Smashing the ceiling: How to break free of DALI technical limits
08 May 2018
DALI (digital addressable lighting interface) is a form of lighting control which allows customised preferences to be programmed. The key benefit of DALI for a designer or installer is that it provides two-way communication, allowing devices such as ballasts, transformers and emergency fittings to report back on their status. This can help speed up installation compared to non-DALI lighting, and makes fault diagnosis much quicker and easier.
While such a system provides flexibility, to realise its full potential careful consideration is needed at the design stage. DALI circuits have some technical limits including a maximum current of 200 mA, maximum cable length, and maximum number of groups of devices and lighting scenes that can be programmed into a line. For lighting designers, the most problematic of these limits is often the maximum of 64 ballasts (e.g. luminaires, sensors) that can be installed on any one line. This is normally sufficient for many rooms but requires each line to be carefully designed to maximise capacity without exceeding the technical limits.
Should a DALI installation require more than 64 ballasts, more lines can be added, each with their own controller which can be linked to the system via Ethernet. However, new controllers can be expensive and also wasteful if an additional controller is only being used for a handful of ballasts. Furthermore, enclosure space is often limited, leaving system integrators with nowhere to go if there are too many lines to control and too many controllers to fit into a small cabinet. If there are not enough I/O channels, or a more powerful controller is required, then the whole DALI control system may have to be replaced and reprogrammed.
A solution to this challenge is to use a modular control system. The ability to add modules while keeping the same controller, allows more DALI lines to be controlled from the same node. Modules can be added without disrupting the rest of the node.
WAGO’s modular DALI control system can accommodate up to 24 DALI lines, and since each module is only 12mm wide, it allows far more control function to be packed into a smaller cabinet space. It enables integrators to purchase and use only what they need, when they need it, allowing systems to be gradually scaled up rather than replaced or redesigned every time an expansion is required.
As well as simplifying operations within the control panel, modularity can help to provide flexibility outside of it too, particularly when it comes to cabling. Modular wiring involves pre-wired assemblies being delivered to site ready to be plugged together without the need for extensive wiring work. All cabling for DALI lighting, as well as other building services can be pre-wired, tested and shipped to site in sections, ready to be put in place and plugged together. In WAGO’s case the trunking to contain the wiring is constructed and assembled off-site simultaneously, saving even more time and costs. Colour-coded plugs and spring pressure connections ensure that wiring errors are avoided, which is ideal for complex systems like DALI lighting, where a single fault can potentially affect a whole line.
WAGO has developed variants of its WINSTA modular wiring system specifically for use with DALI lighting. Pluggable connectors are available for connecting all aspects of a DALI system, from the distribution box to the LEDs and sensors, providing power supply as well as carrying signals for control and monitoring. The scalable system, when combined with modular controls, offers flexibility for futureproof DALI lighting.
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