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Axpert 5K Inverters in parallel


creyneke
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Hi I have two Axpert 5K in verters set up in parallel using grid power to charge the batteries and rely on this in the event of load shedding.

 

My question is that only the slave is putting out power and when it get to 4Kva it overlaods, however the master inverter only puts out 44V? Is this a setting I have wrong?

Can somebody please help me "shed some light on the matter"

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Can you please advise what the wiring should look like, I have had it installed by a contractor.

How will I know if it is indeed paralleled, it does show the master as well as the slave but the master is not giving any load. I know the live and neutral (feed) come into the master and then a live and neutral is taken to the slave.

The live and neutral (load) also comes out of the master with a live and neutral wire going from the master to the slave.

Obviously there is also the communication cables joining the two inverters.

Does anything sound out of the ordinary

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1 hour ago, Coulomb said:

I assume you mean 44 VA. It sounds like your master isn't paralleled with the slave at all, and isn't providing any of the load. Check your AC output wiring and breakers.

I've had two support calls already from people with the new Multiplus who didn't parallel up the outputs correctly. Because this inverter is grid parallel, it ends up pushing half the power out of the input... leading to hilarious results: Whatever you draw on the output of the one, the other feeds the exact same amount into the grid :-)

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Don't these things also have current sharing cabling? A problem on those might make it THINK that the second one is working while it isn't? In which case I concur with Chris. Switch off the slave and see if the power drops out or not.

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6 hours ago, creyneke said:

I have had it installed by a contractor.

I think you need to get him/her back.

6 hours ago, creyneke said:

How will I know if it is indeed paralleled, it does show the master as well as the slave but the master is not giving any load.

What you see is pretty much what I'd expect if the connection from master to slave on the AC outputs wasn't connecting somehow. It could be as simple as a terminal not screwed tight. If you're not familiar with electrical work, don't attempt to fix it yourself.

I'm not hearing anything about breakers at the AC inputs or outputs. Those should be there (three total; the AC inputs can share a higher current breaker). A photo of the wiring might show something obvious.

I agree with others that the most important test is to switch off the slave to see if the master can power the load on its own. There could be something with the current sharing cables, as others have also mentioned. You could be justifiably cranky about the installation not being properly tested.

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If you snipped the cable ties and just opened up that one strip below the inverters, I bet that'd be enough to see something. But the fault might still be inside the lower sides of the inverters too (eg loose screw terminal).

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I'm kind of surprised that no one has mentioned the fact there is no inverting going on here. The Axperts are in bypass. So they have no way of controlling how load current is shared between them. Their current-sharing cables make no difference in bypass mode. So it's not the Axpert's fault, unless the master has a failed relay, which seems unlikely.

There has to be a high resistance, or open circuit, in that part of the path from the master's AC output to the loads, that is not shared by the slave.

There is a load switch on the bottom right of each inverter. Turning it off will disconnect that inverter from the loads. If everything was working correctly, you could turn off either one and the loads would still be powered via the relays in the other inverter. But if the above is correct, turning off the load switch on the bottom of the master will make no difference, however turning off the load switch on the bottom of the slave will cause the loads to brown-out, or lose power completely. If they brown out, you should turn the load switch back on immediately. And in any case, consult an electrician.

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  • 3 weeks later...
On 2018/12/22 at 3:40 AM, weber said:

I'm kind of surprised that no one has mentioned the fact there is no inverting going on here. The Axperts are in bypass. So they have no way of controlling how load current is shared between them. Their current-sharing cables make no difference in bypass mode. So it's not the Axpert's fault, unless the master has a failed relay, which seems unlikely.

There has to be a high resistance, or open circuit, in that part of the path from the master's AC output to the loads, that is not shared by the slave.

There is a load switch on the bottom right of each inverter. Turning it off will disconnect that inverter from the loads. If everything was working correctly, you could turn off either one and the loads would still be powered via the relays in the other inverter. But if the above is correct, turning off the load switch on the bottom of the master will make no difference, however turning off the load switch on the bottom of the slave will cause the loads to brown-out, or lose power completely. If they brown out, you should turn the load switch back on immediately. And in any case, consult an electrician.

I had a look at the inverters and it seems the one inverter is faulty. Even in single mode without the comms and current sharing cables, there was no voltage on the AC output terminals. I had a quick look inside and couldn't see any visible signs of failure though and suspect a faulty motherboard.

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