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From: Nick on 16 Mar 2010 10:23

On Tue, 16 Mar 2010 04:17:07 GMT, in alt.sys.pc-clone.dell, "Brian K"
<remove_this(a)hotmail.com> wrote:

>Understood.

Brian, thanks for all the comments and ideas: very much appreciated.

If you've read the other new posts, you know that it turned out the problem
wasn't the capacity of my UPS, but the output waveform.

So todays new UPS goes back in favor of one with a sine wave output...

--
Nick <mailto:tanstaafl(a)pobox.com>

"The best laid schemes o' mice an' men Gang aft agley." Robert Burns
From: Tom Lake on 16 Mar 2010 12:19

"Nick" <tanstaafl(a)pobox.com> wrote in message
news:bb2vp59mic2hru6s7jg1a2vfghffdjh0co(a)4ax.com...
>
> On Tue, 16 Mar 2010 04:28:24 -0400, in alt.sys.pc-clone.dell, "Tom Lake"
> <tlake(a)twcny.rr.com> wrote:
>
> From what I read in the forums, Dell support suggests three options for
> dealing with this:
>
> 1. Return the computer.
> 2. Get a better UPS
> 3. Don't use a battery backup for the computer

There's a fourth option: Replace the power supply in the 9000 with a standard one.
Keep the old one so if your computer needs service, you can reinstall it and Dell
will never know (Oops! Now they do!). The original is 475 W so a good quality
replacement should be pretty cheap.

Tom L

Remember, There Ain't No Such Thing As A Free Lunch (of course, given your
listed email, you already knew that!)

From: Timothy Daniels on 17 Mar 2010 00:32

"Tom Lake" wrote:
> Also, the PS in the 9000 requires a true sine wave.
> Even if the UPS capacity is ample, the computer
> will quit if the PS is fed anything else.
>
> Tom L

Don't all UPSs output a stepped approximation to
a sine wave, such that the major Fourier component
of the output waveform is a 60Hz sine wave? If they
didn't, how would they be expected to work for
equipment whose power supplies expect a 60Hz sine
wave input?

*TimDaniels*


From: Tom Lake on 17 Mar 2010 06:14

"Timothy Daniels" <NoSpam(a)SpamMeKnot.biz> wrote in message
news:r5WdnXDaXf7cxj3WnZ2dnUVZ_jCdnZ2d(a)earthlink.com...
>
> "Tom Lake" wrote:
>> Also, the PS in the 9000 requires a true sine wave.
>> Even if the UPS capacity is ample, the computer
>> will quit if the PS is fed anything else.
>>
>> Tom L
>
> Don't all UPSs output a stepped approximation to
> a sine wave, such that the major Fourier component
> of the output waveform is a 60Hz sine wave? If they
> didn't, how would they be expected to work for
> equipment whose power supplies expect a 60Hz sine
> wave input?
>
> *TimDaniels*

Yes, most cheaper ones put out a 50 or 60 Hz square wave.
This is sufficient for most equipment. Some equipment,
however, will simply not work unless a true sine wave is present.
Calculate the RMS of each type of wave to see the difference.

Tom L


From: Nick on 17 Mar 2010 22:45

On Tue, 16 Mar 2010 21:32:03 -0700, in alt.sys.pc-clone.dell, "Timothy
Daniels" <NoSpam(a)SpamMeKnot.biz> wrote:

> Don't all UPSs output a stepped approximation to
>a sine wave, such that the major Fourier component
>of the output waveform is a 60Hz sine wave? If they
>didn't, how would they be expected to work for
>equipment whose power supplies expect a 60Hz sine
>wave input?

As Tom said, most of the cheaper UPSs just generate a stepped approximation
of a sine wave.

But there are more expensive ones available that do produce an actual sine
wave output.

For example, on the APC web site: the UPS models I looked at in the
'Computer and Peripheral' section (for Home and Business computers) all had
a stepped sine wave output, but the ones I looked at in the 'Network and
Server' section were listed as having a sine wave output.

From what I Googled on this (after Tom's earlier post pointed me in the
right direction for the cause of my problems), apparently the XPS 9000 power
supply uses Power Factor Correction to comply with new European regulations,
and that's why it needs a sine wave input and can't handle an approximated
sine wave.

(It's been 40-some years since I studied AC theory in a technical school,
but I remember enough to accept that a circuit designed to adjust the phase
angle of sine wave AC would have problems if it was fed something that
wasn't a true sine wave.)

--
Nick <mailto:tanstaafl(a)pobox.com>

TANSTAAFL! (There Ain't No Such Thing As A Free Lunch!) R.A.H.
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