Text 14140, 140 rader
Skriven 2006-11-19 15:08:50 av mike (1:379/45)
  Kommentar till text 14134 av RobertB. (1:379/45)
Ärende: Re: UPS weirdness
=========================
From: mike <mike@barkto.com>

On Sun, 19 Nov 2006 13:28:52 -0500, "RobertB." <rb28@nyu.edu> wrote:

>In article <p38vl253kmvclvkdqn083aabpr4gofbko9@4ax.com>,
> mike <mike@barkto.com> wrote:
>
>> btw, just turned on the clothes dryer, voltage dropped from 116 to 114.
>>
>> For grins I also just turned on the electric oven.  114 to 113.
>
>What do you use to read it? A voltage meter plugged into a wall outlet?
>Digital or analog?

Yes.

I have one of these:
http://i3.ebayimg.com/03/i/000/78/6e/7261_1.JPG

Plus I also have an HP 974a high accuracy digital multimeter (now Agilent)
http://www.home.agilent.com/agilent/product.jspx?nid=-536902463.536879343.00&cc
=US&lc=eng


 /m


>
>
>
>>
>>  /m
>>
>> 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.
>> >
>> >>
>> >>
>> >> > 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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