HOW IT WORKS

While a digital network sounds sophisticated, most of the hardware is common -- ballasts, lamps, controls, wiring -- with the difference that the ballasts are networked to a central computer that enables bi-way communication. This means we can tell each ballast what to do, and the ballast can talk back, giving us information about it's operation.

A DALI-based digital lighting network is based on digital 120/277V fluorescent electronic ballasts, currently available in one- and two-lamp models that operate linear T5, T5HO and T8 fluorescent lamps as well as compact fluorescent lamps. According to manufacturer Tridonic, digital ballasts and DALI interfaces will soon be available for high-intensity discharge (HID), incandescent and low-voltage halogen systems. Digital ballasts "soft start" fluorescent lamps to maximize service life; cut the lamps out at end of life; gradually dim; and start the lamps at any point in their dimming range, from 100% to 1%.

The ballasts are connected using either Class I line-voltage or Class II low-voltage wiring to form a lighting bus or loop of up to 64 ballasts. The digital protocol allows simplified control wiring that provides greater flexibility than traditional 0-10V analog systems. Each ballast is given an address in the system so that it can be individually controlled or grouped in multiple configurations (up to 16 layers of control/scenes). The loop is then connected to any type of DALI-compatible control device(s). Control options include local wall-mounted controls that enable manual push-button switching to select programmed dimming scenes, occupancy sensors, photosensors and other controls.

The lighting manager can individually address each ballast in a building or gang them in groups, then program each ballast or group to dim from 100% to 1% either on a scheduled basis or in reaction to preset conditions, such as available daylight. The lighting components also talk back, providing information that can be used to identify lamp and ballast failure and generate general energy consumption information. The result is high energy savings and extreme flexibility in controlling light levels.