Flickering lights

[woodieallen]

I have a generator with a good old-fashioned alternator thingie. Proper Faraday machine. None of this VFD or inverters malarkey. Had a power cut the other night and fired it up. House was happy as Larry. Everything worked just fine apart from the LED downlighters in one room. They were flickering all over the place. Had to shut my eyes it was that bad.

Now I can understand flickering if the power source is digital but that alternator is surely bunging out pretty much a decent sinewave ?

 

[SammyQ]

Query frequency and amplitude of its produced output? Might just be incompatibility between that and what the LED 'expects'.

 

[Richard_C]

Do you have a dimmer in that room? Maybe the led bulbs are fine but the dimmer is upset by something.

 

[woodieallen]

Do you have a dimmer in that room? Maybe the led bulbs are fine but the dimmer is upset by something.

Yes they are on a dimmer but the argument still applies.....alternators push out a sinewave, don't they ?

 

[Hugh M.]

We had new lights fitted downstairs by a electrician. I don’t want to do electrickery.
Straight away the lights started flickering. They would light at full illumination and then fade to half for a second or two. Then full. Then almost out. Drove us mad and I was going to call him back when we decided to try different bulbs.
No flickering at all. I don’t have any wisdom to impart, except try a different bulb?

 

[John Brown]

Yes, I'd have thought that generators push out a sine wave, but I also wouldn't expect LED downlighters to care that much about the waveform, since they probably rectify it and then regulate it. More likely fluctuations in voltage from the generator which the electronics in the lights don't deal with fast enough. Are the LED downlighters mains voltage, or 12v replacements for halogen?

 

[Chubber]

Yup! Had the same problem unless I turned up the dimmer to max.

 

[Spectric]

but that alternator is surely bunging out pretty much a decent sinewave

At what frequency, also is it centred without any offset ? How is the geny connected to the building ground as it is possible to get earth loops that can cause issues.

No flickering at all. I don’t have any wisdom to impart, except try a different bulb?

First thing is often non dimmerable bulbs or wrong type of dimmer switch that can cause flickering .

 

[Richard_C]

Yes they are on a dimmer but the argument still applies.....alternators push out a sinewave, don't they ?

Your argument does apply. Your lights don't flicker - in theory. In practice though ....

Thinking about it, if you put one of the bulbs in a desk or table lamp and run it off the generator you might find out if it's the circuit, the dimmer or the bulb that is the perceived problem.

 

[Dabop]

It's the dimmer...
'old fashioned' gennies are actually not very stable at all- in either frequency or voltage...
(averaged out over time their output is 'ok-ish' but at any instant in time they can vary by a significant amount)

Both of which are used for controlling the dimmers output...

So having a varying input means they interpret that as control inputs to vary the brightness, which they then do exactly as 'commanded'
ie vary the brightness...

(the only real solution is use a stable inverter/generator, or try and find a replacement dimmer that is less affected by it...)

 

[woodieallen]

We had new lights fitted downstairs by a electrician. I don’t want to do electrickery.
Straight away the lights started flickering. They would light at full illumination and then fade to half for a second or two. Then full. Then almost out. Drove us mad and I was going to call him back when we decided to try different bulbs.
No flickering at all. I don’t have any wisdom to impart, except try a different bulb?

Built-in. No intention of replacing them as power cuts are, fortunately, rare.

 

[woodieallen]

At what frequency, also is it centred without any offset ? How is the geny connected to the building ground as it is possible to get earth loops that can cause issues.

50Hz. No earth loop.

First thing is often non dimmerable bulbs or wrong type of dimmer switch that can cause flickering .

True. But on normal mains supply, no flickering. Puzzling TBH

 

[woodieallen]

Yes, I'd have thought that generators push out a sine wave, but I also wouldn't expect LED downlighters to care that much about the waveform, since they probably rectify it and then regulate it. More likely fluctuations in voltage from the generator which the electronics in the lights don't deal with fast enough. Are the LED downlighters mains voltage, or 12v replacements for halogen?

Mains voltage. In retrospect it must be the replacement dimmer switch. Ostensibly the same type as I had in originally but the manufacturers must have changed the innards because I had a lot of difficulty getting it set up without the lights going ON.OFF.ON.OFF.

You could be right re minor fluctuations upsetting it. If we had a lot of power cuts and I had to run the generator more often then I'd simply replace the dimer with a normal switch.