What does the VA rating on UPS (Uninterrupted Power Suply) mean? Help

[Mahbub]

So somewhere I heard that if a ups says uts 1500VA then the wattage should be roughly half of that. But then i saw this https://www.apc.com/in/en/product/SRV1KI/apc-easy-ups-online-1000va-800w-tower-230v-3x-iec-c13-outlets-intelligent-card-slot-lcd/?range=65883-easy-ups-online&parent-subcategory-id=88976&selectedNodeId=27602448141 sine wave ups.. and it says 1000va 800watt, how? Isint watt supposed to be half roughly? My pc has a sustained load of 500 watts, somewhere I read that this UPS cant handle a sustained 500w load even tho rating says 800 watt..is that so? Help.

[Poinkachu]

16 minutes ago, Mahbub said:

So somewhere I heard that if a ups says uts 1500VA then the wattage should be roughly half of that. But then i saw this https://www.apc.com/in/en/product/SRV1KI/apc-easy-ups-online-1000va-800w-tower-230v-3x-iec-c13-outlets-intelligent-card-slot-lcd/?range=65883-easy-ups-online&parent-subcategory-id=88976&selectedNodeId=27602448141 sine wave ups.. and it says 1000va 800watt, how? Isint watt supposed to be half roughly? My pc has a sustained load of 500 watts, somewhere I read that this UPS cant handle a sustained 500w load even tho rating says 800 watt..is that so? Help.

AFAIK,

It depends on the UPS's power factor (pf)

https://www.eaton.com/sg/en-us/products/backup-power-ups-surge-it-power-distribution/backup-power-ups/powerfactor.html

The power that comes out from your wall socket has a pf too.

https://laurenselectric.com/commercial-services/understanding-power-factor/

 

There's UPS that only has 0.5pf and there's UPS that has more.

Me generally just consider all of them having around 0.5 to 0.7

 

Soo, 1000VA / 800w, a pf of 0.8

[manikyath]

because what you plug into it can have a horrible power factor, and some parts of the UPS are bigger to account for that.

 

go read up on what that means if you want more than a surface-level explanation, but essentially some types of loads make the current lag behind of the voltage sine wave, which makes an extra bit of power 'go back and forth', causing more load on the grid than what is actually consumed.

[Mahbub]

Just now, manikyath said:

because what you plug into it can have a horrible power factor, and some parts of the UPS are bigger to account for that.

 

go read up on what that means if you want more than a surface-level explanation, but essentially some types of loads make the current lag behind of the voltage sine wave, which makes an extra bit of power 'go back and forth', causing more load on the grid than what is actually consumed.

So in laymans terms can i buy this ups (1000va 800w) for a sustained 600 watt load average or should i look for something with higher kva?

[manikyath]

5 minutes ago, Mahbub said:

So in laymans terms can i buy this ups (1000va 800w) for a sustained 600 watt load average or should i look for something with higher kva?

it will do an 800 watt load, with a power factor no worse than 0.8.. so unless you want to use this for power tools you're fine.

[Mahbub]

16 minutes ago, manikyath said:

it will do an 800 watt load, with a power factor no worse than 0.8.. so unless you want to use this for power tools you're fine.

Okk, thanks, i actually have a ups, 1500va 865 waiit. But its shutting off during outage under load even tho load is like 400 watt, then i came to know that its due to the fact that my ups is not sine wave bht stepped wave or something. So i gotta get a pure sine wave one.

[manikyath]

Just now, Mahbub said:

But its shutting off during outage under load even tho load is like 400 watt, then i came to know that its due to the fact that my ups is not sine wave bht stepped wave or something. So i gotta get a pure sine wave one.

have you considered that the battery might just be toast? lead-acid batteries are weird with capacity, essentially runtime goes down exponentially as power draw goes up.

[Mahbub]

14 minutes ago, manikyath said:

have you considered that the battery might just be toast? lead-acid batteries are weird with capacity, essentially runtime goes down exponentially as power draw goes up.

But the battery still gives 5 mins backup.. like out of 10 times outage 6 times it remains on and 4 times it shuts off and restarts

[Electronics Wizardy]

1 hour ago, manikyath said:

because what you plug into it can have a horrible power factor, and some parts of the UPS are bigger to account for that.

 

go read up on what that means if you want more than a surface-level explanation, but essentially some types of loads make the current lag behind of the voltage sine wave, which makes an extra bit of power 'go back and forth', causing more load on the grid than what is actually consumed.

I will argue these days its mostly for bigger number better marketing. Active PFC is basically required on all high power electronics these days, so its pretty unlikely a PC would pull hundreds of walls at a poor power factor. 

 

17 minutes ago, Mahbub said:

But the battery still gives 5 mins backup.. like out of 10 times outage 6 times it remains on and 4 times it shuts off and restarts

When did you get the batteries? The lead acids that are typically used only give about 5 years of life, and if your pulling hundreds of walls a few minutes is expected battery life on them.

[Mahbub]

2 minutes ago, Electronics Wizardy said:

I will argue these days its mostly for bigger number better marketing. Active PFC is basically required on all high power electronics these days, so its pretty unlikely a PC would pull hundreds of walls at a poor power factor. 

 

When did you get the batteries? The lead acids that are typically used only give about 5 years of life, and if your pulling hundreds of walls a few minutes is expected battery life on them.

1.5 years old, and ups rated for 865 watt, on loaf pc pulls 450 max.. like half of the rated and still 4 out of 10 times in power outage under load it shuts off and restarts d pc...

[manikyath]

14 minutes ago, Electronics Wizardy said:

I will argue these days its mostly for bigger number better marketing. Active PFC is basically required on all high power electronics these days, so its pretty unlikely a PC would pull hundreds of walls at a poor power factor. 

yes, defenately on the 0.5pf units.. nothing should have a pf that bad.

[Mahbub]

On 5/26/2024 at 10:52 AM, Poinkachu said:

AFAIK,

It depends on the UPS's power factor (pf)

https://www.eaton.com/sg/en-us/products/backup-power-ups-surge-it-power-distribution/backup-power-ups/powerfactor.html

The power that comes out from your wall socket has a pf too.

https://laurenselectric.com/commercial-services/understanding-power-factor/

 

There's UPS that only has 0.5pf and there's UPS that has more.

Me generally just consider all of them having around 0.5 to 0.7

 

Soo, 1000VA / 800w, a pf of 0.8

So means my pc which has a sustained load at 600w normally can run for at 5 mins for me to shut it down gracefully under load with a 1000va/800 watt ups right? M just anxious 

[Poinkachu]

43 minutes ago, Mahbub said:

So means my pc which has a sustained load at 600w normally can run for at 5 mins for me to shut it down gracefully under load with a 1000va/800 watt ups right? M just anxious 

By my own non-professional guessing, yes. If the battery is at it's prime at least.

But, you should refer to the UPS's runtime chart.

[Mahbub]

44 minutes ago, Poinkachu said:

By my own non-professional guessing, yes. If the battery is at it's prime at least.

But, you should refer to the UPS's runtime chart.

i considered a 2kva online from apc, but damn that shit is expensive af