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rns asked

Multiplus II zooming noise

Multiplus II zooming noise that is very enoying at night. The zooming/buzzing is going through the entire house.

I have the feeling this is more the case when net connected. When I ran the inverter in island mode I also heard the zooming but typically when I had inductive loads like TL lights.

Anything that can be done to reduce the noise ?


In my setup the multiplus II is connected via AC1 IN to the grid, Nothing connected to AC OUT. It is configured to compensate grid loads above 2500w and I use the external AC clamp (the one with the phone jacket) to measure the grid load. At night, loads are never above 2500w so the inverter has nothing to do I would expect. I do see some small power being send from the inverter to the grid (0 to 40w). So I was wondering if the multiplus tries to compensate for inductive loads since at night my grid cos phi does deviate from the ideal 1. (arico in standby and induction cooking plate in standby). I found some cos phi settings in the grid page of the multiplus but I don't understand the options and couldn't find documentation. Not sure cos phi has somehting to do with it but it looks that at night when the multiplus should have nothing to do, the noise is the highest.

Multiplus-II
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3 Answers
Rob Duthie avatar image
Rob Duthie answered ·

Hi

Not realy as it has a transformer as a output any inductive or diode recitifed load will make it hum somewhat, resistive loads are normaly OK.

Also depends what surface you mount the inverter onto has a influence on the noise verbarations.

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rns avatar image rns commented ·
In my setup the multiplus II is connected via AC1 In to the grid, Nothing connected to AC OUT. It is configured to compensate grid loads above 2500w and I use the external AC clamp (the one with the phone jacket) to measure the grid load. At night, loads are never above 2500w so the inverter has nothing to do I would expect. I do see some small power being send from the inverter to the grid (0 to 40w). So I was wondering if the multiplus tries to compensate for inductive loads since at night my grid cos phi does deviate from the ideal 1. (arico in standby and induction cooking plate in standby). I found some cos phi settings in the grid page of the multiplus but I don't understand the options and couldn't find documentation. Not sure cos phi has somehting to do with it but it looks that at night when the multiplus should have nothing to do, the noise is the highest.
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sharpener avatar image
sharpener answered ·

There are several threads on here about noise, though mostly about fan noise. The following may also help, depending on whether the noise is conducted or radiated:

  • apply a sound deadening material to the inside or the outside of the case e.g. carpet tiles or rubber carpet underlay. There are also specialist materials available from marine suppliers for soundproofing engines that are very effective and have the advantage of being fire-retardant.
  • mount the inverter on a more massive background if possible e.g. a stone or masonry wall rather than a stud wall or partition.
  • use resilient threaded rubber mounts between the inverter bracket and the wall
  • build a soundproof enclosure e.g acoustic board lined with fibreglass or anechoic tiles, ensuring adequate ventilation.
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rns avatar image
rns answered ·

Hi, I put behind the multiplus II a rubber mat that is sold for under washing machines.

I bought it here in the local DIY store but looks like this one I found on Bol.com.

Certainly look around because I bought mine for half the price.

I made it the same size as the multi. The mat is also very thick (around 2cm). Maybe thinner would also work.

Before the hall house was zooming certainly at night, now it is quiet. You can still hear the muliplus when in the same room but ths sound is no longer transfered to other rooms.


So my problem is solved. I hope it helps others.


https://www.bol.com/be/nl/p/etm-anti-trillingsmat-wasmachine-en-wasdroger-geluidsdempende-antislip-mat-trillingsdemper-19-7-mm-60-x-60-cm/9300000119079102/?Referrer=ADVNLGOO002029-G-135323023421-S-1743937379997-9300000119079102&gclid=CjwKCAiAioifBhAXEiwApzCztkBK1h0_pv-1tGrIw9C3X00GZRI8uZq-BCrWMc-XSrx7nw9MVt11uhoCjJsQAvD_BwE

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