Home Forums Peripherals & Multimedia Peripherals UPS Backup Battery and Pure Sine Wave Power

pure sine-wave power vs approximated square wave
is it important??
Am looking into getting new UPS battery backup system.
My last one from Tripplite worked great on 10.4 but would crash on 10.5 and 10.6. (never tried it on 10.7)
I will get a new iMac in the future and am looking at APC, CyberPower and Tripplite
Is the pure sine-wave power vs approximated square wave an important issue?
Depending on whom I speak to at APC, CyberPower and Tripplite, I get a different answer.
What seems to show up is the new computers have Power Factor Correction power supply (PFC), and they seem to be more sensitive than the older computers.
Any thoughts or insights on the issue will be most appreciated.
Thanks Mark

I have both a TrippLite OmniSmart and an APC Back-UPS RS. As far as my Macs all running Lion (although I cannot imagine what difference the OS would make in this case) are concerned there is no apparent difference between the two. The APC Back-UPS RS momentarily switches over to battery power sometimes several times a day while the TrippLite OmniSmart seldom, if ever does, even though both are on the same power circuit. I suspect that is because of the OmniSmart's ability to smooth out the incoming line power. To me that overrides any considerations of pure sine vs. square wave output.

The APC is getting pretty long in the tooth and the batteries are due for replacement sometime this year. At that point I will probably replace the APC with another TrippLite OmniSmart. But that is strictly personal preference and a longer history with TrippLite than with APC.

You may have done that in the past, but if not, you might consider replacing just the expired APC battery at a fraction of the cost of the entire UPS.

Thanks for the response Joe. I guess I won't worry about the sine-wave power vs approximated square wave. Mark

Replacing the batteries is just a fraction of the cost of a new UPS, I have replaced the batteries in the Back-UPS before. But as I said, the APC is getting long in the tooth and supposedly the more hits the circuitry gets the more the reaction time suffers. As I said, this one is prone to switching several times a day — particularly in the summer when the electric load is at its heaviest both in the house and the entire grid. On the other hand the OmniSmart has only switched to battery a very few times in the same time frame. The battery replacement issue is more of an excuse than a reason to switch.

I don't think the switchover is a big issue, I have maybe 10 UPSs in my house (long story) and I have taken a wirecutters to the noise makers in most of them because of the racket I get during a blackout.

As for the power, you'll get anything from a very coarse power to a smooth sine wave, or anywhere in between. "modified sine wave" (aka "stepped sine wave") is the most common nowadays and is easiest on your hardware. But most power supplies can take dirty power and still provide clean power to the computer because of the DC conversion that's happening in the power supply.

The short of it is the power supply in the computer steps UP the power to roundabouts 300-350 volts ac, turns it into DC, and uses THAT to step down to the 3, 5, 12, etc that the computer wants. The capacitors at 300v act as a "storage tank" for power, to supply the step-down circuitry during 100% of the 120 volt line power cycle, which isn't producing any power 120 times per second under normal line conditions. So that hardware really doesn't mind all how dirty the power it gets is, because it's going to smooth it out regardless of what it gets. It does make things a little "rougher" on the input, but any decently designed power supply won't be affected by it.

Also the closer to true sine wave you get, the less efficient the inverter in the UPS becomes, and so you get more heat and less runtime on the battery. I have a VERY dirty tripplite "Battery Backup System" (not UPS) at home that runs off a forklift (24v) battery and produces darn near a square wave. (it SMOKED a line conditioner I plugged into it one time) None of my hardware (pmg5, pmg4, monitor, airport, cable modem, dsl modem, routers, switches) mind it at all. It's ancient, but very efficient, and tops out at 2kw. An oldie but a goodie.

(that line conditioner did an admirable job for about 4 minutes, producing a nearly perfect clean sine wave on the output before it tried to ignite its transformer)

I've got two different APC models powering two different computers and ancillary equipment. The older one (with replaced battery) supplies my regular Mac and rarely switches. The newer APC supplies an older Mac that is rarely used, plus a variety of external drives. This is the one that I hear switching fairly often, for no apparent reason (e.g., lights on the same circuit remain stable). Of course, this doesn't say much about how quickly these UPSes respond, or how well they clean the power they get.

It's always better to have a sine wave UPS, they offer better protection, more solid circuitry and usually bigger batteries. They're used in industry, there are no back-upss protecting servers in the jungle.

The non sine wave ones were made to keep up with cheaper UPSs for home. If you want top rate protection and not have to worry about PFC compatibility, then it's well worth it to invest in a Smart-UPS

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Also, the switching times on the Smart-UPSs is much faster than on the Back-UPSs, thereby reducing the wear on the power supply

Good info Thanks,,,I have been looking at APC, CyberPower and Tripplite. Do you have any information on which one would be the best company to buy from. They all have sine-wave power units. Thanks again

About 4 years ago, I purchased a UPS from APC. At that time, I found their sales staff knowledgable and competent. Their tech support was also first-rate.

But as they say, anechdotal observations are not data (especially when lacking comparisons & bench marks, and are made by an unsophisticated observer).

FWIW, I have 2 other APC UPS that are over 10 years old and they still work great. (the batteries lasted about 5 years).

Just bought the CyberPower cp1000pfclcd. So far so good. I turned the power off and the battery took over just fine. Then I hooked up the USB connection and lo and behold it turned the computer safely off after 2 minutes. It is 1000VA / 600W Pure sine wave UPS, with AVR . It got excellent reviews on New Egg and Amazon. The unit is smaller than a lot of the UPS units. So far very happy. One last thing, if anyone decides to get this unit, the instructions say to turn all power off and to unplug the unit before plugging anything in. Thanks to all that responded. Mark

Some of that I'd agree with, some of it I'd tag with a [citation needed], and "they offer better protection" I would have to disagree with. "Protection" is a very general term and sine waves don't cover most or everything under that blanket.

Sine wave power is cleaner, it's easier on the equipment it's connected to. That's about it. It's less efficient, leading to shorter batter runtime (or larger battery requirements for the same time), generates a different (not more or less, different) electrical noise, and has absolutely nothing to do with cut-in delay, sensitivity, or speed.

I would personally put highest "protection" value on fast cut-in (along with cut-in on dirty power, not just power LOSS), at least acceptably smooth power to not stress your gear's power supply, and the best possible runtime. (and fast battery recharge rate - a UPS quality that often gets ignored) Sine wave doesn't factor into most that at all, short of reducing runtime, which is a (-).