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marsys avatar image
marsys asked

MultiPlus II 48/5000 leak curent to groung

Full ESS 3x MultiPlus II 48/5000 in EU Czech Republic
Could someone advise me on this query?
I have checked with a meter for leakage currents flowing through the PE conductors.
I found that the PE conductors from the MPII are flowing currents of around 20mA. These currents vary according to the draw from the batteries ( in Inverter mode).
What are the leakage currents ?


Further if the DC (- pole) circuit of the battery will not be connected anywhere in the installation with PE (with ground ) yet it is connected. When measuring DC against ground (PE) the voltage is measured at +48V. Where does the minus pole connect to PE ? In the inverter?

I don't know the internal PMII schematic if this is possible.

Thank you for the explanation.

Martin


Multiplus-II
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3 Answers
Alexandra avatar image
Alexandra answered ·

@Marsys

The block diagram is in the manual. The inverter when disconnected from the primary source does close an internal relay to connect earth and neutral together for safety reasons.

screenshot-20230217-065118.jpg



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Alexandra avatar image Alexandra ♦ commented ·
On another note, commissions and tests on an inverter system need a specific DMM. You get weird readings with some meters.
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marsys avatar image
marsys answered ·

Hi Alexandra,

This state is clear, the connection of N to PE (earth relay closed) is only if there is no power supply to AC IN. (Backup mode).
The condition I am describing is in operating mode where AC IN is present, the input relays on AC IN are on and the relays on PE are off.

However, this condition does not even explain where the DC is connected - on PE take..
Thank you


Martin

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phoenix avatar image
phoenix answered ·

There are capacitors from phase and neutral to PE. These are to filter noise to earth and will give rise to a current to earth. There are also filter caps on the battery to PE. Due to the high frequency nature of the noise you normally measure the PE current with a specialist current clamp. A normal DVM can give very misleading results.

The AC resistance or impedance of a capacitor drops with increasing frequency giving something called an AC earth. It will make it appear that, for example, your battery is earthed on a functioning inverter. If in doubt, isolate the system, wait maybe 5 minutes and measure the resistance.


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