For the first time in many years I have a 16kw deye that keep on switching the ac input off, then restarting, runs a few Seco ds and switches off. This happens continually. Firstly the electrical is very badly done on The farm. Boer maak 'n plan. So the frequency and voltage is within range. 3 phase supply and we are only using a single phase. 50hz,  and a high 240v. They have run a 3 core 25mm from the transformer but strangely a thick outside od neutral but only a 6mm core. Earthing tested ok but It does not seem to come from the transformer. I think when there is a proper load the N cannot supply. No voltage between N and earth. Like 2 v. Can the N be the culprit? Maybe take the 3 core and run single phase to the house? Any ideas?

1 hour ago, Engel said:

For the first time in many years I have a 16kw deye that keep on switching the ac input off, then restarting, runs a few Seco ds and switches off. This happens continually. Firstly the electrical is very badly done on The farm. Boer maak 'n plan. So the frequency and voltage is within range. 3 phase supply and we are only using a single phase. 50hz,  and a high 240v. They have run a 3 core 25mm from the transformer but strangely a thick outside od neutral but only a 6mm core. Earthing tested ok but It does not seem to come from the transformer. I think when there is a proper load the N cannot supply. No voltage between N and earth. Like 2 v. Can the N be the culprit? Maybe take the 3 core and run single phase to the house? Any ideas?

When running a reasonable balanced 3 ph system there will be a lot less current in the N and that will be the reason it is only 6 sq mm. As you are only using 1 ph the N is carrying the same current as the phase. The N is a bit on the small side. You can disconnect 1 ph on the transformer and use that core for the N. 

It does sound strange that you say the voltage is always high enough but the inverter disconnects. It shouldn't even with the 6 sq mm. 

14 hours ago, Engel said:

For the first time in many years I have a 16kw deye that keep on switching the ac input off, then restarting, runs a few Seco ds and switches off. This happens continually. Firstly the electrical is very badly done on The farm. Boer maak 'n plan. So the frequency and voltage is within range. 3 phase supply and we are only using a single phase. 50hz,  and a high 240v. They have run a 3 core 25mm from the transformer but strangely a thick outside od neutral but only a 6mm core. Earthing tested ok but It does not seem to come from the transformer. I think when there is a proper load the N cannot supply. No voltage between N and earth. Like 2 v. Can the N be the culprit? Maybe take the 3 core and run single phase to the house? Any ideas?

Remove the load from the inverter and see if it stays synchronize to utility if it does then the neutral is the culprit. The 6mm² neutral is a problem in any case you need minumim 10mm² but 16mm² would be best for the 16kw inverter.