Looks like I'm in the market for a new UPS. I'm replacing a RS1500 [www.apc.com]

What features should I look for? I know that there are power quality features that I don't understand, likely because i've never needed to.

I'm tempted to get an APC Back-UPS Pro 1500. The price is reasonable and I can add an additional external battery pack to increase run time. ($189)

[www.amazon.com]

there's also a cheaper model by Cyberpower. ($139)

[www.amazon.com]

advice?

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I have the BR1500. It's great. I really like the monitoring features.

...and yes, you can turn the alarms off.

is pure sine important to you? probably not, but just in case it is, here is an option

[www.amazon.com]

Quote
space-time
is pure sine important to you?

Is there any particular reason that it would be?

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do you hook up a HiFi audio system or expensive TV to it? then I would go for a pure sine wave UPS. If not, doesn't really matter. On the other hand, the model I mentioned is the same price as the APC model you listed, same power, so why no get pure sine wave if it doesn't cost you more?

Space,

That is _cheap_ for a pure sine wave UPS! but, I'm betting it's also an offline UPS vs an online model. I remember contacting APC about getting a 1500 VA UPS for my Mac Pro and they said due to the type of computer, that only a APC SMARTups level UPS is appropriate. A close friend was told the same thing. Apparently, the Backups Pro design wouldn't protect the computer properly. I suspect it is because of the difference between a step wave and pure sine wave UPS and, if I remember correctly, the difference between an online and offline UPS.

If I understand correctly, a pure sine wave UPS recreates as close as possible clean electricity.A nice curve, whereas a step wave, it's boxey and far less like pure juice. Pure sine wave is considered better. I'll admit, I've used UPSs with step wave output for most of my hardware over the years. I didn't switch over to a unit with pure sine wave output until I got my Mac Pro. If I remember correctly, APc SMARTups and similar models produce pure sine wave output and APC BAckups models like the ES, RS and BX series produce step wave output.

With an online UPS, your hardware is always connected to inverter output whether or not there is a power outage. It's soemthing along these lines: Juice goes into the UPS and stored into the battery. The UPS then sends the juice from the battery to your hardware. At some point, the juice is cleaned up prior to getting to your hardware. The hardware never knows whether or not there is an outage. The only time power going to it is interrupted is when there is an outage and the juice stored in the battery finally runs out. Hopefully, power is restored prior to this taking place and/or you've shut the hardware down. If I remember correctly, APC SMARTups models are online models that produce pure sine wave output.

With an offline UPS, hardware gets juice from the battery only during an outage. At the moment of an outage, there is a brief amount of time that electricity isn't being sent to the protected hardware. That is the amount of time it takes the UPS to switch from main power to battery power. Machines with AVR always clean the juice prior to sending it to the hardware whether it's working off battery power or main power. Lower-end UPSs such as the APC Backups ES series and, if I remember correctly, the RS (and BX) series are offline UPS.

I was able to get a SMARTups for a very reasonable price and since it was the recommend choice for my tower and I had the extra cash, I decided to go for it. But, did I really need to get a SMARTups for my tower? Honestly, I can't say with 100% certainty. I wonder what Apple would say on the matter. Step wave vs sine wave and online vs offline.

Robert

If the past five years of using my RS1500 is any indication -

pure sine wave just isn't needed. (maybe for hifi equipment?)

It has AVR, but I'm uncertain if its online or offline.

thanks for the discussion, these are the issues i'm trying to understand.

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Edited 1 time(s). Last edit at 07/31/2011 01:26PM by mattkime.

there's another RS1500 on ebay for $50 shipped. I wonder if its worth it over buying new.

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[www.cyberpowersystems.com]

Pure sine wave output
Line-interactive topology
Automatic voltage regulation (AVR)
GreenPower UPSTM technology
Multi-function LCD panel
HID Compliant USB port
Phone/Fax/Modem (RJ11) and Ethernet (RJ45) line protection
10 Outlets / HID compliant USB and Serial ports
Widely-spaced surge-protected outlets
PowerPanel® Personal Edition UPS Management software
Connected Equipment Guarantee
Three-Year Warranty

Quote
Robert M
With an online UPS, your hardware is always connected to inverter output whether or not there is a power outage. It's soemthing along these lines: Juice goes into the UPS and stored into the battery. The UPS then sends the juice from the battery to your hardware. At some point, the juice is cleaned up prior to getting to your hardware. The hardware never knows whether or not there is an outage. The only time power going to it is interrupted is when there is an outage and the juice stored in the battery finally runs out. Hopefully, power is restored prior to this taking place and/or you've shut the hardware down. If I remember correctly, APC SMARTups models are online models that produce pure sine wave output.

With an offline UPS, hardware gets juice from the battery only during an outage. At the moment of an outage, there is a brief amount of time that electricity isn't being sent to the protected hardware. That is the amount of time it takes the UPS to switch from main power to battery power. Machines with AVR always clean the juice prior to sending it to the hardware whether it's working off battery power or main power. Lower-end UPSs such as the APC Backups ES series and, if I remember correctly, the RS (and BX) series are offline UPS.

Online UPSs don't suck off the battery all the time as you suggest. The AC power is fed into an inverter which simultaneously is used to top off the battery and to feed to a second inverter which cleans up the power going to the jacks. Because the signal is actively being cleaned up in this process, an online UPS is actually less likely to hit the battery to cover a brief power-fluctuation than other kinds of UPSs.

APC's AVR tech is an online UPS design. It uses a transformer to moderate the AC output. During ordinary trim and boost operations the a UPS with AVR should never hit the battery.

...

The shape of the sine wave is generally only of concern if you're running motors (power tools, refrigerators, laundry machines) or charging batteries with a very old (or cheap Chinese knockoff) charger off of your UPS. Don't worry about a "pure sine wave" if you're just using it with computer gear.

Fry's has the BR1500G for $115 for a week (or less) about every two or three months; worth keeping an eye open when in need...

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Sometimes it is what it is...
and then there's times when it's really better.



==

Chak,

Are you sure? Several sources I found online suggest the battery is connected in a manner that ensure there is never an interruption in the flow of electricity. I may have phrased it incorrectly but that appears to be the design, depending on the type of UPS.

Robert

Quote
Robert M
Chak,

Are you sure? Several sources I found online suggest the battery is connected in a manner that ensure there is never an interruption in the flow of electricity. I may have phrased it incorrectly but that appears to be the design, depending on the type of UPS.

I'm not sure what you mean by your second sentence, but here's the top hit on the subject from a Google search:
[www.adeptpower.co.uk]

And this is a good explanation of AVR:
[www.apc-forums.com]



Edited 1 time(s). Last edit at 07/31/2011 05:00PM by Chakravartin.

Chak,

I was somewhat off in my original post but was correct in my description of the end result. Online UPS ensure a continuous flow of juice. Line interactive and offline models both have an interruption slight as it might be, between the switch from main electricity and battery power. There is no interruption with the online models.

Robert



Edited 1 time(s). Last edit at 07/31/2011 05:06PM by Robert M.

Quote
Robert M
I was somewhat off in my original post but was correct in my description of the end result. Online UPS ensure a continuous flow of juice.

Right. My intent was to point out that the hit on the battery isn't what was implied in your earlier post and to talk up AVR. (I won't buy a UPS that lacks AVR.)

I don't think I would spend the extra money for a sine wave UPS for a computer.
Unless you switch to back yard back-up generator a lot. They can be a bit sloppy .

Quote
Buzz
Fry's has the BR1500G for $115 for a week (or less) about every two or three months; worth keeping an eye open when in need...

I 'd definitely take that if i knew it was going to happen.

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There were a couple of threads about this in the past few months. It all depends on what computer you are trying to hook up to the UPS. If you are using a 'puter that has Power Factor Correction (PFC or APFC), then a sin wave UPS like this one (that I bought) would be beneficial

[www.newegg.com]

PFCs will sometimes not be compatible with other UPSs depending on the power delivery wave type. Look up UPS and PFC. Some good articles and comments about this on the internets.

I like CyberPower so far. But, I've not had a power outage since getting it. I'm running a MacPro (four internal drives), external drive and Dell 24inch LCD monitor. APC tends to have loud fans, which is why I went with CyberPower.

YMMV

-Spiff

Spiff,

Glad you posted about this. I have a feeling this is probably why APC recommended a SMARTups for me. I'm going to contact Apple and APC and find out if my Mac Pro has a Power Factor Correction (PFC or APFC) type power supply in it. I already have a UPS that produces sine wave output but it'd be nice to have Apple or APC (preferably Apple, of course), to confirm the type of power supply in my tower.

Robert

this thread would indicate that it does - [discussions.apple.com]

if it does and i have a simpler/older power supply, what happens?

(i'm tempted to do a test!)

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Quote
mattkime
this thread would indicate that it does - [discussions.apple.com]

if it does and i have a simpler/older power supply, what happens?

Absolutely nothing so long as the UPS is rated for more than the maximum draw of the power supply from the computer and all of the other devices that are attached.

Otherwise you may have a brief dip in the power or break in the power or hear an overload alarm when you first boot the computer.

It has nothing to do with the "wave type." (No idea why spiff would bring that up in this context.) Devices with PFC are capable of suddenly kicking up to their maximum power draw when first powered on even though the ordinary demand on them is much less. So, a PFC PSU for a modern desktop tower computer that draws 240w during ordinary operation might pull 720w when you first flip the power switch. If your UPS can't handle the sudden demand then bad stuff can happen.

PFC is a non-issue so long as you follow the guideline of getting a UPS that's rated for at least twice the sum of the maximum draw of all the devices that will be attached to it. You're not likely to tax a BR1500 to the point where you'd ever see such a problem.



Edited 1 time(s). Last edit at 08/01/2011 01:19PM by Chakravartin.

Hi everyone,

I decided to call APC for information and found out a few things. The first is that Mac Pros do have PFC power supplies. My office's 20.1" Imac with a 2.4 GHz Core 2 Duo has a non-PFC power supply.

APC said step wave UPSs _can_ cause problems for computers that have PFC power supplies. Apparently, PFC power supplies are more sensitive than non-PFC power supplies to fluctuations in the waves. The fluctuations of step wave juice can cause them to turn off. Not a proper shutdown. A plain turn off, as if you pulled the plug. As you can imagine this can in fact cause all sorts of issues, hence their suggestion to use a SMARTups UPSs with sine wave output for machines that have PFC power supplies.

APC didn't mention anything about initial power draw. Just the sensitivity to non sine wave output.

I also contacted Apple and am waiting to hear back from then on the matter.

Robert



Edited 2 time(s). Last edit at 08/01/2011 02:39PM by Robert M.

thanks for the research!

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Matt,

My pleasure. I figured, we're talking about it, why not contact APC and Apple and get their thoughts on the matter. Definitely glad I made the call. I'll post what I find out from Apple after I hear back from them.

Robert

Quote
Robert M
Hi everyone,
APC said step wave UPSs _can_ cause problems for computers that have PFC power supplies. Apparently, PFC power supplies are more sensitive than non-PFC power supplies to fluctuations in the waves...

APC didn't mention anything about initial power draw. Just the sensitivity to non sine wave output.

I get the confusion now. We're addressing the same thing from two different perspectives.

This is APC's official statement on the matter of PFC power supplies:
[nam-en.apc.com]

Relevant excerpt:
Although computer power supplies draw only a fraction of their full capacity during it’s steady state(normal operation), PFC power supplies have the potential to draw their full capability during initial inrush. "Inrush" or "Inrush Current" refers to the maximum instantaneous input current drawn by an electrical device when first turned on.

A computer’s power supply may also be subjected to a period of inrush, while the UPS is changing state (switching from utility power to battery power and back). Back-UPS and Smart-UPS SCs may experience up to an 8ms transfer time during this period. This is just long enough to remove power from the PFC power supply, resulting in a momentary inrush of the PFC. Once the UPS changes states from "Online" (passing utility power) to "Onbattery" (passing power from the UPS's internal battery), the momentary inrush from the attched equipment subjects the UPS to the PFC power supply’s maximum power draw, resulting in a potential Overload condition or dropped load.

And this is their white paper on the subject:
[www.apcmedia.com] [pdf]

Notice that they discuss overloads, not wave-forms. The overload is the primary concern. The waveform effects the type of behavior that you might expect after an overload. But the overload is the really bad and easily preventable thing.

When there's an overdraw condition, if the timing is perfect there's the potential for a tiny gap in power in a stepped sine wave product where a pure sine wave product will simply provide less power at that moment. Instead of a brownout you get a blackout.

But it's not gonna happen unless you exceed the normal operating capacity of the UPS.

It's an issue with servers because of redundant power supplies. Peak draw from one PSU on startup may be far less than the UPSs rated capacity, but the second power supply -- which ordinarily draws negligible power -- may double that peak draw when first powered up. If you don't factor in the second PSU when calculating the capacity of the UPS for your rack, you could blow the whole rack.

But it's not an issue if you've calculated the capacity of the UPS properly. And the rule of thumb that says to get a UPS with twice the capacity that you think you'll need covers that situation very well.



Edited 2 time(s). Last edit at 08/01/2011 03:52PM by Chakravartin.

Chak,

Good post but despite it, I'm inclined to follow the advice offered by APC when I spoke to them. Buy online UPSs that offer sine wave output for machines with PFC power supplies. Seems like a simple enough solution. Factor in discounts and the many options available, and you don't have to spend an arm and a leg for it. Even then, if you're spending two, three, four or more thousand dollars on your computer and associated hardware, i.e. Drobo, then a bit more for a good UPS of the recommended caliber is a worthwhile expense.

Robert



Edited 1 time(s). Last edit at 08/01/2011 07:24PM by Robert M.