Step out of the Darkness with DALI Brightness Levels

05 December 2016

Check out 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

What the % power (Watts – W) is referring to equates to the amount of power going to the lamp, not the amount of light coming from the lamp (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, with LED lamps reducing the power (W) to the Lamp from 100% (W) 100% (lm)to 50%(W) results in a light output that is still over 80%(lm) as seen by your eyes

To compound this, DALI configuration software will refer to the target brightness of a lamp in % – but this is actually Arc Power % (W) not brightness % (lm).

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 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 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 different levels (using the light output % scale) then each of the high bays can be individually switched on at different times automatically without any special macro or scripting.

By sending a ramp up to 100% over 10 seconds as an example, with the first on turning on a 0.1% the second at 10% the third at 20% and so on – up to the 11th at 100% – and all the high bays would turn on at 1 second intervals thus reducing the inrush current through the MCB.

Simple DALI Visualisation

RAPIX configuration now shows Light output % by default wherever it appears. from scenes to min and max brightness 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. Bringing a human dimension to setting up a DALI Lighting Control System making DALI simpler, faster and easier.