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I have installed the MultiPlus-II 48/5000/70-50 (v500 firmware) inverter with Pylontech US5000 battery and Cerbo GX (v2.92). While browsing data in Remote Console I noticed that for unknown reason MultiPlus sometimes starts inverting during up to 1 minute when the grid is up and has normal voltage.
Is it some sort of internal self-test that inverter periodically does or is it a sign of issue?
Looks like grid rejection. Can be any number of reasons, usually a sign of a poor grid supply. If you’re connected in real time with a mk3 the ve bus monitor should show why, but it’s next to impossible to get the timing right.
Thank you for your input. Yeah, those issues mostly happen during night so it is impossible to catch it live with MK3. The grid supply is indeed poor, that's why I have installed a double conversion voltage stabilizer, so I suppose even tiny issues in grid supply must be eliminated due to double conversion in the stabilizer.
@Rost If you connect to the system with a mk3 adapter and veconfigure, go to the grid tab and under the grid selection you choose "show NS protection log".
The inverter keeps the last 5 reasons for grid loss/rejection in NVRAM.
You can also show the criteria that the grid code is enforcing by choosing the grid code settings tab.
Between these two, you should be able to identify why your system is behaving the way it is.
(sorry for the rough mobile pics)
@nickdb Thank you for the screenshots. Fortunately this anomaly happened recently so I was able to follow your advice and check the log. Sadly all recorded events happened days before the recent anomaly and corresponded to confirmed grid outages (at VRM there was a dip of input voltage at those timestamps as well). Sending another screenshots of VRM zoomed at recent anomaly and NS log.
@Rost Did you ever find an answer to this. I have the Multi II 10kva and this is driving me absolutely nuts. I get these 1min inverting randomly I noticed mostly during the night 1 to 2 hours appart.
The data doesn't show any drop in V or Frequency from the AC side. I have almost rewired the entire house looking for a rougue neutral or live.
@nickdb - did you ever check remotely an see anything? I saw your screenshots had ZA grid listed. I'm in ZA as well. This is driving me dam nuts I'm about to pay an absurde amount of money to have a logger installed on my AC side to see why the hell the inverter keeps inverting for 1min. Happy to let anyone check remotely as well.
Can one see the NS protection log remotely (i.e. not being connected via Mk3?)
This is just in a space of 24 hours:
Unfortunately in really short outages it doesn't seem to log. It will be one of the parameters in the grid code getting out of whack. The worse the grid is, the more likely it happens.
Mine aren't as often. I suspect it might be an impedance issue but ultimately it is a grid fault.
@myvicrocks I've sent @nickdb my VRM id in February but didn't get any feedback since then. This random switchovers continued to happed once every day or two.
I recently installed a several solar panels and switched my system off-grid so at least for now this issue does not bother me at all.
What I can also add is that this is definitely not some reporting or dashboard bug. I once was near the inverter when this happened and it really switched to the inverting mode for 20 or 30 seconds.
