Can APC's stepped sine wave damage my power supply?

[dredd2929]

I have my system connected to an APC Back-UPS RS 800. My power supply is a PC Power and Cooling 510 SLI. When running off the APC battery, my PCP&C PSU emmits a "buzzing" sound. I have asked both the PCP&P and the APC people and they both agree that the noise results from the step-approximated sine wave that the Back-UPS battery outputs, as opposed to a pure sine wave.

Now here's my question: what adverse affects, if any, can this have on my PSU and/or system? Both APC and PCP&C said that it "shouldn't" have any adverse affects, but they didn't sound very confident. I'm just learning about AC voltage in physics class, so I have a general understanding of the difference between the two. But what is the physical effect on my PSU? If it truly isn't a problem, then I'm cool with that, I just want to make sure the APC doesn't hurt my $229 power supply.

J. J.

 

[MWink]

I had the exact same problem with my (now VERY old) Sparkle 300W AT power supply. I also confirmed that it was due to the stepped wave by trying it on a Smart-UPS and the buzzing went away. It never caused me a problem and that power supply is still in working order to this day. However I too am not 100% sure it wouldn't ever cause a problem.

 

[arcas]

I have 3 UPSes. One is a cheap "modified sine wave" one that killed the electronic ballasts in 2 compact fluorescent lights within minutes of plugging them in. In both cases, the CFL bulb buzzed for a couple seconds then went out. I've used this UPS with a variety of power supplies, linear and switching, over the years and never had any buzzing nor PSU failures.

My other 2 UPSes are APC SmartUPS 1400s that supposedly output a true sinewave. On a whim, I tried one of them with a CFL and the ballast didn't buzz and the light was fine. If you check around for local bankruptcy auctions, you can find these models pretty cheaply these days.

 

[jose]

I have 4 APC's (3 - 500va, & 1 - 650va).. One 500va has a OCZ powerstream, the rest have antec 550EPS units.. None emit a buzzing sound..

Maybe you can try a quality power strip between the ups and the computer to see if it makes a diff..

 

[dredd2929]

Does anyone out there have an APC Back-UPS (one with a stepped sine wave) paired with a PC Power and Cooling PSU that would like to comment on how it's worked for them?

Also, just to clarify, this buzzing happens ONLY when the computer is running off the battery, otherwise the PSU performs flawlessly.

J. J.

 

[Duckzilla]

Doesn't APC have a ridiculous $money$ guarantee for damage caused or not prevented by their back-up power supplies?

 

[imported_rod]

I just finished my Engineering Electrical Systems unit at university last semester. In theory, modified sine wave wont be as efficient as pure sine wave, but it shouldn't damage anything - especially if you have a quality power supply. As far as i can tell, the only damage would be likely to arise from an increased temperature in the PSU - but PSU's rarely seem to overheat.

Also, if you get a power-board with EFI/RFI filtering, it _might_ help to reduce the buzzing. I'm not sure, but what "jose" said makes sense to me.

RoD

BtW, i think what duckzilla said about the guarantee was correct, so you'r probably okay even if something does go wrong.

 

[MWink]

Originally posted by: jose
Maybe you can try a quality power strip between the ups and the computer to see if it makes a diff..

NO NO NO!!! DO NOT EVER plug a surge protector of any kind into a UPS that outputs a stepped waveform! It can be VERY DANGEROUS!

 

[dredd2929]

MWink: OK, will you please explain why it's so dangerous?

Duckzilla: APC does cover damage (caused by/not prevented by) their backup units, but the APC sales rep I talked to said he can't *guarantee* they will cover damage done in that way, which kind of pissed me off. He said I would have to talk to the claims department directly and ask them, which I plan to do tomorrow morning.

J. J.

 

[MWink]

It is dangerous to plug a surge protector into a UPS that outputs stepped wave because some surge protectors "track the sinewave" and they may see the stepped wave as surges and try to clamp them. This can cause the surge protector to burn up (or possibly catch fire) and may also damage the UPS. At least this is what I've heard from multiple sources, including APC.

 

[Vageetasjn]

Originally posted by: MWink
It is dangerous to plug a surge protector into a UPS that outputs stepped wave because some surge protectors "track the sinewave" and they may see the stepped wave as surges and try to clamp them. This can cause the surge protector to burn up (or possibly catch fire) and may also damage the UPS. At least this is what I've heard from multiple sources, including APC.

Would this concern apply to this UPS? In other words, should I unplug the surge protector that is currently plugged into the non-battery-powered outlet on my UPS?

 

[MWink]

Originally posted by: Vageetasjn

Originally posted by: MWink
It is dangerous to plug a surge protector into a UPS that outputs stepped wave because some surge protectors "track the sinewave" and they may see the stepped wave as surges and try to clamp them. This can cause the surge protector to burn up (or possibly catch fire) and may also damage the UPS. At least this is what I've heard from multiple sources, including APC.

Would this concern apply to this UPS? In other words, should I unplug the surge protector that is currently plugged into the non-battery-powered outlet on my UPS?

Yes that UPS outputs stepped wave, however it's ok (well not dangerous at least, though it may void the equipment protection policy) to plug a surge protector into the Surge only outlets, just not the battery powered outlets.

 

[jose]

Well I have 3 APC Backup UPS ES units and a Back-UPS 650 unit. I have always had a cheap Wal-Mart power strip pluged into the units. Just for the convenice of turning everything off w/ one toggle switch..

I also have an old Kensington MasterPiece Plus surge protector plugged into one of the 500va units.

The 500va units are very same unit that Vageetasjn linked to..

I don't have any buzzing sounds at all.. see my sig for the sys configs.. 3 - Antec 550EPS units & one OCZ powerstream 520 unit..

Regards,
Jose

 

[dredd2929]

OK, so will a surge protecter plugged into a battery-backup socket hose my APC or not?

I've come to a conclusion that I *think* explains the buzzing sound in my PSU. I have no doubt that this PCP&C 510 SLI is a very high quality PSU. It is possible it's defective, but highly unlikely as it works perfectly on normal ("true" sine wave) voltage. Since the PSU is being fed a stepped sine wave voltage, it's trying to correct it by smoothing it out, hence the buzzing. Maybe other power supplies don't buzz because they don't TRY to smooth it. I know this PSU has built-in line conditioning. If I'm completely off base here someone please tell me.

J. J.

 

[MWink]

Originally posted by: dredd2929
OK, so will a surge protecter plugged into a battery-backup socket hose my APC or not?

I've come to a conclusion that I *think* explains the buzzing sound in my PSU. I have no doubt that this PCP&C 510 SLI is a very high quality PSU. It is possible it's defective, but highly unlikely as it works perfectly on normal ("true" sine wave) voltage. Since the PSU is being fed a stepped sine wave voltage, it's trying to correct it by smoothing it out, hence the buzzing. Maybe other power supplies don't buzz because they don't TRY to smooth it. I know this PSU has built-in line conditioning. If I'm completely off base here someone please tell me.

J. J.

Yeah I thought the same thing with my old Sparkle PSU. Of course I don't know if it's true or not. I recall hearing that Sparkle was an OEM for PCP&C so maybe that has something to do with it. I don't know, I just know it never caused me a problem. I would still strongly advise you not to plug a surge protector into the battery backup, nothing beneficial will come of it.

Well I have 3 APC Backup UPS ES units and a Back-UPS 650 unit. I have always had a cheap Wal-Mart power strip pluged into the units. Just for the convenice of turning everything off w/ one toggle switch..

I also have an old Kensington MasterPiece Plus surge protector plugged into one of the 500va units.

The 500va units are very same unit that Vageetasjn linked to..

I don't have any buzzing sounds at all.. see my sig for the sys configs.. 3 - Antec 550EPS units & one OCZ powerstream 520 unit..

Regards,
Jose

As I stated before it's not a good idea. See my previous post.

 

[jose]

Been doing it for 16 yrs. w/ diff. ups...

But do what you want.. Doesn't the apc have a gurantee that it will replace any electrical device connected to it ?

But your main problem is most likely the power supply, just rma it.. OR Ask your psu company what UPS they recomend and get that one..

 

[Jeff7]

Originally posted by: MWink

Well I have 3 APC Backup UPS ES units and a Back-UPS 650 unit. I have always had a cheap Wal-Mart power strip pluged into the units. Just for the convenice of turning everything off w/ one toggle switch..

I also have an old Kensington MasterPiece Plus surge protector plugged into one of the 500va units.

The 500va units are very same unit that Vageetasjn linked to..

I don't have any buzzing sounds at all.. see my sig for the sys configs.. 3 - Antec 550EPS units & one OCZ powerstream 520 unit..

Regards,
Jose

As I stated before it's not a good idea. See my previous post.

But he said "power strip" - those things don't have any surge protection built in. They're basically just a few extra outlets wired in parallel with the main plug. It's really not different from how the outlets in the UPS are wired - they are all simply in parallel to each other, and then connected to the inverter's output. A power strip just adds a few outlets.

 

[MWink]

Originally posted by: Jeff7

Originally posted by: MWink

Well I have 3 APC Backup UPS ES units and a Back-UPS 650 unit. I have always had a cheap Wal-Mart power strip pluged into the units. Just for the convenice of turning everything off w/ one toggle switch..

I also have an old Kensington MasterPiece Plus surge protector plugged into one of the 500va units.

The 500va units are very same unit that Vageetasjn linked to..

I don't have any buzzing sounds at all.. see my sig for the sys configs.. 3 - Antec 550EPS units & one OCZ powerstream 520 unit..

Regards,
Jose

As I stated before it's not a good idea. See my previous post.

But he said "power strip" - those things don't have any surge protection built in. They're basically just a few extra outlets wired in parallel with the main plug. It's really not different from how the outlets in the UPS are wired - they are all simply in parallel to each other, and then connected to the inverter's output. A power strip just adds a few outlets.

He does say one of them is a surge protector. Also even most cheap power strips do have some albeit minimal surge protection built in. I had to look a bit to find one that did not.

Been doing it for 16 yrs. w/ diff. ups...

But do what you want.. Doesn't the apc have a gurantee that it will replace any electrical device connected to it ?

Well obviously you didn't read the Equipment Protection Policy. By plugging a non-APC power strip (or surge protector, or extension cord, etc.) into an APC product you have voided the EPP. Actually technically you can't even have an APC product plugged into another surge protector, extension cord, etc.

 

[Zepper]

If stepped sine output would damage switching PSUs, I doubt they would be making them as almost all of the common UPS that peoply buy have stepped sine. Things like synchronous AC motors or fluorescent light ballasts might have a problem with it though, but nothing in common computers or monitors use synchro AC motors.

.bh.

 

[Googer]

Originally posted by: dredd2929
Does anyone out there have an APC Back-UPS (one with a stepped sine wave) paired with a PC Power and Cooling PSU that would like to comment on how it's worked for them?

Also, just to clarify, this buzzing happens ONLY when the computer is running off the battery, otherwise the PSU performs flawlessly.

J. J.

PC Power and Cooling had said on their old style website that you needed to be running thier PSU's on a True Sine Wave UPS. The APC Smart UPS series uses a true sine wave (98% accurate).
I have Two APC Smart UPS'
[*]Smart UPS 1000 NET
[*]Smart UPS 1000XL NET
The XL version is the extended runtime version and NET means that they are networkable across cat 5 for remote shutdowns.

 

[dredd2929]

I finally talked to someone down at APC who knows whats up. He said that yes, APC's Equipment Protection Policy would cover any damage done to a computer's power supply as a result of the battery's stepped sine wave output.

J. J.

 

[nino]

It sounds like the "stepped" wave is using an DAC (digital to analog converter) to recreate the sine wave. With proper filtering the effects should be minimal but with improper filtering there are all sorts of problems since the digital sine wave is an approximation. The extremely rapid step from a voltage to the next step in a VERY small time can cause problems as these are high energy spikes. Even if the difference isn't that much (due to a high bit DAC) so long as the time from the jump from one voltage to another is so close to zero that it is something that should be considerable. Proper filtering will filter this out though.
These steps are like Impulse Functions and have close to an infinite number of frequencies that comprise them. Again, if they are filtered at the UPS then it isn't a problem but I doubt our PC power supplies are designed to handle this wide spectrum of frequencies. You will notice it as a hum because your PCs power supply is also processing these other frequencies along with the 60Hz signal coming in.
Oh well, I guess I got what I paid for too.

 

[dredd2929]

nino: OK, so it's not the type of wave, but the sudden change in type that has the potential to cause problems, right? That makes sense. My only remaining concern is that having my system plugged into the APC will void the 5-year warranty on my PSU. I e-mailed PC Power and Cooling and asked them, but I'm still waiting for a response. Thanks for the insight.

J. J.

 

[Texun]

For what it's worth, and it's probably not much, I have the UPS RS 800 and an OCZ ModStream and haven't heard a peep. Then again I've only used it for a few seconds to perform the test. Haven't seen it in action with a real outage yet.

 

[dredd2929]

Texun: Yeah, I narrowed my choice down to the one I have and the OCZ ModStream. I'm hoping I don't regret my decision. I posted on this very forum a while ago asking for help choosing between the two, and every response said basically they are both good, but if I'm will to spend the extra cash, go with PC Power and Cooling. I've put their power supplies into computers I've built for other people and they've been great. Again, if the only side effect is the noise, I'm not concernced, but if it voids the warranty I'd rather send the APC back and just use a regular surge protector. I guess the PSU could be defective, but it works fine while running in regular AC power. Plus it would be a royal pain in the butt to swap out power supplies, since I've already routed and wire-tied all the cables and stuff. Oh well, live and learn I guess.

J. J.