[rescue] Re: 48v 15 amp power supply kit?

Dave McGuire mcguire at neurotica.com
Wed Aug 6 11:35:02 CDT 2003

On Wednesday, August 6, 2003, at 08:18 AM, Michael Thompson wrote:
> There is reason that the -48VDC telecom power supplies are expensive. 
> They
> are really rectifiers not power supplies. They are designed to be 
> connected
> to the DC load and a string of lead acid batteries. The battery 
> charging
> circuitry is fairly complex and varies the charging current based on
> available power and the battery's temperature. It also has a low 
> voltage
> disconnect relay and alarm circuits.
> Telecom equipment is designed to run at a minumum of -36VDC and a 
> maximum
> of -58VDC or -72VDC. If you can find an unregulated -48VDC power supply
> that doesn't have a battery charging circuit it should be inexpensive. 
> Take
> a look at some of the feroresonant designs.

   ...which of course makes "rectifier" a gross misnomer, like pretty 
much everything else in the telecom industry.  There's a lot more going 
on in there than simple AC/DC conversion.  If it were really just a 
"rectifier", its output would be something like 160VDC.



Dave McGuire                 "You don't have Vaseline in Canada?"
St. Petersburg, FL                     -Bill Bradford

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