[Cialug] redundant power supplies

[Zachary Kotlarek]

On Mar 17, 2012, at 2:58 AM, Dave Hala Jr wrote:

> Has anyone considered making a low cost redundant power supply?  Maybe
> taking two off the shelf power supplies and making a Y connector that
> essentially hooks the two power supplies output up in parrallel?  Is
> this even workable?


Connecting the outputs together in parallel is a bad plan; it's non-trivial to connect more than 1 source and 1 sink to a DC power supply in a non-destructive manner.

If you're trying to connect to A/B power sources you can manage it with a relay -- wire the coil to source A so that when source A is available the coil is active and selects it, and on a failure of source A the spring action of the relay selects source B. The switch isn't instantaneous, but with a typical switching power supply it's fast enough that the output side won't see anything too upsetting.

Unfortunately he same trick doesn't work on the output side, so you can't use it to protect against failure of the PS itself; the cutover time isn't fast enough (and you'd need a lot of relay legs for all the difference voltages, not to mention the higher currents).

	Zach

-------------- next part --------------
A non-text attachment was scrubbed...
Name: smime.p7s
Type: application/pkcs7-signature
Size: 2746 bytes
Desc: not available
URL: <http://cialug.org/pipermail/cialug/attachments/20120317/afc16d74/attachment.bin>