Text 14102, 158 rader
Skriven 2006-11-18 19:01:54 av mike (1:379/45)
  Kommentar till text 14099 av RobertB. (1:379/45)
Ärende: Re: UPS weirdness
=========================
From: mike <mike@barkto.com>

On Sat, 18 Nov 2006 17:15:17 -0500, "RobertB." <rb28@nyu.edu> wrote:

>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.

Normal component tolerances will account for that level of difference. That's
not a critical set-point, so they're not going to use high-spec components.
>
>>
>>
>> > 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 transformer sets the voltage level, say a nominal 120 volts. However, there
is variation around that nominal level depending upon the load that is placed
upon the distribution system.

When I wrote my prior message,m I checked and the voltage in my house was 115
volts.  Now it is 116 volts.  When I fire up the clothes dryer in 20 minutes or
so, it will drop, probably to 112 or so...

>
>>
>> > 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.

OK, they may have had a situation where the existing circuitry could not
deliver enough power to the offices.  The new wiring provides more power, so
the voltage won't sag as much.  In other words, the new wiring may be
delivering a higher voltage to your office.
>
>
>>
>> >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?

You don't buy one unless you are in the power industry, or you run a data
center and are very concerned about power.  Renting for a month or so while you
troubleshoot is better.

But if you want to buy one, think thousands not hundreds.


>
>> 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.

Tripp-Lite is good.  APC is a marketing-oriented company, better UPS's through
better marketing.  Technology-wise, they are so-so.  One of my favorites from
APC was a line in their marketing brochure that went along the lines of, ~there
is no such thing as an uninterruptible power supply because the AC line current
goes to zero 60 times each second.~ Never mind that 60Hz power goes to zero 120
times each second, but they missed the whole concept of uninterruptible power
supplies.  The APC marketing people were trying to say that their 5 to 10mS
break time in clean power was OK.  At the time APC didn't have a real non-break
online UPS, so they tried to convince you that no one did.  I engaged their
marketing department in a snail mail conversation once.  I should have kept the
letters, the cluelessness was astounding....

My preference at this point is Powerware (formerly Best Power technology).
http://www.powerware.com/  Currently I have a Powerware 5125-1500 with one
Extended Battery Module on my home network.  I use NUT
(http://www.networkupstools.org/) to control the UPS and shut down the servers
should the power go down.  I get about 7 hours runtime on battery (NUT shuts
down the media server after two minutes on battery to conserve the batteries
for the firewall, switches, access point, webcam, etc.)

  :)

 /m

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