question

solar-noob avatar image
solar-noob asked

Multiplus II humming noise (it's NOT the transformer)

Hi,

I just got my MP II and connected it to the 48V batteries.
As soon as the inverter turns on, a distinct hum can be heard throughout the room. (it's my home office)

The device is not connected to mains yet and no load is connected to the inverter, just the batteries.

When I opened the unit, I found that it was NOT the transformer that was causing the noise, but the small choke coils (is this the right term?) on the little PCB right of the transformer. I mean those green coils with a few wraps of thick wire around them.

2023-01-28-16-38-47-673.jpg


Is there anything that can be done about it?

Is it perhaps possible to cast the chokes in synthetic resin or the like?

Multiplus-II
2023-01-28-16-38-47-673.jpg (551.5 KiB)
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1 Answer
Elimac avatar image
Elimac answered ·

Have you tried connecting a load? Preferibly the typical load you intend to use. Due to tolerance of the passive componnent values this happens sometimes, but is not necessarily a malfunction. The noise can appear due to specific coincidence of mechanical and electrical parametres and change in frequency and volume depending on the circuit conditions.

You can also try turn off the unit and try accomodate the coils a little, maybe a small change can reduce the vibrations. And yes, your idea is used sometimes.

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