1500VA UPS + Sleepy Mac Pro Wakes Up = Overload

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Level 2

385 points

1500VA UPS + Sleepy Mac Pro Wakes Up = Overload

I have seen a couple of people mention that upon a "USB event" informing a sleeping Mac Pro that the UPS went on battery that the UPS then went into overload. I also have precisely this same problem for a stock Mac Pro. The discussion I am referencing is:

http://discussions.apple.com/thread.jspa?messageID=3052641

My question is, is this normal? The Mac Pro shouldn't draw in an instant over 1440VA (120V * 12A) for a stock system because there isn't any additional electronics requiring that power. If it WERE a fully loaded, fully connected (external devices included) system, then sure I can understand this. However, the computer shouldn't draw what it doesn't need. I DO understand that there can be spikes in current draw, but more than 1440VA? Is this normal?

Is there anyone who has a UPS and a Mac Pro who has put the Mac Pro to sleep, lost power to the UPS (intentionally by pulling the cord or by accidental power loss), had the Mac Pro wake up WITHOUT overloading the UPS? Even when my Mac Pro is the only device connected to the UPS it will overload the UPS upon wake-up.

To add a stipulation, if the Mac Pro is asleep but there is no communcation link (usually USB) between the Mac Pro and the UPS, then the Mac Pro will sleep happily in ingorance of power loss and thus not try to wake up and overload the UPS. However, if you try to wake up the Mac Pro while the UPS is on battery, then that may not be a good thing.

If anyone CAN put their Mac Pro to sleep while on a UPS and lose power, then what is your UPS's ratings and is your Mac Pro the stock configuration?

Thanks. Just trying to determine what is normal for the Mac Pro. Currently I am NOT putting it to sleep and all is just fine even when my CRT monitor has to wake from sleep (we've had two power outages within the last three days, besides my own intentional power loss tests).

Mac Pro 2.66, PB G4 1.5GHz, Mac OS X (10.4.8)

Posted on Oct 10, 2006 2:28 PM

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Answer 1

The hatter

Level 9

60,990 points

Oct 10, 2006 3:03 PM in response to Darrik Spaude

One variable in an excellent thread on the G5 Quad and APC RS1500 was what setting you have for what to do in the event of a power failure.

Is Energy Saver -> UPS Options
set to restart automatically in the event of a power outage?

Also, one person noticed it behaved better with PowerChute than without if the above was indeed selected.

I have the Mac Pro on its own UPS, all other devices and monitor are on their own UPS, so it really would be the Mac Pro alone drawing. But I have not yanked or had power go out while sleeping (I rarely if ever let my system sleep during the day, and at night it gets shutdown so it can't be awakened by pet hitting the keyboard).

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Answer 2

Oct 10, 2006 3:55 PM in response to Darrik Spaude

For a standard usit the 1500VA model should be fine. I have a very non-standard unit running off a 1000VA model and have had no overload issues.

What else do you have plugged into your UPS?

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Answer 3

Darrik Spaude Author

Level 2

385 points

Oct 10, 2006 5:14 PM in response to infinite vortex

Hi Ned,

I have tested the UPS without anything plugged into it except for the Mac Pro, but it doesn't make a difference. The Mac Pro is what causes the overload WHEN IT COMES OUT OF SLEEP. When the system is running there is no overload problem. When the system is running and the UPS is on battery there is no problem. The problem happens when a HUGE current draw happens when the Mac Pro comes out of sleep. I would just like to know if others have this same problem and what is reasonable for a current draw spike when coming out of sleep mode.

The same current draw spike happens when the Mac Pro is turned on. These spikes I mention happen within 1 second of hitting the power button or within 1 second of waking the computer from sleep. At all other times the power draw is reasonable (within Apple's specified limits).

Have you tried waking your Mac Pro from sleep when your UPS is running from battery? I suggest that you not have anything important unsaved or have any open applications (close/quit all apps) if you do venture to try cutting power to the UPS.

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Answer 4

Darrik Spaude Author

Level 2

385 points

Oct 10, 2006 5:22 PM in response to The hatter

Is Energy Saver -> UPS Options
set to restart automatically in the event of a power
outage?

"Restart automatically after a power failure" is disabled. We lost power three times last night. The first two were for a few seconds and then the third went into a brownout condition and then finally black a few seconds later. It stayed out for over an hour. I typically don't like having the computer restart itself after a power failure due to these kinds of possibilities. The power failure the past 3 days is not typical. I CAN understand this option for server-type applications, but for me it isn't necessary.

By the way, I have tested the load capability of the UPS and it appears to be okay. If it is slightly less or slightly more than the advertised ratings, then I wouldn't be able to determine that. I just did was APC suggested to test whether the UPS was faulty. The UPS is an APC Back-UPS XS 1500 (a few days over 2 weeks old).

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Answer 5

Oct 10, 2006 6:00 PM in response to Darrik Spaude

I boot/reboot and sleep/wake all of the time and haven't come across this problem even once. I also have multiple other devices (USB/FierWire hubs and devices) connected to my UPS as well so I think your situation is out of the ordinary.

Have you tried using a different power cable and different socket on your UPS? Also, what display are you using? It's possible your display is drawing too much and overloading your UPS.

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Answer 6

Oct 10, 2006 6:21 PM in response to infinite vortex

My configuration is as below and I have no overload problem: -

1000VA and connected with my MacPro, 23" Cinema Display, Linksys broadband router and 2 external harddrives.

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Answer 7

Darrik Spaude Author

Level 2

385 points

Oct 11, 2006 3:03 AM in response to infinite vortex

I boot/reboot without problems as well as long as the UPS is NOT running on battery. I can sleep/wake okay too as long as the UPS does not go to battery while the Mac Pro is asleep.

To emphasize, under normal power circumstances, there is no problem being connected to the UPS. Under power loss conditions, however, if the Mac Pro was asleep when the power went out then when it tries to wake up it will overload the UPS.

I have a 17" CRT monitor (150W), but I have not connected it to the UPS and the Mac Pro will still cause an overload IF the UPS is RUNNING ON BATTERY.

Ned, I would think that your Mac Pro normally is not booting/rebooting/sleeping/waking while you UPS is running on battery (meaning the UPS is not getting power from the wall outlet). Is this correct? If this is correct, then what happens to your system when it is alseep while the UPS loses power? If you have the USB cable connected to your UPS, does the Mac Pro immediately try to wake up? If you don't have a USB cable connected to the UPS, then if you wake up your Mac Pro while the UPS is running on battery does that work successfully?

I appreciate your time. I'm just trying to emphasize that during a power loss situation when the UPS is running on battery my Mac Pro ALONE will overload the UPS, but at 1500VA I don't think this should be possible.

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Answer 8

Oct 11, 2006 3:21 AM in response to Darrik Spaude

Note that Ned Snowing is in Europe with 240 Volt power. The Mac draws less current at 240 Volts, which may be why he is not having any problem. In the US, with 120 Volts, the Mac Pro is rated to draw 12 Amps, which puts it close to the rating of you UPS. When turned on, or upon waking, the current may be considerably higher, which would exceed the capability of the UPS when running on battery power. Some UPS units can handle large starting currents, but yours, apparently, can't.

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Answer 9

Oct 11, 2006 4:45 AM in response to Darrik Spaude

OK… I just tried mine (boot, reboot, sleep and wake) actually running on battery and not a blip. Actually, if it doesn't happen on a boot it's highly unlikely to happen at all.

Now, having said that, upon pulling out the power cord from the back of the UPS it did go into overload and everything went off. What I mean by everything is my Dell display, FireWire and USB hub and a sleeping Mac Pro. There's no way the current draw at that state is anywhere near enough to cause an overload. I do however suspect that is "overload" is an error state and not an overload state which results in the way the power is removed. My 800VA does exactly the same thing when the power is yanked out and again, there's no way the load on it is anywhere near what is required to have an overload.

I think your problem is how your cutting power rather than the power cut itself.

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Answer 10

The hatter

Level 9

60,990 points

Oct 11, 2006 6:46 AM in response to infinite vortex

The XS uses different components than the RS model (it is not sold direct by UPS but often by consumer electronic stores, Amazon carries it, etc).

You can search APC and they have an article or two on difference between the two. It also lacks RJ45 filtering - useful for your router.

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Answer 11

Darrik Spaude Author

Level 2

385 points

Oct 11, 2006 7:58 AM in response to Malcolm Rayfield

Hi Malcolm,

120V * 12A = 1440VA
240V * 6A = 1440VA

If the Mac Pro draws more than 1440VA, then it is out of spec even if it IS just a spike. The power supply should be covering/dampening spikes. I was told by AppleCare that the power supply is a 980W supply. 980W is the maximum for the whole system but not necessarily NEEDED if there are no devices needing that much power. Apple says 250W for the stock system at peak performance, but it would be nice to know what is the peak spike in power draw. If there are spikes that draw beyond even the power supply's capability, then shouldn't there be a recall for those systems?

Some people have mentioned that even their lights flicker when the Mac Pro (and PowerMac G5) is powered on or wakes from sleep. Is that also normal?

One more thing. If an Apple laptop had a peak power draw spike like my Mac Pro, then the laptop battery would likely overload as well and shut the system down immediately (as in power disappears immediately rather then a nice shutdown process). Can anyone imagine going to wake up one's laptop only to find that upon wake-up the laptop overloads the battery and the system shuts down (that's only possible if you were able to power up the laptop at all which means you'd probably have to be connected to a wall outlet before being able to put the laptop to sleep)?

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Answer 12

Oct 11, 2006 8:59 AM in response to Darrik Spaude

120V * 12A = 1440VA
240V * 6A = 1440VA

Which is close to the 1500VA limit of the UPS;

If the Mac Pro draws more than 1440VA, then it is out
of spec even if it IS just a spike. The power supply
should be covering/dampening spikes. I was told by
AppleCare that the power supply is a 980W supply.
980W is the maximum for the whole system but not
necessarily NEEDED if there are no devices needing
that much power. Apple says 250W for the stock system
at peak performance, but it would be nice to know
what is the peak spike in power draw. If there are
spikes that draw beyond even the power supply's
capability, then shouldn't there be a recall for
those systems?

It would be nice if high powered switching supplies did not have a current spike at turn-on, but they all do.

Some people have mentioned that even their lights
flicker when the Mac Pro (and PowerMac G5) is powered
on or wakes from sleep. Is that also normal?

Normal, but not desired.

One more thing. If an Apple laptop had a peak power
draw spike like my Mac Pro, then the laptop battery
would likely overload as well and shut the system
down immediately (as in power disappears immediately
rather then a nice shutdown process). Can anyone
imagine going to wake up one's laptop only to find
that upon wake-up the laptop overloads the battery
and the system shuts down (that's only possible if
you were able to power up the laptop at all which
means you'd probably have to be connected to a wall
outlet before being able to put the laptop to sleep)?

A laptop runs directly from the DC battery. The input current surge is in the input part of a power supply where the AC is converted to DC. A laptop doesn't have that. Some parts (such as disk drives and firewire ports) use 12 volts directly from the battery, Other parts, such as the backlight and CPU, need higher or lower voltages. These use switching supplies, but since they are running from DC, don't have the large input capacitors and current surges.

The ideal way to handle UPS is to run all the equipment from DC, from a set of batteries. A power supply charges the battery when AC is available. A phone exchange runs that way. Everything is designed to run on 48VDC from a set of batteries in the basement. These are kept charged by AC, or if the AC is off for too long, diesel generators. Some computer companies made 48VDC power supplies as an option for computers they sold to phone companies.

Three-phase AC input would also allow a design without a high start-up current surge, but would severely limit sales for home use.

With high powered AC input switchers, you need a larger than normal UPS, or one that is designed to handle a large start-up current spike. Such an UPS might draw too much power to run on a household circuit.

Mac Pros are getting close to the limit for home use. A dedicated circuit should be used if possible. Apple does not want to stress this, so as not to limit sales.

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Answer 13

Oct 11, 2006 9:11 AM in response to Malcolm Rayfield

I am running an APC Smart-UPS 1500 and have the following connected to it with no issues:

Mac Pro 2.66GHz
23" Cinema Display
External 500GB FW-HD
External DVD-Rom
Router
Wireless Access Pt
Powered USB Hub

Windows P4 2.53GHz PC
2-19" NEC monitor
External 320GB FW-HD
Powered USB-FW Hub

With the Windows PC running and the Mac Pro coming out of sleep mode, my UPS only registeres about a 40% load. The external drives are not on at this time, but even when they are I never register more than a 40% load. The APC Smart-UPS 1500 is very robust and very reliable.

john

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Answer 14

Darrik Spaude Author

Level 2

385 points

Oct 11, 2006 10:07 AM in response to John Carothers

Hi John,

When your Mac Pro is coming up out of sleep, is the Smart-UPS running on battery? I am assuming not. As I've said previously, I don't have any problems when the UPS is being fed power from the wall outlet. My XS-1500 works fine when the power is coming in through the wall (probably about 30% load with the Mac Pro and 17" CRT monitor).

APC could not give me an answer as to whether the Smart-UPS 1500 would work or not when on battery backup. The Smart-UPS 1500 (SUA1500) has a 1500VA/1050W rating whereas the Back-UPS XS 1500 has a 1500VA/865W rating. The true sine wave output from the Smart-UPS series provides more total power than the simulated sine wave.

My guess is that your system would immediately overload if your Mac Pro came out of sleep mode when the UPS switched to battery backup (even if the Mac Pro was the only device connected to the battery backup ports--all other devices connected to non-battery or another power source). However, like I said, APC couldn't give me an answer as to whether the Smart-UPS 1500 would handle it any better. Not that I want you to try killing power to your UPS while the Mac Pro is sleeping (and connected to the UPS via USB cable), but it would be interesting...

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Answer 15

Oct 11, 2006 10:46 AM in response to Darrik Spaude

I will give it a try this weekend when not doing anything else. Will let you know what happens.

john

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