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Multiplus overload while on standby with shore present

Multiplus ii is setup in ups mode with 5kw generator on AC1. With generator running, the inverter shuts down when a 15a motor starts. This happens with and without power assist. This motor easily starts and runs and does not overload the generator when connected directly to the generator. Why is the multiplus even trying to take the load? Why is it overloading the inverter if the load is well under the generator's capacity (inverter should not even be interfering)?

MultiPlus Quattro Inverter Charger
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@Tojohn

The load is still passing through the inverter electrically. A 15a run amperage means a higher start amperage so there would be an overload.

For loads like that a bypass switch would be beneficial.

So the power assist feature only works up to the capacity of the inverter and not the sum of the inverter and grid/generator?

@Tojohn

This is my understanding of it. The power assist feature assists up to its own max capacity and so shaving off the peak draw from grid/shore.

I am only speculating as you don't mention the size of your Multi. The 3kva only has a 32A transfer switch, but even a 5kva which has a 50A will struggle with a big motor.

A motor can draw more than five times it's run current to start up unless you have a soft start on it. So your 15A motor for a few seconds may be drawing over 75A, that is more than 100% overload for the 3kva.

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