UPS VA Rating

[seekermeister]

When an UPS has both surge and backup/surge outlets, does the VA or wattage ratings include both, or only the ones that run on battery?

 

[SledgeDG]

I'd have to make an educated guess but from the logical POV it seems like those ratings apply to the battery buffered outlets only since the others are basically just extended, unbuffered wall outlets.

You'll find that whatever is connected to those ports shuts down if you pull the main plug on the UPS

-DG

 

[Mike Connor]

When an UPS has both surge and backup/surge outlets, does the VA or wattage ratings include both, or only the ones that run on battery?

That depends on the UPS.

The VA ratings are not the same as the Wattage ratings ( strange as this may seem! VA is different to Watt. The VA specs are for complex power. Watt = real or active power.

You may find this of interest;

AC power - Wikipedia, the free encyclopedia

Uninterruptible Power Supply (UPS) FAQ

Regards....Mike Connor

 

[seekermeister]

I'd have to make an educated guess but from the logical POV it seems like those ratings apply to the battery buffered outlets only since the others are basically just extended, unbuffered wall outlets.

You'll find that whatever is connected to those ports shuts down if you pull the main plug on the UPS

-DG

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.

 

[seekermeister]

When an UPS has both surge and backup/surge outlets, does the VA or wattage ratings include both, or only the ones that run on battery?

That depends on the UPS.

The VA ratings are not the same as the Wattage ratings ( strange as this may seem! VA is different to Watt. The VA specs are for complex power. Watt = real or active power.

You may find this of interest;

AC power - Wikipedia, the free encyclopedia

Uninterruptible Power Supply (UPS) FAQ

Regards....Mike Connor

Different, but it seems that there is a ratio between them that is constant, so for all practical purposes they are the same.

 

[Mike Connor]

When an UPS has both surge and backup/surge outlets, does the VA or wattage ratings include both, or only the ones that run on battery?

That depends on the UPS.

The VA ratings are not the same as the Wattage ratings ( strange as this may seem! VA is different to Watt. The VA specs are for complex power. Watt = real or active power.

You may find this of interest;

AC power - Wikipedia, the free encyclopedia

Uninterruptible Power Supply (UPS) FAQ

Regards....Mike Connor

Different, but it seems that there is a ratio between them that is constant, so for all practical purposes they are the same.

They are not the same. Not in any way at all. There are no ratios or anything else similar between them. They use different SI. Units ;

http://en.wikipedia.org/wiki/International_System_of_Units

and are calculated differently.

1 W = 1 J/s.

1 Watt =

= 1 Volt • 1 Ampere

A volt-ampere (VA) is the unit used for the apparent power in an electrical circuit.


Regards....Mike Connor

 

[seekermeister]

You may be right, but every 1000VA UPS that I have seen, always had 600 watts of power. It seems that this was true of other units also (in terms of a ratio), but I could be wrong.

 

[Mike Connor]

You may be right, but every 1000VA UPS that I have seen, always had 600 watts of power. It seems that this was true of other units also (in terms of a ratio), but I could be wrong.

The results are specifically dependent on the equipment,how much power it uses, and how it uses it. There is no "ratio" of Watt to VA. They are totally different things.

The three units concerned here are;

W ( Watt )
VA ( VoltAmpere)
var (Volt-ampere reactive )

Only effective power, the actual power delivered to or consumed by the load, is expressed in watts. Imaginary power is properly expressed in volt-amperes reactive.

While both the volt-ampere (abbreviated VA) and the watt have the dimension of power (time rate of energy), they do not have the same meaning. Some devices, including Uninterruptible Power Supplies (UPSs), have ratings both for maximum VAs and maximum watts.
The VA rating is limited by the maximum permissible current, and the watt rating by the power-handling capacity of the device. When a UPS powers equipment which presents a reactive load with a low power factor (e.g., a computer), neither limit may safely be exceeded.[3]


Quoted from; Volt-ampere - Wikipedia, the free encyclopedia


Regards....Mike Connor

 

[Phone Man]

I have a APC 750VA that is rated at 450 watts and this rating is for the UPS output only. It has 5 UPS outlets and 5 surge only outlets. Three of the surge only outlets can be setup to turn on/off by monitoring one of the UPS outlets marked Master. If it sees 0 power draw on the Master outlet it will turn off these 3 outlets. This feature can be turned off if not needed. At present all of my computer stuff (PC, LCD Monitor, Cable Modem, Router, Vontage Unit, Wireless Phone System) is on the UPS ports and I draw 148 Watts. I also have a scanner and when it is scanning I hit 170 Watts. We are always having power hits during rain storms my UPS system is great. I also have one on each of my TV systems.




Jim

 

[seekermeister]

You may be right, but every 1000VA UPS that I have seen, always had 600 watts of power. It seems that this was true of other units also (in terms of a ratio), but I could be wrong.

The results are specifically dependent on the equipment,how much power it uses, and how it uses it. There is no "ratio" of Watt to VA. They are totally different things.

The three units concerned here are;

W ( Watt )
VA ( VoltAmpere)
var (Volt-ampere reactive )

Only effective power, the actual power delivered to or consumed by the load, is expressed in watts. Imaginary power is properly expressed in volt-amperes reactive.

While both the volt-ampere (abbreviated VA) and the watt have the dimension of power (time rate of energy), they do not have the same meaning. Some devices, including Uninterruptible Power Supplies (UPSs), have ratings both for maximum VAs and maximum watts.
The VA rating is limited by the maximum permissible current, and the watt rating by the power-handling capacity of the device. When a UPS powers equipment which presents a reactive load with a low power factor (e.g., a computer), neither limit may safely be exceeded.[3]


Quoted from; Volt-ampere - Wikipedia, the free encyclopedia


Regards....Mike Connor

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?

 

[Mike Connor]

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

 

[SledgeDG]

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]

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?

 

[seekermeister]

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.

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?

 

[Mike Connor]

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]

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;

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?

 

[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;

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

 

[SledgeDG]

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

 

[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?[/QUOTE]

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

Regards....Mike Connor

 

[seekermeister]

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

Although you say it far better than I do, I keep getting the feeling that we are saying the same thing, in different ways. That was not true in the beginning of this discussion, but I feel that I have learned something, due to your tutorship. I doubt that dwelling on this particular point is going to accomplish much more though, because I'm at my saturation point. Thank you for your patience.