I am installing a Multiplus II 15000 / 48 / 200. The AC input is a 230v grid connection fused at 80A. The load will be connected to the AC output. My question is does the cable, connectors and circuit protection for AC out need to be rated to take the 80A + 54A assist current ? This would total 134A which is more than readily available single phase isolators, 25mm cable and phase blocks etc. Is it perhaps that the Multi will limit the assist to 20A so the output current never exceeds the 100A rating of the internal transfer switch ?
Apologies if this has been answered elsewhere but I can’t seem to find a definitive answer, it’s not an easy thing to test! Thanks
Hi @aitchjs ,
As far as I’m aware the MP2 you mention comes as 15000/48/200-100
15000Kva / 48v / 200A charging / 100A passthrough (MPII 15000/48/200-100)
So as far as I’m aware, in theory it can supply:
100A incoming from AC1 input which is then ‘passed through’ + 100A from power assist function (inverted 100A supplied from battery bank)
Your system needs to be fused to protect the cable, and the cable needs to carry the maximum potential current drawn over your circuit.
Fusing
E.g a cable should be fused with a fuse NOT exceeding the the current carrying capacity of the cable.
So:
1.) Fusing must protect the cable, and therefore NOT exceed the Cable current carrying capacity (4Cs)
2.) What is the maximum potential current that can be drawn over a circuit conductor (cable).
3.) 4Cs must be >= the maximum potential current drawn, this determines your installation cable sizing.
4.) Remember to fuse each cable of differing 4Cs, with the relevant fuse for that cable or your cable becomes the fuse!
I personally fuse at 80% - 90% of the 4Cs, but that’s a personal choice, but DO NOT fuse > the 4Cs.
There are readily available single phase isolators and fuses to handle 134A (but they may not seem inexpensive, compared to low amperage domestic circuit MCB’s etc).
There is readily available cable that is easily capable of carrying 134A.
Are you actually going to draw 134A Ac?
Have you conducted a ‘power audit’ of your installation circuit (all the devices drawing power that would be in use)?
IF YOU ARE IN ANY DOUBT - CONSULT A QUALIFIED ELECTRICIAN WITH EXPERIENCE OF SUCH INSTALLATIONS - DO ASK TO SEE EVIDENCE OF THIS.
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