question

@Paul Campbell

The Multi won't 'derate' an AC load (how would it do that anyway?). It will do as it's told and continue until it's had enough, then trip. It does have overload time tolerances though.

It could be managed with the IgnoreAC function, but you'd need to tell it exactly what you want. I'd use Assistants rather than Virtual Switch, as there you have multiple options available for Ignore-AC, like say, Voltage and/or SOC and/or ACLoad.

Assistants....

In the dedicated AC-Ignore, it presents "coupled" or "paired" conditions.

If when accepting AC because of VDC ignore AC again when VDC is X for Y

If when accepting AC because of AC Load ignore AC again when AC Load is X for Y

The assistants do not provide this.

I am not new to this, as a software engineer, but trying to achieve the same as above in the "Programmable relay" assistant is causing much tongue poking, face making, beard scratching, and grumbling about other programmers.

I'm either missing the point or these are completely junk.

None of the conditions are inter-dependent, they are only ordered for precedence. A programmable relay can set the flag, but it cannot base a condition on the flag set from previous assistants. All conditions are non-exclusive OR. Hmmm. It's like one of the aptitude tests they give you in programming exams.

Maybe I need my coffee. I will be back tomorrow.

So the closest I can get is using the "Generator start stop" assistant to control the "general flag" based on paired conditions around "AC Load" and/or "Battery voltage".

That gets me to exactly where the "Dedicated AC Ignore" left me.

If I add a further assistant which, say, regardless of what the generator start stop set the flag to, over rides it with "Do not ignore AC" if the "Overload pre-alarm" is active for 10 seconds.

I will have to wait to an appropriate time to test as it involves an AC reset. My worry is it will ping-pong on and off AC because the overload flag will clear instantly when the Grid AC kicks in. The inverter will immediately enable again and cutout again after 10 seconds.

Having a "paired" condition like:

"Do not ignore AC in when overload pre-alarm is set.

While accepting AC due to overload, ignore AC again when load is less than x watts for y seconds."

Or even:
While accepting AC due to overload, ignore AC again when no overload alarm exists for 5 minutes.

If I could make one feature request it would be to have more than one general flag and for those flags to be accessible in the subsequent assistants conditions. This will allow you to chain assistants into more complex inter-dependant conditions.

Making a proper logic builder UI with AND and OR conditions and even sub grouping would be really exciting, but very expensive to do in a Windows GUI from 1995.

Even better. If victron release the documentation and SDK for "Private assistants".

That's true. It is a good bit of kit and I'm not disappointed I bough it. I'm just struggling with the user interfaces while I find a way to get under them.

Also, it's not like I'm running someone's life support on the circuit! It's a few PCs, it's not like I have never pulled the plug on them. So what if I leave the AC Accept at 650W and the inverter does indeed get too hot and quit. The PC goes off, it goes dark. The inverter re-enables, the main load (the game and gfx card) is gone, the PC reboots back up. No real hard done.

It may be the case, that as it's in an unheated garage it's unlikely to be above 20*C except on the warmest summer days and it may run at 650W for the few hours I game in the evenings and never bother. I gamed for an hour last night and no alarms recorded. It was running between 550W to 650W and did for 2 minutes drop back to grid when load spike at 710W.

I have been following this thread @Paul Campbell as it seems connected to one of mine. I too find the description of the Assistants and Virtual Switch very counter-intuitive despite having had a lot of experience with Boolean algebra and logic circuit design over several decades. I don't use them because they will not do what I originally wanted (see this thread) but Node Red proved to be the answer.

So if you have a GX device in your system that may be the answer for you too. It may then be possible to do your own stepwise derating on temperature (just as I have done on battery voltage), then the algorithm will reduce the inverter power so the trip point is never reached.

You said in the other thread your Multiplus 24/800/16 only supplies the one circuit. Perhaps you could explain what the overall goal is. Protecting your gaming sessions from grid failure? Arbitraging between peak and off-peak electricity tariffs?

The goal is part financial and part just "hobby".

I figured I might try and generate some of it using an off grid system.

Guilt free gaming and also doing my part as a home worker to offset my carbon use.

I gamed on the inverter last night and it produced 550W without fault until the battery caused a fail back to grid.

This brings in an example where the basic "When VDC is less than X" is insufficient. SoC would be better. Under 550W of load the battery voltage is pulled down maybe half a volt. So when it hits the transfer voltage, it switches over but the voltage bounces back up to 26V and the estimated SoC was 40% still. It did switch back to solar as there was still 100W coming in, when I stopped gaming and load fell back to 100W.

SoC or load factored VDC is necessary. I think when I checked the Victron battery monitors that produce SoC are expensive. I believe the smallest smart shunt is £140 or something?