0-10V Dimming Large Number of Fixtures

eeRyanC

Member
Location
Seattle, WA, USA
Hello,

I'm interested to see if anyone has experience using a single 0-10V dimming signal to dim 100s of fixtures in a warehouse or sales floor. I'd like to be able to dim several hundred LED fixtures on a large sales floor (~40,000 square feet). The fixtures are dimmable, but I don't know what the input resistance on the 0-10V dimming signal terminals is so I have no way of knowing whether voltage drop on the signal line could pose a problem (which would produce undesirable varied light output levels across the floor). Tracking down this information from the fixture provider is proving to be a challenge (understandably).

Has anyone worked a similar project? Were you able to simply daisy chain the 0-10V signal to all the fixtures or did you have take steps to account for voltage drop?

Thanks,
Ryan
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
0-10V signals tend to expect a fairly high input resistance.

My guess is that trying to wire that many fixtures in parallel is doomed by Ohm's Law.

is there any chance at all that each fixture has a retransmitting output to daisy chain to the next fixture?
 

hillbilly1

Senior Member
Location
Atlanta,Ga
Wally World uses the 0-10 Vdc dimming on their fixtures and don't seem to have an issue, they have two systems though, but I think it is because they dim the grocery at a different level.
 

gar

Senior Member
120601-1612 EDT

You can determine the input resistance of the dimmer control by applying a 10 V signal to one unit and measuring the input current. My guess is 1,000,000 ohms and possibly as low as 10,000 ohms. If you had 100 fixtures and the input resistance was 1 megohm, then the total load would be 10,000 ohms. But if each one was 10,000, then the total would be 100 ohms.

You need to know if the 10 V input circuit is isolated from ground (earth, EGC, etc.). If not isolated, then probably there is or will be a ground path noise problem

.
 

eeRyanC

Member
Location
Seattle, WA, USA
Thanks for all your replies and input. Here are my follow-up comments in no particular order:

is there any chance at all that each fixture has a retransmitting output to daisy chain to the next fixture?
I've never seen this as an option.

What does daisy chain mean?
I meant wire everything up parallel. Not sure if I'm understanding talk about wiring a row in "series" correctly, since if it's really like it sounds, wouldn't that divide the voltage (i.e. 10V to 5 fixtures wired in series would deliver 2V each). I'm going to assume this usage of series is just referring to the wiring pattern on the floor.

You can determine the input resistance of the dimmer control by applying a 10 V signal to one unit and measuring the input current. My guess is 1,000,000 ohms and possibly as low as 10,000 ohms. If you had 100 fixtures and the input resistance was 1 megohm, then the total load would be 10,000 ohms. But if each one was 10,000, then the total would be 100 ohms.
I wish I had a sample fixture to try this out. Problem is we're using a new fixture here but I'll keep that in mind for when I do get my hands on one.

Wally World uses the 0-10 Vdc dimming on their fixtures and don't seem to have an issue, they have two systems though, but I think it is because they dim the grocery at a different level.
That's encouraging - thanks.
 

GeorgeB

ElectroHydraulics engineer (retired)
Location
Greenville SC
Occupation
Retired
My son, for 5 or 6 years, did digital lighting control design, construction, and commissioning support for theaters and portable performances. I'm ignorant, but suggest that you use Google to search DMX lighting and see if it will simplify your system. The components are made by many and will allow such things as sequencing startup and shutdown, grouping AND CHANGING grouping without rewiring .... all the PLC type advantages.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
... Tracking down this information from the fixture provider is proving to be a challenge (understandably). ...
Why is that? Did you give their engineering department a call?

I've generally had pretty good luck calling mfgs engineering dept.

ice
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
... Not sure if I'm understanding talk about wiring a row in "series" correctly, since if it's really like it sounds, wouldn't that divide the voltage (i.e. 10V to 5 fixtures wired in series would deliver 2V each). ...
Nah - If you are going to wire in series, you use a current loop. There is a lot of 20ma current loop stuff out there. So put a 500 ohm resistor across each input, wire 500 lamp inputs in series. At 20 ma that gives 10 volts across each input and all are the same.

That's about 5000V across the string - piece of cake ~:)-)ice
 

hillbilly1

Senior Member
Location
Atlanta,Ga
120601-1726 EDT

What does daisy chain mean? Connected in series, parallel, or a repeater amplifier in each unit? How many in one daisy chain?

.
Daisy chain is parrallel too, it's just looping from one to the next until you get to the end, your not "Tee" tapping. Daisy chaining introduces more resistance in the total run because of the long total resistance.
 

n1ist

Senior Member
Location
Massachusetts
wire 500 lamp inputs in series. At 20 ma that gives 10 volts across each input
Then you need a current source with 5000 volt compliance and high voltage wiring. Common in airport runways, but not for 0-10v dimming.
 

iceworm

Curmudgeon still using printed IEEE Color Books
Location
North of the 65 parallel
Occupation
EE (Field - as little design as possible)
Then you need a current source with 5000 volt compliance and high voltage wiring. Common in airport runways, but not for 0-10v dimming.
Absolutely :blink:
Thanks for picking up on that. I've been waiting - hoping it would not go un-noticed.

ice
 
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