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Strange power issue on Mecer 8Kw


Pierrep
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Hi everyone

I need some help, I have a strange power issue with the Mecer 8Kw

New system currently is powered by 24 x 360w panels, 4 x Pylons completely off grid

Once all panels is up it will be a parallel system, 2nd 8Kw inverter and panels not yet connected at all

So first i noticed when i plugged in the rs232 coms cable into laptop the usb mouse stops working, checked 2nd mouse and same thing.


Once the usb port of the inverter touches the laptop port this happens.

Later that day i notice on my alarm system touch screen it is showing communication failure (rs485 comms) intermittently, expanders zones stays open

Something's up

Above was working with eskom power 100% until to inverter took over.
Eskom cables is disconnected completely at pole(farm)

Issue is day and night
So googling earth issues sounds to be in the right direction and phoning my electrician which is 100's of km's away

Check leakages from L & N to earth

So i tried bonding N with earth - same
N bond and all earths to pipe is same
All earths connected to copper water pipe only - same
Only inverter earth to waterpipe - same
no earth at all - same

Then i completely disconnected the first inverter and connected the 2nd inverter only to do the same.

Anything else to check or other suggestions?

 

 

 

 

 

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4 hours ago, Pierrep said:

So first i noticed when i plugged in the rs232 coms cable into laptop

Exactly how are you doing this? The "obvious" way is to use a standard CAT-5 or so data cable, since it has RJ-45 connectors at both ends, and your laptop has an RJ-45 socket. But the laptop would be using it properly, as an ethernet port. The Axperts abuse the connector and put RS-232 on it, in a non-standard configuration. So the "obvious" way is the wrong way.

You have to use the provided RJ-45 to D9 cable, and provide your own USB to RS-232 adapter to connect to that. Axperts were designed when there were still a few computers that had RS-232 ports on D9 connectors. Such computers all but non-existent now, hence the need to provide a USB to RS-232 adapter.

It's possible that you have damaged the ethernet port of the laptop, and possibly other I/O ports (such as the presumably USB ports that the mouse connects to). But hopefully the current was limited, and didn't actually damage the laptop, once the bad cable was removed.

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Thanks for reply

I'm using the db9 cable with a serial to usb converter.

This is how i used watchpower on 2 other systems no issue
.
The serial cable is working perfectly with watchpower.


The issue is that it is knocking out other system communications running rs485 like my alarm system as well, this leads me to believe the scale of if there is a problem is larger than the laptop's mouse.

Also on this, this morning once the panels got more sunlight the inverter switched the 220v side off and was showing error 55.


Happened a few times.

So i proceed to check the charging amps which went up to 80+ amps.
So i changed the battery charging amp to 20A and then to 30A.
A minute or two later the fans was starting spinning really fast and i rechecked the setting and it went back to 80A charge for a few seconds and slowly gone down.
So it seems like when the batteries was charged a bit this stopped happening.

I'm not sure if the Pylontech batteries is controlling the charge rate.

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6 hours ago, Pierrep said:

So googling earth issues sounds to be in the right direction

Yes. With the above information, it sounds like an earthing issue. You should have one and only one connection from the neutral bar in your switchboard (DB), to your earth bar, and the earth bar should connect to a good earth, such as your metal pipes.

The neutral to earth connection (bond) should be before any Residual Current Devices.

Was your laptop charging when the mouse stopped? If you run the laptop without the charger connected, does this prevent the mouse from stopping? Generally, chargers would be isolated from earth, so this should make no difference.

I assume that you have a removable display on the 8 kW models. I don't know how they isolate the RS-232 port in there. I wonder if there is some weird fault bridging the isolation in the inverter. But since using the second inverter makes no difference, it would have to be a similar fault in both removable displays, which sounds very unlikely.

Do you have any high powered radio transmitters out there? (A wild shot.)

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With or without the charger the mouse would stop working.
When unplugging the rs232 cable and removing mouse cable and plugging it back in it will only start working again.
There are some times when the mouse would work for a few seconds and stop again.

high powered radio transmitters = no - however a 5ghz dish for internet which is about 15meters away ontop of the roof with pole
This would not be the problem, if only the inverter is running, all loads disconnected it also does this

On the neutral bond i have done it in the db
For now all i can think of is to improve the earth with couple of earth spikes and flat copper bar.

Google search on this does not show that this is a common issue, so makes it more difficult to fault find

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Can you measure the AC voltage between some metal part of the laptop and some metal part of the inverter? Before and after connecting the inverter to the laptop. I'm wondering about induced voltage, hence the query about radio transmitters. I don't think a microwave dish would be the problem, those things should focus the RF energy pretty well. 

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@Coulomb

Before connecting my laptop shows ac voltage out of range - going past 1000Vac?
After connecting around 270vac

Connecting the housing to earth then all seems to work well - test like 20vac

Yesterday i have dug up a 3 meter trench with 3 earth spikes and added some salt

All that remains is that in the morning with sunshine here by 8am the inverter settings are somehow changed to charge 80A insted of 40A i have set it at.
Inverter will shut down and restart until 2nd time and stay off
While standing there changing back the settings the inverter will keep doing this.
Shutting down 50% of the panels it cannot go to that charge rate and sets it to 30A on solar

Same with generator(7Kw) connected, will go way past the setting 40A on utility charge - its like testing the capability of the incomming utility?
 
This i have asked my supplier but no response

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On 2021/01/27 at 8:28 PM, Pierrep said:

Before connecting my laptop shows ac voltage out of range - going past 1000Vac?

I don't have great faith in that reading, sorry. More than 1000 VAC would cause way more problems that stopping the mouse from working,

 

On 2021/01/27 at 8:28 PM, Pierrep said:

All that remains is that in the morning with sunshine here by 8am the inverter settings are somehow changed to charge 80A insted of 40A i have set it at.

I don't know how the dual MPPT models work. Maybe the 40 A max that you set is per MPPT, so 80 A max between the two MPPTs. So if you want 40 A max into the battery, use 20 A setting(s) (20 A per MPPT).

 

On 2021/01/27 at 8:28 PM, Pierrep said:

Same with generator(7Kw) connected, will go way past the setting 40A on utility charge -

That I can't explain. It may pay to read the manual (paper, PDF, or online) carefully, perhaps reading between the lines of Chinglish if necessary.

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