Trailing edge versus low voltage

[jumpjamesjump]

I'm an electrician but know jack about LED lighting. Buying my first home and thought that this is a could time to learn, but seems a little more complex than I first thought.

So the plan was just to use 230v dimmable LEDs (Luceco EFTE45BS30) with trailing edge dimmers. But then the more high end sellers of LEDs are recommending 1-10v dimmers, what it the main advantage of using transformers and low voltage versus trailing dimmers? Smoother dimming? More effecient?

thanks very much

 

[Lucien Nunes]

Smoother dimming, better compatibility, slightly better efficiency.

230V control is a workaround that allows for some compatibility with existing tungsten installations, but by using the 230V circuit to provide the control function as well as the power, both are compromised. Phase-angle control 230V dimmers (whether leading edge or trailing) work by reducing the average voltage seen at the lamp, by chopping off part of each half-cycle of the mains. That's ideal for a filament lamp but won't work for an electronic device that by its nature, converts whatever you send it to a constant output. Therefore, dimmable 230V LED fittings / lamps have to detect what is coming in to know what the brightness should be, then use that to control a step-down driver circuit that is capable, up to a point, of dealing with whatever waveform and voltage is available. The power conversion stage would work better with a nice full 230V but it has to make do with the chopped waveform. The dimmer would also work better with a nice resistive tungsten load, but has to make do with the quirky, self-regulating LED driver circuit. As a result, some lamps don't like some dimmers and vice versa. Dimming to very low levels tends to be impossible as the peak voltage is not high enough for the driver to function. etc.

Separating the control and power into two separate circuits avoids one interfering with the other, allowing better compatibility, a full control range down to zero, less electrical noise etc. The AC-DC power supply works at constant efficiency from the steady 230V, and a high efficiency PWM dimmer stage modulates the brightness in response to the control signal.

 

[jumpjamesjump]

Smoother dimming, better compatibility, slightly better efficiency.

230V control is a workaround that allows for some compatibility with existing tungsten installations, but by using the 230V circuit to provide the control function as well as the power, both are compromised. Phase-angle control 230V dimmers (whether leading edge or trailing) work by reducing the average voltage seen at the lamp, by chopping off part of each half-cycle of the mains. That's ideal for a filament lamp but won't work for an electronic device that by its nature, converts whatever you send it to a constant output. Therefore, dimmable 230V LED fittings / lamps have to detect what is coming in to know what the brightness should be, then use that to control a step-down driver circuit that is capable, up to a point, of dealing with whatever waveform and voltage is available. The power conversion stage would work better with a nice full 230V but it has to make do with the chopped waveform. The dimmer would also work better with a nice resistive tungsten load, but has to make do with the quirky, self-regulating LED driver circuit. As a result, some lamps don't like some dimmers and vice versa. Dimming to very low levels tends to be impossible as the peak voltage is not high enough for the driver to function. etc.

Separating the control and power into two separate circuits avoids one interfering with the other, allowing better compatibility, a full control range down to zero, less electrical noise etc. The AC-DC power supply works at constant efficiency from the steady 230V, and a high efficiency PWM dimmer stage modulates the brightness in response to the control signal.

Hi and thanks very much for the reply, really useful.

Would you pretty much just not use dimmable LED on a trailing edge switch? Or they do have decent functionality, just not for fairly low light levels?
What brand/product do you use yourself? The going rate seems to be £100 per a light when going for 0-10v which is too much

 

[davesparks]

I would always go for an option where dimming is controlled by a control signal which is seperate to the mains feed to the driver whenever it is possible.

Sadly there seems to be a general refusal in the industry to accept anything other than the way we used to dim incandescent lamps for new installations.

For retrofit applications yes it's much easier to go with mains dimming, but it's not hard to run a bit of 2 core flex with the lighting cables on a new build to allow 0-10v control.

 

[jumpjamesjump]

I would always go for an option where dimming is controlled by a control signal which is seperate to the mains feed to the driver whenever it is possible.

Sadly there seems to be a general refusal in the industry to accept anything other than the way we used to dim incandescent lamps for new installations.

For retrofit applications yes it's much easier to go with mains dimming, but it's not hard to run a bit of 2 core flex with the lighting cables on a new build to allow 0-10v control.

Is there a brand that you use with reasonable prices?

Also which cable should I run for the 0-10v setup? Don't have the money at the moment but may just get all the low voltage cable in position when installing the mains voltage lights so I can change over in the future.

 

[davesparks]

Is there a brand that you use with reasonable prices?

Also which cable should I run for the 0-10v setup? Don't have the money at the moment but may just get all the low voltage cable in position when installing the mains voltage lights so I can change over in the future.

I use eco-600 downlights made by eco-star.
I've always found them to be very good quality and pretty cheap, the standard, mains dimmable, version is less than £30+vat
The 0-10v version is around £80 if I remember correctly.

For the 0-10v signal it depends on the requirements of tbe installation.
If there's no particular requirement for a specifuc cable type then I normally use 2 core flex, 0.75 or larger.

 

[pc1966]

If you are looking for conventional style dimmers that work OK with most dimmable LED lights these are worth trying:

VARILIGHT V-Pro Dimmer Series for Dimmable LED Lighting

Choose Varilight V-Pro dimmers to control dimmable LED lighting.

www.varilight.co.uk

But if you want wide range, etc, then you need to look at the more specialised arrangements with extra wires.
[automerge]1588521759[/automerge]
Seems they also do the 10V controllers, but not used them yet:

VARILIGHT Specialist Modules

Varilight Intermediate and 2-way dimmer modules

www.varilight.co.uk

 

[jumpjamesjump]

I use eco-600 downlights made by eco-star.
I've always found them to be very good quality and pretty cheap, the standard, mains dimmable, version is less than £30+vat
The 0-10v version is around £80 if I remember correctly.

For the 0-10v signal it depends on the requirements of tbe installation.
If there's no particular requirement for a specifuc cable type then I normally use 2 core flex, 0.75 or larger.

Thank you, on that basis that's what I'm going to go for, nice to be able to sell a product that you can't pick up from the local screwfix or toolstation branch for future clients xD I'd be able to use the 1.5mm twin and earth for a future changeover then and then just change the dimmer type.

 

[davesparks]

Thank you, on that basis that's what I'm going to go for, nice to be able to sell a product that you can't pick up from the local screwfix or toolstation branch for future clients xD I'd be able to use the 1.5mm twin and earth for a future changeover then and then just change the dimmer type.

1.5 is overkill and expensive for the control signal, you wouldn't even run the mains feed 1.5.