On 10/27/2009, JIM WIESE wrote:
There is an exception to your last sentence though. There are DC
telecom
span supplies that are used to power remote equipment but that have no
signaling within them. They are typically greater than -120VDC to ground or
greater than +-120VDC to ground (240VDC across T/R), but must be less than
+-200VDC to ground (400VDC across T/R). The current to ground must be
limited. These are RFT-V circuits in North America which are an extension TNV
and originated in Bellcore/Telcordia GR-1089-CORE. There is no requirement
for an RFT-V to have signaling on them, but they use the telecom network and
twisted pair telecom cable for distribution.
Hi Jim:
Thanks for clarifying this. I considered the span power case and thought I
might be over-simplifying my explanation, but I wasn't sure that the separate
classifications for span power applied in this case, since the voltage
involved is 48V.
As a thought question, I considered a hypothetical case where, for whatever
reason, a company simply provides 48 VDC power to a collection of separate
buildings. My thinking was that if they are providing only power, the network
would not be classified as a telecommunications network.
This does not mean that the hazards of outside exposure would not have to be
considered, it just means that the system would not fall neatly into the
classification of a "Telecommunications Network."
Joe Randolph
Telecom Design Consultant
Randolph Telecom, Inc.
781-721-2848 (USA)
[email protected]
http://www.randolph-telecom.com <http://www.randolph-telecom.com/>
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