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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.
Thanks @nickdb - well in ZA I would not be surprised at all. Any suggestions which parameters on the grid code I should check first / tweak.
Impedance from/on the grid?
I am in ZA but not using the ZA grid code as I have used the following, happy to take any guidence on any of the parameters to tweak, despreate now on these multis II mini-inverts going on as those relays and contactors are dam loud on the Multi II 10KVA :)
@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.
Hence why I started searching
We looked at rosts install but its impossible to get data remotely and vrm isn’t designed for this.
An electrician will check voltages but little else and the reality is these conditions are grid related and transitory, so you’d have to be connected in realtime which isn’t practical. Even knowing the issue, there is little you can do about a weak grid. It’s annoying but the way it is.
A logger will provide some clarity, but it is an expensive intellectual exercise.
Quick question in your screenshots above I saw you were using the grid code for ZA, I noticed it has wider ranges example under voltage 195.5V where currently I am using AC low disconnect at 208V.
Questions:
1. On the grid code settings what I would think would trigger the inverter to invert would be the under voltage and/or frequency changes out of the set range. Is there any other setting that would trigger the inverter to change mode to inverting? I know it's academic but I want to run the logger so would like to know what I am checking.
2. I read up on the "weak AC" setting it seems to change the algorythm on monitoring AC input, would this help in any way?
3. I see you used the ZA Grid code, have you experienced any issues using this grid code? My installer chose the settings I have above as they have experienced "issues" with the ZA grid code.
I am using pretty beefy batteries x2 BSLBat 15.4kw
I've not had issues with the grid code.
I have actually recorded the same symptoms, at the same time, on systems within a 10km radius of me, so I am sure it is the grid.
It is not voltage related, though we have serious low voltage issues here, and I am still on defaults.
Check your NS log and see if it is being recorded, just don't leave it for too many loadshedding outages as the log only tracks the last 5 events.
Weak AC won't help, it is for generators and causes other issues.
I do agree though things like the NS protection Log should be data one can download off VRM. Even if it's a "advanced" feature one has to turn on for a period to be able to do detailed remote logging.
Of course this is all at the helm of Victron wanting to enable this or prioritising it over other important features they have in the pipeline.
