UPS VA Rating

seekermeister said:

Your posts definitely demonstrate a superior knowledge to my own, and are educational, but then I only understand a fraction of what you have said, so it still leaves me going in circles. Despite all of the theory and equations, are there any 1000VA UPSs that aren't also rated at 600 watts?

Yes. lots of them;

1000VA ups - Google-Suche

The rating depends on the equipment itself.

Regards....Mike Connor

seekermeister said:

I'm sure that you are right about the surge outlet going dead when the UPS is unplugged, but I also read on at least one UPS, that 2 out of the 4 surge outlets are switched off when the PC was shutdown.

Right....those are the ports that are just surge protected. they are not backed up by the battery. Thus they aren't part of the nominal VA capacity.
For instance my old Belkin UPS had 4 protected slots and 4 "passthrough" which I used for equipment that wasn't "mission critical" in a power outage like a printer or so.

seekermeister said:

Mike Connor said:

seekermeister said:

Your posts definitely demonstrate a superior knowledge to my own, and are educational, but then I only understand a fraction of what you have said, so it still leaves me going in circles. Despite all of the theory and equations, are there any 1000VA UPSs that aren't also rated at 600 watts?

Yes. lots of them;

1000VA ups - Google-Suche

The rating depends on the equipment itself.

Regards....Mike Connor

Okay, then that begs the question as to just how important the VA rating is, when loads are usually calculated in watts, as far as the end user is concerned?

The VA rating is important because it tells you the maximum possible current the equipment can handle. It has nothing to do with the power the equipment delivers. Va ratings are only relevant to AC power ( Alternating Current). Phase differences in the power cycles cause various effects.

The Wattage tells you the maximum power the equipment can deliver.

A computer is a reactive load and thus both ratings are important.

More info;

http://en.wikipedia.org/wiki/Volt-ampere

Regards....Mike Connor

seekermeister said:

Mike Connor said:

seekermeister said:

Okay, then that begs the question as to just how important the VA rating is, when loads are usually calculated in watts, as far as the end user is concerned?

The VA rating is important because it tells you the maximum possible current the equipment can handle. It has nothing to do with the power the equipment delivers. Va ratings are only relevant to AC power ( Alternating Current). Phase differences in the power cycles cause various effects.

The Wattage tells you the maximum power the equipment can deliver.

A computer is a reactive load and thus both ratings are important.

More info;

Volt-ampere - Wikipedia, the free encyclopedia

Regards....Mike Connor

I'm trying to translate this into terms that I can comprehend and use. Regardless of how great of a load that an UPS can theoretically use, it seems that the bottom line is how much it actually delivers. I can understand that it wouldn't be good for the actual load to always be at the maximum design limit, so that might be a factor in determining life expectancy of the UPS. If that is true, then the greater the spread between wattage and VA that there is, the better...right?

No. The values are independent.

One states how many Amperes the unit can handle.

The other states how much power it can deliver.

Neither of these limits may be exceeded when using a reactive load.

10 amperes at 10 volts gives you 100 watts.

12 amperes at 8.3 volts gives you 99.6 watts. But if the va limit is 10 amperes you will damage the system by doing it

The power output is roughly the same, but in one case the current is too heavy for the equipment.

20 amperes at 5 volts = 100 watts. But if the va limit is 10 amperes, you have exceeded it by twice the limit.

In all cases the wattage is the same but the va is different.

If a system can only handle a current of 10 amperes, then that is all it can handle.

How much power it can deliver is another matter. It might be able to deliver 10 amperes at 100 volts = 1000 watts, but the current must still not exceed 10 amperes.

Sorry if that is not clear, it is quite a while since I tried explaining this to anybody.

The life expectancy of most UPS equipment is largely dependent on the batteries used. If a UPS uses a generator as backup, then the batteries are only used to bridge the blackout time of a few minutes maximum, and prevent surging. The generator then takes over. When mains power returns everything goes back to normal.

Good systems will have good battery maintenance cycles built in.

Most small private systems are only basicallly designed to let you save your work and shut down safely. Most modern disc drives have some built in safeguards and can use rest-rotation to complete a write if the power goes off.

Regards....Mike Connor

Another question just popped into my head...an UPS that I'm considering buying only has 4 battery outlets on it, and is rated @ 600 watts. would all of those watts be available from each of those 4 outlets, or is it like with some power supplies that have multiple rails, each having it's own individual portion of the total wattage available?

Unless specifically stated by the manufacturer, those 600 Watts are the max power you could draw from the 4 battery buffered ports combined. So if you need more you need a bigger model.
I only use them to safely power down Data server (Unix REALLY doesn't like to be shut off improperly). That means, the screen, modem router etc don't draw from the battery.

-DG

Another question just popped into my head...an UPS that I'm considering buying only has 4 battery outlets on it, and is rated @ 600 watts. would all of those watts be available from each of those 4 outlets, or is it like with some power supplies that have multiple rails, each having it's own individual portion of the total wattage available?[/QUOTE]

That's normally the total amount of power the unit will deliver.

Regards....Mike Connor