Unstable voltage supply - affecting lighting.

[mikegibbons500]

Hi,

I have had lighting installed in my flat. Although my fitter is still bein g helpful he is running out of ideas.

The lighting is all led controlled using rako rdl250c units:

-in-line-dimmer.html.

The problem I have is that there is noticeable changes in light intensity w hich becomes very evident when the leds are dimmed. The best way I can des cribe it is that the leds look like candle flames. I don't think it is a m ains frequency flicker.

Now that I look carefully at traditional halogen lamps elsewhere in the fla t I can also detect a less pronounced flicker.

My guess at what is happening is that I have an unstable voltage supply. N ote that block of flats (7 flats in total) does not have a gas supply so al l of the heating and cooking is on the electric supply. The leds react fast er that the halogen lamps so that the intensity changes are more evident.

Any advice or ideas appreciated. The total load of led lights is about 150 watts (20 downlighters plus led strips).

Mike

[Andy Burns]

Unfortunately that's exactly the wrong type of dimmer for LEDs, you need trailing-edge dimmers for most dimmable LEDs (do you know that the LEDs used are all dimmable?)

Additionally the dimmers need to be able to work *down* to 5W or 10W whatever your smallest set of LED lamps are, rather than *up* to 250W for incandescent loads.

[Andy Burns]

Looking at the spec sheet, the minimum load is 20W. LED downlighters vary in power, but 2.5 to 4.5W is typical, so depending on yours, you may have problems if they're controlled in groups of fewer then 5-8 downlighters ....

[tabbypurr]

ing helpful he is running out of ideas.

0w-in-line-dimmer.html.

which becomes very evident when the leds are dimmed. The best way I can d escribe it is that the leds look like candle flames. I don't think it is a mains frequency flicker.

lat I can also detect a less pronounced flicker.

Note that block of flats (7 flats in total) does not have a gas supply so all of the heating and cooking is on the electric supply. The leds react fa ster that the halogen lamps so that the intensity changes are more evident.

50 watts (20 downlighters plus led strips).

LEDs are less affected than halogen. But trad dimmers and minimal loads don 't mix well

NT

[Adam Aglionby]

On Saturday, August 1, 2015 at 9:03:56 PM UTC+1, [e-mail] wrote :

ing helpful he is running out of ideas.

0w-in-line-dimmer.html.

which becomes very evident when the leds are dimmed. The best way I can d escribe it is that the leds look like candle flames. I don't think it is a mains frequency flicker.

lat I can also detect a less pronounced flicker.

Note that block of flats (7 flats in total) does not have a gas supply so all of the heating and cooking is on the electric supply. The leds react fa ster that the halogen lamps so that the intensity changes are more evident.

50 watts (20 downlighters plus led strips).

Halogen ripple may be getting superimposed by the dimmers for the LEDs.

Wrong type of dimmer generally for LEDs, but then Rako`s MR16, downlighter lamp, range dosen`t exist:

ml

it does in docs though

df

Some MR16 lamp makers will reccomend trailing edge dimming, even then won`t dim to zero and will usually start at above 10%.

Trailing edge dimmers are expensive and relatively easy to blow up.

Some dimmable lamps are better than others and play nicer with some types o f dimmer better.

Rako`s solution of using 12V lamps, dimmable in some form, with a Constant Voltage driver makes more sense.

Your fitter new to LEDs........

[Brian Gaff]

To be honest I do not think there would be much you or your electrician could do other than to take a hand held led light that shows the issue and ask some of the other flat owners to try it. If only yourself gets the issue, you would need the leccy folk in, but if its general and you cannot convince others to complain with you, I doubt the leccy folk will be that interested.

The effect you mention is not new with dimmers at low levels. Back in the

1970s down muy garden, I could not use a dimmer on an ordinary bulb as it wobbled in brightness apparently randomly. Brian

[Brian Gaff]

Often one tungsten light on the system will sort this issue, but as he says halogen are doing it, this might be a bluish white herring!

Brian

[dennis]

The OP could put a couple of halogen lamps in the circuit to see if it is the load being too small??

[mikegibbons500]

ing helpful he is running out of ideas.

0w-in-line-dimmer.html.

which becomes very evident when the leds are dimmed. The best way I can d escribe it is that the leds look like candle flames. I don't think it is a mains frequency flicker.

lat I can also detect a less pronounced flicker.

Note that block of flats (7 flats in total) does not have a gas supply so all of the heating and cooking is on the electric supply. The leds react fa ster that the halogen lamps so that the intensity changes are more evident.

50 watts (20 downlighters plus led strips).

Many thanks for all the replies. I don't think the minimum load issue is a problem the circuits have 9x5watt, 6x5w and 5x5w on them. I will double c heck all the part numbers to see if the wrong type of dimmer is part of the problem.

Mike

[Andy Burns]

Are the downlighters using GU10 lamps? If so, perhaps your installer could try replacing one of the dimmers with this type to see if it solves the flickering ...

Presumably it will be compatible with whatever form of remote control you have for the existing dimmers?

[Adam Aglionby]

Its not a straight resistive load unfortunately, adding a resistive load even a small one may help the dimmers behave better, try a 15w pygmy lamp in paralell.

[tabbypurr]

being helpful he is running out of ideas.

ty which becomes very evident when the leds are dimmed. The best way I can describe it is that the leds look like candle flames. I don't think it is a mains frequency flicker.

flat I can also detect a less pronounced flicker.

. Note that block of flats (7 flats in total) does not have a gas supply s o all of the heating and cooking is on the electric supply. The leds react faster that the halogen lamps so that the intensity changes are more eviden t.

150 watts (20 downlighters plus led strips).

a problem the circuits have 9x5watt, 6x5w and 5x5w on them. I will double check all the part numbers to see if the wrong type of dimmer is part of t he problem.

Maybe, maybe not

NT

[Fredxxx]

Most traditional/old (leading edge) dimmers are sensitive to mains noise as they use DIACs as a crude way to time the turn on of the TRAIC or Thyrister. I've looked at more current circuits, obviously made to a price, that still use DIACs.

Trailing edge are more complex.

For general info:

[Fredxxx]

Agreed.

[Adam Aglionby]

Thats a cheap wall plate dimmer, the Rako`s will use proper zero crossing detection , MPU and opto isolated triac for firing.

Still can get problems with the triac latching even on hard firing dimmers with low loads.

Trailing edge are vulnerable to accidental connection to inductive loads, a wound lighting trafo for instance, acts somewhat like an ignition coil.

Not a fan , still cant get to zero.

[Fredxxx]

The problem I have is that there is noticeable changes in light

I'm rather cynical of what's in a black box. Microprocessor is mentioned, but it would have to be if there was a wireless interface. Many microcontrollers have their own on chip temperature measurement that might account for this unit's "temperature shutdown" feature.

[Adam Aglionby]

It`s cheaper nowadays,on the BOM, MPU be cheaper than a diac :-)

even on the `bay, Attiny 13, 50p each

DB3 diac 20p each

[Bill Wright]

Yeah, paint them black as well.

Bill

[dennis]

Only if they are the dichroic kind and the fitting is heat proof. You do know that painting plain reflector types is dangerous? and fitting the dichroic kind is dangerous in some fittings.

[mikegibbons500]

ing helpful he is running out of ideas.

0w-in-line-dimmer.html.

which becomes very evident when the leds are dimmed. The best way I can d escribe it is that the leds look like candle flames. I don't think it is a mains frequency flicker.

lat I can also detect a less pronounced flicker.

Note that block of flats (7 flats in total) does not have a gas supply so all of the heating and cooking is on the electric supply. The leds react fa ster that the halogen lamps so that the intensity changes are more evident.

50 watts (20 downlighters plus led strips).

Thanks again for the responses - very interesting paper Fredxxx. I have sp oken to Tech Support at Rako. They agree that leading edge is not the firs t choice to dim leds. However it can produce an acceptable outcome. As st age one of the experiment they have suggested that I try one of the leds th at they have rated as excellent in the tests (eg Enlite by Aurora) in one r oom. So I wil give that a try.

Mike