd L. Davidson 2007-01-24, 3:26 am |
| "Phillip Devoll" <phillip@devoll.org> wrote:
>Most larger switches (phone systems like sbc or att and ect use) are
>negative 48 volts....
*All* larger switching systems are...
[color=darkred]
>"Rack" <someone@aol.com> wrote in message
>news:l9rth.26713$gS1.13133@trndny01...
>to
>ground
>far
--
Floyd L. Davidson <http://www.apaflo.com/floyd_davidson>
Ukpeagvik (Barrow, Alaska) floyd@apaflo.com
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