Jay-Dee Posted July 20, 2020 Posted July 20, 2020 Good morning all... I am having an odd issue with a new Axpert King Parallel setup. On Friday last week, I added a 2nd inverter to my setup and connected everything as per the manual diagram for 2 inverters. When turning the systems back on, they immediately tripped the Mains' Earth Leakage and would not allow it to be put back up. The inverters still were powered up due to battery and PV but the newly installed unit had set itself to HS and the original to SL while providing an F72 error. I removed the return / load wire from the 2nd unit and just left the original one connected.. Turned both back on and all was well. The original unit with Solar connected has HS and the 2nd unit was SL.. This worked for about 2 hours until they tripped the post inverter earth leakage and when checking the units they had reverted back to SL and HS on the "incorrect" units with an F72 error. I turned off the new unit, disconnected the comms cable and left it until Saturday afternoon. I then reconnected the new unit exactly the same as per Friday but this time started the old / original unit up first, let it go online correctly and then only turned on the new / 2nd unit. They worked perfectly and everything ran as it should (PV on the HS / primary unit.. Mains connected and battery connected to both with all comms cables installed correctly). The units changed modes between SBU / SUB and Utility with no issue and Sunday ran like a charm. This morning when PV generation kick in, the program changed from SUB to SBU without an issue but 20 mins later, the Mains' Earth Leakage tripped again. No errors on the units and the Earth Leakage went backup without an issue.. About 20 mins later, it tripped again but this time the HS and SL had changed, F72 error was back and the Earth Leakage would not go back up. I have removed the load / return feed from the new / 2nd inverter, removed the comms cables and power both back up... The primary unit is function 100% with load, battery and PV... the new / 2nd unit is on perfectly but doing nothing beside testing the earth (with no issues for the last hour). Am I missing something? Is there supposed to be something connected inline with the load / return feed to prevent this from happening and what is an F72 error. I initially through it was a firmware difference error but they are both running identical firmware version. Thanks in advance... Really want to get this stable before adding PV to the 2nd unit Quote
Coulomb Posted July 21, 2020 Posted July 21, 2020 16 hours ago, Jay-Dee said: the newly installed unit had set itself to HS and the original to SL while providing an F72 error. Which one is master (HS) and slave (SL) is supposed to be random, unless you power one up first, then it's always the master. It should not matter which one is master. F72 is a current sharing fault. Check your current sharing cables (the red and black twisted pairs). Also check that your firmware isn't rather old. I can't recall what version an error to do with monitoring paralleled units was fixed. Quote I removed the return / load wire from the 2nd unit and just left the original one connected.. Do you mean you removed only the neutral wire from the second unit's AC-out terminal? Do you have breakers on the two AC-out actives? If so, why not use those to isolate the second inverter from the loads? Turned both back on and all was well. The original unit with Solar connected has HS and the 2nd unit was SL.. This worked for about 2 hours until they tripped the post inverter earth leakage and when checking the units they had reverted back to SL and HS on the "incorrect" units with an F72 error. Quote The units changed modes between SBU / SUB and Utility with no issue and Sunday ran like a charm. Are you using ICC or similar to change output source priority? Is your earth leakage breaker before or after the inverter? It should be after. Possibly the problem is that one inverter has some leakage to earth via the EMI capacitors, but not enough to trip the earth leakage, but two do. Quote
Jay-Dee Posted July 21, 2020 Author Posted July 21, 2020 Thank you for the above... I think the other similar post referring to the F72 error has answered my issues and that is difference in lengths of AC output / return cables. I am most likely going to scrap the cluster, sell my inverter and simply purchase a bigger one that I should have done so originally as you know I am having the firmware issues too Thank you for all your input. I really appreciate Quote
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