If you only need 300W of +48VDC load, it makes perfect sense.

On Tue, Nov 27, 2018 at 1:31 AM TJ Trout <[email protected]> wrote:

> Chuck,
>
> Are you sure the eltek's don't have the chassis ground bonded to the
> positive output ?
>
> So I'm assuming the complication here is that if you reverse the wires,
> when you try to power a +48v device, and it's negative input is bonded to
> chassis ground and you have a ground path between the two (like a metal
> rack) or possibly somehow through the AC ground/neutral you cause a direct
> short circuit?
>
> I see mentions of DC-DC converters, but I don't see the point of using a
> 300w RSD converter with a 2000W rectifier shelf?
>
>
>
> On Mon, Nov 26, 2018 at 2:57 PM <[email protected]> wrote:
>
>> It is 48.  Period.  You choose the reference if you want one.
>>
>> If you tie the + terminal to chassis ground then the – terminal is the
>> hot –48 VDC terminal.
>>
>> If you tie the – terminal to chassis ground then the + terminal is the
>> hot +48 VDC terminal.
>>
>> If you don’t tie either to chassis ground, then you will have to have a
>> common return bar that is on the opposite rail from your fuses and circuit
>> breakers.
>>
>> *From:* TJ Trout
>> *Sent:* Monday, November 26, 2018 3:40 PM
>> *To:* AnimalFarm Microwave Users Group
>> *Subject:* [AFMUG] Eltek Valere J series -48 or +48
>>
>> I'm looking at the Valere series and I can't seem determine if it's +48
>> or -48, seems like it's +48 but I thought all the telecom stuff was
>> positive ground.
>>
>> How do you go about powering negative ground loads from a positive ground
>> power source?
>>
>> I'm assuming you can leave out the neutral and isolate the chassis?
>>
>>
>>
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