DALI Lighting
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A building’s lighting efficiency is often poor because light is provided when and where it isn’t needed. Improved lighting controls minimize this loss, and a new generation of control gear has emerged with improved reliability and adaptability.
The latest electronic protocol is called DALI, or Digital Addressable Lighting Interface, and describes how lighting ballasts must perform. DALI ballasts are digital dimmable ballasts that permit the DALI system to control fixtures individually or in groups. The DALI protocol allows the lighting control system to be integrated with a computerized building energy management system.
Each DALI ballast has a unique electronic address; each is connected to an unswitched power supply and to a pair of low-voltage control wires. With this simple wiring scheme in place, the programming is done remotely through the DALI controller or a computer. A DALI controller can operate as many as 64 ballasts while also collecting information about energy consumption and component failures from all the fixtures on its network.
Earlier automatic lighting systems demonstrated that taking control completely away from the occupant may fail. Faced with automatic control they disliked, occupants found ways of overriding the controls, eliminating most or all of the possible savings. The DALI protocol, on the other hand, allows the light switching and dimming to occur at any grouping of luminaries, rooms, or offices. Compact reliable occupancy sensors and light-level sensors inform the automatic switching and dimming. However, occupants may use local wall switches or hand-held remote controls for manual dimming and switching of lights in their work area to override the automatic control temporarily or to reprogram the DALI control.
Earlier systems, which relied on signals between one and ten volts, required extensive rewiring in order to add fixtures or change the control scheme. The necessity to design switching, dimming, and component locations into the building’s blueprints was a big disincentive to using the first-generation lighting-control systems. The newer systems are less expensive than the older system, in addition to being flexible and modular. DALI components—ballasts, controllers, and sensors—fit together like Legos; if the space changes its use, the lighting system can easily change with it.
For small offices, you can now buy light fixtures that have built-in occupancy sensors, light sensors, and controllers. A control sold with the fixture lets the occupants dim and switch the light manually to override the automatic dimming if desired. Office lighting suppliers now sell floor lamps that provide direct and indirect dimmable lighting as part of the lighting energy management system. These floor lamps have remote dimming and switching equipment that can be controlled by DALI controllers.
