My three-phase system occasionally drops the AC output for a few seconds while the grid itself stays up. As far as I can tell, one Multi RS loses contact with the other two, all three shut down and then restart. My NAS on AC-out logs the outages, but VRM shows almost nothing.
System
3× Multi RS Smart 48/6000/100, three-phase, firmware v1.31 (all three)
Cerbo GX MK2, Venus OS v3.80 (Large); the outages below happened on v3.79
64 kWh LiFePO4 battery with CAN-bus BMS (shown as “Generic Can-bus BMS battery”, fw v6.22)
SmartSolar MPPT 450/100, fw v1.29
ESS with Dynamic ESS (trade mode), grid connection 3×25 A
Generic energy meter (VE.Can) for two EV chargers on the input side
What happens
Outages on 3 Oct ~20:55, 6 Oct ~19:26 and 22 Oct ~15:34 (times from the NAS log)
The grid (Liander) does not fail at those moments
VRM shows no alarm or outage, except “Network incomplete” on 3 Oct
The installer could not find the cause
Something I noticed
VRM shows a separate state of charge per phase / Multi RS, and they differ a lot: right now L1 22 %, L2 44 % and L3 36 %. L2 is discharging while L1 and L3 are charging, while the BMS reports 44 %. I’m not sure whether this is just each unit’s own estimate or a hint of an imbalance.
Questions
What typically causes a Multi RS in a three-phase setup to lose the other units? Cabling, VE.Can / sync termination, firmware, BMS?
Which logs or settings can I enable to capture the exact moment and the unit involved? The VRM log interval is now 1 minute.
Are the different per-phase SoC values normal, or could they be related?
Check the rj45 plug on the rs 6000, if the plug is inserted you can not pull it out because the clip…but,
On my rs 6000 the clip didn’t hold the rj45 in the socket sometimes causing communication errors, I had this problem for several months before I was aware of the faulty rj45 socket inside the RS6000, new cables didn’t help, now a simple matchstick keeps the plug in the socket, and never had a communication error again.. I do believe it was a error with the 3p75ct meter.
I have sometimes error code 42 (Error Code: #42 - Inverter shutdown (ground current too high: >30mA) on phase1 followed by Error Code: #76 - Network incomplete putting us in the dark.
Odd thing is that error 42 is an isolation fault on solar side, which also happened when there was no solar attached to that multi rs.
I also experienced this situation when I updated the cerbo.
Do you see the same error codes? #42 i don’t always see in vrm but through victronconnect on the device itself.
The inverters shut down because there are insufficient units to operate a networked setup. Check if all required units are powered on and that the CAN interface cables are connected properly. All units remain off until the installation is fixed, after which the units resume operation.
Related configuration settings in VictronConnect are “Prevent CAN network islanding” + “Number of inverters in the system” and “Continue with missing phase” in the System section.
There is a setting to prevent it from shutting down the system though.
@Frisianstar: all RJ45 plugs have been checked and seat firmly. The VE.Can/UTP cables between the three units were replaced on 30 Oct.
@jog: good tip about VictronConnect. I checked the history of all three units through VRM in VictronConnect:
Date
HQ2531AWRTH (L2)
HQ2531J7F2Q (L1)
HQ2531MCNMW (L3)
3 Oct
#76 Network incomplete
none
#76 Network incomplete
6 Oct
none
none
none
22 Oct
none
none
none
30 Oct
none
#10 low battery voltage (min 47.15 V)
#10 low battery voltage (min 47.20 V)
There is no #42 on any unit.
On 3 Oct only L2 and L3 logged #76. The L1 unit logged nothing, so it looks like L1 dropped off the bus and the other two lost it.
For 6 and 22 Oct nothing was logged on any unit, although the NAS on AC-out did record outages then. On 22 Oct battery voltage dropped to about 47.9 V on all three.
The #10 errors on 30 Oct were on the day the cables were replaced.
The per-unit SoC still differs a lot right now: L2 27% (charging), L1 43% (discharging at about 60 A), L3 47%. All three share one battery bank.
My questions:
Is such a large per-unit SoC difference normal with one shared battery? Could it point to a problem with L1?
If one unit drops off, is it sensible to enable “Continue with missing phase” so AC-out on the other phases stays up?
Is there a log, on the GX or in the units, that records why a unit dropped out on 6 and 22 Oct, given that VictronConnect shows nothing for those days?
@lxonline Thanks. Yes, all three units run firmware v1.31.
Thanks also for the manual excerpt. “Continue with missing phase” is still off (default). If I understand correctly, enabling it would keep AC-out up on the other two phases when one unit drops off. Is that the recommended setting for a 3-phase Multi RS system like this, or is there a downside?
Settings (identical on all units, synced): system configuration three phase, Prevent CAN network islanding: on, total number of inverters: 3, inverters per phase to start: 1, Continue with missing phase: off, switch phases as group: on.
We have a three-phase heat pump, so I’ll keep “Continue with missing phase” off.
So if I understand correctly: when one unit loses CAN contact, all three switch off by design, and the real question is why that unit loses contact. The VE.Can/UTP cables were replaced on Oct 30, so I’ll monitor whether the dropouts come back. Is there anything else I should check or log in the meantime?
@jog: in my error history I only see #76 (Oct 3) and #10 (Oct 30), no #42.