BENYA’S ART & SCIENCE
Control Devices vs Control Systems By JAMES R. BENYA, PE, FIES, FIALD What started as a dream in the 1970s – a computermanaged, building-wide lighting control system – has become a commodity of sorts. About a quarter of the product introduction and promotion emails I get daily are for some lighting control system, the majority using wireless networking methods of one technology or another. There are systems oriented towards office buildings, street lighting, high-end residences, smart homes, restaurants, hotels, retail, industrial buildings, and schools. Some are specialize for indoor lighting, others for outdoor lighting, and a few for lighting everywhere. One thing they all have in common – they are chosen to meet the control requirements in our energy codes, to meet the control requirements in voluntary standards like LEED or WELL, and/or to meet the control requirements of the building developer or a utility rebate program. With all of the choices in the marketplace, how does a designer choose? After all, every basic LED lighting driver needs only two standard control inputs - switched incoming power of any normal voltage (120 to 277 volts in USA, 120 to 347 volts in Canada) and dimming with 0-10 volts (not including low voltage drivers used in PoE and some other systems). This leaves only one other standard method – switched phase-cut dimming – as being another significantly different type because of residential lighting and lighting retrofits into older dimming systems. This the first major consideration – what types of lighting loads are you using?
This alone is not as easy as it seems. For instance, there are both solid state drivers and transformer drivers for certain LED systems, like linear lighting. LED drivers for tape light, for example, might be transformer drivers for which phasecut dimmers may be best. But solid-state drivers are most common for LED technology in general. It is best to get the recommended dimming information from the luminaire or system manufacturer. You may end up using some of each. Next, are you using lighting control devices or systems? A device is assumed to be unitary, like a wall switch or dimmer. A system assumes the use separated devices, like a low voltage or digital control device or station, and a driver that responds to specific commands from the device. A system might be one or more control stations controlling many lighting devices having different responses to the commands from the stations. In systems, you will likely have a mixture of driver types, especially in residential and hospitality projects. Third, primarily when using systems, you need to contemplate the complex of sensors and switches that will create inputs. Some functions, like dimming one channel up and one down, will be set according to a solar time (“astronomic”) schedule. Others might ensure that the lights will only operate with people present (“occupancy”), according to the settings of a manual control station, or a certain ambient light setting, or a combination of the three.
Photo Credit: AdobeStock - Gorodenkoff
12
designing lighting