Is 500V UPS enough?

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K

Knight

Broken In
Hi All,
My config is AMD 2600+ (barton 512K), ASUS A7N8X-E Deluxe Mobo, 500watts SMPS, 512 MB DDR RAM, ATI Radeon 9600XT DisplayCard, Samsung Samtron 55V (15 inches), Logitech keyboard and mouse.

At present, i have 500V UPS(Brand - SBS). Is this ok?

Or do I have to replace it with a 800V UPS?

Please clarify.
 
OP
K

Knight

Broken In
thanx

Hi all,
thankx for the reply.
my another worry is will it enought to handle 500wSMPS, 15 inche monitor and ATI Readion 9600XT?

one of my friedn todl tha ATI radeon 9600 based cards need mor power supplyl. he asked me to go for 800V.

does it make sense?
 
I

icecoolz

Cyborg Agent
thats not true,

I have a 17inch monitor and a 500W SMPS with a Geforce 6800 mate and I dont have any issues whatsoever.....
 
A

amitsaudy

Ambassador of Buzz
500 VA will do the job.
But your backup time will be very short but long enough to shutdown
ur system safely.
But cant say how reliable your ups is 'SBS'?..must be some local brand.
Always buy APC.
 
I

icecoolz

Cyborg Agent
Pradeep....thats not referring to the voltage its VA as in Volt Amps so its correct. Ofcourse the output for India is 230 volts mate so dont worry abt it.
 
T

theraven

Technomancer
hmmmm well since u already have it .. go with it till i dies down
after that go in for an 800va

my apc 500 va died down on me i got rid of it .... next buy is a 1kva for me !!

so think abt the amt of backup time i need ...
at that load .... i think ur 500 va will give u 7-10 minutes of backup time MAX ... so that should be enuff for u
the main thing is gettin protected by voltage surges .... and shuting down safely .... which 5 min should cover for most of us !!!
 
A

AlienTech

In the zone
The VA rating has nothing to do with backup time. VA is the volts * Amps that the unit takes in or you pay the electricity company. Usually the unit has an efficiency rate of 60%. Since it has to convert 240Volts AC down to 12V DC to charge the battery. Then it has to convert the 12V DC into 240V AC. IF the UPS uses SMPS power supply you get a higher conversion rate. So you have to take the UPS rating of 500VA and convert it to Watts which is the output rating. So 500VA becomes like 300W atts. (Volts * amps = Watts, as you can see Volt-Amps is the same as Watts but one is used for input while the other is used for out put here.)

The backup time depends on the battery size. The drain also affects it since there are problems with the battery draining too fast shorting the backup time a lot. IE a battery can last longer if you drain it at a less rate. So a 7AH (amp hour) battery can last 10 minutes with a 300 watt load on it, while the same battery can last 30 minutes with a 150W load on it. Even though the load is only half at 150Watts than at 300 Watts, you get triple the time and not double. This is due to the battery characteristics. So putting 2, 7AH batteries in parallel would give you 30 minutes and not 20 (since each battery would give you only 10 minutes, 2 must give you 20, instead it gives you 30).

As you can see, a number is just a number... If you do not know what they mean, it really can mean almost anything. A cheap 800VA might not be all that much better than a well quality made 500VA UPS.
Also a well made UPS will handle flutter in the power lines and feedbacks caused by people turning on motors and fans. These send HUGE milli second spikes down the power lines and can cause lockups.
 
P

pradeep_chauhan

Cyborg Agent
no no the funda behind VA and watts is a bit more complex A new variable called power factor is also involved so 500 VA is the rating for a "Pure" load ie having a power factor as 1 this is true only for a resistive load like say a room heater or an iron. Now all other eqpment have a lag or lead power factor lag = inductive loads and lead = capacitive loads. genrally the power factor is taken as 0.8 so the load in watts is now given as V*I*Pf so we have 500VA*0.8=400w this is the load the ups can supply at a max. Also this is the unit by which power coy charge customers not VA.

The other thing is that ups do not use smps power supply, the power supply is in the pc , monitor and say printer all of these are smps. The invertor or ups use tecniques like pwm (pulse width modulation) or high freq modulation to convert the low 12V DC to 220-240V AC .The conversion factor depends to a great extent on the tecnique used and also newer tecniques like use of torridal transformers ets raise the conversion efficecy to good about 80% Also the conversion efficency increases with higher battery voltages used (conductor loss reduces) so new designs use 24 V (2 x 12V btty) to achive this. The backup time as rightly said depends on batt AH (Ampear hour)capacity of the backup batty used. The other thing that needs to be addressed is the switch over time and spke protection in the O/P supply.
The design of UPS is a vast field and the best way to avoid all this jargon is to buy a good 500VA UPS from say TVSE or APC and enjoy. Personaly i use a APC and TVSE ups to power my 4 PC. two each on one ups one has a 17 inch monitor other are regular 15inch I get a backup time of about 5-8 mins.
 
P

pimpom

Cyborg Agent
Hello AlienTech, I was about to post something similar to yours but
you beat me to it. I've often seen ppl equating VA rating to backup
time. Your explanation is technically correct but I'd like to add some
qualifying statements.

In practice, there could be some truth in saying that higher VA =
longer backup time in the sense that an 800VA UPS meant to provide a 10-minute backup will have a battery with a higher Ampere-hour (Ah) rating than a 500VA unit with the same 10-minute backup time.
Therefore, with the same load, the 800VA unit will provide longer backup than the 500VA model.

But I'm not really arguing with the points you made. I think most
people usually mean that more VA means longer backup, period. In that sense, they're wrong of course. If a choice is available, it makes more sense to buy a lower VA UPS with a larger battery, or an external battery model.

Personally I use a 600VA UPS with a 70 Ah external battery. And I often install heavy-duty UPS'es with upto 150 Ah batteries for people who have to keep working even when there's an extended power outage.
 
T

theraven

Technomancer
well since u guys are talkin abt my post
ill just make it clear
pimpom said:
In practice, there could be some truth in saying that higher VA =
longer backup time in the sense that an 800VA UPS meant to provide a 10-minute backup will have a battery with a higher Ampere-hour (Ah) rating than a 500VA unit with the same 10-minute backup time.
Therefore, with the same load, the 800VA unit will provide longer backup than the 500VA model
Click to expand...
that was my only point ;)
going into technical details wasnt required so i simply put it in lay mans terms ... cuz the above quote holds true for sure
Ah ratings of batteries are set to match the VA ratings ;)
anyways ... really nice description m8's
i personally hate going into ratings in such details :(
 
A

AlienTech

In the zone
pradeep_chauhan said:
no no the funda behind VA and watts is a bit more complex A new variable called power factor is also involved so 500 VA is the rating for a "Pure" load ie having a power factor as 1 this is true only for a resistive load like say a room heater or an iron. Now all other eqpment have a lag or lead power factor lag = inductive loads and lead = capacitive loads. genrally the power factor is taken as 0.8 so the load in watts is now given as V*I*Pf so we have 500VA*0.8=400w this is the load the ups can supply at a max. Also this is the unit by which power coy charge customers not VA.

The other thing is that ups do not use smps power supply, the power supply is in the pc , monitor and say printer all of these are smps. The invertor or ups use tecniques like pwm (pulse width modulation) or high freq modulation to convert the low 12V DC to 220-240V AC .The conversion factor depends to a great extent on the tecnique used and also newer tecniques like use of torridal transformers ets raise the conversion efficecy to good about 80% Also the conversion efficency increases with higher battery voltages used (conductor loss reduces) so new designs use 24 V (2 x 12V btty) to achive this. The backup time as rightly said depends on batt AH (Ampear hour)capacity of the backup batty used. The other thing that needs to be addressed is the switch over time and spke protection in the O/P supply.

The design of UPS is a vast field and the best way to avoid all this jargon is to buy a good 500VA UPS from say TVSE or APC and enjoy. Personaly i use a APC and TVSE ups to power my 4 PC. two each on one ups one has a 17 inch monitor other are regular 15inch I get a backup time of about 5-8 mins.
Click to expand...

good post..

But I have a UPS that uses SMPS, made by megatech. IE it does not have a transformer to convert 240V to 12V.

Also the power factor in countries are different.. Some countries will lead or lag the voltage. Which is why some equipmenet like fans and motors will work well in one country but not another even if the voltage and frequency are the same. It is also why you get a higher or lower bill for a particular device even if the price for electricity is the same.

I hooked up a 120AH one to the megatech maxium 500 :) I get hmmm dont know since I havent run it long enough except for a few hours. The unit can not charge the battery properly if the battery gets discharged but since power failure is only for 1 hours in a 100 it works out.




-----
To those who don't know about AC/DC voltage-currents.. In AC the voltage goes from 0V to 240Volts. But the current which is the power or omph used to drive your device does not follow the voltage, It can lag or lead the voltage like the crankshaft in a car engine. Both voltage and current have to be multiplied to get the omph factor like at the center of the crankshaft there is no power to turn anything.

This means the maximum omph you get might not be at 240V but at 120V when the current is at max. You can kind of fix this by using a capacitor in series to store the current for the times its missing.
 
P

pradeep_chauhan

Cyborg Agent
AlienTech
The use of SMPS for converting 240V to 12 or more precicely 15.5V for charging the btty is very common, What i was refering to is the up conversion from 12 to 240v. Also The comment that "Also the power factor in countries are different.. Some countries will lead or lag the voltage." is not correct . Every one wants to keep the Power Factor to 1 This is why there are massive capacitor banks at power distribution stations that are switched in / out to correct the lag No one or no company will want to vary the power factor as it causes the machines to loose there opimal performance. In USA and europe every home / factory has to assure that the power factor is not dropped due to their load and each place has a power correction equipment connected to the mains inlet point. Thus power factor is a "drawback" that one has to live and fight. In india also if you see the good quality tubelight fixtures made by say bajaj or CG you will find a 1or 1.2 uf 400v capacitor connected. This is to correct the lag created by the inductive load offered by the choke used in the tube lights.
In case of UPS if you open one and see you will see a 0.47 to 0.68 uf 400v capacitor connected at the output (towards the PC) to overcome the lag created by the filter choke or the pc load.
A long time (1990 when i was doing my BE) back i too made a project that auto corrected power factor for the industry Tha time it was a hot topic and something new but over the times the devekopment of new semiconductor devices the fabrication of this unit has become child's play.
 
Sinnet

Sinnet

Broken In
m8 500 VA is ENOUGH :)
i have a AMD Athlon 2800+
i run 2 hdd's , both 160 GB SATA and 1 CDRW and
1 DVD RW and a radeon 9600 and a 17" monitor on my
500 VA APC Back-UPS :)
and it runs fine and gives me decent backup time :)
so no worries and u dont need to go in for a 800 VA UPS :)
enjoy :)

PS : my system has 4x 80 mm cooling fans and the system still runs
stable :)
 
P

paid

Journeyman
UPS-cum-Invertor for longer backup

We hardly get 30-45 minute backup on UPS, for longer backup UPS-cum-Invertor's now available in market with backup of 4-5 hours.
Someone using UPS-cum-Invertor plz. write your review with brand name and price......Thanks
 
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