Hi Victron Community, I'm new here - hello!
I just installed a three phase Victron system with 3x 5kVA Multiplus 2's, 1x 450/200 Victron MPPT (13kW Solar), Cerbo GX, 2x ET340 (Grid + Solar PV). I also have 3x 5kW Solaredge inverters on the AC side. I have a 160kW battery bank with Batrium BMS.
I've had it up and running for about a week and it's has been working beautifully - ESS was working well and have drawn nothing form the grid. Yesterday something weird happened and the feed in and draw from the grid was swinging wildly between -4kW and +4kW. It seemed to be happening on Phase 2 only and it seemed like it would start off with the correct readings for the grid meter and AC loads and then it would ramp up and suddenly think 8kW was being drawn from the grid so would ramp up to compensate then suddenly the grid meter would read 0 and it would ramp down again only to repeat again 30 seconds later. 
I think it started when I connected a big load to the AC Load side initially (3 phase car charger 17kW total) but continued after I switched it off. I turned off all the loads on that phase and it still continued. Kinda feels like it went into cardiac arrest! Also - the recorded AC input current on that phase dropped to 0 at the time - it definitely wasn't 0, I confirmed this with a fluke current meter.
My initial thoughts were that it must be the grid meter feeding incorrect data to the Cerbo and this morning was going to swap the ET340's to see if it fixed it, but fired it all up first and it's been working perfectly again for the last 6 hours. It's not possible that the 63A limit of the ET340 was exceeded - I have a 50 amp breaker on it and I just don't have any loads that are big enough. Any ideas?
