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schneller avatar image
schneller asked

Is it safe to use a triac based soft starter on Victron Multipus II

I am in an off grid scenario with a 5kVA Multiplus II and need to start a 2kW motor. The inverter is capable to start and run the motor but the initial surge current is pulled completely from the battery pack while the MPPT lags behind to increase power output.


I am considering to add a triac based soft starter to the motor to reduce the inrush current, but I am concerned the firing angle method where the motor is rapidly switched on and off during the startup sequence may damage the inverter. The image below shows how these soft starter typically start a motor. Image obtained form https://www.machinedesign.com/learning-resources/engineering-essentials/article/21833971/soft-starters

Is my concern valid or is the inverter capable to handle a rapidly switching inductive load like this?


1721037586313.png


Multiplus-II
1721037586313.png (221.9 KiB)
1 comment
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kevgermany avatar image kevgermany ♦♦ commented ·

Triac based controls on hairdryers etc. give problems. I'd guess it would be the same here.

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2 Answers
Guy Stewart (Victron Community Manager) avatar image
Guy Stewart (Victron Community Manager) answered ·

Hi @Schneller,

This method of soft starting is not soft on the inverter, I would not recommend it.

It is not necessarily going to damage the inverter, but it is going to sound terrible, and you will not be any better off.

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Alex Pescaru avatar image
Alex Pescaru answered ·

Hi @Schneller

I am also totally off-grid in the middle of the city... :-))

The MPPT will always lag behind.

Depending on the equipment and necessity, you can use a VFD.

Also leaving things as they are, the MPPT will "put back" what was drawn from the batteries.

This is how my equipment does.

Alex

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