Brightgreen Dimmable LED Downlights Cont

Sorry to re-open this thread, but I have nothing to do with the Brightgreen but wanted to share my experience with it...

The D900's work on just about any dimmer and I have personally used them on the standard wired C-bus dimmers (the L5508D1A). We were purchasing them for about $120inc GST. At 16 watts they are not the most efficient LED on the market but have a great amount of light output. When it comes to dimming, don't expect them to dim like a halogen. A client that would dim their lights to 20% at night could not achieve this effect with this LED. At a rough guess, they dim by about 60% only.

 

I personally am always interested in knowing more about LED.

 

As I've previously mentioned elsewhere here on the forum, I've just changed over from 12V halogen to ECO-12 LED's. The ECO-12's are behaving perfectly on my L5504D1A and I can dim them to any brightness level in much the same way as I could with the halogens. The characteristic of the LED light is far more favorable, and they're throwing enough light I can illuminate about 10 sqm of floor space per lamp from a 2.3m ceiling height (mine are the 60 deg wide angle lamps). I'll be changing the halogens in my kitchen to ECO-12 cool white this week sometime.

 

What do they Cost ??

 

This is the ECO-12...you can contact the distributor through their website for pricing...they are in the sub-$100 price range, depending on quantity.

 

Update: Actually I've found they behave slightly differently to halogen when dimming. From OFF when ramping UP they jump to a mid brightness level, from where you can dim down to any other level....I'll experiment with the ramp rates in Toolkit and see if I can get better control of this. But overall I am very happy with their behavior on CBUS.

Update2: I put the ECO-12 on a watt meter and the lamp is drawing 11 watts @ full brightness. Compare this against my 12V halogen with Crompton electronic transformer (which the ECO-12 has replaced) draws 54 watts. So not only am I covering a greater floor area with the ECO-12 than the halogen, I'm only using a quarter of the energy to do it!

 

just sparking up an old thread but Im just in the process of testing my C-Bus system in house.

With a Brightgreen D900 (16W) connected to my L5508D1A there is considerable buzzing from the dimmer module. The light however seems to dim resonably well. Can anyone share if this is normal?

Also, I also have a L5504D2U as well in my system and the same Brightgreen downlight dims well without any buzz from the module. The dimming however is limited and does only seems to go down around 50%.

 

Whenever you use an electronic load, such as an electronic halogen transformer or an electronic LED driver, on a Leading Edge dimmer the turn-on of the dimmer results in a large in-rush current to the LED driver. This large current spike can be in the order of 10's of amps, even for a small LED load. This creates stress in both the dimmer and the LED driver. This high current spike causes a rapid change of flux in the inductor inside the dimmer, making it buzz more audibly. Good LED drivers can handle the current spike and associated current oscillation, bad drivers can't. I can't comment on whether the Brightgreen driver will handle this long-term. It's also wise to keep the channel load well below the rated maximum as this current spike also stresses the dimmer Triac. Even if the light output looks OK it is possible that the dimmer is not working correctly resulting in excessive dimmer channel dissipation and lots of stress for the LED driver.

Using the trailing edge dimmer (L5504D2U) results in a whole lot less stress on everything, as trailing edge dimming is the correct method of dimming electronic load types. The main down side when using this dimmer with the Brightgreen LED down lights is that the light output at minimum brightness is still very high, as you have observed. You also lose a little bit of brightness off the top-end however the amount of light lost is probably not discernable with the naked eye.

The number of lights you have connected to the dimmer channel can have an affect on the minimum brightness too. The more lights you add, generally the lower the minimum brightness becomes.