UPS (no no, not the delivery guys)

Gandalf · Post by **Gandalf** » Sat Dec 27, 2003 10:10 am

I've been thinking of buying a UPS -- interruptable power supply -- for quite some time now. I have my eyes set on one of Merlin Gerin's smaller models. One of the Pulsar Ellipse series (don't know which one yet, somewhere inbetween 500 and 800VA).
However, I have one consern .. silence. Does anyone know whether these things make any noise? (beit electrical or coil whine or whatever).
Another concern is efficiency. Do they cause any power to be "lost" (the charhing of the batteries not included of course!) or can you get every last drop of power back out of it?

thx =)

Post by **Ralf Hutter** » Sat Dec 27, 2003 10:48 am

I've got an APC SmartUPS 700 and it has a very, very slight bit of transformer noise but I've also heard some APCs and Belkins that have a very noticeable transformer buzz to then. It seems to be sort of hit or miss. Your best bet would be to listen to the version that you're thinking of buying, or at least buy it from somewhere with a liberal exchange policy in case it's too loud.

Putz · Post by **Putz** » Sat Dec 27, 2003 11:58 am

I have two APC units @ ~500 and ~650VA. The 500 is four years old, and buzzes noticeably when it kicks in to correct dirty or low input power, but is silent when it's idle, running the power straight through (which is most of the time). The 650 is new (three months old) and I can't hear it under any circumstances (unless maybe if I put my ear literally right up to it when it kicks in to correct power).

YMMV, of course.

Xfinity · Post by **Xfinity** » Sat Dec 27, 2003 1:06 pm

Have an APC Back-UPS RS 500VA that I recently bought and I do not use it because it has a very noticeable transformer buzz to it. I am building (read buying) a case to trap the transformer buzz. So I agree to test the UPS unit you are planning to buy.

Gandalf · Post by **Gandalf** » Sat Dec 27, 2003 2:13 pm

Aye. Sounds like a plan. I might as well fork up a few more euro's and make sure it's silent.

Sam Williams · Post by **Sam Williams** » Sat Dec 27, 2003 4:52 pm

I've got an APC SmartUPS 700 and it has a very, very slight bit of transformer noise but I've also heard some APCs and Belkins that have a very noticeable transformer buzz to then. It seems to be sort of hit or miss.

That's for sure. I have a SmartUPS 700 as well, and it's extremely loud - in fact, the loudest piece of equipment I now own, post-silencing project.

mpteach · Post by **mpteach** » Sat Dec 27, 2003 5:45 pm

my ups is loud when the line voltage drops and the inverter kicks in, and its even louder when the power goes out completley because after 20 seconds this stupid beeping noise comes on.

During normal conditions though i doesnt make any noise.
I kind of like to know how my line is doing.
Im lucky if the voltage drops once a week for a few seconds and maybe a minute outage once a month.
You must live in a place with very unrellable power.

Gooserider · Post by **Gooserider** » Sat Dec 27, 2003 9:25 pm

Agreed, that has been my experience as well... Some units are silent, many or most there is some transformer noise, but I've never found it to be that much.

It seems to me that some of the difference is in what type of unit you are dealing with. The standby type supplys that pass line power through during normal operation, and just kick in when the power goes out of spec. seem quieter, probably because they just need a little charger.
The "TRUE" UPS that continually takes line current and regenerates clean power from it's internal converter seems more likely to make noise since it has to have a bigger transformer.

Gandalf also asked about efficiency, and how much power was lost by the UPS itself. I'm not an expert, but my understanding is that 'standby' type units are quite efficient, using only the power needed to charge their batteries. OTOH, the "TRUE" UPS will consume more juice, (and generate more heat) since it has some level of transformer loss.

While the standby type units are probably better from a noise and efficiency standpoint, at least in theory the constant online units do offer better surge protection, line conditioning and arguably more reliable switchover in the case of power failure. (even the fastest standby unit takes some fraction of a second to come up, but an online unit by definition has no switchover time.)

I would tend to say that if your power is clean and reasonably reliable, you can get away with a standby type unit. If your power is noisy and not so reliable, or if you are 'mission critical' get an online unit.

Gooserider

mpteach · Post by **mpteach** » Sat Dec 27, 2003 9:42 pm

I think that standby units are good enough for almost all people. Modern PSUs can take voltage highs, lows dips, thats what theyre made for. They have voltage regulators and capacitors. They take fluctating current AC and produce a stable DC voltage.

Why havet the UPS do the same thing. The psu do the regulation, u just need an ups for the outages.

Trip · Post by **Trip** » Sun Dec 28, 2003 1:37 am

I use an APC Back-UPS 500. I've had it for 3 or 4 years, silent as far as I can tell, though if the power goes out it beeps like an alarm to let you know. I think I turned that feature off now though.

Shuriken · Post by **Shuriken** » Sun Dec 28, 2003 5:46 am

My APC Smart UPS 2200 makes a hell of a noise when it kicks in. This baby is cooled by some huge fans.

But other then that it is dead silent. I can still hear some very faint coil buzz but most people wont notice (me got excellent hearing

)

Gooserider · Post by **Gooserider** » Sun Dec 28, 2003 9:44 pm

mpteach:
I think that standby units are good enough for almost all people. Modern PSUs can take voltage highs, lows dips, thats what theyre made for. They have voltage regulators and capacitors. They take fluctating current AC and produce a stable DC voltage.

Why havet the UPS do the same thing. The psu do the regulation, u just need an ups for the outages.

For most people I sort of agree, at least in theory. But I also know that there are power failure modes that will seriously smoke a normal power supply, even with a surge protector, I've been in buildings where they've happenned (A dumpster truck picked up the neutral return wire from the power drop, as I recall, and put 220VAC across most of the 110VAC in the building - smoked all sorts of stuff!) Some of these failures will get past the power supply, and smoke the rest of the PC. In such cases, the more protection you have between the line and the PC, the better the odds of the PC surviving.

An isolation transformer type supply will protect the PC from more failure modes than just about any other method. Many will also function during brown-outs (In CA, better known as 'Grey-outs') to keep the power to the PC's PSU in a normal range, with a far wider range of tolerance than most PC PSU's. Yes, modern PSU's are far better at tolerating bad power than old ones, but they still aren't as good as a good UPS...

Another factor that might be worth considering is that handling power irregularities is hard on a PSU, and can cause it to fail - why not take the load off it?

I would stand by my earlier statement that IF you have generally clean, reliable AC power, then a standby unit is probably adequate as you suggested.

However, if you have problematic power with frequent interuptions, and lots of surges, sags and spikes then an online UPS, especially an isolation type UPS will probably give you noticeably more protection.

It is also worth noting that most 'mission critical' hardware specs call for online power protection (normally redundant, and multiply sourced...) If you ever want to see high reliability in action, take a look at the phone co. - you will see dual battery banks, located at opposite ends of the buildings, with independent charging systems. All of the telco electronics will have dual 48VDC inputs, getting one feed from each bank. I used to work on voice mail systems that went into telco's, our systems were contractually required to be up 99.999% of the time - in other words we were allowed to be down a total MAXIMUM of 30 minutes per year, including maintainance.... In theory, you could walk up to one of our systems and reset, turn off, or physically remove any one part and at WORST loose the calls that were actually in progress at that moment.... Actual practice wasn't quite that good, but was close to it.

Gooserider

Gandalf · Post by **Gandalf** » Mon Dec 29, 2003 3:13 am

Thankfully my line is rather clean. It dies on a nearly daily basis (well, sort of), but it's clean

.