question

chrisu avatar image
chrisu asked

Multiplus II GX cycling humming sound

Hi there,
my Multiplus-II has a cycling humming sound which you only hear when it is in ESS PassThrough Mode. When inverting or loading,you can't hear it.


At the beginning it is quiet, but after some minutes, it starts to vibrate and gets louder and you can hear (and feel) in the whole house through the wall and ceiling. But then, the sound gets quiet again and after some minutes, it starts again.

You can hear it even when there is no load.

Is this normal? It is very annoying because you hear this sound through the walls in the whole house. Maybe some internal cable touching something?

Multiplus-II
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4 Answers
nickdb avatar image
nickdb answered ·

Are there any specific appliances or devices that are on at this time which might have variable speeds or thermostats - hairdryers etc?

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chrisu avatar image chrisu commented ·

No, the sound is also there when having nothing connected to Out1 and having zero load.

It is quiet first, then it gets louder and vibrates and then it cycles down.

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nickdb answered ·

Perhaps send a capture of the sound. MP2's have a rather annoying fan that pulses (much discussion on the subject in the forum). Mounted on a resonant surface it just gets worse, this would be relative to load though, especially when inverting.

Conventional transformer hum, not withstanding.

From your edit, it does sound like the fan.


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chrisu avatar image chrisu commented ·

no, it is not the fan. fan is off. It is the transformer. I'll try to capture.


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chrisu answered ·

Now i Made a capture. It begins from switching from Island Mode to ess Mode. Sound is not rralted to Load. At the end it gets more quiet but it is a Cycling Sound.

https://1drv.ms/u/s!Agv1S40tcTV1hrx6N3uW-1B9i59RqQ

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dangos answered ·

Hi @chrisu


Did you ever get to the bottom of this? I have a similar thing happening here since a grid outage this morning (plus a battery failure).

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