We’ve got a system comprised of a Multiplus II 48/5000/70, a Victron MPPT 250/60 Tr, a SEPLOS 14.4Kwhr battery, and a Fronius 5.0 Inverter. It’s a 230V single phase setup (we live in New Zealand).
What we’re noticing is that on a “hot day” (one where we are generating about 7.5 kW peak for a hour or so), there are a couple of strange ‘restarts’ of the Multiplus. When the issue happens, the LEDs on the charge side of the Multiplus all go out (i.e. all of the Mains/On, Absorption, Bulk and Float go out) - only the LEDs on the inverter side are present. There’s also a strange “ratchet” or clicking sound when the intermittent fault occurs.
There is nothing in the Alarm or Event log indicating a fault, but when we visit the online VRM we can see that the VE.Bus State has changed to Inverting (it is normally at either Bulk or Absorption). Monitoring on the SEPlos battery pack shows normal operation throughout (i.e. no alarms or issues).
There’s also no actual power outage - we’ve checked with our neighbours, and also devices on the non critical loads side haven’t restarted (i.e. if we check the uptime of devices on the non power backed up side they are normal).
How can we figure out what is wrong ? Is it likely that there’s a fault with the Multiplus II unit ? If so, how can we get additional information ?
I’ve got the MP II 24/3000 and it does the same. The clicking sound is the safety relay test. It will do that before it reconnects to the grid.
Mine generally does it around 7am, maybe twice per month. I’ve come to the conclusion that it’s some slight grid instability that is enough to upset the multiplus, but not enough to cause a noticeable brownout to grid connected appliances. It reconnects to the grid and carries on.
Nothing in the alarm/event log, but a change of bus state on-line. I’ve never seen it happen, just heard it, but it seems correct that the mains on light + charging lights go out.
Having a closer look at things, what I’ve noticed is that on a “hot day” (where the Charger side of the MP drops), the AC Input voltage is getting up to about 250V. Compare that with a colder day, and it’s at least 5V lower. I’ve attached graphs of both a ‘hot’ and ‘cold’ day. In NZ, our grid is nominally 230V - but the higher voltages will be related to the MPPT 250/60 Tr pushing out more energy.
Reading the spec sheet of the MP, it’s supposed to be good for up to 270V, but perhaps some hardware based reset is occurring due to the higher voltages ? It’s odd that nothing at all is logged - given that you get quite a bit of noise from the MP (and symptoms like the lights flickering etc on the critical loads side as the transfer switch kicks in).
Here’s what the VE. Bus State looks like when the fault occurs - it’s always centered within a couple of hours of the peak of the day:
A possibility is the inverter stops as it may have hit a V limit as specified by the grid operator and can be found in the gridcode setting. If you set (click on gear) graph to show min and max values. you will see actual values. It may be around 253V depending on local grid regulations.
Thanks very much @ejrossouw! I think you’ve determined the cause. We had a total of 9 of these Charger Shutdowns yesterday, so it’s good to understand what’s happening.
Our Country / Grid Code Standard is “New Zealand: AS/NZS 4777.2:2015(AC Neutral Path externally joined)”. As part of the configuration, there’s this setting:
I wonder why Victron does not log anything in the event logs or raise an alert/notification when these trip settings occur - it makes it difficult to troubleshoot what’s happening (and to me it looked like a hardware fault).
Anyway - really appreciate the help. Our grid in NZ is supposed to be at 230V, so >248V is getting quite high. I guess I get in touch with our lines company and ask them to check our neighbourhood transformer.
With Thanks,
Patrick
Edit: Here’s a better view showing the 248V for more than ~10 minutes and the 9 restarts more clearly:
When a system is injecting, it has to raise its voltage to just beyond the current value to enable current flow into the grid. If your cables are too thin at some point in your system (or a high-resistance joint), it will push the voltage up more rapidly than the system can correct, so it trips. An IR camera can help find hot joints or cables. Another cause is a lot of PV on the same neighbourhood transformer - some can/some can’t push power upstream.
I’ve looked a more detailed look at my night-time trips and they nearly all are caused by a momentary drop in local volts.
