Online/double-conversion UPS economy/high efficiency modes?

Joseph Chin l-nanog at
Thu Dec 6 21:41:04 UTC 2012

That is so old-school FUD re line-interactive vs double-conversion. Very
much the tubeless vs tubed tire debate all over again. Buy well-engineered
quality brand products (ie Emerson/Liebert, Schneider/APC) then it will be a

-----Original Message-----
From: Mike [mailto:mike-nanog at] 
Sent: Thursday, December 06, 2012 9:17 PM
To: nanog at
Subject: Re: Online/double-conversion UPS economy/high efficiency modes?

On 12/06/2012 12:49 PM, William Herrin wrote:
> Hi folks,
> I'm looking at several brands of rackmount 3kva double-conversion 
> UPSes, such as Tripp Lite and Eaton Powerware. I'm specifically 
> looking for something that will work as a line-interactive UPS until 
> the power starts to misbehave and will then switch to 
> double-conversion mode until a while after the last power bump.

I recently went to the tripplite 16kva online double conversion ups and did
note the increased ineffeciency. However, the financial cost of that
ineffeciency doesn't appear to be more than $40 - $60 / mo. So I am
wondering at your scale with only a 3kva model, really, what is the final
dollar cost to you versus the effort and dubious benefits of writing scripts
or depending on embedded logic to do the right thing? 
The whole reason you have online double conversion vs line interactive, is
to have the best available protection, and when you are on line interactive
- even if it can switch - you are still taking that risk of power issues
that will jump your ups and hit your connected equipment anyways.


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