Re: UPS protection

Discussion in 'A+ Certification' started by Tom MacIntyre, Oct 1, 2003.

  1. On Wed, 1 Oct 2003 02:08:26 -0400, "Glenn \(SBfan2000\)"
    <> wrote:

    >My employer is searching UPS devices for four pieces of equipment and am
    >wanting opinions!
    >
    >The devices are all medical (lab) equipment and require the following:
    >
    >1 610VA (thinking a Belkin 1200VA, for about 50min backup time!)
    >2 4.5amp (thinking a Belkin 1200VA, for about 60min backup time?)


    Hmmm...4.5 A @ 120VAC is 540 W, arguably slightly less than the 610VA
    (depending on the power factor), and the time is slightly longer, so
    there appears to be a relationship. If you're right with one, you're
    probably right with the other.

    >3 consists of 4 devices, computer - 8.0amp


    I think you're very high on this value...unless it's some special and
    very inefficient computer, I can't see it consuming 900 watts or VA.
    I've been wrong before, and haven't had a chance to test a modern PC
    (I do realize that it may not be a PC, but that is a fairly high
    amount of power for a semiconductor device not trying to amplify an
    electric band) on a power measurement device, but it sounds high to
    me.

    >, LCD monitor - .5amp,


    Again, sounds high...60 watts is enough to run many 32" TV's (I have
    measured this one). Again, I may stand corrected later.

    >dot matrix printer - 2.0amps


    Possible at peak activity, I guess.

    > and urine tester - 1188watts


    About 10A...what in the heck does this thing do? Does it spin like a
    washing machine in the spin cycle to separate the various urine matter
    from the fluid?

    > Thinking APC Smart UPC 3000VA, but would like about 45 min run time,
    >suggestions??? How much backup time for APC 3000va


    If the battery capacity is proportional (actually you might need
    slightly better depending on your calculations for the first 2
    scenarios) to the Belkin unit for the VA, possibly close at least.
    Again, this is guesswork on my part, and partly based on intuition.

    >4 20amp, thinkin APC Smart UPC 3000, but would like about 45 min run
    >time, suggestions??? How much backup time for APC 3000va
    > (APC's website doesn't give runtime for half/full load so I can't
    >figure how much runtime 3000VA would provide)


    Again, if one is okay, so is the other, as the wattage/VA are about
    the same.

    >
    >I think I've been doing my math right?? Amps multiplied by 120volt


    for watts is correct.

    >and
    >watts multipied by 1.4! Is this right!


    If you're trying to compare VA and watts, it depends on the power
    factor, and that depends on the resistive, capacitive, and inductive
    aspects of the load. I don't know if I could even fudge a good
    layman's explanation, although I'd likely understand one.

    Here's the way I remember it...for a purely resistive load, the power
    factor is zero, and watts=VA. The more capacitive or inductive a load
    becomes, combined with the resistance present, the higher the power
    factor. Your 1.4 (it would be closer to 1.41414, repeating decimal,
    the sine/cosine of 45 degrees) would assume that the resistive and
    reactive (combined inductive and capacitive) values are equal.

    >The lab people want a run time of
    >at least 45min although I don't think the cheap office manager is going to
    >want to swing the necessary $$$!! The third device (urine tester) above has
    >a line conditioner on it, the AVR feature in the UPS will take over its job,
    >correct?
    >
    >Basically I have no problems building/repairing computers but haven't had
    >much experience with selecting UPS devices!
    >


    But...you have done some homework, and are asking for it to be
    checked. Barry Watzman may have some input on this, I'd think. :)

    Tom
    Tom MacIntyre, Oct 1, 2003
    #1
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  2. Tom MacIntyre

    David Hough Guest

    I'll bet if you put an amprobe on it, you'd see the whole thing drawing
    1 amp idle and when printing a report it might max out at 2.
    David Hough, Oct 2, 2003
    #2
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  3. The AMP rating on most (not all devices) is worse case scenario. Generally
    when a computer boots up it is drawing the most power that it will ever
    consume, it has to get the harddrive(s) spinning and other related things
    like that. But once running it is drawing less power. Just like a car
    battery, it only draws major power when the vehicle is starting but after
    it's running it could run on a lot smaller battery. But you don't want to
    put a 200 CCA (cold cranking amps) battery, which would run most vehicles,
    in a vehicle that needs 400 CCA to just get started.

    So if all computers on this backup were to be started, at the same time, on
    battery power they might draw the full 8amps.

    Philip


    "Glenn (SBfan2000)" <> wrote in message
    news:...
    > I too thought the 8.0amp on the computer was outrageous but thats what the
    > label on the power supply says!
    >
    >
    > "Tom MacIntyre" <> wrote in message
    > news:...
    > > On Wed, 1 Oct 2003 02:08:26 -0400, "Glenn \(SBfan2000\)"
    > > <> wrote:
    > >
    > > >My employer is searching UPS devices for four pieces of equipment and

    am
    > > >wanting opinions!
    > > >
    > > >The devices are all medical (lab) equipment and require the following:
    > > >
    > > >1 610VA (thinking a Belkin 1200VA, for about 50min backup time!)
    > > >2 4.5amp (thinking a Belkin 1200VA, for about 60min backup

    time?)
    > >
    > > Hmmm...4.5 A @ 120VAC is 540 W, arguably slightly less than the 610VA
    > > (depending on the power factor), and the time is slightly longer, so
    > > there appears to be a relationship. If you're right with one, you're
    > > probably right with the other.
    > >
    > > >3 consists of 4 devices, computer - 8.0amp

    > >
    > > I think you're very high on this value...unless it's some special and
    > > very inefficient computer, I can't see it consuming 900 watts or VA.
    > > I've been wrong before, and haven't had a chance to test a modern PC
    > > (I do realize that it may not be a PC, but that is a fairly high
    > > amount of power for a semiconductor device not trying to amplify an
    > > electric band) on a power measurement device, but it sounds high to
    > > me.
    > >
    > > >, LCD monitor - .5amp,

    > >
    > > Again, sounds high...60 watts is enough to run many 32" TV's (I have
    > > measured this one). Again, I may stand corrected later.
    > >
    > > >dot matrix printer - 2.0amps

    > >
    > > Possible at peak activity, I guess.
    > >
    > > > and urine tester - 1188watts

    > >
    > > About 10A...what in the heck does this thing do? Does it spin like a
    > > washing machine in the spin cycle to separate the various urine matter
    > > from the fluid?
    > >
    > > > Thinking APC Smart UPC 3000VA, but would like about 45 min run

    > time,
    > > >suggestions??? How much backup time for APC 3000va

    > >
    > > If the battery capacity is proportional (actually you might need
    > > slightly better depending on your calculations for the first 2
    > > scenarios) to the Belkin unit for the VA, possibly close at least.
    > > Again, this is guesswork on my part, and partly based on intuition.
    > >
    > > >4 20amp, thinkin APC Smart UPC 3000, but would like about 45 min

    > run
    > > >time, suggestions??? How much backup time for APC 3000va
    > > > (APC's website doesn't give runtime for half/full load so I

    can't
    > > >figure how much runtime 3000VA would provide)

    > >
    > > Again, if one is okay, so is the other, as the wattage/VA are about
    > > the same.
    > >
    > > >
    > > >I think I've been doing my math right?? Amps multiplied by 120volt

    > >
    > > for watts is correct.
    > >
    > > >and
    > > >watts multipied by 1.4! Is this right!

    > >
    > > If you're trying to compare VA and watts, it depends on the power
    > > factor, and that depends on the resistive, capacitive, and inductive
    > > aspects of the load. I don't know if I could even fudge a good
    > > layman's explanation, although I'd likely understand one.
    > >
    > > Here's the way I remember it...for a purely resistive load, the power
    > > factor is zero, and watts=VA. The more capacitive or inductive a load
    > > becomes, combined with the resistance present, the higher the power
    > > factor. Your 1.4 (it would be closer to 1.41414, repeating decimal,
    > > the sine/cosine of 45 degrees) would assume that the resistive and
    > > reactive (combined inductive and capacitive) values are equal.
    > >
    > > >The lab people want a run time of
    > > >at least 45min although I don't think the cheap office manager is going

    > to
    > > >want to swing the necessary $$$!! The third device (urine tester)

    above
    > has
    > > >a line conditioner on it, the AVR feature in the UPS will take over its

    > job,
    > > >correct?
    > > >
    > > >Basically I have no problems building/repairing computers but haven't

    had
    > > >much experience with selecting UPS devices!
    > > >

    > >
    > > But...you have done some homework, and are asking for it to be
    > > checked. Barry Watzman may have some input on this, I'd think. :)
    > >
    > > Tom

    >
    >
    C. Philip Cutler II, Oct 2, 2003
    #3
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