UPS Output Questions

[jayflash]

The UPS I recently installed works as intended, keeping the PC, monitor and modems running. The connected load is about 200VA and the UPS is rated at 900VA or ~540 watts.

The voltage is well maintained under load and when unloaded, my meter indicates 60Hz from the UPS. However when the UPS is unplugged and providing power to the connected equipment, the meter indicates 240Hz. Could my meter be responding to the distorted, stepped-wave, output?

Is it better not to run electronics too long from a modified or non sine-wave source such as UPS systems which don't regenerate a pure output?

How do cheaper, home use, UPS units switch to battery power quickly enough to keep the PC from turning off?

Thank you ahead for any replies.

 

[45/70]

I'm certainly not the the best person to answer your question, jayflash. I use UPS's all the time, but have never really "gotten into them", so to speak. One thing I have observed though, when the battery goes dead, in at least some makes (OptiUps, as I recall) everything shuts down and you're dead in the water until you replace the battery. This suggests to me, again being far from an expert, that the UPS dosen't switch at all. It would appear that the UPS floats the system all the time, or at least partially floats it, if that's possible.

Dave

 

[shadowjk]

Some other makes just emit a continous beeping at you until you get up and replace the battery you were supposed to replace 3 years ago...

Most UPSes float charge the battery, but the battery and inverter is not connected. They do manage to switch to battery+inverter fast enough that computer doesn't die. Well, most computers anyway. The ATX spec requires computer powersupplies to provide power for quite many milliseconds after mains powerloss actually, but low quality PSUs, especially if a capacitor or two has leaked, will not give you as much flexibility.

The most expensive kind of UPSen convert mains to 12V first, keeping the battery topped up, and then run the inverter, even when on mains. This gives no switching time at all in case of powerloss. They're also noisy and often equipped with cooling fans.

 

[Illum]

The most expensive kind of UPSen convert mains to 12V first, keeping the battery topped up, and then run the inverter, even when on mains. This gives no switching time at all in case of powerloss. They're also noisy and often equipped with cooling fans.

sounds like server grade UPSs....supposedly Xantrax has something like that too with the inverter/transfer switch/battery charger as one unit.

 

[matrixshaman]

It's hard to say on the 240 Hz frequency without an O-scope but since most UPS's are made to protect computer equipment it doesn't make sense it would use a damaging output unless something is actually wrong with that particular unit. It is of course always best to shut down ASAP if you do have a power outage.

 

[Light Sabre]

From my experience, UPS batteries only last ~5 years even if the UPS is never used. That's assuming that it is plugged in for 5 years. I now put an install date sticker on a new one. I do a UPS test once a year to see how long they last. I boot up the PC & monitor. No programs running, only the desktop is on the screen. I pull the plug and start a timer and see how long it runs. Or I might use a couple 100W light bulbs as a load and do pretty much the same thing. If it doesn't last very long, I usually just buy a new one. I save the SLA's if they still hold any kind of charge, and use them for my home electronic projects.

 

[bshanahan14rulz]

Pretty sure UPSs use relays, since there is an unmistakable, audible *click* when it switches over.

as for your 240Hz measurement, not a clue. Be interesting to find out, though. have you used equipment on this particular ups yet?

 

[jayflash]

Yes, b14rulz, the PC, monitor, cable and phone modems all work normally when powered from the UPS. I'm thinking when the UPS is under load the waveform gets worse and fools the meter. An oscilloscope is probably needed.

 

[alpg88]

all your comp. equipment has power supplies, bridge rectifiers(plus couple of other things), that turns ac to dc, it really makes no differnce 60hz or 240hz. only 3.3v, and 5v dc, get to motherboard, drives..ect. anyway.

 

[Closet_Flashaholic]

I suspect that your meter is picking up the modified sine-wave (stepped) voltages. Without an oscilloscope, it is just a guess, but it makes sense. 60 hz x 4 steps would be 240 hz.

I also use an inexpensive 800 watt belkin UPS that's 5 or so years old. I replaced the 2 12v SLA batteries last year. (I also put the date on the batteries so I know how old they are when they need to be replaced again. My UPS is also a modified sinewave, but I have no problem running my Quadcore, 2 24" monitors and a 19" printer for about 10 minutes which is the max time to complete a print. I got so tired of having my photographic prints ruined because of a brief power interruption. I also believe that it extends the life of my computers and peripherals because it also has voltage surge protection as well.

After having a UPS for over 5 years now, I would never be without one again. Well worth the money (and I'm a cheapskate)...

 

[Gazoo]

I'm certainly not the the best person to answer your question, jayflash. I use UPS's all the time, but have never really "gotten into them", so to speak. One thing I have observed though, when the battery goes dead, in at least some makes (OptiUps, as I recall) everything shuts down and you're dead in the water until you replace the battery. This suggests to me, again being far from an expert, that the UPS dosen't switch at all. It would appear that the UPS floats the system all the time, or at least partially floats it, if that's possible.

Dave

I have an opti-ups 1500B pure sine wave UPS. The batteries can be hot swapped so the UPS does not need to be powered down when replacing them. Not sure what would happen if the batteries went dead but I have found nothing about it shutting down. Anyway it has been great. It can even power equipment as a stand alone inverter...it does not need to be plugged in at all. It takes three 12 volt 7 amp batteries and they are wired in series.

However don't think a UPS will protect from everything. I have cable Internet with TWC. I learned this the hard way when lightning came in through my cable. I am sure it traveled through the lan cable from the router to my computer. It took out the wireless router and the cable modem. Also wiped out my computers motherboard and/or power supply. I replaced both to be safe. It was costly so from now on when we have storms here I unplug the lan cable going to my computer, and also unplug the computer from the UPS. We do have a lot of power surges here and the UPS does take care of it. I would not be without it.

 

[shadowjk]

Also keep in mind that no UPS or surge protection can protect you against a direct strike.

 

[jrmcferren]

If you are reading 240 Hertz you are likely picking up on the 4th harmonic of the UPS instead of the fundamental frequency. Stepped sine waves (square waves with a small delay at zero) are full of harmonics due to their square wave nature. You probably need to get a scope or a proper frequency counter to find out the true frequency of the UPS.

 

[sylathnie]

As pointed out above there on two basic types of UPSes. On-line and offline.

On-line UPSes filter all power into and out of an inverter. This means that if the power goes up or down in voltage the UPS will actual boost or clip the power to keep the voltage level proper for the computer. This type of UPS tends to be much more expensive. The upside is that they maintain an almost perfect isolated level of power for your device.

Offline UPSes run power straight to the PC and click a big set of relays into place whenever the power goes above or below a certain threshold. You normally only miss 1 to 2 cycles of AC and most electronics don't even notice. These are usually much cheaper. Most consumer grade UPSes are of this type.

You electronic are seeing a sine wave that is close enough for their usage. If it keeps everything up then you are fine. As a warning a UPS will suck it's batteries dry to keep things running. This can be very hard on SLAs over the long run.

A few links:
http://www.liebert.com/information_pages/information.aspx?x=got_ups
http://en.wikipedia.org/wiki/Uninterruptible_power_supply

I personally use a combination of UPSes. I have a very large UPS that I use to provide long run time with a smaller Online UPS that gives me very stable power. The smaller UPS is plugged into the big one.

I will point out that having a UPS plugged into a UPS is usually a bad idea. In my specific case my large UPS is so far over spec from the small online one that damage is unlikely.

 

[45/70]

I have an opti-ups 1500B pure sine wave UPS. The batteries can be hot swapped so the UPS does not need to be powered down when replacing them. Not sure what would happen if the batteries went dead but I have found nothing about it shutting down.

Well Gazoo, you may have me there. It's been a while, but as I remember, that's the way it happened. It could be, however, that this....

Some other makes just emit a continous beeping at you until you get up and replace the battery you were supposed to replace 3 years ago..

happened as well. This type of failure always happens at the most inopportune time and I may just remember inaccurately.

Dave

 

[Gazoo]

Well Gazoo, you may have me there. It's been a while, but as I remember, that's the way it happened. It could be, however, that this....


happened as well. This type of failure always happens at the most inopportune time and I may just remember inaccurately.

Dave

I am really looking forward to the day when they start putting LifePo4 batteries in these things. I know its cost prohibitive from the manufacturers point of view, but those of us that understand LifePo4's vs SLA's know the many benefits and the fact that they pay for themselves. I would love to convert mine over to LifePo4's but have no idea how I could do it...how to charge the batteries and integrate them with the UPS is the problem.

 

[jayflash]

The APC Back-UPS XS 900 I'm using has a pair of hot-swappable, 7Ah 12v, batteries, surge protectors for the LAN cable and modem plus "Automatic Voltage Regulation."

The AVR claims up to a 12% boost at 94 - 109vac. Apparently, the UPS is "on-line" because the boost regulation does not draw current from the batteries. Unless, perhaps, it switches over when voltage drops below 94vac.

BTW, the UPS is plugged into a US made (Houston, TX) iEPS "Smart Power" digital power filter, which also protects connected phone lines from my internet phone modem. This unit, itself, was rather expensive.

Are there any recommended suppressors which can be installed between the outdoor cable feed and the splitter that supplies three TVs & the PC?

 

[VidPro]

The AVR claims up to a 12% boost at 94 - 109vac. Apparently, the UPS is "on-line" because the boost regulation does not draw current from the batteries. Unless, perhaps, it switches over when voltage drops below 94vac.

?

that is a "Regulated" UPS, which regulates the input power when it browns and surges slightly without (nessisarily) switching over to battery.

we found that regulated power supplies are much better than the ones that only switch to battery power, probably just because the design is better.

 

[VidPro]

Is it better not to run electronics too long from a modified or non sine-wave source such as UPS systems which don't regenerate a pure output?

How do cheaper, home use, UPS units switch to battery power quickly enough to keep the PC from turning off?

Thank you ahead for any replies.

the switch occurs in miliseconds, so the AC stuff doesnt much know it from a dip in the AC sine wave which is dipping up and down at 60Htz already. some cheap units, do NOT reliably switch fast enough though for SOME devices. especially when the load is neer its capacity.

On the Solar/wind forum, there are people who have used "the parts of" a UPS to run a PC continually off of Solar, by connecting a mondo car type battery up and charging it direct with solor/wind. they dont report the pc having trouble with this, but the unit does get warm running continuous, so there is some indication that they have the board exposed to air cooling better.

as mentioned many items running off of the AC are converted to DC, then they use chokes caps and other stuff to clean up the DC, Caps (capacitors) are like very fast batteries, and can hold the power up in stuff for a tiny ammount of time. blending out any messes made by the nasty AC being fed in. at least it is "modified" square wave, and not full square wave, like some cheaper converter items (and cheaper UPSes too).

If there was going to be any issue with the "differences" in the AC power for running a PC, it would more likly be from them stupid "switching" power supplies, which are more dependant on the AC sine wave for thier conversion, a Linear, or magnetic or transformer type power supply wouldnt have much trouble at all. the switching ones already suck so badly, it probably doesnt help them at all, but replacing them with a real power supply doesnt hurt anything.