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martin-van-biljon avatar image
martin-van-biljon asked

VE.bus voltage high and not stable causing output voltage to be unstable and trip

We have a 5kva MP setup with a 5kw fronius grid tie inverter.

We see the ve bus voltage to be very erratic during sunny hours of the day when the battery is full.

The battery voltage is stable but the VE.BUS voltage go as high as 64Vdc, causing a output voltage imbalance and the inverter trips out.

It is a 5kwh BSL battery with comms to the gx device.


What can cause this issue?dc bus.png,unstable-output-voltage.pngdc-bus.png

Froniusmultiplus ve.busmultipus
dc-bus.png (47.2 KiB)
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Alexandra avatar image Alexandra ♦ commented ·

@Martin van Biljon

Are you feeding back to the grid?

Do the spikes happen at the same time as large loads dropping off and high PV production?

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martin-van-biljon avatar image martin-van-biljon Alexandra ♦ commented ·

yes, at the moment it's feeding back.

We also set the feed in limit off and it still tripped.


We set main input off and did some checkings and did updates on the fronius inverter, and it also tripped out without mains even on.


My only thinking is that there is a problem in comms between the 2 inverters, and that the MP then trips out without any alarms.


I did use the guide for the settings on the fronius inverter and everything is correct according to fronius and some victron guys.


I am wondering if its not a faulty relay, or whatever is monitoring the bus voltage.

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martin-van-biljon avatar image martin-van-biljon martin-van-biljon commented ·

Oh, and it seems that it only happen in sunny times. no big loads happening and. Over the weekend it seems like it tripped the same times on Saturday and Sunday.

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