Off grid - Overload at 7.5-8.4kw on MP2 10KVA 48v - advice needed

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h2009 asked Mar 23, '24

Off grid - Overload at 7.5-8.4kw on MP2 10KVA 48v - advice needed

Hi there,
I cannot figure out why I'm getting overload alarms at just over 7.5kw load on any phase (3 phase). I do connect to the grid during off-peak hours with no alarms, this only happens when I'm off grid (relays open).

Can someone advise me on why this happening and a solution for this. Basically the this is trigged from a hot tub running.

Here is my setup:

3x MP2 10kva on v506
16x Pylontech batteries US5000 connected in banks of 2x
Batteries never go above 25c
Environment where the equipment is at 20c
Running at 240v at 50hz

Multiplus-II 3 phase alarm

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Answer 1 · 2024-03-23T21:10:14Z

Alex Pescaru answered · Mar 23 at 09:10 PM

Hi,

Off-grid it means that the MP2 is inverting, so 10 kVA at a cosphi of 0.8 doesn't mean a maximum of 8 kW?

On-grid it's just a matter of transferring that power consumption from grid to loads directly, so no alarms.

Advice: need a bigger MP2, the 15kVA.

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Answer 2 · 2024-03-23T23:45:37Z

h2009 answered · Mar 23 at 11:45 PM

Thank you. I thought this would be the case physical limits. My issue is I don’t have the space for the larger units, so I was hoping for another method (wishful thinking I believe).

On the flip side, I assume even if I cool the MP2s down to say 10c it will have minimal impact, as I guess the limit is hard coded to send an alarm?

Is there a method to phase balance as required or again is that wishful thinking?

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nickdb ♦♦ commented · Mar 24 at 06:46 AM

At 10C you should be able to delay/prevent it derating which will happen if you run it at max for sustained periods.

But still, without grid, that unit is undersized.

The airflow isn’t ideal in these units so they still tend to derate.

I have seen a site fit an extraction hood to the outlet and “pull” air through the unit.

That improved its performance somewhat.

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