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Nicholas Wessels avatar image
Nicholas Wessels asked

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:

MultiPlus Quattro Inverter Chargerfrequency
victron-ac-output.png (16.3 KiB)
victron-ac-output.png (26.6 KiB)
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Schalk van der Merwe avatar image Schalk van der Merwe commented ·

Hi @Nicholas Wessels

Has this been resolved for you? I have a similar problem where the MP-II has a bigger variance on output frequency than on the input frequency. My problem is a little bigger than yours: ESS does not activate so all loads are only supplied by AC, not DC regardless of battery SoC, PV production. more info here. My distributor and Victron HO is dealing with it, will post updates on that post. I would gladly replace lights if it resolved my problem... hehehe

But I want to know if you were able to 'clean up' the variance please? All comments and feedback from Victron i have is input and output Vac and Hz will be the same while is passthru, but I do not see it. My problem is blamed on variance in input Hz, so I am hoping maybe to pick your brain.

I am also waiting of feedback from a friend on a AC filter. I have heard of success with them when connecting to cheap generators. Maybe just maybe it will clean my grid Hz enough for ESS to work.

PS. we are also hoping to hear if Victron could assist with a script or something I can load on the inverter, to make it less sensitive towards this grid input frequency variance, as our local municipality said it is within acceptable variance". But this was just a suggestion, we'll see.

Customer house:

steyn-saldanha.jpeg

and my own house, in same neighborhood:

bay-solar-saldanha.jpeg

Other houses in same municipality, but different towns:
botha-langebaan.jpeg

fourie-langebaan.jpeg

Currently it is suggested that being close to an industrial area, the equipment used by industries is what is causing the variance in the grid frequency.

My concern is why is it worse on the output than on the input. My understanding is a pure sinewave inverter is supposed to match it or clean it up, not make it worse. I am an installer, but still have a to to learn.

If you don't mind, please contact me on 072 437 7620 or schalk@baysolar.co.za, or assist me with your details.

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8 Answers
Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Nicholas Wessels

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


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Nicholas Wessels avatar image
Nicholas Wessels answered ·

@Daniël Boekel (Victron Energy Staff)

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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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

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.

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Nicholas Wessels avatar image Nicholas Wessels Daniël Boekel (Victron Energy Staff) ♦♦ commented ·

" 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?

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Daniël Boekel (Victron Energy Staff) avatar image Daniël Boekel (Victron Energy Staff) ♦♦ Nicholas Wessels commented ·

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

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Nicholas Wessels avatar image
Nicholas Wessels answered ·

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


victron-ac-output2.png (26.3 KiB)
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Nicholas Wessels avatar image
Nicholas Wessels answered ·

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:


victron-ac-output3.png (48.8 KiB)
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Daniël Boekel (Victron Energy Staff) avatar image
Daniël Boekel (Victron Energy Staff) answered ·

Hi @Nicholas Wessels

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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maremotomoto avatar image
maremotomoto answered ·

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


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Nicholas Wessels answered ·

@Schalk van der Merwe sorry but I never really got an explanation on this issue but in the interim I did replace my batteries to a much more sizeable 20kwh Lithium Ion battery which may have stabilized things.

However I have noted that the output frequency never exactly matches the input frequency.

Output appears to usually be about 0.1 hz less than the input frequency but still within an acceptable range.

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Trevor Bird avatar image
Trevor Bird answered ·

For what it’s worth, I have an intermittently flickering dimmer feeding a LED light too but my problem has nothing to do with any inverter as it occurs when on mains. It is very annoying and the fault would not occur with an incandescent light. Is it possible the problem has nothing to do with the Victron equipment? I also have the same fault with a sensor light at my front door. I have not looked into it but it has occurred after incandescent lights have been replaced with LEDs.

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Alexandra avatar image Alexandra ♦ commented ·
@Trevor Bird

Some dimmers work with triacs and the chop the sine wave to reduce power. Thats the flickering you see.

I cant stand them myself. Many inverters that have the construction like the Victrons also are not fans of the chop sinewave action. Sometimes there is weird buzzing in the units as well. Depending on how cheap the dimmer circuit is.

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