How 0-10V dimming ballast works in Lighting control?
As the title.
In this control system, there is a photosensor to sense the light intensity and a occupancy sensor. When there is a user entering the room the occ sensor will sensed and photosensor will sense the light intensity outside the window. If it is above 500 lux it will not on the light and below 500lux dimming ballast will come into place. Do anyone know what is the proportion or how the dimming ballast varies?
Go to the loytec website and find their L-DALI manuals and check out the sections on constant light control.
One of the modes is with occupancy and an outdoor sensor.
Maybe it will help. I've used their controller and the constant light control works well. There is no reason you would have to use DALI either. Just bind the output to another controller.
A one channel controller could have up to 16 constant light outputs.
Here is a table of typical lighting recommendations. As you can see your 500 lux on/off point is appropriate for standard office areas. Your actual question, I believe is, at what ratio do you vary the ballast once it is on.
I think you would need to look at the total lux of your light and compare with your dimming ballast to see if the range is a linear scale and if so then if the lux in the room was only 250 lux and you wanted to make up the other 250 lux with your electric lighting you could do the calculation percentage based on how many lux the lighting will provide to make up the missing 250 lux and bring you back up to 500 lux.
Hope this helps... Can you give us a part number of the dimming ballasts you are using?
Activity and Illumination(lux, lumen/m2)
Public areas with dark surroundings 20 - 50
Simple orientation for short visits 50 - 100
Working areas where visual tasks are only occasionally performed 100 - 150
Warehouses, Homes, Theaters, Archives 150
Easy Office Work, Classes 250
Normal Office Work, PC Work, Study Library, Groceries, Show Rooms, Laboratories 500
Supermarkets, Mechanical Workshops, Office Landscapes 750
Normal Drawing Work, Detailed Mechanical Workshops, Operation Theatres 1,000
Detailed Drawing Work, Very Detailed Mechanical Works 1500 - 2000
Performance of visual tasks of low contrast and very small size for prolonged periods of time 2000 - 5000
Performance of very prolonged and exacting visual tasks 5000 - 10000
Performance of very special visual tasks of extremely low contrast and small size 10000 - 20000
The lux scale is highly non-linear, so when the outside light level is 500lx, this is very dark and the inside light will be much less.
On which external lux level the inside light is switched on has to be adjusted individually for every room - at least for every orientation of the building.
Usually this is done by using a lux-meter where you read the lux sensor value of the outdoor brightness and the actual indoor lux level at different operating points and enter this data to the controller. The controller than will calculate a setpoint curve to dimm the lamps.
If possible it is much better and more accurate to have indoor lux sensors in all rooms instead of a single outdoor sensor for all rooms. Also the 0-10 volt dimming is less precise than DALI because you have some loss on the cable so that the voltage between the controller and the ballast drops depending on the cable length.
Another thing a good controller does is, that it does not dimm immediatly when the light is turned on but is starts with a certain light level and keeps this level constant to warm up the flourescent lamps - since the brightness increases when the lamps warm up.
Hope this helps!
Originally Posted by TheControlsFreak
Can you give me example of how you calculate, any dimming ballasts will do.
one more question, is the dimming ballasts voltage directly proportional to the light (that is what I always thought)?
As 709 stated the scales involved are almost always non-linear. But if you look at the documentation of the ballasts you are wanting to dim I believe they will have some sort of scale whether linear or not, stated from the manufacturer.
Originally Posted by Blackhaze
The other thing to remember is that just because the 0-10v is linear to the amount of light given off by the fixture, it does not mean that the power consumption is linear as well. So if you have a dimming ballast at 20% your power consumption for the fixture will still be about 50% or so. This is a bare minimum that the ballast needs to light the fluorescent bulbs.