how much is 350VA in watts?

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jkoXP

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Dec 14, 2001
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im trying to figure out if this UPS is enough for me.

my PS is 250 watts, my monitor is
Voltage : 100-240VAC, 50/60Hz, Auto Switching
Power : On mode: <85W, Standby Mode: <10W, Suspend Mode: < 10W, Off Mode: <5W
Inrush Current : 50 A (max

would this be sufficiant enough for my needs?? even while watching a DVD movie on my pc, (speakers not included on bat backup)
 
H

HonkeyDonk

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Oct 14, 2001
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It should be fine, but to answer your question in your thread:

Power (Watts) = Voltage (Volts) * Current (Amperes or Amps)

So, 350 VA (Volts * Amps) = 350 Watts.
 
M

MWink

Diamond Member
Oct 9, 1999
3,642
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Technically VA=Watts. Though you get very different answers when asking different UPS companies. The equation I saw a long time ago was 1VA=.7W.



<< would a Belkin 350VA Regulator Pro Gold Series - UPS be good enough? >>



Not IMO. Belkin power protection products suck!
 
N

notfred

Lifer
Feb 12, 2001
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I see: 250 watt PSU, 85 Watt monitor. That's 335 watts. The UPS is 350 watts.... Why wouldn't it be enoguh?
 
J

jkoXP

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Dec 14, 2001
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<< would a Belkin 350VA Regulator Pro Gold Series - UPS be good enough? >>



Not IMO. Belkin power protection products suck![/i] >>




why do they suck?
 
P

Priit

Golden Member
Nov 2, 2000
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When talking about UPS output power, VoltAmpers doesn't equal watts (UPS output is not DC)!!! Read this for example...
 
K

kt

Diamond Member
Apr 1, 2000
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A safe way to eyeball it is to take the amount of wattage used by your equipments and divide it by 0.7 or 0.6. That's the VA rating you would want for your UPS. It's a good estimate, but not the most accurate way. The most accurate way is to measure each and every individual devices and calculate the combined wattage drawn by them.
 
J

jkoXP

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Dec 14, 2001
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ok, so the 350 or the 420 for what I need? please let me know, i dont know crap about this stuff....... thanks for the help. im looking at the belkin units at bestbuy, i do not have much $$ for this either.
 
M

Mark R

Diamond Member
Oct 9, 1999
8,513
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Your PC base unit, if it is of a mid-end spec, will probably use about 80 W when operating.

The problem is that VA (Volt-Amperes) are not W (Watts). They measure different things. VA is voltage x current, whereas W is power. In an AC circuit, the equation P = VI does not necessarily hold where V and I are rms (average) values; instead the equation is often represented as P = VI x Pf (Pf is known as power factor).

A typical PC PSU has a power factor of 0.6 - this means that for every 0.6 W of power that it actually uses (and that your electricity meter records), it uses 1 VA from the supply. So your PC which is using 80 W of power would actually be drawing 1.1 A (from your 120 V supply) - therefore 133 VA.

You may have heard of new PFC (power factor correcting) PSUs, these are much the same as conventional supplies but they have a power factor much closer to one, typically about 0.95. The advantage of these, is that when used with a UPS, they use less capacity, the batteries provide more run time, and the UPS runs cooler (in the above example, the PC takes 133 VA from the UPS, and to provide this the UPS must take at least 133 W from the battery, but the PC only uses 80 W, leaving 53 W to be wasted as heat in the UPS).

A monitor typically has a Pf of about 0.7, and a 17" will therefore use about 130 VA.

A 350 VA UPS will therefore be sufficient for your needs, but you may find that a larger capacity one will offer spare capacity, in case you want to add other devices, and you will get significantly increased reserve time.
 
J

jkoXP

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Dec 14, 2001
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<< Your PC base unit, if it is of a mid-end spec, will probably use about 80 W when operating.

The problem is that VA (Volt-Amperes) are not W (Watts). They measure different things. VA is voltage x current, whereas W is power. In an AC circuit, the equation P = VI does not necessarily hold where V and I are rms (average) values; instead the equation is often represented as P = VI x Pf (Pf is known as power factor).

A typical PC PSU has a power factor of 0.6 - this means that for every 0.6 W of power that it actually uses (and that your electricity meter records), it uses 1 VA from the supply. So your PC which is using 80 W of power would actually be drawing 1.1 A (from your 120 V supply) - therefore 133 VA.

You may have heard of new PFC (power factor correcting) PSUs, these are much the same as conventional supplies but they have a power factor much closer to one, typically about 0.95. The advantage of these, is that when used with a UPS, they use less capacity, the batteries provide more run time, and the UPS runs cooler (in the above example, the PC takes 133 VA from the UPS, and to provide this the UPS must take at least 133 W from the battery, but the PC only uses 80 W, leaving 53 W to be wasted as heat in the UPS).

A monitor typically has a Pf of about 0.7, and a 17" will therefore use about 130 VA.


thanks for the good answer! :) would a 420 or 500 be better for my needs? shutdown time is not too important, cus ill have the software just shut it down pretty quickly...
A 350 VA UPS will therefore be sufficient for your needs, but you may find that a larger capacity one will offer spare capacity, in case you want to add other devices, and you will get significantly increased reserve time. >>

 
amdskip

amdskip

Lifer
Jan 6, 2001
22,530
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just got a new APC back ups office 500, runs XP1800 w/17" monitor for 10 minutes idle, 5 minutes if you are doing something
 
M

MWink

Diamond Member
Oct 9, 1999
3,642
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<< why do they suck? >>



Belkin surge protectors consistently fail to shut off when the protection has been damaged. I know multiple people who have had things protected by Belkin surge protectors fried. They also got horrible reviews from Consumer Reports. I would not touch a Belkin surge protector much less put my computer on one.
 
J

jkoXP

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Dec 14, 2001
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ahhh. ok, how about the Blackoutbuster B6U-2 by Nextgrid ?? I found it on pricegrabber.com for $99 shipped, how are those?

see I need something w/ atleast 420VA and AVR for a low price $100 or less
 
J

Jerboy

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Oct 27, 2001
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In contrary to common beliefs, VA DOES NOT EQUAL watts in an AC circuit where inductance and capacitance are involved.

my UPS is rated at 320VA, 180W, so it is designed to handle a load with PF in the neighborhood of 0.6.


Your PSU output wattage doesn't equal its input wattage.

Computers draw current in very funny waveform and measurement requires expensive instruments, so the best most of us can do is guesstimate..

I don't think that 350VA PSU is enough for your setup, because my 320VA UPS goes into overload protection when I connect my 17" monitor and my computer at the same time.

 
J

Jerboy

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Oct 27, 2001
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<< The most accurate way is to measure each and every individual devices and calculate the combined wattage drawn by them. >>




Most unrealistic way too since it is prohibitively expensive.

You need to have:

volt meter, true RMS ammeter and an oscilloscope ($1500 or so at least)

or

Watt meter(I'm not talking about Watt's up? thing) that can properly calculate awkward waveform drawn by computer PSU, power factor, capable of handling high crest factor. True RMS voltage and current are measured, then the phase difference is calculated on the fly. Something like this costs $1000



 
J

jkoXP

Banned
Dec 14, 2001
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the lights are the only thing that seem to dim, dosnt seem to bother the pc, since i was right there. should I get the UPS anyways?
 
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