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Cover 1_rto4 - Illuminating Engineering Society

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Willard L.<br />

Warren,<br />

PE, LC,<br />

FIESNA<br />

Asophisticated new lighting<br />

control system that uses digital,<br />

rather than analog, signals<br />

to control the light output of a<br />

ESSAY<br />

BY INVITATION<br />

which particular lamps and ballasts<br />

are in need of replacement.<br />

The DALI system can be programmed<br />

to turn units on or off, or<br />

dimmed from 1-100 percent light<br />

output, by means of a simple low<br />

voltage control wire that loops<br />

through the building to every fixture.<br />

Further, when DALI is used in<br />

conjunction with a building management<br />

system, every lamp and<br />

ballast can be addressed to determine<br />

if the lamp or ballast is in<br />

working order. This status report<br />

can be gathered, either on-site, or<br />

at the central office of a maintenance<br />

contractor, to determine<br />

how many replacement lamps and<br />

ballasts are required, what kind<br />

It can<br />

feed back<br />

information<br />

on which<br />

particular<br />

lamps and<br />

ballasts are in<br />

need of<br />

replacement.<br />

Figure 1 — User interface<br />

Figure 2 — DALI software<br />

digital electronic ballast was recently<br />

introduced into this country<br />

The new digital electronic ballast<br />

and its control will replace the analog<br />

electronic ballast as the international<br />

standard in a few years<br />

because of its incredible versatility.<br />

The acronym for the new control<br />

protocol is “DALI,” which stands for<br />

“Digital Addressable Lighting Interface.”<br />

The beauty of DALI is that it<br />

allows the user to address every<br />

individual digital ballast, and program<br />

its lamp’s light output. And,<br />

because DALI is a two-way system,<br />

it can feed back information on<br />

they are, and where they are located.<br />

This saves time and money<br />

when servicing multiple sites in<br />

the same geographical area, like<br />

department stores, chain stores<br />

and supermarkets.<br />

The DALI system also allows digital<br />

ballasts to be controlled wherever<br />

they are in the ceiling, so if<br />

changes are made in the arrangement<br />

of departments on a floor,<br />

the lighting luminaires do not have<br />

to be re-wired, just re-addressed.<br />

Because the DALI system controls<br />

every individual ballast, it allows<br />

the user to assign every fixture to<br />

any one of 16 different groupings<br />

of luminaires in the space, and create<br />

multiple operating modes or<br />

scenes. Lighting levels can also be<br />

adjusted to respond to conditions<br />

like energy cutbacks, daylight harvesting,<br />

occupancy status, or the<br />

system can be used to turn any<br />

part of a large office into a conference<br />

area, with the ability to dim<br />

any fixtures needed to facilitate<br />

audio/visual presentations.<br />

The DALI system can be<br />

accessed either by a PC or a Palm<br />

OS device. Figure 1, the user-friendly<br />

PC screen, shows how easy it is<br />

to set the output of the ballast and<br />

assign it to one of 16 fixture groups.<br />

In the third step of the DALI program,<br />

the user selects the fade<br />

time and fade rate of each ballast.<br />

Figure 2 shows the control plan of<br />

three groups of luminaires, how<br />

they will be dimmed, and at what<br />

time. The user simply draws the<br />

fade and time curve with a PC<br />

mouse, and each group of ballasts<br />

creates the desired scene, as programmed.<br />

The PCs or Palm controllers<br />

can be located at several<br />

locations on the floor and changed<br />

at any time.<br />

Many American and European<br />

manufacturers have already signed<br />

on to provide hardware for this new<br />

16 LD+A/May 2001 www.iesna.org

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