Victron

[Dylboy]

Hello

This may be long winded or not but I have been doing some AC work for a guy who does Victron and then yesterday I took the bottom bracket off the multiplus II 5KVA, 70A. And it said the below pic, I assume the impedance they mean is the External Earth Loop Impedance but that "+j0.18ohm " I do not understand, basically it's the letter j there ?


I assume the 0.28ohm is external earth loop then the +j is the earth loop from inverter to the DB it is fed from... So then a total Zs of 0.46ohm.

Am I correct in the above ?


Then I had a call that the ELU (Earth Leakage Unit) on inverter output intermittently trips when Eskom comes back, there is the internal relay for N and E but the Earth Loop of the Main DB is 0.54ohm so is that why the ELU trips as the Earth loop is too high for it and greater than the combined 0.46ohm?

I can hard wired a N and E but that can not be done past council but since the inverter is an appliance then it can be argued but for now just wanting clarity on the above impedance stuff.



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[Derlyn]

It will be interesting to find out where they got that info.

The max earth loop impedance allowed is dependent on the current rating of the circuit breaker protecting the circuit and the voltage.

The impedance shall be such that it allows a current at least twice that of the circuit breaker rating to flow in the event of a short circuit to earth, thus ensuring that the said breaker trips.

Readings of higher than that on the photo are therefore still acceptable.

[Derlyn]

I don't think that is referring to earth loop impedance. It is referring to the impedance of the network. 2 completely different monsters.

[Dylboy]

Yes I have no idea what this Network impedance is, first time I have seen it

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[Dave A]

Yes I have no idea what this Network impedance is, first time I have seen it

I was hoping someone else would step in on this one. You are dragging back memories of material I last did over 40 years ago

The short answer is that network impedance in AC circuits has a real and "imaginary" component. The "imaginery" component when using vector notation is indicated by the preceding j as you have discovered. The combined result isn't obtained by linear addition, but by ...

In fact, here's a quick crash course for you.
(Thank goodness for the internet).

[Dylboy]

Hahaha thank you for answering though haha!

And awesome, had a quick read of the link and I remember all these Vector things... Remembering and understanding is 2 different things in my case hahaha. But I see that letter j there again.

Thanks so much ! Will have a deeper read later and to find my books on all that stuff

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[Derlyn]

Wow !

Thanks Dave.

That brought back some good memories of my ham radio days.

Keeping that antenna matched to the transmitter at different frequencies was always the biggest challenge.

Ex ZR2WB and ZS2J.