Sudden "shutdown" on APC UPS

It may be that this unit is not sufficient at 500 VA for a 2.7

The APC 'selector' shows nothing below 650VA for a basic dual G5 config.:

http://www.apcc.com/tools/ups_selector/index.cfm

If you search on "UPS" in this forum you will find some posts that recommend nothing less than 1500VA.

The setup below appears to work with a reasonable battery run-time on a Smart-UPS 750VA (230 volt).

A 500 is way underpowered for a G5 2.7 but should at least power the system for a short period.

Being 2 years old I'd suspect the battery has reached it end of usefull life.

Others here have suggested a 1000 watt minimum for the PM G5's and a display.

David,

Yes, I've had this exact problem. I'm not sure exactly which UPS I have (I'll have to check when I get back to the studio) -- but basically what you describe is exactly what I'm experiencing. The machine is working fine (no overheating, no kernel panics or other types of crashes/freezes). Then all of a sudden, the machine powers off as if I had pulled the plug out of the wall (even though it's plugged into the UPS).

/sergio

Is your un(dis)graceful shutdown initiated by a fluctuation in the mains supply (like David's)?

If not, this may be of interest:

Everett Marshall, "Power Supply Failure?", 11:13am Sep 10, 2005 CDT

If your UPS is underpowered for the new machine (and it is), it won't run it even for a little while. Your computer will just go dead immediately. Time for a new UPS.

David,

If you or have you tried to unplug the g5 from the ups (into a different outlet or strip) and did that solve the problem?

I purchased a dual 2.0 g5 brand new 2 weeks ago and this has happened twice. I just logged in this morning to find you post and it sounds like we have the same problem.

My ups is APC: back-ups- es 725 ( 1 year old?) and have all the plugs filled in with periphals / monitors.

I have recommended in the past a minimum of 1000VA and prefer a 1500VA UPS for use with Dual G5 Macs.

I have a dual G5 2 GHz model, with a 19 CRT monitor being run from a APC XS 1000 UPS. This UPS is able to provide about 10 mins of run time with just the CRT and computer turned on, even less when external drives are up and running. While this may seem adequate, it is actually borderline for the system in question. One example of this, is when the UPS is turned on, it performs a battery load test, to ensure the battery is up to snuff. If I turn on the G5 and monitor while the load test is occurring, the UPS will fail and shut off. So even with a 1000VA UPS it is marginal for this system. This UPS will be replaced at some point, but for now is providing good enough service for a small home office.

A second system, a dual G5 2.5 Ghz, also with two internal hard drives, and a LCD 21 inch wide screen display, is connected to an APC XS 1500 UPS. This UPS also has an Ethernet switch that serves the room the computers are in, attached to it. The XS1500 has no problem passing its battery load test, even with all the devices turned on. It also provides about 25 mins (estimate) of run time if just the Mac, monitor, and Ethernet switch is turned on.

While many people consider a UPS an after though to there computer purchase, I think it is better to plan for it along with any other parts of your computer purchase. Connecting a computer system to an undersized UPS is asking for problems, when you least want to have them, during a disastrous power outage.

Anyway, my recommendation is a 1000VA unit minimum, and 1500 as a better choice. As for manufacturer, we currently have all APC, but have used Trip-Lite, Belkin, and others in the past, all with good results as long as you size the UPS correctly.

Tom N.

Thanks for the info Tom?

One thing I still don't get is why the UPS will cut off the power like as mentioned above, the plug was pulled out of it.

It must only happen for a split second becuase i was looking at my speaker when it happened last and the green light on it did not go out at all.??

Power supplies in devices have a number of capacitors that store electrical energy. They are there to smooth out the voltage so the device they are powering sees cleaner voltage.

In the case of your speakers, chance are the LED producing the green light was the only load seen by the speakers power supply. As a results, it will take awhile before the LED draws enough of the energy to go out.

You can try this yourself to see if it is the case. Turn on your speakers, so the LED is lit, don't have any sound playing. Now unplug the AC cord powering the speakers and watch the LED. It will probably remain lit for a while before it finally fades away.

As for why the UPS is cutting out, thee are many reasons why that may be happening. Over and under voltage can both trigger the UPS to change to battery power, and if the load seen by the battery it to large, the UPS will just shut down to protect itself.

Tom N.

very interesting... thanks for the info. looks like i need to start planning for a bigger ups.

1500 as you say.

at least its not my new g5 🙂