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Testing UPS Output Waveforms

lttlabs.com

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Re: Testing UPS Output Waveforms

#31

Post by bob1029 »

mbesto wrote: post #6

Curious - what actual real life issues do real world people encounter with dirty AC waves? Like I always hear the proverbial "this could cause harm to electronics" but are there real world tests of electronics failing? Does it fail over time or because of a one time instance? Same thing with under/over voltage.

Audio amplifiers can be strongly affected by noisy waveforms.

Class D amplifiers and other topologies that depend upon SMPS for power delivery are usually unaffected. Class A/B is where you will typically hear it.

Re: Testing UPS Output Waveforms

#32

Post by elevation »

LabsLucas wrote: post #2

Testing the output of some UPSs from around the office. Checking out the results and finding avenues for further exploration.

Great to see LTT in this space, you're well positioned for it (access to a variety of hardware.) Would love to see a more developed experiment design.

Would love to see how the waveform changes over load -- perhaps test at 0, 10, 20, 40, 80% load.

Also, how does waveform vary as the battery depletes?

Another metric is how capacity varies with load. If a UPS gives me 1 hour @ 100w, will it give me 10 hours @ 10w? How long will it power an idling rpi5 (<1w)? How long will it give my workstation PC?

Re: Testing UPS Output Waveforms

#33

Post by scottlamb »

dylan604 wrote: post #19
scottlamb wrote: post #10

I would be curious to see how LifePO4 power stations compare. * These power stations are better than conventional (lead-acid battery) UPSs in the sense that they're cheaper, more flexible, have dramatically longer battery life, and require battery replacement less often. * ...but I haven't seen any that claim to be "line-interactive" or even say specifically when they fail over (other than a total power cut). They do…

Can these LifePO4 batteries be safely drained to 0% and then charged numerous times?

Yes, thousands of times, an order of magnitude improvement over lead acid. And the increased capacity means that they're much less likely to hit 0% (or whatever defined cut-off you set) during a typical outage anyway.

Re: Testing UPS Output Waveforms

#34

Post by michaelt »

tredre3 wrote: post #28
chimpontherun wrote: post #9

I've noticed that ALL the devices I plug into my UPSes have external power bricks. Most of them are either 5V, 12V, or 19V So, I replaced all my UPSes with LiFePO4 batteries supplied by Victron AC->12V chargers. Routed the battery contacts directly to all devices that consume 12V (WiFi AP, network hubs, SLA 3d printers). Used 12V -> 5V adapters to supply 5V / USB2 devices (R-Pi servers). For 19V, Drok DC-DC boost con…

> Evidently, AC waveform generation is extremely power-hungry I've tested a dozen models from APC. The inverter used in those devices uses roughly 15-20W with no load. Then for any load they have about 85% efficiency. Then you have further losses into any PSU connected there because they tolerate square waves but aren't optimized for it. So yes, in the end, less than 40% of the battery capacity in cheaper UPSes is ac…

> The UPS consumes almost nothing when AC is on, so that can't be that.

Back in the 1990s, one could buy a "double conversion" UPS that converted AC to DC then back to AC, at all times. This was, supposedly, the best type of UPS (in my experience they were also the least reliable)

Re: Testing UPS Output Waveforms

#35

Post by mikeyouse »

mbesto wrote: post #6

Curious - what actual real life issues do real world people encounter with dirty AC waves? Like I always hear the proverbial "this could cause harm to electronics" but are there real world tests of electronics failing? Does it fail over time or because of a one time instance? Same thing with under/over voltage.

Modern furnaces are weirdly sensitive to ‘clean’ AC power. Mine won’t work on bad non-inverter backup generators and interestingly to me, doesn’t work on non-bonded (ground-neutral) power from an inverter generator. Had to chop the cord off a drill and build a bonding plug last winter when I finally figured out why it wouldn’t run.

https://rvelectricity.substack.com/p/diy-generator-bonding-p...

Re: Testing UPS Output Waveforms

#36

Post by [deleted] »

mbesto wrote: post #6

Curious - what actual real life issues do real world people encounter with dirty AC waves? Like I always hear the proverbial "this could cause harm to electronics" but are there real world tests of electronics failing? Does it fail over time or because of a one time instance? Same thing with under/over voltage.

[deleted]

Re: Testing UPS Output Waveforms

#37

Post by alnwlsn »

mikeyouse wrote: post #35
mbesto wrote: post #6

Curious - what actual real life issues do real world people encounter with dirty AC waves? Like I always hear the proverbial "this could cause harm to electronics" but are there real world tests of electronics failing? Does it fail over time or because of a one time instance? Same thing with under/over voltage.

Modern furnaces are weirdly sensitive to ‘clean’ AC power. Mine won’t work on bad non-inverter backup generators and interestingly to me, doesn’t work on non-bonded (ground-neutral) power from an inverter generator. Had to chop the cord off a drill and build a bonding plug last winter when I finally figured out why it wouldn’t run. https://rvelectricity.substack.com/p/diy-generator-bonding-p...

I discovered the same thing a few months ago with my home's furnace (which was a bit of a shock, because one reason for picking natural gas is so you can still have heat when the power is out). It runs just fine on a pure sine wave inverter though.

Re: Testing UPS Output Waveforms

#38

Post by Aurornis »

michaelt wrote: post #34
tredre3 wrote: post #28

Earlier quoted context omitted.

> Evidently, AC waveform generation is extremely power-hungry I've tested a dozen models from APC. The inverter used in those devices uses roughly 15-20W with no load. Then for any load they have about 85% efficiency. Then you have further losses into any PSU connected there because they tolerate square waves but aren't optimized for it. So yes, in the end, less than 40% of the battery capacity in cheaper UPSes is ac…

> The UPS consumes almost nothing when AC is on, so that can't be that. Back in the 1990s, one could buy a "double conversion" UPS that converted AC to DC then back to AC, at all times . This was, supposedly, the best type of UPS (in my experience they were also the least reliable)

This is called an online UPS and it's still a thing.

It's not a good option for home use because it's always sending power through an inefficient path. The devices we use have power supplies that can handle transients and fluctuations.

Re: Testing UPS Output Waveforms

#39

Post by jsiepkes »

michaelt wrote: post #34
tredre3 wrote: post #28

Earlier quoted context omitted.

> Evidently, AC waveform generation is extremely power-hungry I've tested a dozen models from APC. The inverter used in those devices uses roughly 15-20W with no load. Then for any load they have about 85% efficiency. Then you have further losses into any PSU connected there because they tolerate square waves but aren't optimized for it. So yes, in the end, less than 40% of the battery capacity in cheaper UPSes is ac…

> The UPS consumes almost nothing when AC is on, so that can't be that. Back in the 1990s, one could buy a "double conversion" UPS that converted AC to DC then back to AC, at all times . This was, supposedly, the best type of UPS (in my experience they were also the least reliable)

As far as I know the more expensive UPS models are all still "online" (ie. double conversion) UPS'es.

These are also the only variants which will protect you against things like a phase ending up on neutral in a 3 phase power system. I've seen this happen twice. Fried a lot of equipment.

Re: Testing UPS Output Waveforms

#40

Post by krunck »

mbesto wrote: post #6

Curious - what actual real life issues do real world people encounter with dirty AC waves? Like I always hear the proverbial "this could cause harm to electronics" but are there real world tests of electronics failing? Does it fail over time or because of a one time instance? Same thing with under/over voltage.

I've had servers that would not power on with non sinusoidal power.
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