Check any DALI configuration software or documentation and chances are that the term Direct Arc Power will be used at some point.
For example: a DALI Short address (single Luminaire) or DALI Group Address (a number of luminaries) can be set to go to a particular light level by issuing a Direct Arc Power Command.
In simple terms for example: all lights in DALI Group 3 go to Direct Arc Power 50% etc.
In the command, the Power % refers to electrical power in Watts (W). This is the amount of power going to the lamp, not the amount of light coming from the lamp (in Lumens – lm)
You may think that the difference between % power to the lamps and % light from the lamp would be closely matched but in fact they are not!
For example, reducing the power (Watts) to the Lamp from 100% (W) (and therefore 100% lumens) to 50% (Watts) results in a light output that is still seen by our eyes as over 80% in lumens.
To compound this, DALI configuration software refers to the target brightness of a lamp in % – but this is actually Arc Power % (Watts) not brightness % (lumens).
So setting a scene to 50% results in the lamps in that scene going to around 85% brightness.
To get a DALI scene to go to what we see as 50%, you need to send a Direct Arc Command of 3%!
That’s right! 3% of the power (W) gives 50% of the light output (lm)
Not Just for DALI Dimming
RAPIX DALI One Channel and Two Channel relays have the unique feature of being able to set to a Turn on threshold.
If you had 11 high bays, by setting a number of RAPIX DALI relays in a DALI Group to each use Turn on thresholds (using the light output % scale) then each of the high bays can be individually switched on at different times, automatically, without any special macros or scripting.
By sending a ramp up to 100% over 10 seconds as an example, with the first relay turning on a 0.1%, the second at 10%, the third at 20% and so on – up to the 11th at 100% – then all the high bays would turn on at 1 second intervals thus reducing inrush current through the MCB.
Simple DALI Visualisation
RAPIX configuration software shows Light output % by default wherever it appears: from scenes, to min and max level settings – bringing a human dimension to setting up a DALI Lighting Control System.
Everything used to commission a DALI system – from scene setting to min. and max. brightness settings is treated this way dependent on which option is chosen.
RAPIX Lighting Control: Bringing a human dimension to setting up a DALI Lighting Control System makes DALI simpler, faster and easier.