I have a 3 phase ESS setup based on MPII 48/5000/70. Currently when the Neutrals of the crital AC Out are combined together and I power on the system, the AC IN circuit breakers trip. I can’t figure out why it happens, so any advise is welcome.
When activating the system with the AC IN under power, the AC out disabled in the ESS and the AC out circuit breaker off, the main keeps blinking and after 30 seconds the AC In circuit breaker trips.
When activating the system without AC IN, the system starts normally and the AC PV Systems even start connecting to the off grid setup after I enable the ‘Inverter AC output in use’ and charging the batteries.
In some of the troublehoot scenario’s, the Cerbo sounds the alarm of Grid lost, before the AC in trips.
This installation is already 14 months operational in an AC grid parallel configuration. And it works like a charm. It keeps the grid meter 0 in a multiphase regulation until the batteries are fully charged by the 3 one-phase PV installations. These solar installations are each connected to it own phase. When batteries are full the excess is fed into the grid.
At installation time the electrical wiring was prepared to make the whole system off grid ready. The AC OUT1 has its own 3phase cable back to the house on which also the PV inverters are connected.
The critical loads were never activated, nor connected to house installation as I knew the 3 1phase B-type breakers would not suffice.
The change I now made to the system is to connect the 3 critical outs to their own 3phase C characteristic circuit breaker.
Going back to the basics of troubleshooting:
There are a couple threads in this forum that might appear applicable, but that I test troubleshoot and elinated.
I have now completely unwired the AC out and isolated the 3 live wires. And have the 3 Neutrals combined. When combined, the AC IN still trips.
• Firmware of the MPII I update this morning to v552 and for the Cerbo to V3.53
• There is no possible connection between the Neutrals of the AC in and AC Out as they are disconnected/isolated completely. I went back to the basic installation setup for progamming the system.
Did this after a hint by Dick Streefland on a different post "perhaps the neutrals of AC IN and AC OUT connected externally?" as the house wiring was done by an electrician.
• There is no load on the Critcal out (tested the correct working though with a lamp)
• Tested it with the PV systems connected and disconnected
• Tested it with and without the C Characteristic circuit breaker : Easton 3P -25A -243020
• Checking wires and connections
• Disconnected/Reconnected the ground to the house installation
Asking Co-Pilot: What can be wrong with a multiplus if the main keeps blinking and after 30 seconds the circuit breaker trips.
It answers:
If your MultiPlus inverter’s main light keeps blinking and the circuit breaker trips after about 30 seconds, there could be several potential issues:
1. Overload or Short Circuit: The inverter might be drawing too much current or there could be a short circuit in the system2.
2. Faulty Wiring: Incorrect or loose wiring connections can cause the circuit breaker to trip.
3. Ground Fault: A ground fault in the system can lead to the circuit breaker tripping.
4. Faulty Breaker: The circuit breaker itself might be faulty and tripping prematurely.
5. Inverter Fault: There could be an internal fault within the inverter causing it to malfunction.
It’s important to carefully check the wiring and connections, ensure there are no overloads, and possibly test with a different circuit breaker. If the problem persists, it might be best to consult a professional electrician or contact the manufacturer for further assistance.
Have you possibly swapped L and N at the output of the multis?
A problem like this is always very difficult to solve from a distance.
Does the overcurrent release trip ‘normally’ or does it ‘pop’ due to a short circuit?
Thanks for the response. I would describe it more as a ‘pop’. Each phase to a multi has its own circuit breaker, ie 3 type B 16A. All 3 trip. On a very sole occasion while troubleshooting 2 out of 3 trip.
Could it be bad circuit breakers on the AC IN?
Tomorrow I will double check on the possibility that I might have swapped L and N. I will let that know.
If the circuit breakers are next to each other, a short circuit in one of the circuit breakers may cause the magnetic releases of the others to trip as well.
Why don’t you switch on the fuses individually … what happens when the 2nd one is added …
and @DuivertNL : How could I determine that?
The ESS I can see it balance over the 3 phases, so I do believe there is a proper connection to the grid.
Moreover, I think I read in the past, that if phases are swapped, the 3 phase setup throws an error code on wrong phase rotation.
Do i understand correctly that you have 3 separate breakers on ac in ? What country are you in? Are they normal circuit breakers (L and N) or earth leakage (L, N and earth) (dont know how they are called in english )
Hi Steffen, I do not fully understand your suggestion. With the connection to distribution switched off, you mean. The Neutrals from the AC out combined and then switching on the AC IN circuit breakers 1 by 1?
Hi Marc, A certified electricien installed those breakers, so they are not Ali express. But I am curious though: what is not allowed? As I am in NL, I’d like to comply with regulations
