RS 900

[Anonymous user]

I bought an APC Back-UPS RS 900 about a year ago. This thing really surprised me. It adds battery power to supplement when the house power drops a little too much, or goes out altogether. That is really nice. But, if there is a power surge, it kills power to my system. Now, the whole reason for having a UPS is so that the power is "uninterupted". So, why would APC make a UPS that kills power when there is a surge? Had I known about this, I would never have bought this unit. The company has never replied to the emails I have sent asking about the logic behind this "feature". Any comments?

Thanks,

~Dave

[voidstar_apc]

That should probably be better labeled as "surge-only". Battery backed outlets are also surge protected, but surge-only outlets are not battery backed.

The reason you have outlets that are surge protected but not battery backed is because the UPS can only provide 540 W of power during an outage yet you may want to plug in and protect more than 540 W of equipment from harmful surges.

[BillP]

It's not a "feature." It's something clearly going wrong. There may be a compatibility issue between your computer's power supply and the UPS. Try to connect something else to the battery backup outlets - radio, lamp, speaker, anything - and pull the plug. If they turn off, the UPS is broken. If they stay on, your power supply doesn't like the UPS' output when on battery (step-approximated sine wave). This issue seems to be recurring more and more often.

[Anonymous user]

There are separate outlets on the UPS. Some are for surge protection. And some are for battery back up. So, I'm guessing that I cannot have both at the same time. Otherwise, why the separate outlets?

Dave

[Anonymous user]

That might be true for the surge only. However, when I get a power failure, the equipment is powered by the battery just fine. I have it loaded to about 50% capacity, so there's about 20 minutes of run time before the Power Chute turns the system off. During a power failure, everything keeps running like nothing happened. It's beautiful.

The UPS battery back up outlets might have a surge protection, too, BUT that protection consists of killing power to everything that's plugged in to the UPS, and the red light comes on with a sound. The red light is labeled "Overload". And it remains on until I turn the UPS off, and back on again. Then it goes through a self test, and is then ready to power up the system again. This is just how it works. And I don't know why APC would design the thing like that.

Dave

[Techie_apc]

Dave,


Could you please let us know the exact model and serial number of the UPS? What are the equipment you have attached to the Battery Backup outlets? Are they directly attached to the battery backup outlets or through Power strip? Is the Overload flashing or solid? What is the power consumption of the load which PCPE showing when you see the Overload light in the front of the UPS?

[Anonymous user]

I listed the exact model number in the first post in this thread. What is the relevance of the serial number? I am willing to provide it if it's that important.

I have a 19" LCD monitor, a Dell XPS Gen 5 computer, an HP C6380 wireless printer, a cable modem, a wireless router, and a small speaker connected to the UPS. PCPE says the UPS is providing 189 watts out of a 540 possible. It says I have 23 minutes of battery time.

When the red Overload light is on, it is on steady. And since the power to my system is cut instantly upon the overload, I can't check to see what the power consumption is on the PCPE. The system is dead at that time.

Dave

[Anonymous user]

Yes.

Dave

[BillP]

A couple of other people have been reporting issues using their Dell XPS systems with a step-approximated sine wave UPS like the one you have (see Referenced content removed). The power supplies seem to require a pure sine wave output, which is only offered by the Smart-UPS models. Some, like one of the posters in that thread, chose to replace the power supply in the computer rather than invest in a more expensive UPS.

[voidstar_apc]

>
I just read those posts and it has nothing to do with the problem I am reporting.

Dave
>

Hi Dave,

You said that your problem is that the UPS cuts power when there is a surge. I assume you believe it's happening due to surges because of the red "overload" light being lit... correct?

The red overload light means that the UPS thinks the devices connected to the battery-backed outlets are drawing too much power. That's different from a line surge. The UPS simply cannot provide more than 540W / 900VA.

Buzz suggested trying to use the UPS with a different load to see if it works correctly, because the power supply in many Dell XPS computers seems to draw power in excess of their rated power, require a pure sine wave, or both. From your testing, it seems that the UPS does not overload when powering other equipment.

[Anonymous user]

You seem to be correct and I was wrong in my assumption. My intuition told me that overload meant that too much power surged through my house outlets causing the UPS to cut off. It seems that I was wrong about this. But I don't see how using it with other equipment unplugged and then plugging it back in proves anything. My computer operates most of the time just fine. It seems to be only when the lights flicker and maybe even goes off and then back on that the Overload "condition" occurs. So, naturally I connected the problem to the power going in to the UPS. I see no possible way for my computer or anything I have connected to the UPS could all of a sudden try to pull more power than the 540 Watts which the UPS can handle. It's only drawing 189 Watts normally with everything running, and says I have 23 minutes of battery power run time. You mean that you think my computer, or something else running on the UPS, randomly surges and tries to draw more than 540 Watts? That would have to mean that something I'm using is probably having a ground fault short, or some other stray voltage situation. Right?

Dave

[voidstar_apc]

>
You seem to be correct and I was wrong in my assumption. My intuition told me that overload meant that too much power surged through my house outlets causing the UPS to cut off. It seems that I was wrong about this. But I don't see how using it with other equipment unplugged and then plugging it back in proves anything. My computer operates most of the time just fine. It seems to be only when the lights flicker and maybe even goes off and then back on that the Overload "condition" occurs.
>

I guess that depends on your standard of proof. Typically pulling the plug is a worst-case scenario for the UPS and it's easy enough to do, which is why we suggest it. I guess you could connect it to other equipment that consumes ~200W and see what happens when the light flickers.

>
So, naturally I connected the problem to the power going in to the UPS. I see no possible way for my computer or anything I have connected to the UPS could all of a sudden try to pull more power than the 540 Watts which the UPS can handle. It's only drawing 189 Watts normally with everything running, and says I have 23 minutes of battery power run time. You mean that you think my computer, or something else running on the UPS, randomly surges and tries to draw more than 540 Watts? That would have to mean that something I'm using is probably having a ground fault short, or some other stray voltage situation. Right?
>

What's happening these days is that European regulations are forcing power supply manufacturers to move away from a simple, cheap and robust design to ones that include power factor correction (PFC). That requires the power supplies to, at every moment in time, choose how much current to draw from the power line. How well they work on UPSes depend on how this is designed. Some work fine. Some decide to draw a lot more current when they notice a power problem while the UPS is transferring to battery. This can be overcome with a beefier BackUPS. Others simply don't like the modified square wave output of a BackUPS at all and require a SmartUPS.

[Anonymous user]

Ok, I will give that a try. Thanks very much.

Also thanks to those who tried to help my with this problem, and was patient with me even when I didn't correctly understand the problem myself.

Dave

[BillP]

Do you know what the power supply is rated at in terms of wattage? An [SMT750|http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SMT750] or [SMT1000|http://www.apc.com/products/resource/include/techspec_index.cfm?base_sku=SMT1000] might suffice, depending on your answer.

[Anonymous user]

I'm not sure about that. The Owner's Manual lists 2 different power supplies for his machine. One is a 460 Watt and the other is a 650 Watt. Not sure how I find out what this one is for sure. It's not a traditional PS like on most machines I've had. It has 2 small fans at the bottom of the tower case, and there is no data on the back.

Dave

Message was edited by: Dave49

[BillP]

Hmm... Well, the 750 model can handle up to 500w, so that would be fine if it's the smaller 460w power supply, though it might not suffice if you have the bigger supply. If you'd rather err on the side of caution, you could get the SMT1000, since you're also connecting some other equipment... Though it would definitely be overkill if you have the 460w one.

I suppose you could try to give Dell a call to see if they can help determine which one it is?

[Anonymous user]

Just to follow up on this issue. I was able to get a replacement ups from the company, and everything that was on the old one is on the replacement. the power has gone off twice since then. Once it was for a few hours, and once it was off and on pretty fast. The replacement ups performed perfectly. No issues at all. So that re-enforced in my mind that there was some defect in the original that is not in the replacement. Thanks for all the advice, but sometimes it's actually the unit that is bad.

Dave

[Anonymous user]

I just read those posts and it has nothing to do with the problem I am reporting.

Dave

[Anonymous user]

I bought an APC Back-UPS RS 900 about a year ago. This thing really surprised me. It adds battery power to supplement when the house power drops a little too much, or goes out altogether. That is really nice. But, if there is a power surge, it kills power to my system. Now, the whole reason for having a UPS is so that the power is "uninterupted". So, why would APC make a UPS that kills power when there is a surge? Had I known about this, I would never have bought this unit. The company has never replied to the emails I have sent asking about the logic behind this "feature". Any comments?

Thanks,

~Dave

[Anonymous user · Accepted solution]

So, what UPS could I get that would solve my little problem?

Dave