Measure resistance between the ground terminal and the positive terminal and also between the ground terminal and the negative terminal. It should be very high - on the order of MegaOhms.
It’s not an absolute test as there could be active circuit elements or diodes between the power and ground that the meter doesn’t supply enough voltage/current to trip when measuring. If you get a low resistance (<1000 ohms) between a power supply terminal and ground it’s a good indication they are tied together internally and that the supply is not isolated. Mark > On Oct 22, 2020, at 10:35 AM, Josh Baird <joshba...@gmail.com> wrote: > > Stupid question - but how exactly do I verify this with a multi-meter? > > On Thu, Oct 22, 2020 at 10:32 AM Mark Radabaugh <m...@amplex.net > <mailto:m...@amplex.net>> wrote: > A quick check with the multimeter shows the +/- terminals isolated from the > ground. > > Markings on the supply say 20-60VDC. As long as you get polarity correct I > believe they don’t care where the ground reference is. > > > <IMG_3548.jpeg><IMG_3549.jpeg> > > Mark > > >> On Oct 22, 2020, at 9:50 AM, Josh Baird <joshba...@gmail.com >> <mailto:joshba...@gmail.com>> wrote: >> >> Slim chance, but does anyone know if I can power a 3930 off of a +48VDC >> system? >> >> The spec sheet says: DC Input: -48, -36, +36, -24, +24 VDC (nominal) >> >> Does it seem odd that it can accept -/+36 and 24, but not 48? >> >> An AT&T tech installed a 3930 at one of our sites and wired it directly to >> our +48VDC ICT DC system, and it's working, but we don't have any other >> equipment (other than a MT) running off of this bus yet. I'm worried that >> if we power something that isn't isolated (and expects +48VDC), we may >> release some smoke. >> >> Should I just stick an isolated DC/DC converter in between the Ciena and our >> rectifier just to be safe? >> -- >> AF mailing list >> AF@af.afmug.com <mailto:AF@af.afmug.com> >> http://af.afmug.com/mailman/listinfo/af_af.afmug.com >> <http://af.afmug.com/mailman/listinfo/af_af.afmug.com> > > -- > AF mailing list > AF@af.afmug.com <mailto:AF@af.afmug.com> > http://af.afmug.com/mailman/listinfo/af_af.afmug.com > <http://af.afmug.com/mailman/listinfo/af_af.afmug.com> > -- > AF mailing list > AF@af.afmug.com > http://af.afmug.com/mailman/listinfo/af_af.afmug.com
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