1-10V dimming

[bernardgreen]

I feel you need to make sure this whole system works before you let the contractor leave with his money.

You may find you have lamps with some difficult control problems.

AdrianUK is correct.
The lights you have will contain 1-10v ballasts which require a current sink to operate. (a resistor, or more usually an electronic control unit)

If that is the case, which now seems likely, then the leads between the ballast and the variable resistor used as the control will need some carefull consideration. This design of dimmable ballast is best suited to single lamp installations where the controller resistance is close to the ballast. There may be little if any protection from voltages induced on the control lines. Therefor the wires to the controller may need to be protected from interference from other circuits. The wires from ballast to controller may carry fluctuating voltages coming out of the ballast ( the ballast works on the varying resistance of the controller ) which might affect the control of other ballasts if the control wires are bunched together. The longer the control wires the more chance of unstable control.

You may even have to have a separate control resistor for each individual ballast as commoning up the control lines to a single control may not work and may even damage the ballasts.

 

[ccam108]

OK thanks for the replies everyone. The lights weren't sold to be used with the pulsar unit, we are waiting 'til January for the controller to be installed, as "only one company in Britain make them and they cost £500" apparently.

Commoning the control lines to control two fittings from one dimmer is exactly what the contractor proposes to do. I managed to convince them to run a separate feed from each fitting anyway for future-proofing.

If, as you say, they require a resistance to dim, will 30m of 1.5mm T&E not have such a high resistance that they will never dim to off?

I checked the control wires connected to the light only and read 0V DC and 22V AC, which I assumed to be capacitive coupling. So the ballasts definitely do not output 10V.

I might give Hacel a phone to find out what they have to say on the matter.

Colin C

 

[davelx]

If, as you say, they require a resistance to dim, will 30m of 1.5mm T&E not have such a high resistance that they will never dim to off?




Colin C

No because the resistance of the control cable will be a very small fraction of the controller's resistance range. This may be of use:

http://www.aboutlightingcontrols.org/education/papers/dimming.shtml

 

[ccam108]

OK, since these fittings are not compatible with 0-10V theatre dimming, I take it this will work in a grid faceplate?

Colin C

 

[Lectrician]

Looks the job, and says it can control several ballasts with a single dimmer.

 

[ccam108]

Perfect. Might just get some then.

In future I might want to control from two places. I take it the only way to do this is through a two-way switch to select the dimmer, or through relays?

I suppose with relays I could do some fancy stuff selecting multiple fittings from one dimmer...

Colin C

 

[Spark123]

Easiest way is just having the variable resistors (think they are 47k) in parallel, then "Lowest takes precidence". Just have to make sure nobody tinkers with the other dimmer, maybe even keyswitch it out.

 

[bernardgreen]

I have just looked at the circuit of a stage lighting dimmer module ( make un-known as it is from an applications manual for thyristors ) which uses a variable resistor as the control.

It has a range of from near zero volts to 10 volt signal on the control input.

Two of these could not be connected in parallel to one control resistor.

There is also a comment about screening the control leads if they are more than a metre in length and several are installed side by side.

(( ccam108 I have sent you a private message about controlling from two places. ))

 

[electronicsuk]

Your only solution is to buy a new controller for the lights.

I think that's a little extreme. If the controller you already have is worth keeping, I expect it wouldn't be too difficult to use the 0/10v to drive a transistor which would then in turn provide a variable current sink to the dimming ballasts.

You might even find the manufacturer makes a DMX interface, if the lights are intended to be used in halls and the like.

Seems a bit odd to use T+E for control signals. I take it that the contractors were either tightwads or not particularly adept at installing this sort of lighting?

 

[ccam108]

Seems a bit odd to use T+E for control signals. I take it that the contractors were either tightwads or not particularly adept at installing this sort of lighting?

Option 2 (minus 6 words)

 

[ccam108]

Ordered one of those dimmer modules and an MK grid frame etc from CPC to do us for Christmas. I have plans for a better system controllable from front and back of the hall using them but will have to wait and see what is happening with this expensive unit the contractors are supplying. Hopefully that can be cancelled.

Thanks for the help everyone.

Colin C

 

[333rocky333]

Find out from hacel what make and model ballast is in the light.
You will then have more options of what you require.