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sharpener avatar image
sharpener asked

Variable speed pump drive compatible with Multi?

Has anyone got experience using one of these variable speed pump drives on a Multi 5k inverter?

It looks quite compact so I am concerned that it may not have sufficient (or any) filtering on the input. If it uses a simple rectifier to provide an internal DC supply it will conduct over a very small angle near the top of the input sine waveform and I am worried the Multi will not be able to handle the heavy current pulses involved.

The proposed pump has a 1200W 3-phase motor so would not in itself be a problem.

Multiplus-II
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2 Answers
Alex Pescaru avatar image
Alex Pescaru answered ·

Hi @sharpener

From my knowledge, the device that is "building" a DC source for making later a variable frequency sinewave, if it's properly built, is responsible with making sure it has enough energy in that DC "storage" to handle high current pulses.

My 4.8kW inverter is more than capable to supply power to 2kW VFDs.

Alex

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sharpener avatar image sharpener commented ·
Thanks. What model of VFD are you using, can you post a link?
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Alex Pescaru avatar image Alex Pescaru sharpener commented ·

We experimented with both of the below. The inverter was a Multi RS Solar.

They were used to drive some CNC motors at my friend glass factory.

https://vyboelectric.com/product/variable-frequency-drive-22kw-230v-a550-vybo-electric/

https://www.fluxcon.nl/en/compact-variable-frequency-drive/compact-variable-frequency-drive-22kw-230v-1-phase-input-3x230v-output/


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sharpener avatar image
sharpener answered ·

So the Variable Speed Drive described above does not work properly with the 5kVA Multi and I suspect the "spiky" current waveform it draws is the problem.

A harmonic filter on the input to the VSD would seem to be the obvious solution. Can someone point me in the direction of ready-made filters for using this drive with a 1200W pump motor, or suggest a design process to make my own?

TIA

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