Which UPS?

[Scott Allen]

On 14 June 2012 12:18, D. Hugh Redelmeier <hugh-pmF8o41NoarQT0dZR+AlfA at public.gmane.org> wrote:
> Anyway, going through a 48V DC intermediate would seem to double
> inefficiency: two levels of power supply.

Exactly the point I was trying to make originally when I tried to show
that (for home situations) sticking with a 120VAC output UPS would be
better than a DC output UPS, during times when the mains are up.

> But I'm no expert and the
> devil is in the details.  I think 48V DC is just a telecom convention
> dating back to the days before transistors.  Is there anything
> technical to recommend it now?

Not really. Multiples of 6V or 12V are desirable if standard if you
plan to use standard lead acid battery technology. However, higher
voltages may present problems, such as what Stewart Russell mentioned
earlier:

On 11 June 2012 11:57, Stewart Russell <scruss-Re5JQEeQqe8AvxtiuMwx3w at public.gmane.org> wrote:
> Any domestic DC system much above 12V is going to be looked at askance
> by ULC and any other certification body. DC arcs don't quench, so the
> approvals people have traditionally considered DC to be a fire risk.
> This is changing, partly because domestic solar systems for MicroFIT
> are suddenly causing a whole lot of 600V DC systems to be installed on
> people's roofs.

-- 
Scott
--
The Toronto Linux Users Group.      Meetings: http://gtalug.org/
TLUG requests: Linux topics, No HTML, wrap text below 80 columns
How to UNSUBSCRIBE: http://gtalug.org/wiki/Mailing_lists