APC UPS clicking on/off battery power when powered by generator 1

[goombawaho]

So I have a customer that has a whole house generator powered by natural gas. They want to be able to use their computer during power outages, so I switched the computer over to an outlet that IS powered by the generator. An aside: Apparently "whole house" doesn't mean 100% of the outlets are wired.

The generator technician was there today to test the generator. He flipped the switch ahead of the breaker box, killing power to the house and the generator started up and kicked in about 15 seconds later. Voila - power. But........ the APC Back-UPS 500 was clicking (switching back and forth from AC to battery) about every two seconds.

So, the question: Is the UPS getting old and sensing poor power input quality or is the generator power output not clean enough, resulting in the UPS switching over to battery?

I could get a more expensive on-line double-conversion UPS like this, but I'd better be darn sure it will take care of this issue to spend this money IF a cheaper UPS would fix the problem.
Link

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[DrB0b]

Did you meter the outlet to see what power is actually at the plug and if it is steady or fluctuating?

Learning - A never ending quest for knowledge usually attained by being thrown in a situation and told to fix it NOW.

 

[goombawaho]

The generator tech said things were in range. So,............... No. I didn't.

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[karlisi]

We had the same experience with generator and UPS, we suspected frequency fluctuations or bad sine form on output.

===
Karlis
ECDL; MCSA

 

[kjv1611]

I'm no expert on electricity, but I will say I did a ton of research a while back on surge protectors and UPS units. One thing I found from other "experts" - assuming they are, as I have no way of verifying, but they sure sounded the part, was:
[ol 1]
[li]UPS units generally produce dirty electricity in that it has more fluctuations and such[/li]
[li]Generators produce worse dirty electricity.[/li]
[li]What you really want is a flat line output, cleaned up perhaps by a surge protector that has a line filter, or just flat buying an expensive surge protector. SurgeX and

are 2 good ones. I've purchased 2 Brick Wall surge protectors - one for my home, and one for the sound system at church. I think the surge protector at home did help clean up some of the electricity coming to my main computer area, though I've never actually tested to be certain. I have been able to tell at times on Audio recordings when I've done some of those at home, so that is a test.[/li]
[/ol]

Those surge protectors I mentioned aren't cheap, but if you browse eBay, and can be patient about it, you can usually find a good deal there. Also, there was at least one site that sold the Brick Wall units, I believe it was, at a slight discount over the direct from manufacturer price.

If you want to read up on it, Brick Wall has some links on the right side of this page about how their surge protectors/suppressors are different. I forget at the moment what that type is called, but they do not use MOVs or whatever the little capacitors are called. So in theory, these would also never have to be replaced to have clean energy as compared to standard ones with the MOVs that eventually pop/dry out as I recall.




"But thanks be to God, which giveth us the victory through our Lord Jesus Christ." 1 Corinthians 15:57

 

[FredWagner]

Another possibility is a line conditioner before the UPS - it will boost or buck voltage fluctuations from the generator, so the generator sees a constant voltage. I have an APC Line-R 1250 under my desk. Since this floor of our building was rewired, it hasn't been as active as when I put it in, but they do solve some problems.

Fred Wagner
(retired, but still involved!)

 

[kjv1611]

Yeah - the line conditioner option is usually cheaper than the high-end surge protectors. The surge protectors do the same thing as a line conditioner just in the way they operate. Something about sending to positive instead of ground or something, besides the MOV deal.. I forget the details now.

"But thanks be to God, which giveth us the victory through our Lord Jesus Christ." 1 Corinthians 15:57

 

[goombawaho]

Strange this: my home generator and a cheap APC Back-UPS does NOT have a problem. And my generator is less fancy. I'm pretty sure your correct that the sine wave is dirty coming from the generator. These people have plenty of money, so should I go for the "fancy" double conversion UPS? I just want to be sure that this will fix it.

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[FredWagner]

The line conditioner I've been using has a tapped transformer and relays in it - so it adjusts the transformer tap to keep the output voltage within a narrow range. When there are power problems, you can hear the relays clicking, and watch the LED's that show the relative input voltage. Even if you don't use one continuously, they can be useful in diagnosing power problems - particularly overloaded wiring issues where voltage sag becomes an invisible issue.

Fred Wagner
(retired, but still involved!)

 

[goombawaho]

Another possibility is a line conditioner before the UPS - it will boost or buck voltage fluctuations from the generator, so the generator sees a constant voltage.

I think you meant "so the UPS sees a constant voltage" - correct?

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[edfair]

Have you considered trying your UPS on their system? Some are more sensitive than others.

Would you consider trying their UPS as a 2 wire? Just in case there is a problem with the sensing. But would require unplugging anything that uses the UPS for shunting ground.

The line conditoners I've seen in the past were Ferro-Resonant transformers. Great for transient stuff but ineffective for frequency shifts or sags.

Then there are the full time converters. Last one I had hands on was 1KW and in excess of 125 pounds with external battery about the same weight. It took what was supplied (within reason) and gave what was needed. But it tended to eat the switching transistors.

Ed Fair
Give the wrong symptoms, get the wrong solutions.

 

[FredWagner]

Goom - you're right - the generator is the likely source of fluctuations (rotational speed changes under load, mechanical governor), so the Line Conditioner is keeping the UPS from seeing the fluctuations coming from the generator.
Ed - the law firm I worked for in the 90's had two Ferrups units - multiple wet cell batteries to cover hours of backups - originally there was a 3KW unit for the phone and the single Netware server, we built a new server room and added a dedicated 5KW Ferrups that took care of multiple servers, routers, and the rest of the network gear. One thing about the big battery capacity - once a year the building did a 24 hour powerdown. I learned to gracefully shut down the servers, but to leave the routers and communications gear running - trying to get T1's reconnected is not an experience to repeat willingly!

Fred Wagner
(retired, but still involved!)

 

[technome]

During Sandy, the neighborhood was running on generators, as a whole we lost a number of electronic devices, so a UPS not accepting the power would not surprise me. Also it could be the batteries are aging; once batteries are nearing replacement age, UPS units trip easily.
Should you go for an online unit, get it from a supplier other the Egghead, their return/warranty policies have seriously gone down hill... pitiful.


........................................
Chernobyl disaster..a must see pictorial

http://www.kiddofspeed.com/default.htm

"Computers in the future may weigh no more than 1.5 tons."
Popular Mechanics, 1949

 

[goombawaho]

What about a line interactive UPS?? Looks like it's between a regular UPS and a double conversion model. Says it "interacts with the AC power line to smooth out the waveforms and correct the rise and fall of the voltage".

Link

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[hairlessupportmonkey]

A decent multimeter to test the mains frequency might be revealing.

I also suspect that the generator might be within tolerance, but not for the UPS. (as already stated.)

ACSS - SME
General Geek

 

[technome]

"line interactive UPS?"
The issue with anything interacting with the line is the circuity in the UPS needs to react correctly, and in time, to power anomalies or weakened battery states, which standard UPS units may or may not be capable of ( as is, non online backup units are "interactive", they disengage a power source, and engage an inverter system) ; I have a interactive line conditioner (with a multi tap transformer) before a UPS units at one site, it helps but the system still has issues with power problems (as the conditioner is not using an isolation transformer) and weak batteries. An online battery backup TOTALLY isolates the load from the line source and there are no switching delays.

Online unit with generators

http://www.upssystems.co.uk/knowled...ower/part-6-matching-a-generator-to-your-ups/

I have connected Fluke meters with peak voltage/frequency hold ability, not much help; the power anomalies which affect UPS unit or mobos often will not be picked up by a multimeter, you need a dedicated power analyzer, which cost thousands or very expensive to rent.

Go for the online, just not from egghead.


........................................
Chernobyl disaster..a must see pictorial

http://www.kiddofspeed.com/default.htm

"Computers in the future may weigh no more than 1.5 tons."
Popular Mechanics, 1949

 

[goombawaho]

Looks like the Smart-UPS line of UPS from APC can handle usage with a generator.

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[goombawaho]

Well, nature has provided my customer with a 36 hour power outage. The Back-UPS 550 was squealing like a pig when I went over there and NOT providing ANY power. I plugged in an old Belkin F6C1250-TW-RK which is a dual battery unit. It powered everything but then I noticed it switching over to battery every few minutes for a second or two. The house lights were flickering, so their generator is obviously not putting out clean power. I think the Back-UPS just exhausted its battery due to switching over so often.

It looks from this article like an online UPS is the best choice for situations like this - running on generator power for extended period. But, they are quite a bit more expensive than an line-interactive UPS ($412 TrippLite SU750XL 750 Online vs. $280 APC Smart-UPS 750 line-interactive).

Link

Off-line and line-interactive UPS technology

An off-line (including line-interactive) UPS passes mains power to the critical load. An off-line UPS may have some surge suppression and filtering, but will have no power conditioning. A line-interactive UPS will have some power conditioning functions, but will focus entirely on correcting voltage variations by means of a transformer and an automatic tap-switching feature. This has no effect on frequency variations, so the line-interactive UPS reacts to out-of-spec frequencies the same way as the off-line UPS, i.e. it will transfer to battery. When the battery is depleted, the off-line or line-interactive UPS will shut down the critical load.
Why on-line UPS technology works best with generators

On-line or double conversion UPS designs are ideal for use with generators because they accept input power with relatively wide variations in voltage and frequency. An on-line UPS actually re-develops the waveform. The AC input from either the mains or a standby generator is first converted to DC by the rectifier. The DC current is used to charge the battery. During an outage, DC current from the batteries is reformed by an inverter back to perfect sine-wave AC for the critical load. Newer models also use power factor correction to provide an even wider input voltage range.

Because of this double conversion (AC to DC, then DC to AC), variations in the input frequency are of little concern. Therefore the same frequency variations that would cause an off-line or a line-interactive UPS to transfer to battery power have no effect on the on-line UPS.

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.

 

[FredWagner]

Goom - great post! Your description of the double conversion UPS reminded me of a situation back when I was working in Omaha in 1986-87 - we had a custom database application running on a standalone PC in a lumber mill over in Iowa - HUGE rotary saws cutting up trainloads of logs, absolutely terrible power. I brought in what we called a 'full floating' UPS - I think it may have been an APC 700, and solved the problem.

Fred Wagner
(retired, but still involved!)

 

[goombawaho]

Thanks. Actual solution = a better generator, but that might be like $8000, so (maybe) a new UPS is more practical.

"Living tomorrow is everyone's sorrow.
Modern man's daydreams have turned into nightmares.