I only realised at 6:30am, when I awoke without power.
Switched the inverters off and on, and they’re quite happy now, but confused and a bit concerned as to why it would have happened. We’re well versed in load shedding, obviously, and this is the first time I’ve seen that.
It was 4am, so minimal AC power draw (1.5kW, 5.8A at the time it alarmed), and batteries were at 50% when it happened.
Batteries was at 95% charged. running them high the last week/2 to keep them ready for all the load shedding.
Unit was dead, did not know about the hard power cycle switch, luckily Jaco quickly informed me about it, cycled and came back, happy, had load shedding at 7am this morning and so far so good. But concerning why…
My only “different” thing was a 0.75kW borehole bump that was running.
Was wondering if that, being an inductive motor, could have caused an “overload” when the inverter switched over from the grid going off. I’d be surprised if that was the cause, but I don’t have any other suggestions.
While on grid, the input and output are tied together, and the inverter acts like a AC-coupled inverter, just feeding both sides (with some control to prevent feedback into the grid, etc).
When the grid fails it opens the transfer switch. For a split second (while the transfer switch opens), the inverter is trying to power the entire grid… but usually this is not a problem. It disconnects quickly enough, there is a bit of a dip in power, the lights dim a little… you go on your merry way.
An overload happens when the Multi is unable to generate a sine wave that hits the required RMS voltage. If you’re exceeding the inverter capacity BUT it manages to still make the correct voltage, you get an overload warning, and the inverter keeps running (as long as it does not overheat, which it will in time). If you exceed the inverter capacity by 20%, but it still manages to hit that peak voltage, then there is a different timeout (but still, generally, it is not going to die), and if you go past that, then there are more rules as to how it acts, how many cycles (50Hz cycles) it will continue trying to hit the voltage before it shuts down.
And then, it will restart 3 times, and only after hitting an overload 3 times in a row will it shut down.
Edit: Got confused between your site and george’s. Removed a bit of text here
Now I’ve looked into your site before, and you do tend to overload things a bit at times… so without going in there again… could it just be that again?
It’s possible, but given it was 4am with pretty much just the essentials + a borehole pump running, it seems unlikely.
Happy to post logs/graphs if you tell me what to look for.
And your firmware is fully up to date? There were rare cases of such overload issues before firmware 482 (if memory serves), so it is also important to make sure you have new firmware.
In my case yesterday, load was under 600Watts, and Iv;'e set max invert to 2500watts.
Mine did not try and do anything 3 times, grid dropped and it drops completely at the same time.
I switched all loads off, nothing, eventually Jaco phoned back (quickly) and told me about the hard cycle button…
G
so. my big loads are on the non essential line.
What was causing some over loads are running a dish washer and washing machine together, and then having some instability in the grid, which then causes the inverter for a second to “help”.
Also previously had the inverter set to max invert of 1700watts… which just never worked, it actually resulted in the inverter shutting down and restarting, (this has not not happened recently)
G
This is completely inconsequential when the grid fails. I have my inverter set to a max inverter power of 0W at night (to prevent discharge) and it still picks up the load seamlessly when the grid fails.
At my own site I had a similar issue a few nights ago, but in my case I had a low battery alarm (which I have to fix still). My ESS dynamic cut-off curve is set a bit high, and the diswasher was finishing the drying cycle at the time, dropping the voltage below that curve and switching off on low battery. But then I had a clear low battery alarm also.
