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Help..New PC around 50K

mobo

Broken In
My point is that 600VA=360W is pure BS, if we don't talk about what the load being plugged into the UPS is.

The UPS does not define the power factor of the output, the load does(i.e. the PSU). Surely you know this..
The PF for modern active PFC(Power Factor Correction) PSUs approaches unity, meaning the power they draw is almost the same as the power they actually use.(this is a highly simplistic way to put it)

It is mainly for home inverters that PF is a significant consideration - ceiling fans for example are an inductive load - they have low PF of ~0.6, meaning a 60W fan would need 100VA capacity.

Now what I don't know, is if the UPS is capable of running a 360 watt PC load with a PF of ~1(i.e. almost 360 VA), and they extrapolate that figure to 600VA as a form of marketing BS, or if the UPS is really capable of 600VA, and they assume your load would be reactive in nature(which a PC isn't), having PF of ~0.6.
 

mobo

Broken In
I don't want power backup still and I calculate voltage on smps website that my pc need only 400w so still i need 1kvm ? Sorry but it cost rs.5500 that's why I am asking..

You may be able to get away with a 600VA UPS, assuming it really is 600 VA. Higher capacity UPSs unfortunatly also come with higher backup, driving up the price.

If you really want the best voltage stabilisation, you would need a CVT. It's one of those very heavy old school stabilisers which you might have seen with ACs or even TVs back in the day. CVTs will, however, set you back by almost as much as the UPS. Cheaper stabilisers are digital in nature(IC controlled). These are the cheap ones that weigh nothing - almost all ACs nowadays use these. I can't say how good they really are - your PC is much more sensitive than your AC.
 

whitestar_999

Super Moderator
Staff member
My point is that 600VA=360W is pure BS, if we don't talk about what the load being plugged into the UPS is.

The UPS does not define the power factor of the output, the load does(i.e. the PSU). Surely you know this..
The PF for modern active PFC(Power Factor Correction) PSUs approaches unity, meaning the power they draw is almost the same as the power they actually use.(this is a highly simplistic way to put it)

It is mainly for home inverters that PF is a significant consideration - ceiling fans for example are an inductive load - they have low PF of ~0.6, meaning a 60W fan would need 100VA capacity.

Now what I don't know, is if the UPS is capable of running a 360 watt PC load with a PF of ~1(i.e. almost 360 VA), and they extrapolate that figure to 600VA as a form of marketing BS, or if the UPS is really capable of 600VA, and they assume your load would be reactive in nature(which a PC isn't), having PF of ~0.6.
I don't know why you are insisting on this but here it is to simplify your confusion(about mixing pf factor of psu which is indeed near to 1 with pf factor of ups):
How do I properly size my UPS? - Power Solutions
It is a de-facto standard in the industry that the Watt rating is approximately 60% of the VA rating for small UPS systems, this being the typical power factor of common personal computer loads. In some cases, UPS manufacturers only publish the VA rating of the UPS. For small UPS designed for computer loads, which have only a VA rating, it is appropriate to assume that the Watt rating of the UPS is 60% of the published VA rating.
Example #2: Consider the case of a 1000VA UPS. The user wants to power a 900VA file server with the UPS. The file server has a Power Factor Corrected power supply, and so has a Watt rating of 900W and a VA rating of 900VA. Although the VA rating of the load is 900VA, which is within the VA rating of the UPS, the UPS will not power this load. That is because the 900W rating of the load exceeds the Watt rating of the UPS, which is 60% of 1000VA or around 600W.
 
OP
A

akil49

Broken In
May be I am wrong....
Yesterday I talked with electrician and he told me that in India power company Only supply 240 valts power ..Means your computer needs 240 power to start up.he said if you buy 600v or 1100v ups ..Ups acdept only 240v ..Yes if you buy 600v you will get less betrery backup den 1100v ups..So my question is why we need more valts UPS..?
Big confusion here..Plz reply
 

mobo

Broken In
I don't know why you are insisting on this but here it is to simplify your confusion(about mixing pf factor of psu which is indeed near to 1 with pf factor of ups):
How do I properly size my UPS? - Power Solutions

That was an interesting read. They do talk about active PFC PSUs, but then conflate that with 'PF of UPS'(*), which is a misnomer. The wattage they say comes from the 'typical power factor of common personal computer loads', but isn't that 'typical load' an active PFC PSU?

If you treat the word of a UPS company as gospel, do you also beleive that your 20,000 W PMPO speakers draw that much from the wall? Or that 2080ti will give 600 FPS against 1080ti's 100? Marketing =/= reality.

You should consider reading up on sinusoidal wave, phase, and reactive loads for more clarity.

For buying-advice, of course it can't hurt to be conservative.

(*) UPS's do have a PF, but that does not apply here. I can clarify that if you want.
 

mobo

Broken In
May be I am wrong....
Yesterday I talked with electrician and he told me that in India power company Only supply 240 valts power ..Means your computer needs 240 power to start up.he said if you buy 600v or 1100v ups ..Ups acdept only 240v ..Yes if you buy 600v you will get less betrery backup den 1100v ups..So my question is why we need more valts UPS..?
Big confusion here..Plz reply

whitestar, mobo and the electrician! Now that's an argument I wouldn't want to find my self in the middle of!

So how come you can run a 6 Watt CFL on 220 Volts?

All India-specced UPS's are 220V, this shouldn't matter to you.

The only difference between 600VA and 1100VA UPS is how much max load they can run at a time. You can't run 800 W on a 600 VA UPS.

The only reason 600VA UPS's have lower backup than 1100VA ones is because they have a 7AH battery, as opposed to the typical 2*7AH for higher capacity UPS's.

NB - If OP only wants a stabiliser and no backup, meaning the UPS will run in bypass mode, wouldn't that allow a higher load to run than what the UPS is capable of on battery? @whitestar_999 would you agree?

I guess the question is - Do UPSs have any stabilising at all, apart from the high and low voltage cut-off.
 

whitestar_999

Super Moderator
Staff member
Nowadays PMPO vs RMS is accepted by even companies & they now even publish this in their specifications(aka RMS values). However even APC,generally considered as no.1 ups brand,clearly states this:
Runtime Chart for Back-UPS
In above link APC clearly states that full load provided by their usual home UPS is 60% of VA rating then why would you or anyone should assume a value higher than that or like you said "Marketing =/= reality so shouldn't we assume even lower values than this(aka a pf even lower than 0.6).

I am not sure UPS will be bypassed when using anything before it(aka stabilizer or spike guard) so the power limit still holds true.If you plug a 500W load into a 600VA UPS then ideally it should not start.UPS may have a bit of voltage stabilizing effect in the form that they do alter the waveform to match modified sine wave but ofcourse it will not match the effect of a voltage stabilizer.

P.S. I do know basics of electricity from 12th class physics though obviously not as much as an electrical engineer.
 

mobo

Broken In
It just doesn't add up. Either the VA is 360VA(extrapolating from PF of PC being ~1), or you can run a ~600W load(if it has PF of ~1). The first case is gross cheating, and the second case means you can ignore the 0.6 standard if you know the power factor of your load. Now I don't know which case it really is.

AFAIK unless it is an on-line UPS, it will directly pass on whatever voltage it is receiving, intervening only if it goes beyond the high/low limits.
 
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