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Right Traditional type of lighting network installa- tion.
Far right Centralised driver and control system with reduced complexity.
over temperature. • High performance step-less pseudo ana- logue dimming with 8 and 16 bit resolutions available. • Significantly higher efficiency and PFC - each output stage can be >98% efficient and maintains efficiency when being dimmed and the summation of output power means that PFC should be on average higher than individual drivers. • Taking out redundant components from individual drivers means that higher quality components can be used. For example, replacing the AC/DC stages of 24 drivers with just one large AC/DC stage means the components are higher quality with im- proved performance and potentially longer lifetimes. • In a similar manner, adding supports for multiple dimming protocols in a 24 chan- nel centralised driver means that the cost is divided by 24 times thus making it cost effective to add additional protocols where it would be cost prohibitive to add these in a single driver topology.
Maintenance & Lifetime • Centralised LED drivers are usually located in ambient temperatures of 25ºC, which significantly improves lifetime compared to single driver solutions with electronics that operate between 80º and 110ºC. • Higher quality components mean no elec- trolytic capacitors are used on the output stages; only solid-state polymer capacitors which have lifetimes of 100Ks hours com- pared to traditional driver solutions that use electrolytic capacitors of 5000 hours. • Higher quality components are used in the AC/DC conversion process, ensuring longer life solutions. • Spare output channels within a driver can be easily used to support additional requirements, or back up in the event of a channel failure. • Centralised drivers are easy to access in the event of changes to the system, unlike traditional drivers located by the fixture often in the ceiling void.
• Centralised drivers can be located up to hundreds of metres away from fixtures, enabling drivers to be placed indoors even if fixtures are outdoors, thus mitigating the need to source IP rated drivers.
Improved Functionality • Multiple control protocols in one product removes the need and therefore expense of several intelligent driver products. • Ability to include Ethernet and WI-FI interfaces to allow Internet based commu- nication. • Complete monitoring, maintenance and management of project installations. • The ability to connect occupancy and day- light sensors directly to drivers and enable them to be virtual units.
Centralised drivers offer an excellent bridge between a fully integrated solution and the common standalone driver systems yet a fully integrated solution offers an alterna- tive set of advantages which include:
Integrated sensor systems within the fixture itself • Sensors can control LED outputs in re- al-time. • No need for separate sensor installation or wiring as these are built directly into the fixture, saving material and installation costs. • Ability to provide active feedback for tuneable white control or ambient light sensing without network traffic.
Integrated DC Driver output stages • Smaller output stages that contain a mi- croprocessor to allow flexibility at the fix- ture level such as changing forward currents for constant lumen applications. • Microprocessor that can handle a dimming control protocol.
Centralised power units • The units just distribute DC voltage power lines so is safe electrically • Very easy to configure and move fixtures
as it just needs to be hooked up to the power DC power lines and whatever control bus protocol. • Similar to constant voltage applications in that units are all powered in parallel, so easy to install.
Clearly LED fixtures still require power to be provided to them but some network topologies are easier to use than others from a control bus prospective. For exam- ple, standalone driver solutions require a dimming protocol bus to be connected to each LED driver, which adds a considerable installation burden. However, using a cen- tralised driver solution reduces the amount of control protocol cabling as the driver handles multiple LED fixtures but requires just one control connection per driver. Indeed, it is possible to connect IP enabled LED drivers to standard WI-FI routers and allow drivers to be connected wireless- ly without a great deal of expense. For example, a quality WI-FI, 4 port router can be purchased for £50 (and as low as £9.95 for lower quality versions) that could control four different centralised drivers that in- turn can control up to 144 separate fixtures wirelessly. Therefore, for an extra 35 pence per output an installation can make each fixture wireless enabled, which is not possi- ble if the drivers were standalone as adding wireless would add several pounds to the cost of each driver.
SPECIFY SAFE CONTROL SOLUTIONS There are clearly significant advantages to networked control systems. However, a big potential pitfall to their future exploitation is network security. Lighting is critical to physical security and as smart lighting be- gins to be installed across current and new residential and corporate constructions. An abuse case such as the ability of a network intruder to remotely shut off lighting in locations such as hospitals and other public venues could result in serious consequences or at least provide significant embarrass- ment.
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