Converting Watts To Amps And Vice Versa

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I'm looking at buying a Universal Power Supply for my computer and related
peripherals, and need help on how to convert between amps and volts, and vice
versa, so I know what size UPS to get.  Here is what I got from all the
peripherals:  

iMac 2.5-1.25 A, 120 W
LCD Display 1.5 A
Mac Mini 85W
External Hard Drive .65A 51-80VA
Amp 85W
Lamp 8W, 80 mA

Can anyone tell me how all this watts, volts, amps conversion works?  All it
gives me is confusion.

Re: Converting Watts To Amps And Vice Versa
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peripherals, and need help on how to convert between amps and volts, and vice
versa, so I know what size UPS to get.  Here is what I got from all the
peripherals:

Did you mean "Uninterruptible Power Supply" ?

Sylvia.

Re: Converting Watts To Amps And Vice Versa

"Dave Henning"

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**  Surely you mean an " Un-interruptible Power Supply" ??

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** I reckon a 300 watt job should do you.

 Go for a 500 watt if you want to be very safe.

 Remember, it will only run the gear for a few minutes in either case.


..... Phil






Re: Converting Watts To Amps And Vice Versa
Yes I did mean "uninterruptible", no idea where "universal" came from ;).  Think
I'll try and seek out a 500 watt one.  Thanks.

Re: Converting Watts To Amps And Vice Versa
You want to know your total watts

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+120W

_Probably 12V, so +18W, say 20w for ease

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+85W

+80W (actually less, but shrug)

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+85W

+8W


Say 400w
Is your power requirement.



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Doesn't make sense



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Apologies. I misread the initial post.................



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This would be the minimum you need to buy.


You can go higher than this, as this will give you longer running time
if the power fails, even with a smaller load than the rating of the
UPS
It also provides some headroom in case you add more devices to it
later on.

For example I have a 1600va UPS on my system, for the reason is that
this longer running time will keep the ADSL modem on for 2 hours or
so, this allows use of the internet via the laptop (run from its own
battery) and the VOIP phone for blackouts that happen during work
hours when you need to have these things online.  A 8w CFL can be run
from it as well and will run for some time if the power fails at
night.

If you need longer run times than this, or want to run higher powered
devices, it would be time to look at a generator.


Re: Converting Watts To Amps And Vice Versa
I don't need to run devices of the battery very long, just long enough to s=
afely shut my Macs down, to prevent hard drive damage.  I'm currently looki=
ng at this one, http://www.apc.com/products/resource/include/techspec_index =
.cfm?base_sku3D%BE700G-AZ&total_watts3D%200

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http://www.apc.com/products/resource/include/techspec_index.cfm?base_skuBE%700G-AZ&total_watts20%0

**Unless you have an extremely ancient Mac, hard drive damage due to a power
failure is incredibly unlikely. All hard drives manufactured in the last 20
years operate using a system where the heads retract under power down
conditions. This is a mechanical operation and thus unencumbered by power
loss. Prior to modern hard drives, we used stepper motor drives in cheaper
systems, where damage was possible, if the heads were not 'parked' under
power down conditions.

The real reason for using a UPS, is so you can save your work, or so the
operating system does not run into problems when premature shut down occurs.
I'm not a Mac user, so I don't know much about the things (other than that
they are slow and frustrating to use, but ever since Windows XP, shutting
down Windows prematurely has not been a problem. I guess Macs are not as
sophisticated. Macs appear to be style over substance.


--
Trevor Wilson
www.rageaudio.com.au



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True, I haven't seen a drive that needed parking since the early
1990's, and even then it MIGHT not really have needed it, but we
played it safe.

IIRC, at power off, the rotational inertia of the platters is
sufficient to allow the platter motor to generate enough power to
ensure the heads get safely parked.

Haven't used or seen a Mac. Many seem to rave about them for some
reason, I have no idea what is good about them over a PC, unless they
are needed for specific tasks or industry, or is it just a MS bashing
exercise / status symbol of some kind ?.




While not relevant to the situation you describe,

I have had problems with hard drives giving problems when the power
supply is overloaded that probably should be taken into account when
choosing a UPS.


Symptoms were: one drive would run hot and may "click" like it is at
the end of its life. Other drive will be fine. Drives worked fine in
my computer, which had a 500w supply at the time.

After a lot of confusion over this problem, removing the Antec power
supply, fitting a larger capacity generic power supply fixed the
problem.
I have heard of other problems involving past Antec supplies, but this
one took the cake.  The computer shop where we bought our parts had
seen this several times, and it was their advice that solved the
problem.


This year I saw a similar case where a guy had 6 hard drives in his PC
and the power supply wasn't big enough. Really weird problems
including Drives randomly "disappearing" from "my computer" and this
would sometimes rearrange the drive letter, and/or not be able to find
the boot drive at restart as well as the problem mentioned above. Some
programs or files wouldnt work or be located properly
as the letters had changed.

Advised him to either get a massive power supply, & add extra fans to
get rid of the heat, and wear the extra power bill
or get a 1.5TB and dump the old 2-300g units. He chose option #2 and
dumped the old drives on Ebay.   This fixed the problem and dropped
the case temperature substantially.


Another thing I notice is that many of these "high wattage" supplies
may have substantial stated amperage on various rails, but with most
of them, the wire gauge looks inadequate to deliver this current to
the devices without a lot of loss. About the only exception I have
seen in the low cost range was the AC BEL "tru power" unit

Re: Converting Watts To Amps And Vice Versa
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Err, Watts has no time parameter.
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Well, UPS's are really just a device for elegant, but immediate
shutdowns, or if you are really serious, to fill in till the generator
kicks in. However the number of people who take this on board is
infinitesimal.


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Some of us use largish ups's
say 3500 watts plus a squad of external batteries tobesure tobesure

--
X-No-Archive: Yes


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Many are the occasions when we've had power glitches long enough to
cause a PC to reboot, but for our UPS.

Sylvia.

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I don't know what your (or anyone elses) environment is like, but isn't a
UPS a bit like bottled water in many cases, ie. the normal reticulated
utility is good enough in practice? Sure, for a business full of critical
servers it's a nobrainer, but in a home environment, what's the impact of
the occasional power brownout?

Me and most of the other people I know have run many computers and related
devices for many years directly on the raw mains, and never had a
significant problem.






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Perhaps some places are more prone to glitches than others.

Prior to installing a UPS, I certainly had computers reset as a result
of power glitches, and lost work in the process - OK, not much work, but
some.  I can't say how often, but I can say they were annoying when they
happened.

Sylvia.

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Where I am, the 11kv lines go out of town for about 30km, much of
which there are lots of trees nearby, and even goes under the sea to
an island. Because of this, any time there is a decent summer storm or
strong wind that blows stuff around or branches go flying, we lose
power at the drop of a hat, or cop brief but damaging dropouts.

On the PC I had from about 2004-6 these "dropouts" would instantly
power off the PC, and in some cases, it would not turn on again unless
you turned the mains off for 10min. Other times the power supply would
simply refuse to turn on at all, and had to be "forced" on by
momentarily grounding the power on (green wire) in the ATX plug to the
motherboard. After this it would again work fine.

When you have several of these losses in one night, it gets very
irritating, especially if the power might only be off for seconds or a
couple of minutes. A UPS with substantial capacity will tide you over
no problems, I have not been without it since, and have had no more of
these problems. Has saved me a lot of time and effort, and probably
helped avoid PC damage that costs  a lot in downtime and
inconvenience.
"Dirty" power like this is another reason to have a good UPS.

We also have people we do work for who are in remote areas on SWER
lines.  UPS are a godsend here, especially the ones that can switch
the output mains voltage up and down as the incoming line voltage
changes.


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Wouldn't just turning on autosave be a cheaper solution? Works for me
anyway.

MrT.



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I have fixed quite a few computers with bricked m/b (power went off/power glitch
during BIOS upgrade) and stuffed Windows (power went off/power glitch during
updates or new driver install). By default Windows reboots on blue screen so
second scenario usually produces endless loop of booting up, blue screen (not
long enough to read), reboot, blue screen... thanks Microsoft!

Tom

Re: Converting Watts To Amps And Vice Versa
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That rather suggests that people are doing unnecessary BIOS upgrades.

Sylvia.

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