# Multiplus Quattro AC frequency Hz variations

I've been trying to get to the bottom of why we have some flickering LED downlights in our house, especially those on dimmer switches. Dimmer switches are notoriousely sensitive to frequency variations.

I've been looking at my Multi's AC Output metrics from the VRM and I noticed that the frequency can sometimes drop as low at 48.34 Hz.

According the Multi's specs, there should be about a 1% variation on the 50 Hz output, which I calculate should only go down to around 49.50 Hz.

Can anyone tell me if this frequency variation that I am having is unusual for a Multi, or is that normal? I am wondering if this points to some type of fault?

This issue is occurring when we are running off the grid on ESS settings.

See screenshot below:

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why my frequency is nonstable by passthrough?... can´t understand the Problem?

1600342046931.png (48.8 KiB)
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Daniël Boekel (Victron Energy Staff) answered ·

Please ask your installer to check your system, battery voltage is all over the place - there may be issues with DC wiring, DC Connections, DC fuses or the batteries themselves.

Real frequency variations between input and output can only happen when AC-input is disconnected.

Your installer can also explain how things work and do measurements.

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I also see that dip in AC Output frequency corresponds exactly to the spike in Battery Voltage leading me to believe it could be related to ESS. See below:

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Here is another good example, AC Input is 50.10 Hz and output is 48.58 Hz for exactly the same time:

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I am worried about the output frequency, not input frequency. If you look at the screenshot, the input and output frequency are different.

Or am I misunderstanding you?

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if the AC-input is connected, the multi cannot alter the grid frequency, so what you're seeing is a measurement difference, probably caused by:

-accuracy of measurement

-sample rate / moment, when ac-in is measured before / after ac-out then it can be frequency has changed between measurements.

Daniël Boekel (Victron Energy Staff) ♦♦

" the multi cannot alter the grid frequency" - is this the case even if we are running on ESS and the load is being supplemented by PV?

Only if you have a generator as input, you cannot change the grid frequency.

Daniël Boekel (Victron Energy Staff) answered ·

The Multi cannot change the input frequency, so it has nothing to do with the multi's frequency.

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