Dimming calculations

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normbac

Senior Member
I have a sensorswitch photocell dimming sensor specs state sinks up to 20mA up to 40 dimming ballast @ .5 mA
the LED cans specs show output at 500mA which is possibly including the driver?
I am obviously missing something. How do I determine mA on the dimming ballast. Any input appreciated not sure how to calculate amount of cans I can put on this photocell. Tech support on both product were no help.
 

GoldDigger

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I have a sensorswitch photocell dimming sensor specs state sinks up to 20mA up to 40 dimming ballast @ .5 mA
the LED cans specs show output at 500mA which is possibly including the driver?
I am obviously missing something. How do I determine mA on the dimming ballast. Any input appreciated not sure how to calculate amount of cans I can put on this photocell. Tech support on both product were no help.
It looks like the sensor/dimmer is meant to work with a 0-10V control line going to a control input on the dimming ballast.
Are you sure you do not have dimmable ballasts intended to work with a series voltage or phase controlled dimmer?
A current of 500ma sounds more like the controlled current to the LED bulb.
 

normbac

Senior Member
It looks like the sensor/dimmer is meant to work with a 0-10V control line going to a control input on the dimming ballast.
Are you sure you do not have dimmable ballasts intended to work with a series voltage or phase controlled dimmer?
A current of 500ma sounds more like the controlled current to the LED bulb.

After reading more on specs it is a reverse or forward phase I am not to familiar with this type of setup it was on the plans to use the sensorswitch dimming photocell so I was researching how this would work. Apparently it won't can you recommend a indoor dimming photocell sensor there are forty can lights within the area that require auto dimming. It is considered primary and secondary day lit zones for t-24 requirements
 

GoldDigger

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Location
Placerville, CA, USA
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After reading more on specs it is a reverse or forward phase I am not to familiar with this type of setup it was on the plans to use the sensorswitch dimming photocell so I was researching how this would work. Apparently it won't can you recommend a indoor dimming photocell sensor there are forty can lights within the area that require auto dimming. It is considered primary and secondary day lit zones for t-24 requirements
The reverse or forward phase controlled dimmer is almost certainly one which is intended to get its dimming information from the applied line voltage. No way that it can be remotely controlled with only a control signal (low power). So the biggest problem is that your cans are not particularly suitable for mass control of any kind.
And there is a limit to the number of full power cans that can be put on one circuit with a conventional two wire dimmer.

You might be able to find a professional lighting controller that will accept input from one dimmer/sensor and use it to control as many separate power circuits as needed using phase control. Either professional architectural lighting or stage/theatrical lighting equipment.
The alternatives would include
1. putting in lots of phase control dimmer sensors with each one wired to as many of the cans as it can handle, or
2. Changing out all of the cans to ones which use 0-10V control inputs. To make that work you would have to pull at least one additional wire to each of the cans (all in parallel would probably be OK)
 

Electric-Light

Senior Member
I have a sensorswitch photocell dimming sensor specs state sinks up to 20mA up to 40 dimming ballast @ .5 mA
the LED cans specs show output at 500mA which is possibly including the driver?
I am obviously missing something. How do I determine mA on the dimming ballast. Any input appreciated not sure how to calculate amount of cans I can put on this photocell. Tech support on both product were no help.

The numbers tell me you're dealing with 0-10v. 0-10v is a gas pedal.
The fluid is handled by the light fixture.

The 0-10V won't be more than 1mA, so if you're not controlling more than 20, just hook up. If you are... Do you have a multimeter that can do mA? Connect the multimeter in mA mode where you would connect the dimmer's 0-10v control. If you have 10 fixtures, and you measure 10mA, then it's about 1mA each. If you see 5mA, then it's about 0.5mA each.

When the mA meter is hooked up, the lights will drop to minimum brightness.

Phase dimming is a valve that directly handles the flow.
 

GoldDigger

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Location
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Occupation
Retired PV System Designer
The numbers tell me you're dealing with 0-10v. 0-10v is a gas pedal.
The fluid is handled by the light fixture.

The 0-10V won't be more than 1mA, so if you're not controlling more than 20, just hook up. If you are... Do you have a multimeter that can do mA? Connect the multimeter in mA mode where you would connect the dimmer's 0-10v control. If you have 10 fixtures, and you measure 10mA, then it's about 1mA each. If you see 5mA, then it's about 0.5mA each.

When the mA meter is hooked up, the lights will drop to minimum brightness.

Phase dimming is a valve that directly handles the flow.
All good suggestions, E-L, but I am still unconvinced
that these LED drivers are designed for 0-10V control in the first place.
Do they have a third control-only lead wire?
 

Smart $

Esteemed Member
Location
Ohio
All good suggestions, E-L, but I am still unconvinced
that these LED drivers are designed for 0-10V control in the first place.
Do they have a third control-only lead wire?
Best if OP'er provides product make and model, or better yet, links to their documentation.
 

iwire

Moderator
Staff member
Location
Massachusetts
All good suggestions, E-L, but I am still unconvinced
that these LED drivers are designed for 0-10V control in the first place.
Do they have a third control-only lead wire?

I would guess 90% of the LED drivers I install have a pair of leads on them for 0-10 volt control.

But I agree with Smart, we need more info.
 

normbac

Senior Member
I would guess 90% of the LED drivers I install have a pair of leads on them for 0-10 volt control.

But I agree with Smart, we need more info.
After further research the cans do say constant current led drivers with dual dimming forward and reverse phase And 0-10v
 

Electric-Light

Senior Member
After further research the cans do say constant current led drivers with dual dimming forward and reverse phase And 0-10v

I wasn't sure if the can said 500mA 120v... or just 500mA.

If it requires an EXTERNAL DRIVER, 500mA means that you need to select a driver that specs 500mA output, and the load's wattage falls within the range of watt for the driver. For example, if the driver is 10-50w, 500mA. You can connect a 500mA 30W load on it.

How dimming is interfaced is completely up to the driver you select.
It could be 0-10v (tethered remote control), phase control, WiFi, Blue Tooth, DALI or whatever.
The difficulty with 0-10v is really that you have to run the additional pair of control wires.
 
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