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joeccv avatar image
joeccv asked

Multiplus output vs inductive/capacitive loads

I posted recently about the Multiplus 3kva and sensitive equipment , but let me ask a more direct question here:

In reveiwing a document from victron stating the overload capabaility of the Multiplus series inverter, they state that for startup current of an inductive/capacitive load (0.7 power factor), double inverter size is needed. See attached sheet.

We currently spec'd the Multiplus 12/3000/120 for use to power our equipment (cut sheet attached). Our equipment has a max consumption of 2700va with power factor of 0.7.

My math shows this will pull 1890 watts at max. On average it pulls about 300w as read on our power meter. We don't have much more data about how long it consumes it's maximum current but it doesn't seem to be very long, and certainly not continuously.

First question: When following the Victron recommendation of "double inverter size" on the attached slide, is this only for overload scenarios?

Second question, if the Multiplus 3kva is rated at 3000va or 2400w continuous, does this equate to a power factor of 0.8? And does this number affect the actual power consumption of the unit plugged into it?

Thanks again.

Multiplus Overload Data.jpeg

MagPro Main Unit.pdf

MultiPlus Quattro Inverter Charger
multiplus-overload-data.jpeg (127.1 KiB)
magpro-main-unit.pdf (415.8 KiB)
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Jason - UK avatar image
Jason - UK answered ·

Hi @JoeCCV . Yes you are correct regarding the power factor. For example, I have a 5kva Multiplus II GX. When I have majority of inductive loads, I can pull a constant 4.4, maybe 4.5kW form my unit (power factor of about 0.9) but when I am running a resistive load like the double oven which is 4.4kW, its about 4kW from the inverter (0.8).

Regarding the double inverter size, it depends on the inrush of your equipment. I have a 1.8kW direct online compressor but when it initially powers up, it hit 2.8kW for a millisecond or 2. Because the Multiplus is grid connected, it doesn't react to the inrush, it lets the grid do that but it deals with the constant load very well. If I had a 4kW compressor, my 5kVa would never cope with the inrush of my compressor but because the inrush is so short, the inverter might not go to overload so eventually it would fail.

My advice if you really want to be carful is to find out the inrush current and for out the power factor of the equipment. Also, the air temperature and ventilation has an impact of the performance of the inverter. I have my inverter under the stairs in my house. When I shut the cupboard door, my inverter heats up the cupboard causing the inverter to throttle back on the output when it get really hot under the stairs. Because of this, I have to leave the cupboard door open unit I have got round to fitting some ventilation.

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kevgermany avatar image kevgermany ♦♦ commented ·
@JoeCCV

To add, you can also find boxes that limit the inrush current. Soft start is one name they go under.

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joeccv avatar image joeccv kevgermany ♦♦ commented ·

Thank you for the replies.


@Jason - UK , the power factor of the equipment is 0.7. So will it's pfc max consumption remain 1890 watts (2700va x 0.7) or would I need to use the multiplus' 0.8 power factor in this calculation?


@kevgermany they are useful for AC unit's but I'm not sure this would work on this unit. It is a magnetic stimulation device. See attached cut sheet. (Adding to OP as well)


MagPro Main Unit.pdf

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