Insteon 0-10v dimming ballast

[apostolakisl]

I had a lutron dimming switch http://www.lutron.com/TechnicalDocumentLibrary/369147.pdf connected to a dimming led light and replaced it with the Insteon dimmer.  But the Insteon doesn't dim it.  I checked voltage output and indeed the Insteon varies voltage based on percentage set.  Perhaps the issue is a sinking voltage vs an output voltage?  Anyone with experience on this?  Perhaps the Insteon is outputting volts rather than sinking volts?

[ELA]

Hello apostolakisl,

    It sounds like just as you suspect.   The Lutron Dimmer states that it is sink only.    I do not have much experience with 0-10 volt dimmers but I do with basic control theory.

0-10V is normally a voltage controlled circuit.  It is usually a high impedance input with very little current flow.      This can make it susceptible to noise.

      When sinking current control is used that is often referred to as current loop control.  ( e.g.  4-20ma loop).   This is more immune to noise.   It sounds like the  Lutron dimmer is more of a hybrid.

Have you measured the  Lutron output  voltage( without a load) when dimming?

Do you have the specs on the dimming led light?    If you wanted to experiment you could try various resistance values between the leads of the led light control inputs ( violet & grey wires?)     If you can control it with just a  variable resistor and no voltage source that would be telling.

If you really wanted the Insteon to work you might be able to convert between voltage control to current control by adding a transistor  in-between. ( with a bit of experimentation),

 

[apostolakisl]

@ELA

Wouldn't sinking and sourcing be the same thing just with different locations for the 3 parts of the voltage splitter (a voltage source, a fixed resistor and a variable resistor)? 

I suppose a key difference would be in a sinking scenario, there would be current on the control wire and in a sourcing scenario you would only have a potential on the wire, which I assume is where the issue of noise can be different.  Though I'm not sure how much noise would matter since the fixture could just read an average potential on the wire and ignore noise.

This fixture/switch is at my church and I'm not there to play with it right now.  While I was there, I indeed measured output from the Insteon device and it outputs a voltage between 0 and 10 depending on what brightness I set at my ISY.

I haven't measured the Lutron, but I would expect it to measure zero volts on its own no matter what.  If I were to measure impedance, I would expect that I would find a varying resistance across the purple/grey wires as I move the dimmer position.  When I left the purple/grey (signal) wires unconnected, it was full brightness.  When I shorted the wires, it went to min brightness, consistent with a voltage sourcing fixture.  I didn't measure the potential across the grey/purple from the fixture, but I would expect 10v (when open).  

Anyway, I just don't understand why Insteon would sell a voltage sourcing dimmer switch.  Per the world renowned expert (Google), sourcing dimmers are only used in theatrical lighting.  Who the heck would use Insteon in a theater?  I feel like something must be wrong here.