0-10V

[sunray]

In a village hall I have just made an alteration to the Strand Wallrack dimmer wiring to provide switchable hard/dim outputs and a bit of a chat about the 5 fluo house lights with 0-10V dimming which are about to be changed to LED turned into another project.

I made the mistake of suggesting incorporating them onto the DMX line using a DeMux. After crawling around loft areas and chasing wiring we have established:

1) the faders in a grid switch consist of a simple variable resister with only 2 wires (not wired as a pot), 0% = 0V and 100% = ~80Vac (0Ω & 65kΩ when disconnected).

There is obviously an interface somewhere between the fader and the 0-10V wiring, as yet not found so I have no idea what is there.

2) with the 0-10V line disconnected the lights default to full (makes a lot of sense to me). On the circuit towards the lights 10V appears and then shorting the circuit snaps the lights off. I see the 0-10V from the interface

 

I've dealt with lots of 0-10V within control systems, especially things like BMS valve and damper actuators which revert to the 0V state. The outputs from the controllers have sufficient drive capability to operate a relay. Inputs to controllers usually have facilities to add pullup.

 

My question is simply are architectural lighting systems likely to have a high impedance drive capability, in other words when set to 100% will it be safe to short the line? (Not something I'm accustomed to), Without knowing what the interface is I can't look it up.

The reason I ask is the hall owner doesn't want any changes to the lighting which is likely to affect them in normal use such as a changeover switch whereas adding a multiway socket for the demux shouldn't affect them when unplugged.

Edited November 18, 2023 by sunray

[richardash1981]

Looks like https://assets.lutron.com/a/documents/10v.pdf may be relevant.

Theatrical conventional "positive" control (so not old Strand kit, but most other analogue dimming) compiles with the ESTA E1.3 standard (https://tsp.esta.org/tsp/documents/docs/ANSI_E1-3_2001_R2016s.pdf see section 6), which requires each controller to be a current source, supplying a small DC current down the control line to the dimmer in order to turn the dimmer on. The inclusion of a blocking diode prevents controllers from sinking any current from the control line, and so allows multiple controllers to be wired in parallel for Highest Takes Precedent (HTP) control - this is how the two banks of faders in a simple 2-preset desk are also connected. The dimmer will float to 0V control and no output without a controller connected.

Architectural control follows IEC 60929 Annex E (which also covers DALI digital control, confusingly). Probably copyright infringing link here at the moment, see page 63. The ballast (dimmer) is the current, it sources a current up the control line to the controller, which has to be sunk by the controller in order to turn the dimmer off. The dimmer will float to 10V control and full output without a controller connected (which is useful for optionally dimmed components). The current supplied by the dimmer can be anything from 10 uA to 2 mA in the standard. Theoretically this allows for a 2-wire dimmer with a variable resistor on the end, but only if you have a good idea how much current the dimmer is going to supply in order to chose the correct resistor!

The IEC standard is not completely explicit about how low an impedance you can drive the control line from, but given that the allowed voltage range goes to zero volts (and up to 11V) then a short circuit on the line (or other low-impedance current sink) is perfectly acceptable. It certainly is a voltage drive system, not a current based one, which is why the wide range of currents is possible. It's not clear exactly how multiple controllers on the same ballast are supported (if they are), but such a system could be constructed using blocking diodes a bit like E1.3, but the diodes would be the other way round, and the control would be Lowest Takes Precendent, with the lowest set controller determining the light output. There is a "pedestal" that requires up to 1V to be treated as off, which makes this work better.

If you try to control IEC 60929 architectural dimmers from an E1.3 theatrical controller (demux) then the blocking diodes in the demux will prevent the current from the dimmer from being sunk, and so the dimmers will stick full on. You could obviously have an interface between the two (which could be on the detachable side of the multipin plug proposed) which would effectively have to have a unity-gain voltage follower for each control line, with the output blocking diode connected so it can only sink current (the reverse of theatrical norms, with the anode to the dimmer and cathode to the voltage follower). The procedure would be to turn on the house lights at the normal controls, then dim them off from the Demux as required. A simple op-amp circuit should do the trick, but will need split +/- supply rails in order to work around 0V. Most op-amps will sink 10mA without issue, if you want to control the 5 ballasts on a single line then 50mA needs a bit more care, or use 5 op-amps, one per ballast (assuming the control lines are not commonned). If your ballasts source less than 10mA then there may be no issue at all.

The new LED ballasts may or may not dim all the way off at 0V of course, and will almost certainly have a step getting there, but they are different issues!

[sunray]

Wow what a fantastic reply.

My voltage and short circuit tests tally with your description. I didn't know about the blocking diodes in theatrical controllers so that could very well have tripped me up. I think we would possibly be looking at using one of theseas the hall will very sensibly become 3 circuits. Stated as 20mA O/Ps, I've just tested one and it sources an 800 ohm 12V relay (SRMV in control terms) OK and sinks it from 12V too so no signs of blocking diodes. Have also tested with one set of existing fluo fittings (has a convenient junction box where other tests were made). I'm pretty sure there are no diodes in the existing controller from the tests I've already made. The benefit being the small size and be able to permanently fit (via multiway connector) within the existing stage DMX arrangements but thinking further the outputs are floating in the absence of power or DMX so potentially wouldn't matter if the multiway plug were forgotten to be pulled.

I wondered about adding blocking diodes to the existing wiring but wondered about the 0.7V drop taking it right down to 0%, and the usual snap off point for the replacement LED fittings. Also whether that would be a bridge too far for hall owners.

The 5 lamps I mentioned is actually about 28, I omitted the word circuits, some have about 8 fittings and one circuit would potentially become 16 so it seems I'll need to be checking sink current and also on the new fittings.

Thanks for the plethora of information including the IEC document, you have given me loads of ideas.

 

The one thing I need to verify is all of the existing wirings 0Vs are common before I can do much more.

[sunray]

So I've had a little play today and☹️ after the brilliant advice I was hoping it was going to be a breeze.

As suggested the existing control system doesn't have any source ability, only sink.

First problem; the existing fluo lights don't all dim to zero which I was not aware of, even with a direct short across the 0-10V line. So requires isolating mains too for 'full off'.

Second; the white demux unit in previous post will happily sink the light control 1.4mA or 12mA for a 12V relay to 3.7mV. After adding a 1N4001 diode it sinks the relay to ~630mV but strangely sinks lights to ~950mV and that is not low enough for off.

As we are very consious of not wishing to interfere with the normal operation in any way, we have called it a day for now and plan to have another look when the new LED lights have been fitted, currently planned for March due to the number of bookings.

Apparently during discussions with the installers there has been some suggestion the modules may include DMX capabilities so that is something to look forward to.