question

@Henrik

That is an interesting experience. Thank you for sharing it. Stuff like this keeps you on your toes (and sometimes scratching the head) for sure.

I do have a question though, did the GX not give a phase rotation error?

@Alexandra

No, the Venus GX did not detect this error, there was neither the error highlighted in the GX console menu nor a respective alarm sent/logged. Because of this we searched several hours into various wrong directions.

I guess the rotation error detection does not work in the particular case for some reason. It is probably also quite unusual that during regular operation, one power input gets changed into opposite direction and the second remains in correct direction. Maybe somebody at Victron could try to reproduce this case.

@Henrik

Wiring the generator to AC 1 input would prevent this issue also. The Quattro will only accept the AC 2 input when no voltage is measured on AC input 1. Obviously, grid would then be wired to AC 2 input.

We also noticed the contradiction in the VENUS manual which suggest to put the grid on AC1:

Option: "Do not run generator when AC1 is in use"

"This option is ideal for back-up systems where a Quattro has mains/grid electricity connected to its AC-in 1 terminal, and a Genset connected to its AC-in 2 terminal. With this option enabled, the Genset will only start after a mains failure."

This was the reason why we connected the grid to AC1.

So I propose to either change the option in the VENUS GX menu or solve it that way that such an error is somehow identified and clearly reported as an alarm.

I have had similar a similar issue. If there is any voltage on the grid side of the master inverter, generator will not be accepted. I had to add a 3 phase window comparator, that also detects incorrect phase rotation, on the input.

We just had a similar (but worse) problem. Two phases on Mains were fused together so we ended up with 2 phases coming down 3 lines. I.e. Our red and blue phases were identical in all respects and yellow was different. Another way of explaining this is that L1-L3 voltage was 0 instead on 380 volts despite all 3 phases having individual voltages of 230 volts. Victron did not accept the power as it was genuinely bad but also did not give an error (as an aside when phase rotation is reversed - which we have had in the past - Victron gives a perfect phase rotation error on our system - we did have to set this up as an alarm).

When the battery hit 25%, the generator turned on as expected but was not accepted on AC2 because there was still power on AC1 (even though it was not accepted power). Personally, I think this is a shortcoming in the current software.

We swapped the generator to AC1 and mains to AC2 as recommended and have figured out how to deal with a whole host of other challenges which we have (due to not all loads being on battery backup and an ATS between the generator and Victron. However, we are left with one challenge… When good quality mains comes back, the Generator does not turn off until it meets the requirements set (e.g. battery SOC returned to 80%) even though good quality mains is available. Does anyone have a clever solution for this?

Thanks for everyone adding their experiences. Just for completion another case when the same issue occurs: Brown-Out situations: Voltages on AC1 are still there but too low to be accepted as usable (in our case between 183V-188V on all phases during noon times). Generator starts but AC2 is not getting used because AC1 in still has "some" voltages.

From my point of view there should be a logic improvement in the Victron firmware to better assess "power presence".