Lighting, DALI, LED strips, and many questions

knx
hardware
dali
Tags: #<Tag:0x00007f51e42743f8> #<Tag:0x00007f51e42741f0> #<Tag:0x00007f51e427bf90>

(Simon Tennant) #1

I’m hoping someone can help me clarify my thinking on lighting.

I’m working through the lighting plan for my new apartment and am trying to rationalise the lighting selection and also trying to understand the quality constraints.

Here’s the current (very rough) plan involving many LED strips (the marked yellow bits): https://drive.google.com/drive/u/0/folders/0B5wjuCDgARyRZFI2VUNWSFJDZTA

Assumption 1: It seems like the right way to power these strips is using DALI ballasts/drivers/transformers (probably driven through a DALI/KNX bridge).

Assumption 2: LED strips seem like the right way to do background lighting. I’ve not been the greatest fan of LED strips until attending the Light Expo in Frankfurt. Some of the vendors were showing off LED strips with good CRI values. Light that would make an apartment feel less like a cheap disco and more like a home.

So I’d like to put together the shopping list of LED strips, DALI ballasts, and DALI downlighters. And then weave in the right OpenHAB rules.

I’m stuck at the point of understanding the tradeoff between installing White/warm-white, RGBW and RGBWW LED strips?

Is it realistic to expect good, natural light from a RGBW[W] based system? I’m guessing DT8’s “tunable white” goes somewhere along the lines of this but would appreciate other’s experiences before I invest into DALI.

I’m also stuck at the point of knowing which DALI controller to use. I’ve seen DALI transformers and DALI controllers and DALI ballasts. Would I be right in assuming that I need:

  • one DALI controller (that will be controlled by KNX)
  • one DALI transformer to power the DALI bus
  • per LED strip, a DALI ballast ?

And finally - DALI flicker: Is 1KHz PWM for dimming etc decent? Is LED flicker at low light levels still an issue?

So to tie this all back to OpenHAB, I’m keen to avoid a HUE-like LED strip and go with a more open system that can then be controlled in OpenHAB (for example, detect motion, turn on passage lights in proportion to how late it is at night - don’t blind me going to the toilet).

Long and rambling but would really appreciate any pointers on putting together a lighting system based on DALI.

Edit: are there any plans for an OpenHAB DALI binding?


(Skinah) #2

Milight make some strip controllers that would allow you to use any LED strip in a DIY setup and still have easy support in openhab via my binding you will find if you search EspMilightHub and build a opensource hub with an esp8266 which is very easy. They also have downlights and more so you could have more lights all using the same protocol.

Have you considered DMX as another option?

Personally I would only choose lights which have two types of white that you can mix if a natural white is what you are after. All my lights I can blend any white I prefer and also they can get warmer as I dim the lights as I prefer a warmer white when the lights are turned down.


(Alex Forrow) #3

@imaginator How did you progress with this? I’m also interested using DALI/KNX


(Simon Tennant) #4

Hi Alex.

This is an ongoing exploration and I’m hoping to actually wire everything up in the new year.

LED Strips:

I’m really excited about some of the high-CRI 5 channel LED strips (RGB + Warm White + Cold White).

That said, it looks like my life would be much simpler going for a RGBW based LED strip since the DALI controllers don’t seem to go beyond 4 channels.

Drivers:

So far it looks like the best way to drive these is using a ballast as close as possible to the LED strip. I was recommended the Lunatone Ballasts. However these can only drive four channels rather than the 5 channels. Apparently the solution is to use two drivers - one RGB, one CW/WW.

I was able to find the following 5 channel drivers which I’ll order and test out: https://www.sunricher.com/rgbwa-5-channels-dt8-dali-dimmer-sr-2309ea-rgbwa.html#product_tabs_related_tabbed

Controlling:

I ended up going with a KNX to DALI Gateway. Ideally there would be a nice DALI binding instead of hopping through KNX.

Heat:

I’m looking at LED profiles from https://ledprofilelement.de/ for heat dissipation.


(Ahmad Yazan Tibi) #5

Hello dear,

Comparing DMX with DALI, which one you prefer and why?

Also about Milight, is it practical for big areas?


(Skinah) #6

I have no idea as I have never used or looked at DALI. If you have a really big area with lots of lights that can all be seen at the same time then DMX is designed for this. If you have ever seen a large stage show (rock concert) all the lighting is DMX as it is very fast, robust and has low delay so all the lights change at the same time to your eyes. Most other options are too slow to control too many lights in the same room without seeing a delay between the reaction of the globes.

Milight is not one I would recommend if the person setting up the system did not live at the house. It has a bad ‘feature’ where if you turn the light off and back on again, then try and control it with a message the globe will become unsynced and stop working until it is synced back up. If it is for your own house and you understand this limitation and also that it is unidirectional they are very cheap and work well. I have this happen 1-2 times a year and it is quick to fix. This can be worked around to a degree but a brown out power situation right before Openhab sends a command out and the globe ends up unsynced. The opensource bridge that controls Milight can be made to broadcast 200m radius through multiple plaster walls so it can cover a large area and multiple bridges could be setup.

One thing I found was a big factor in selecting the lights was that some light fittings do not take globes as they have their own LEDs built in, so do not take Milight. Other light fittings show off the globe and look ugly with Milight and other lights the Milight was a perfect fit and quick way to get automation working and leave the house able to be reversed back to standard wiring and globes. Often 1 setup does not fit everything especially if RGB+ WW + CW is desired.