system reboots when ups unplugged

[dementg]

I received a Belkin Universal UPS 800VA at Christmas. I connected it to an old Compaq Proliant 800 which I use as a home firewall/server. According to the pdf manual I downloaded for the computer, the power supply should be 240W. The UPS is advertised to handle up to 450W. There is no monitor attached to the computer, and the computer is the only device attached to a battery backed outlet. I installed the monitoring software on a laptop and connected it to the usb port. The software indicated that the UPS was charged to 91% and running at 20% load. I then tested the UPS and it caused the computer to reboot.

If I unplug the UPS, the power supply in the computer seems to switch on and off several times before it stabilizes. Naturally this causes the computer to reboot. Someone else in another thread experienced a similar problem with this UPS, but it was on a much larger system than I'm using.

thread525-513679 that other thread, it was apparent that his problem was that the UPS was overloaded, but that doesn't seem to make sense in my case. Is there some other problem that could be causing this? I will be returning this item to the store, but I'm not sure whether I should get a larger Belkin, or if I should just get a better brand, like maybe a 700VA APC. Any recommendations? Thanks.

 

[netmanrick]

Go with APC. Did you try any options in the Belkin management s/w?

Rick Harris
SC Dept of Motor Vehicles
Network Operations

 

[josepablomir]

It sounds to me like an Inverter problem. If the unit is under warranty go to replace it.

Another possibility is the battery, but I'm not sure because in this case it sounds strange that the system stabilizes itself after some seconds. I bet for the Inverter (the output feedback circuitry to be more exact).

If you can change it by an APC don't doubt it!!!

Regards,

Jose.-


_________________
Pablo Mir

http://www.pablomir.com

pm@pablomir.com
NJ, (973) 699-2043

 

[dementg]

Thanks. I guess I'll go the APC route then, hopefully they aren't too much more expensive. Based on your responses, it sounds like I don't need a bigger UPS.

I did look around in the software but I don't remember changing any options. Unfortunately I've already uninstalled it and boxed it up so I can't use it to jog my memory. I did try the "10 second test" or whatever it was called - that caused the same rebooting problem as when I unplugged it. The graphic showed the inverter being engaged and didn't give any error messages. I used the software from my laptop so it stayed on while the server was rebooting.

Thanks for all your help.

 

[dementg]

I returned the Belkin to the store, and got an APC Back-UPS ES 725VA. I hooked it up to the server (Proliant 800), and it has the exact same problem the Belkin had. When I unplugged the UPS, the server's power supply switched on and off about once a second for about 20-30 seconds before stabilizing. This is even longer than it was doing it with the Belkin 800VA. So based on that pattern, maybe a higher power UPS will not have the issue at all... but clearly the UPS isn't overloaded so there must be more to it.

The Proliant presumably has a 240W power supply. I tried the APC on 2 other computers, one of them an old lightweight computer, the other an HP Kayak with a 350W power supply and more components installed in it than the Proliant has. The UPS worked fine on both of those computers, so apparently there's a compatibility issue with the Proliant's power supply. I'm guessing Compaq is really special and needs a pure $inewave UPS. I'm not willing to spend that kind of money, so I guess I'll just use the APC on my desktop computer (The HP). Maybe I'll switch out the Compaq's power supply someday and see what happens.

Unless anybody has an alternate theory, I guess the case is resolved. Just wanted to let you know what happened. Thanks for all your help.

 

[MrAPC]

You may want to try the SmartUPS 700 from APC.

Unit outputs Sinewave and only costs $89.99 from RefurbUPS.com

 

[stallard]

The power supply on the Proliant 800 requires a Sine Wave input, both the Belkin and the APC UPS you mention output a stepped approximated waveform (or simulated waveform).

The SU700NET provides sine wave output (as do many others), I would recommend you ask for a UPS with this feature specifically.

 

[josepablomir]

Strange!

Why would an SMPS "require" sine wave only input?
The only reason that comes to my mind could be voltage auto-selection circuitry. Some of this circuits are "blinded" by the "longer" peak voltage stage that the stepped wave seems to have to simple R-C circuits used to sense "mean" voltage in a cheaper way.
Maybe is a problem of that particular power supply?
Have any other person here had similar problems with similar servers? I'm just curious.

By the way!!! What about switching time? Do you think it is possible the problem to be the switching time? Maybe that model of power supplies has a very limited tolerance (due to small input capacitors). Or maybe the server hardware represents a high load condition to the power supply, and, once again, the input capacitors act like inappropriate (smaller, once again). But this alone doesn't explain the "bouncing" effect.

Regards,

Jose.-


_________________
Pablo Mir

http://www.pablomir.com

pm@pablomir.com
NJ, (973) 699-2043

 

[stallard]

The problem appears to be with the stepped sine wave not the switching time, this occurs with the Proliant 800 and the Prosignia 200.

 

[zeitghost]

Does the Proliant suppy have power factor correction?

I'd imagine that putting stepped square waves into such a PSU might confuse it a bit.

rgds
Zeit.

 

[jddipqd]

I have the similar problem with KME UPS 500VA and PowMax power supply 300W.
When I cut AC power system reboots, but im my case just once.
The UPS was tried on two other machines and it worked without problems.
I don't think that it is a problem with sine wave because after the reboot, system worked on battery power without problems.

 

[josepablomir]

jddipqd: Ikeep thinking the problem is insufficient capacity in the input capacitors.

The easy solution: replace the UPS for an On-Line unit. Those UPS don't have transfer time!

But if you want to experiment and know something about electronics, or have an electronics technician in your organization, you can add capacitors to the power supply (in parallel with the existing ones) or replace those for bigger ones. BECAREFUL: this is risky, you have to be extra careful when opening a power supply, even a disconnected one (the voltage in those capacitors may last some hours), and those capacitors are polarized, so you have to connect them in the right position (failure to do that may cause a noisy explosion). I recommend that to be done by an electronics technician only!

Regards,

Jose.-


_________________
Pablo Mir

http://www.pablomir.com

pm@pablomir.com
NJ, USA

 

[dementg]

I just checked this thread again and see its still being discussed. For what it's worth, I've had numerous momentary brownouts in this area and they have never caused the server to reboot. So subjectively it seems that the capacitors are stable and adequate.. but of course I have no means of really testing what kind of switchover time that PSU can tolerate.

 

[candlepower]

Have you checked the serial connection on the Motherboard?

You could go back and forth to the store forever to replace "broken" power supplies when the answer could be so simple.