With the device unplugged, measure resistance from the - input to either
the chassis or to the ground connection if it has one. If you get
little or no resistance then you're definitely looking at +48v.
I don't think that's definitive though...there could be a "ground" bus
on the circuit board that isn't connected to actual earth ground.
------ Original Message ------
From: "Gilbert T. Gutierrez, Jr." <mailing-li...@phxinternet.com>
To: af@afmug.com
Sent: 8/19/2016 12:11:49 PM
Subject: Re: [AFMUG] 48v and -48v
I believe both my Netonix Switch and Mikrotik CCR both are +48v.
Gilbert
On 8/19/2016 7:06 AM, Chuck McCown wrote:
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