I have a three-phase off-grid installation of 9 x Quattro 10k. All are programmed to 230V AC output
HOWEVER, we are measuring 270V AC output directly from the terminals inside the three inverters on phase 2. Phase 1 and 3 are producing 230V
Online, the VRM reports that ALL inverters are outputting 230V.
What could be the cause of this?
Good morning,
Reconfigure 3 phase “fixed” in bus first.
Check all firmware, should be the same in all inverters.
Set the system temporarily to 220V and then back to 230V, send to all inverters.
Frequency is 50Hz I presume, is that stable?
Regards, Jeroen.
What is the AC IN voltage on the problem phase?
Good morning,
Check your AC out out cabling once more, neutral to neutral, etc, I have seen before cabling switched.
Is (are) the earth relais on? Switch it off.
Disconnect all AC in cabling, island mode, switch on and see.
Is there an assistant which want to switch the grid on?
Then the inverters will “follow” the voltage of the grid, but if still red it will hoover.
Check phase rotation.
Regards, Jeroen.
Hi - This issue happens with NO AC IN. There is a generator to supply AC IN, but the problem occurs even with the generator off
Hi
Thanks for the info so far. Further information is that the system has been functioning fine for years - this is not a new installation. Also, we removed ALL AC out cables from the inverters and the problem remained.
Frequency is mostly stable 50 Hz, but there are Fronius PV inverters on the AC out (which were also turned off to test) so sometimes the frequency is shifted upwards to lower solar production.
There only assistant is the PV assistant for the Fronius
I will try some of the suggestions - it’s a remote off-grid site, so will have to arrange to get to site to attempt these options.
Thanks again
Stuart
If in doubt swap two systems around, faults will follow if it is a system issue.
Connect a 500w heater to each phase and check again with a quality meter, fi fluke
Good afternoon,
Can we see your VRM as a guest only?
Maybe that gives us some better ideas.
Regards, Jeroen.
Hi Jeroen
The very strange thing is that the VRM is reporting that each phase is producing 230V! But physical measurements show that this is not the case for Line 2 where we measure 270V from the inverter terminals themselves (without anything connected!)
Good morning,
Yes, this I understood very well.
Please, disconnect the grid, if not done already?
Sometimes it wants to “follow” the grid voltage when there is a command to go to the grid.
Then, on the main board inside, right next to the grid and out connections are these resistors, quite big, these “measure” the voltage.
Maybe one is dirty, burned, hot, etc.
Easiest is to look with a boroscope, instead opening.
Disconnect the battery, and drain the capacitors before putting in a boroscope.
I do not have a photo right now, but we have had that before with a client not using a filter.
Can you program the phase 2 inverters to standalone, only with the battery connected, then you can see which one individually is “faulty”.
Regards, Jeroen.
Good morning,
I said grid above, meaning actually in.
I’ve checked further, when you use the gen, is it then 3x230?.
If not, your voltage regulator in the gen might me the issue.
Even not running but connected, it might interfere with the AC in of the inverters, yes, the main relais in the inverter is off, but the measuring point is at the AC in side, always measuring.
Best thing we say here, switch to stand alone with only the battery connected, if ok, then 1 by 1, AC out reconnect, if all ok, then 1 by 1, AC in reconnect, in this way you will find the “faulty” inverter(s).
Check the generator voltages as well.
These gen voltage regulators fail quite often (5-10 years), easy to replace.
Regards, Jeroen.
Wow - Thanks for all the feedback. I will be on site this afternoon and will check all I can!
Thanks everyone for the assistance.
This was partly resolved by
So I reset the system to only use 6 inverters by excluding all the original masters.
We’ll see if we can get this faulty inverter repaired
Good evening,
Good to give us the feedback.
Something gave most probably over voltage or were your inverter boards dirty?
Did you check the generator output as well?
These little transformers inside the inverters on the AC in are 260V, so above, they will produce also more to the main board, with all consequences…
If there is grid or gen input, then these are the primary source to feed the main board, secondary the battery.
If you open the inverter, you see close to the AC1 in a white 2 pin connector on the main board, coming from the AC1 in, hard wired.
If you pull these off, then you run solely on battery power.
Very handy in areas where there are lightning strikes, you see?
Did you have recently a lightning strike?
Regards, Jeroen.
Hi again
The generator output is good. We expected that this may have been caused by a lighting event.
I will investigate further into those 2-pin connectors and may disconnect them to further protect the system
Thanks again for the assistance.