Random Power Panic (but not from an actual power outage)  

RE: Random Power Panic (but not from an actual power outage)

Many UPS will not output a nice sinewave  but a "modified sinewave" as my normal UPS says. I looked it up on the oscilloscope and it looks like the top and bottom has been chopped off. It is nicely rounded off and I have not seen my computer equipment complain yet. On a heavy load like the laser printer (heater for the fuser) the distortion gets worse as the load increases. With the very cheap units they (depending on the brand) will output an almost square wave. My laptop charger runs very hot on those as its efficiency goes down.

All this to say that I assume the "Power Panic" function has to act rapidly as it will run on the stored energy from the electrolytic capacitors from the power supply and it has to do a save and do an orderly shutdown before running out. A crappy non-sinewave output from the UPS might trigger the Power Panic circuitry in a random fashion. 

Another possibility is that some UPS have fairly strict limits in power output an a short surge in current demand initiate a gap or sag  in output that triggers the Power Panic circuit.

I have not look at the circuit to understand why it does not work when you use the printer switch however.

I will try running my MK3S on my UPSs and see if I can confirm. I have an industrial one that has a 100% fully isolated near perfect sine output at all time and a real crappy one.  More to follow.....

Cheers and happy printing.

RE: Random Power Panic (but not from an actual power outage)

@richnormand

Thanks for the response and for the testing. I'm eager to know the results. The UPS on the Prusa is for sure a cheap one. So...

RE: Random Power Panic (but not from an actual power outage)

@richnormand

I did some reading about modified sine wave UPS. From what I read, while main power is supplied the UPS passes the since wave from the utility company. It's when the UPS is on battery power that it passes the modified sine wave.

The Power Panics that are causing me trouble occur while the UPS is still on mains power. Could this just be 'dirty' mains power?

RE: Random Power Panic (but not from an actual power outage)

@raylepper

Did a test this morning with my Powerware 1250Watt UPS while offline (ie: on battery power). The Prusa was happy, no issues.

As far as I know, unless put in bypass mode, it completely isolate and filters the power line while supplying a sinewave.

It goes in battery mode with the same invertor when the line is not available.

My other two UPS are a NOMA 400Watts with the "modified sinewave" output and a cheap APC 500 for the modem/router. From what I know those two just passively filter the powerline and pass it along without buffering like the Powerware does.

I did not realise you were having issues while on the mains when this happened. I though it was while on UPS power during the storm.

While other devices might be perfectly happy (with large power supplies that get rid of sags or ripples) on the line the Power Panic might not be so happy since it has to act fast.

Assuming this is still happening, suggestions:

1) remove your UPS and power the printer directly. If the issue goes away it could be switching by the UPS itself. For example my APC clicks an internal relay about once a day to go on battery for a fraction of a second and immediately goes back to mains. This is likely to test the state of the batteries under load? The 1950s mixer in the kitchen drives it nuts with the spikes generated by the old motor. The other two UPS are not phased out by it....

2) In several jurisdictions the power company can lend you a line quality monitor that will log any deviation due to spikes, sag, frequency etc.. This might be worth looking at.

3) Does this issue happen all the time or was it only during the storm. Depending on your location (for example the services are all buried where I live) although the storm might be a few kilometer away the powerline could still feed a lot of spikes and stuff to your location.

4) Contact Prusa directly to see if they have seen similar issues in the past? Might be a known problem?

OK ran out of ideas at this time. I'll update should I thing of something else.

Keep digging and happy printing.

RE: Random Power Panic (but not from an actual power outage)

@richnormand

Very helpful. Thanks for taking the time to help me. It happened 2 times today. Following the last of them I placed an inexpensive Panamax (Max8) between the mains and the UPS. The Max8 is supposed to filter out noise and spikes. If the PP goes off again in this config I will remove both Panamax and UPS and run on mains for a while. If no PP then I can be pretty certain it's the UPS. I'll post results as soon as I get some.  (unfortunately I just finished about 40 hours of parts printing. Next few days will be much less.)

RE: Random Power Panic (but not from an actual power outage)

Some UPS perform poorly with Power Panic enabled,  (Powe panic may be reacting to a power issue that is too short for the UPS to respond to. )

when using a UPS, if you remove the black and white power panic wires off the Einsy, you disable power panic, and you may well find that the Printer then works as expected with the UPS. 

regards Joan

RE: Random Power Panic (but not from an actual power outage)

@joantabb

Bingo. I disconnected the Power Panic leads and connected the PSU to the existing (cheap) UPS. Completed about 30 hours of printing (longest print 4:55) without a single issue. Thanks to everyone who commented/helped me on this issue.