[c-nsp] OT: DC Power supplies

[Bob Tinkelman]

>>> This is slightly OT, but does anyone know of a product that can
>>> take 2 DC power inputs (A and B side) and put that out on a single
>>> output (C?).  I have a redundant feed that I need to attach to a
>>> non-redundant device and would like to keep as much redundancy in
>>> the loop as possible..
>>> 
>>> Any info or pointers would be great.

>> Two diodes should do it.  I don't know if anyone has produced a
>> commercial implementation.

> They have.  This has come up before...I was looking for such a
> thing some months (year?) ago.  IIRC, they're called C source fuse
> panels or something similar, and are basically externally just
> like a normal A/B 48v DC fuse panel except that the outputs are
> all C (combined A/B with diodes I assume).
> 
> We have one or more of these deployed.  I'll see if I can find out
> exactly what they're called.


We use Hendry fuse panels, such as ones listed below:
http://www.hendry.com/php_scripts/view_product.php?prod=/fuse_panels.htm

For most of the panels we've used, one of the ordering options
(code "F" towards the end of the part#) is the "Fail Safe Circuit"
option, which is described as "Provides redundant power to bus A
or B if either loses power."

If you haven't used this type of fuse panel before, this may
seem a bit cryptic.   The panel is designed for use in a rack/
cabinet with dual DC power feeds (bus A and bus B).  The panel
has an A-side and a B-side, with some number of fuses on each
side.  Equipment with dual power supplies would get connections
to two fuse positions, one on each side.  Without the Fail Safe
Circuit option, the panel acts as if it were two separate panels,
one for each side.  With the option, it does what you want.

--
Bob Tinkelman <bob at tink.com>
ISPnet, Inc.    718.464.4747