How do i perform a galvanic test?

On Tue, Dec 8, 2015 at 10:24 AM, Chuck McCown <[email protected]> wrote:

> The designer may or may not have tied the positive output to the chassis.
>
> You would have to galvanically isolate it and see if there is a voltage
> from negative to chassis.
>
> You might be OK or you might have to isolate it from the rack.  If you do
> isolate it, make sure to put a sign on it that it is hot so someone does
> not lay a tool on it or touch it with a metal ladder etc  that could ground
> it out and cause lots of sparks.  I personally don’t feel –48 unless I am
> hot and sweaty, so to me it is not much of a shock hazard but may be for
> others.
>
> If you do isolate it, remember that the input AC probably has a ground
> wire that will tie the chassis to earth ground.  If the +48 is tied to the
> chassis, you are going to have to disconnect the input ground too.
>
> And it is slightly possible, in an old and lousy design, that the AC
> neutral could also be tied to the chassis.
>
> *From:* Gino Villarini <[email protected]>
> *Sent:* Tuesday, December 08, 2015 4:12 AM
> *To:* [email protected]
> *Subject:* [AFMUG] Isolating a -48 rectifier?
>
> So, i was wondering if isolating a -48 dc rectifier from the rack/ground
> would turn it into a polarity agnostic device?
>

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