Comments on: Backup Power http://www.snell-pym.org.uk/archives/2007/09/16/backup-power/ Sarah and Alaric Snell-Pym living in interesting times Wed, 19 Nov 2008 19:05:32 +0000 http://wordpress.org/?v=2.5 By: @ndy Macolleague http://www.snell-pym.org.uk/archives/2007/09/16/backup-power/#comment-53859 @ndy Macolleague Tue, 18 Sep 2007 13:21:48 +0000 http://www.snell-pym.org.uk/archives/2007/09/16/backup-power/#comment-53859 <p>You needn't worry about low voltage stuff. Sometimes you have a floating output on the LV side of the transformer. Things like Ethernet are happy to wander between equipment connected to different phases. Normally (always) the cabling is decoupled from the equipment by isolating transformers in the socket.</p> You needn't worry about low voltage stuff. Sometimes you have a floating output on the LV side of the transformer. Things like Ethernet are happy to wander between equipment connected to different phases. Normally (always) the cabling is decoupled from the equipment by isolating transformers in the socket.

]]> By: alaric http://www.snell-pym.org.uk/archives/2007/09/16/backup-power/#comment-53770 alaric Mon, 17 Sep 2007 13:51:07 +0000 http://www.snell-pym.org.uk/archives/2007/09/16/backup-power/#comment-53770 <p>As long as the neutrals are commoned, I <em>think</em> that sort of thing is OK. If you have two 240v supplies that are 240v RMS against the same neutral but out of phase, then after going through a PSU, they'll produce the same 12v or whatever compared to the same 0v line. I think!</p> <p>However, if I had two mains connections to the house, I don't think I'd be able to common the neutrals since they could come from different transformers with different neutral connections, so commoning them could in principle cause large currents to flow...</p> <p>But if I set up anything of my own that makes electricity to use the same neutral as the mains incomer, all should be well ;-)</p> As long as the neutrals are commoned, I think that sort of thing is OK. If you have two 240v supplies that are 240v RMS against the same neutral but out of phase, then after going through a PSU, they'll produce the same 12v or whatever compared to the same 0v line. I think!

However, if I had two mains connections to the house, I don't think I'd be able to common the neutrals since they could come from different transformers with different neutral connections, so commoning them could in principle cause large currents to flow...

But if I set up anything of my own that makes electricity to use the same neutral as the mains incomer, all should be well ;-)

]]> By: Matt http://www.snell-pym.org.uk/archives/2007/09/16/backup-power/#comment-53769 Matt Mon, 17 Sep 2007 13:46:50 +0000 http://www.snell-pym.org.uk/archives/2007/09/16/backup-power/#comment-53769 <p>just watch out that if somehow two devices became connected to each other - network switch? - and the two end computers were on different supplies, different phases (or out of phase), then fun might occur!</p> just watch out that if somehow two devices became connected to each other - network switch? - and the two end computers were on different supplies, different phases (or out of phase), then fun might occur!

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