Dimming LED's - What are the options

Discussion in 'C-Bus Wired Hardware' started by pspeirs, Dec 21, 2013.

  1. pspeirs


    Nov 23, 2013
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    Hi All,
    I see a number of threads all concerning dimming LED downlights. What would be the best or most economical option for doing this.
    Some of the options I see are:

    Use a LE dimmer unit, however I believe the LEDS don't actually get turned off and can stay in a dimmed state rather than switching off. Is this the same problem when using the Universal dimmer unit.

    Use a 0-10V analog output unit. Again, I understand that they will not actually get turned off.

    Using 5101R which may work and has relay control to turn the load on/off at a preset lever? I believe this is how I read it. I also understand that it is posisble to use only one or two electronic ballasts on this unit. How many LED downlights could potentially be connected to one ballast?

    Going for DALI options. How is this actually integrated into the C-Bus network.

    pspeirs, Dec 21, 2013
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  2. pspeirs


    Aug 1, 2013
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    Hi Pspiers,

    The problems with dimming LED lights are LED flickering, horrible dimming curves that don't even seem like the lights are dimmed, and light leakage where lights glow when they are meant to be off.

    If you use a good quality DALI LED downlight you shouldn't have any of these problems, for example the DALI Galaxy LED downlight range (if I shouldn't be linking to product due to forum rules can someone please PM me and I will remove the link, but it is hard to find dimmable LED downlights that will just work in every situation)

    DALI is controlled through CBus by a DALI Gateway that converts any CBus command into a digital pulse that the lights will respond to.

    DALI lights are always powered, as each light must be ready to accept the turn on command. You can use a relay to turn them off but I would advise against it as you would probably use more power as shown in this article.
    Last edited by a moderator: Dec 28, 2013
    jaied, Dec 28, 2013
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  3. pspeirs

    ashleigh Moderator

    Aug 4, 2004
    Likes Received:
    Adelaide, South Australia
    There are a number of options for LED dimming.

    In the end the effectiveness is ALL determined by the LED driver.

    There are a number of phase dim drivers which are very effective on C-Bus (and a number that are not).

    Alternatively, use a DALI driver with a lamp that is designed for such a driver. Again you can't just take a lamp and attach any old DALI driver - you still need to buy them as a pair, or buy a lamp and driver designed for each other.

    In MOST cases for DALI you need to check the driver dimming range (some are rubbish and only go down to 10%, or 5%. A really good one goes a lot lower). You also need to check that the output voltage and current range are suitable for the lamp its being attached to. This check will cover 90% of the driver / lamp compatibility issues that might come up.

    There are a number of Australian design phase and DALI lamps and drivers around. PM me if you want more information.
    ashleigh, Dec 28, 2013
  4. pspeirs


    Jun 13, 2007
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    Hi Jaied,

    Seen several posts from you lately extolling the virtues of DALI LED solutions, which is great, but I think it is only fair for you to note, (perhaps via your signature file) that you are actually from a DALI products reseller/installer so people can consider that your advice given may be to an extent, talking your own book ie may not be completely objective.

    You are the tech contact on the DALI domain that you keep linking to and whilst that's not a bad thing, you might want to more correctly address statements like 'but I would advise against it as you would probably use more power as shown in this article.' to actually read 'but I would advise against it as you would probably use more power as shown in MY article.'

    To address potential bias in your posts you should probably also note the additional 'control' cabling required for DALI and therefore termination/supply costs (similar to/as also required by DMX, 0-10V and DSI system) to each light/light string and also the fact that it is actually an 'overlay/duplication' control system to a fair degree mirroring the C-Bus control system itself (both have a data bus and power supplies) and therefore requiring additional tools and knowledge for the installer/electrician possibly making fault finding more difficult, particularly in residential scenarios where often diagnosing C-Bus issues can be difficult for those with less experience or in-frequent exposure.

    Don't get me wrong, I am not anti-DALI by any means, or any other control technology that can take the sometimes significant headaches out of LED dimming for installers, both in residential and commercial uses. I just think the discussions here on the forum should never smell like a marketing exercise from vested interests and when promoting a given solution, you should always try to state additional costs and skills required above and beyond the norm in an objective way. After all, a phase cut LED driver requires nothing more than the standard C-Bus dimmers and there are now several LED brands including Clipsal that have good dimmable LEDs without requiring a full duplication of control system. That being said, DALI, 0-10v and other systems have their places.

    If you promote where you are from and note when referred to articles are actually yours, it gives readers a clearer understanding of where your information stands from a perspective of objectivity. I note there is a new forum added below particularly for 3rd party/commercial marketing announcements, links and information.

    If we all do as you suggest and remove all the C-Bus dimmers, then remove all the C-Bus light circuit control relays, you end up with a 'switchplate' network on C-Bus and a 'Load control' network on DALI. Install DALI switchplates and its sayonara C-Bus network, something I don't want to see anytime soon. (There, see I acknowledged my bias :p)

    Have a good one,

    bmerrick, Dec 29, 2013
  5. pspeirs


    Nov 3, 2009
    Likes Received:
    Both DALI DSI and 0-10V can work in Cbus.
    also leading eadge or trailing edage (SCR) also work.

    DALI LED driver(dimming 0.1%-100%)
    DSI LED driver (dimming 0.5%-100%)
    1-10V LED driver(dimming 10%-100% or other)
    SCR LED driver(dimming 1%-100%)
    samluo, Dec 31, 2013
  6. pspeirs


    Oct 26, 2007
    Likes Received:
    get the order right

    Hi Paul
    You've summarised the main dimming options.
    The key item as Ashleigh mentions is the driver compatibility. I highly recommend you research and test the driver type you prefer, on the dimmer source you plan to use.
    What you really want to determine is what will work for your installation at a cost you can afford.
    From what I know I can answer you this:

    Phase cut dimmers: Both the LE & universal dimmers have a voltage that remains even when the group is 0% (off). This is normal but plays havoc with some (poor) LED drivers. You may find a LED & driver that works fine, e.g. the Baricade from Lumitex.
    0-10V dimming: this does work OK, but the components are less common (so typically more expensive) and you need to run the dimming control wires from the Output unit to each driver for each separately dimmed circuit. Osram make a 0-10V LED driver. Also this does not control the mains voltage (240V) of the driver.

    The 5105R uses 0-10V dimming so see the comments above, it is not a separate type. If you have just one dimmed component it is a great solution as it also controls the 240V for that load.

    DSI diming: Is essentially a digital version of 0-10V and wiring is the same. Components not as common (as it is a proprietary product of Tridonic Atco) and programming is easy via toolkit (C-Bus).

    DALi: this also works fine but the components are expensive, you need a separate power supply for each DALi universe and you need to do a second lot of programming and wire the dimming control wires from the Output unit to each driver. If you don't program the DALi side you can simply buy more C-Bus dali converters and wire the dimming control wires from the DALi units to the driver for each separately dimmed circuit. NOTE that DALi also does not control the mains voltage (240V) of the driver. I would not recommend DALi for a residential installation unless you have deep pockets.

    Happy lighting :)
    Last edited by a moderator: Jan 2, 2014
    Matthew, Jan 2, 2014
  7. pspeirs


    Aug 1, 2013
    Likes Received:
    Hi Brad,

    Thanks for the advice on wording posts, I would like to put a link in my signature but didn't know if it was allowed and thought that it maybe viewed as marketing. But I will now look at setting up my signature and consider your advise when wording my posts.

    I do not agree that just because its possible to install DALI switches that people want to remove their CBus systems, after all anybody can install a rotary phase dimmer but that doesn't mean CBus phase dimming is required less. My bias is that DALI is beneficial for CBus solutions, after all one of the DALI Group board members is a Schneider representative.

    We promote that the 'additional' costs of DALI can be avoided with proper planning and support. For example you are correct that DALI requires control cable, but with proper planning you should be installing and pulling 'less cable' over all. Please see our artical regarding how DALI reduces cable.

    An experienced DALI integrator would want to spend additional time on DALI programming, however as Matthew mentioned in a residential application if you just want to imitate phase dimmer style implementation in a few rooms you don't have to program any DALI if you don't want to and instead purchase additional CBus DALI converters.

    In regards to the difficulty with DALI fault finding we know all to well as we are helping a new electrician or system integrators every week with troubleshooting their DALI installation's that are often controlled by CBus, but we have found that with experienced support that it is usually easy to identify where problems are occuring, even with first time DALI installers.

    I will check out the new forum, again thank you for the advice.
    jaied, Jan 3, 2014
  8. pspeirs


    Mar 24, 2006
    Likes Received:
    Brisbane, QLD, Australia
    Hello jaied

    I think you are doing an excellent job of promoting DALI.
    The websites you link are an excellent source of information.
    The products on sale seem reputable and reasonably priced.
    In fact I have just ordered some.

    In response to the original post.
    It is not hard to reply that there are many suitable led solutions which can run very well from CBus dimmers.
    I am very happy with the performance of Pierlite Starbust on standard leading edge dimmers.
    There is no underlying problem with doing it that way, using products which are designed for the job.

    For many jobs DALI offers little benefits and some negatives.
    Push button dimming does work for CBus to DALI but it does not work very nicely due to communication between the two networks.

    I feel you and samluo have painted DALI implementation in a more favourable light than it deserves.
    It's not the be all and end all of dimming LED's.
    If the original poster takes your information on board he will be lead to believe that DALI is the best solution for dimming LED's.

    This is not the case in many situations and the answer is as simple as purchasing suitable components.

    Especially when it comes to domestic installations.

    In response to whoever said that DALI can save money due to wiring arrangement.
    I would like to add that this is unlikely to be the case in a domestic situation.
    DarylMc, Jan 6, 2014
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