Not sure. Presumably a 48V poe device could have a negative ground. I
was told not to connect -48 to a Cambium 450i, which might imply there's
a negative ground there.
Packetflux PDU has a negative ground. It's not specifically 48v, but I
think it accepts 10-60. When I connected -48 to it I saw that you
couldn't actually switch the loads on and off unless you turned off all
of them. Oh, and all the current went through one port...I think the
one with the shortest cable.
Harris Stratex XP4 had three connectors on the power plug: +V, -V, and
Common. That one could be connected as either +48 or -48.
I'm not sure I've seen anything specific that was +48...excepting maybe
the 450i, but that's not confirmed.
------ Original Message ------
From: "Chuck McCown" <ch...@wbmfg.com>
To: af@afmug.com
Sent: 8/19/2016 10:06:21 AM
Subject: Re: [AFMUG] 48v and -48v
Curious, what types of things use +48?
-----Original Message----- From: Gilbert T. Gutierrez, Jr.
Sent: Thursday, August 18, 2016 7:19 PM
To: af@afmug.com
Subject: [AFMUG] 48v and -48v
I have a site that I am converting to DC from AC. All of the gear
powers
at traditional 48v with a negative ground. I have a PTP800 though that
I
am told is -48v (ground tied to positive). How do I get -48v for the
PTP800?
The site has a NewMar DIN-UPS 48-10. It states that the outputs are
isolated (it has 2) but I do not think they are isolated from each
other, just from ground. To tell you the truth I am lost. I was
thinking
maybe a DC to DC converter of some sort.
Thank you,
Gilbert
