ld trAPC Back UPS RS 900 - crazy problem

[Anonymous user]

This all makes no sense to me, so I'll try posting here. Bear with me, because there's a lot of information, mostly logical contradictions!

1) I've got two APC units, one is an old Backup Pro 1100, which is functioning perfectly. The other is a relatively new Back UPS RS 900 (about 18 months old, but only been used for the last year for reasons I won't bore you with, it sat in its box, unopened, for almost 6 months).

2) Both units are on the same electrical circuit. This would seem to eliminate any problems with the power supply, unless the RS 900 is somehow more sensitive than the Pro 1100.

3) The problem ONLY occurs in the small hours (I keep unusual hours, I'm usually online for about 3 hours from 1am Eastern). During the normal working day, the RS 900 functions perfectly. The PC is usually powered off for the night by 7pm, I have no idea when the problem stops and starts, only that it happens between 1am and 4am but not between 8am and 7pm.

The problem - well, basically the battery backup cuts in repeatedly, three or four times a minute, but only for a second or two each time. The Pro 1100 does NOT do this. The problem also doesn't happen every night, some nights the unit is fine, no power problems whatsoever.

Now, to try to eliminate any other ideas :-

1) The RS 900 is plugged directly into the wall socket.

2) All that is on the backup is a 19" LCD monitor, a small Linksys router, a 2GB external hard drive and the PC, a Gateway Phenomx4-based desktop. No, I haven't forgotten the modem, I'm sufficiently out in the wilds that I have to use satellite internet, and HughesNet are most explicit about plugging the modem directly into a wall socket (why, I'm not entirely sure, but there you go, it's their modem!)

3) I am running Linux on this PC, and also on the other one that's connected to the other UPS. Debian and Kubuntu respectively, before someone asks me. These are the only two PCs I have in the house. I cannot run Windows other than in a virtual machine on my PC, and I suspect that running the software that came with the UPS in a virtual machine wouldn't achieve a great deal. 🙂 (Afterthought: I suppose I could try running it under WINE - anyone know whether this can be made to work? There is native third-party UPS software that comes with Linux, I haven't investigated that but if anyone knows whether this will work with the RS 900, I can give that a try too.)

OK, I think that's about it. You can hopefully see the problem I'm having. Unless the two UPSes have different thresholds for the battery backup to kick in, it's not the mains power because the other UPS doesn't have a problem. If it's the RS 900 that's the problem, then WHY does it only happen in the small hours? This has been going on for a couple of weeks now, so yes, I am quite sure about the timing.

Anybody have any ideas? It's driving me crazy trying to think of something that would fit the symptoms, plus I don't fully trust the RS900 while it's doing this, but I don't want to have to can it and buy another if the problem is elsewhere.

Message was edited by: brian_m - afterthought where indicated.

[Anonymous user]

It's exactly as you would expect if the power had dropped for a second or two, I think. The 'overload' and 'replace battery' LEDs are never lit. The 'online' LED goes out, the 'on battery' LED comes on, and then a second or two later there is a single short beep, the 'on battery' goes out and the 'online' is lit again. The beep definitely coincides with the return to 'online lit' rather than 'on battery lit'.

The sticker on the bottom has two numbers, an implausibly large serial number and "BR900", which I assume is the model number that you've asked for. I can't see anything else on the unit which could be a model number.

One other thing did occur to me - I tried running the unit without any loading, i.e. just the UPS plugged into the mains and that was it. The symptoms were unchanged.

I also spoke to my power company about this. Their tech manager said he'd occasionally heard of UPSes having fits, but that the transformer we were on was way UNDERloaded, he would feel happy putting at least ten more households on it. He did promise that next time one of his linemen was out here, he would have him fit a voltage monitor to our supply, but that might not be for a week or so yet (we're quite a way out from their base).

I hear what you say about the sensitivity, but there has to be something more to it than that, to account for the time dependence. I'm running everything through the UPS at the moment, but since it's not in that small-hours window, the UPS is behaving perfectly, and (to circumvent Murphy's Law) has been doing so for the last 40 minutes or so.


A question my power company wants me to ask you - I quote...

Would the UPS be sensitive to minor changes in voltage that are
within the acceptable NESC range of voltages. In the early morning
hours, it's possible that something along that fairly long circuit is
being shut down. Automated voltage regulators might then adjust the
voltage downward (relatively slowly: I think it takes a few minutes),
but voltage at your home would still be between 117V and 123V.

Might this be the answer combined with the sensitivity? I've been using the UPS with all the kit connected for two and a half hours now (0800-1030), and there hasn't been a SINGLE cut-in. This time dependence is absolutely clear. I suppose it's possible that it's some temperature-dependent artifact working on the power lines and/or meter outside the house - it would need us to have a really cold day for me to check that.

Message was edited by: brian_m - updated with question from my power company.

[BillP]

Hi Brian,

Thank you for providing us the information above. I wanted to check with you if the BackUPS 900 exhibits any weird behavior whenever it cuts power. Does it beep, chirp or produce a constant tone? How about the LEDs or LCD, does it show any kind of indicator of what is happening or is it a total blackout with not LED/LCD lit and no tone at all?

When it comes to threshold, one thing that we normally adjust is the Sensitivity of the unit we can provide you with the steps but not until you give us the exact model number of the UPS. Every model has a different way to adjust the sensitivity manually, when it comes to the software you are right. APC PowerChute Personal Edition runs only on Windows environment. I have heard from most folks/customers in our forum that on Linux platforms they are using APCUPSD, keep in mind that this software was not created by APC thus we do not offer any support.

[Anonymous user]

No, it doesn't answer the main question. I was told that if I provided my exact model number, I would be told how to adjust the sensitivity. I can't use the software provided with the unit because I run Linux.

[Anonymous user]

Well, it's now more than two weeks, closer to three, since I posted the reply with the model number, as requested, and absolutely no response as regards tweaking the sensitivity as suggested, nor any response to the question I posed on behalf of my power company.

During all that time, I'm evidently supposed to have continued with a UPS that's cutting in and out on a regular basis.

I don't think so. I bought another UPS, and this one is functioning just perfectly, not a single cut-in since I installed it.

Is anyone surprised when I say that this time I bought one from Cyberpower?

Now, their tech support may be as bad as APC's obviously is - I've needed no experience of it so far, and long may that continue. I DO know that it can hardly be any worse, going on my experience.

Now, I'm off to post a few scathing reviews of APC on various sites. I've about $110 (to the best of my recollection) worth of wasted money to work off, so that should keep me going for a while.

[voidstar_apc]

>
Well, it's now more than two weeks, closer to three, since I posted the reply with the model number, as requested, and absolutely no response as regards tweaking the sensitivity as suggested, nor any response to the question I posed on behalf of my power company.
>

Sorry to hear that tech support hasn't been responsive to your questions. I'm glad you're satisfied with your Cyberpower unit.

I believe the answer to your power company's question is that the UPS will trigger on any line fluctuation. Sensitivity to these is adjustable based on the sensitivity parameter. For example, if the line suddenly changes from one acceptable voltage to another acceptable voltage, the UPS will go on battery until the line stabilizes. This is mainly for reasons of speed: the UPS can't wait to tell what the line's long-term behavior is when making the decision to go on battery... in another situation, the voltage could go away entirely and when that's detected, it may be too late to keep the load up.

You mentioned that the UPS triggers only at certain times of the day. The UPS is insensitive to time except for a weekly self-test which will look like a momentary on-battery event at the same time every week. So if you're seeing this more often over a small window of time, it's almost certainly a reaction to a line phenomenon and the UPS is doing what it's designed to do. It makes sense that utility work on off-hours could do this.

There are unit-to-unit variations and design differences between UPSes so it's not unusual for a line anomaly to trigger one but not another. That said, I would have expected adjusting the sensitivity to have made a difference.

I hope that answers your questions.

[BillP]

I apologize if I was not able to get back to you on time. I was caught up on a 2 week training and has limited access to the Internet.

I know it is too late but here is what I have found out for your UPS when it comes to adjusting the sensitivity.

- Turn the UPS off and unplug all the loads.
- Press and hold the power button and wait until all four LEDs started flashing.
- Once the LEDs started flashing, release the button. To change the sensitivity you need to press the Power button again and cycle through all the different states. You also need to press the button quick or else it would exit the programming mode.
- Here are the different sensitivity settings: Low (Flashing On Battery LED), Medium (Flashing On Battery and Overload LED) and High (Flashing On Battery, Overload and Replace Battery LED). Set it to your desired setting by letting flashing LED/s turn off in accordance with the settings that I have said, the lower the sensitivity the wider the voltage range it can accept.
- Also, flashing Online LED while in programming mode would exit that mode

[voidstar_apc · Accepted solution]

Hi Brian,

I Googled "RS900" and found the manual on the APC web site:

http://www.apcmedia.com/salestools/ASTE-6Z7V73_R0_EN.pdf

Page 2 has manual sensitivity adjustment options.

That said, if:
- UPS only transfers when we suspect there's an actual line anomaly and
- UPS does not transfer often enough to deplete the battery or cause excessive wear on the relays
... then you should consider leaving the sensitivity as-is. This is because lowering the sensitivity delays the transfer to battery during a real power failure. The longer it takes to transfer to battery, the more likely the load will not hold up. Sometimes that's the only option when the power line is inherently noisy such as when running from a generator.

Also although it's not supported, I agree with JonPro that you might find APCUPSd helpful.

All the best.