Walli Dimmer LED bulbs fluctuating brightness level

[mi38k 4]

Hello, I have Walli Dimmer connected in 3-wire installation to a light with 3 dimmable LED bulbs (3x14W) and when I set brightness let's say below 50 %, I can see the light to slightly changing the level of brightness - like if the dimmer is having hard time to maintain the desired level. Lower the brightness set, the more apparent the fluctuancy is. It is not like flickering where the bulbs would be flashing, there are just a small changes in brightness. Is it normal? Would Bypass 2 help in this case?

 

In fact I have two exactly same connections in two rooms and both behave the same way.

 

Thanks in advance for any responses.

[mi38k 4]

@m.roszak: This might also help. I did some small testing and now I can provide consumption graphs which show the behaviour. Following two graphs show two different lights, each with multiple LED bulbs of the same type. First I started on 1% level (both dimmers are set to start at 15 % of range, which is even more than calibration value) and you can see some variations in consumption in both lights (which correspond to apparent change in brightness), but they do not appear to be synchronised, so I think it might not be a power grid issue after all. When I changed brightness to 40 %, consumption appears to be stable and also there are no apparent changes in brightness.

Please login or register to see this image.

/monthly_2022_05/image.png.0e18f73873d8b45a773103cddca57380.png" />

 

Thanks!

[m.roszak 560]

Remember that dimmer reports W after % threshold.
If power is low (~5W) 10% threshold (default setting) is only 0.5W, on 20 it is 2W - so you will not be able to see small fluctuations on hgher levels and you don't see every fluctuation on lower values. 

[jakub.jezek 353]

@mi38k, I do not have names of the lights we tested, so I cannot exaclty say what they were. Some were big bulbs, some looked like UFO and some were normal.

 

@m.roszak, maybe this issue is due to LED technology as a whole. Max. switching power for LEDs on Fibaro Dimmers is 200VA?

 

Also Interesting article:

Please login or register to see this link.

[mi38k 4]

Well, another update, I just had visit of an electrician who supposed to install my QUBINO Qubino 3-Phase Smart Meter, which he didn't because he did not have right equipment in the end, but when I told/showed him behaviour of the incandescent bulb, he automatically said that next time he also brings the equipment to check power grid...

[petergebruers 1,265]

This is from my 2015 archive about flickering and pulsing of "Dimmer 2" in specific circumstances in Belgium. This problem was much, much reduced in later firmwares and then even later a param was added to be more immune to "ripple control pulses" on the grid, @m.roszak already mentioned it and @mi38k said it didn't help.

 

What you see here is obvious, you see the shape of the triangle change - which means power to the bulb changes and our eyes can detect this amount of change.

 

You might not immediately see what causes this, it is more subtle: the total period (of the sinewave that is cut here) changes which looks like the period or phase of the whole scope plot is changing.

 

It is caused by "switching manoevers" as we call them in Belgium, which are operations on the grid to keep the "Voltage" of the grid stable. This typically happened after 23:00 because the load decreases, and generators are taken off the grid.

 

The unfortunate truth is that this type of dimming control is "not regulating" anything, there is no feedback from the power measured to the dimming level. I am not sure if that would even work.

 

It might also depend, as mentioned by @jakub.jezek on the tehnology used inside the bulb. IIRC some bulbs like the "Philips Warm Glow (in 20151) used a more sophisticated type of dimming control than the most recent no-name LEDS I have bought. But even then it wasn't perfect. It isn't perfect because I should have mentioned, I still use that dimmer and bulb from 2015...

 

If you are really sensitive to this (I am) and like low dimming levels (I do) then I think the only options are systems that rely on a stable DC supply, like a RGBW LED strip controller (which needs 12 to 24 V DC and gives light intensity that is rock solid). Or "Smart Bulbs" because they afaik always start by creating a stable DC internally. But then you have other challenges (sync of 3 bulbs.... control of the bulbs).

 

One lqst thing which might be trivial but I didn not see it mentioned: did you try forced "leading edge" versus "trailing edge"? The dimmer does a good job at auto detecing that but trying the other setting makes sense if you want to find out which is the most stable 

 

 

 

[mi38k 4]

Hi @petergebruers, thank you very much for such detailed answer. To be honest, I just thought that LED bulbs should automatically work with trailing edge only, but now I see that they work also with leading one. I will play with this settings as well!