Text 14099, 105 rader
Skriven 2006-11-18 17:15:16 av RobertB. (1:379/45)
  Kommentar till text 14096 av mike (1:379/45)
Ärende: Re: UPS weirdness
=========================
From: "RobertB." <rb28@nyu.edu>

In article <dhtul2l6e6vab4k0c5um3j4q4b9lvlgkoj@4ax.com>,
 mike <mike@barkto.com> wrote:

> On Sat, 18 Nov 2006 14:43:15 -0500, "RobertB." <rb28@nyu.edu> wrote:
>
> >Any EEs out there or people who know electricity? I have two APC UPS
> >SmartUPs in my office, a smallish 750 VA unit attached to my G4 iMac and
> >a large 1000VA unit attached to my ancient Micron and my new iMac
> >core2duo (Yowza!).
> >
> >Here's the deal. Previously, I used to not turn the Micron on much so I
> >would shut the large SmartUPS off at night (since the computer was only
> >on a couple of days a week at most). However, the new iMac, like all
> >Macs, has an Energy Saver feature, so I simply put it to sleep at night.
> >Easy. When it's on, the usage light on the large SmartUPS doesn't even
> >go on, the machine is energy efficient. (The Micron, which has a couple
> >of externals attached causes it to move up one notch). So there's no
> >real voltage draw. OK. I noticed, twice now, that in the morning when I
> >come into the office, the Voltage Trim light is on, indicating high
> >voltage on the line. However, it only appears on one of the SmartUPS.
> >Both machines are in the same room and, as far as I know, connected to
> >the same circuit. After a while, the Trim light goes out.
> >
> >FYI, about two weeks ago, the same thing happened one night to the 750VA
> >UPS. The Voltage Trim light was on for several hours, then went out. I
> >have no idea why it would affect one UPS and not the other,
>
> One UPS might have a slightly different threshold to enable the trim
> capability.  For example, the UPS may switch over to trim mode when the
> voltage is over 132 volts (+/- 2%).  So one UPS may switch to trim mode
> at 133 volts, the other at 129 volts.

Oh, that's interesting. They are the same model, not sure if the specs are
identical.

>
>
> > why it seems
> >to happen on a regular basis, and why it would come and go.
>
> The voltage may be higher in the morning when the load is low.  I know
> the voltage in my house is high (122 volts) until around 6:45am or so
> when lots of people start waking up.  Then the voltage starts the
> descent for the day, the lowest being early evening, or when I run my
> electric clothes dryer...).

Isn't high voltage usually the result of something happening on the mains. The
local transformer down the street or something?

>
> > The owner of
> >the building (an old tenement) installed a new boiler about six weeks
> >ago and I'm wondering if they did something weird.
>
> A new boiler could be more efficient in its electrical usage, reducing
> the load on the system, therefore increasing the voltage.  Or, they
> could have run a new electrical line for the new boiler (this is done if
> the old stuff wasn't quite up to spec).  The new boiler connection to
> the main electrical line could be on the other phase from your office.
> Which will result in a very different voltage pattern in your office,
> i.e., when the furnace goes on you office voltage will increase. (long
> story, I can explain if you want...)

Not sure I'd understand it if you did. <g> Been a while since I opened a
physics textbook. <g>

>
> > At one point this
> >summer they were running new cabling up the walls on all the floors, but
> >I have no idea if they ever connected the stuff.
>
> They don't run cabling for their health. :)   Chances are they connected
> it to something. Was it power cabling, or data cabling?.

Power cabling. New BX cable. Not sure why, exactly, but probably to meet some
code requirement. They don't do anything here unless they absolutely have to.
Actually, they ran it inside a trough in the hallway.


>
> >I can't figure it out.
> >The voltage trim light just went out about 10 minutes ago. Bizarre.
>
> I only touched on a few of the possibilities.  When I had a similar
> problem in my office, I had to rent a Dranetz power analyzer to help
> track the root cause down. (http://www.dranetz-bmi.com/) Turns out there
> was an issue at the main breaker box for the building.  Once that was
> fixed, everything was fine.

Yeah, a friend recommended one of those. How much do those things cost?

> P.S.  I would never use an APC UPS on any piece of equipment I care
> about.  But that's just my opinion....

Oh boy. I can't tell you the number of arguments this has generated in the past
(I remember the old Canopus on Compuserve, where there were a couple of
long-running battles about UPS device). A lot of people like Tripp-Lite (I
still have a couple of their voltage conditioners), but APC is easier to come
by. They're supposedly very good, but I'm no expert. I'm not sure any of the
other companies make SoHo hardware in this range.

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