New Look of Lighting Control

Understanding dynamic lighting keypads and touch screens, along with available control topologies.

New Look of Lighting Control
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They're sleek, with curves and styling reminiscent of commercial buildings all over Europe. With the press of a button or a screen touch, a situation-appropriate lighting scene immediately activates.
This isn't a vignette from the latest futuristic Hollywood thriller. It's the new breed of lighting control input devices that are starting to make their way to North America, including keypads with electronic labeling of buttons and touch screens, both encased in a variety of avant-garde fascia.
Electrical contractors who want to differentiate their offering from competitors are taking a hard look at lighting control, including these European-type devices with which building occupants interface. Why? Increased aesthetic value allows an owner to better differentiate a building, while also increasing occupant convenience. Lighting control makes it easier for users to create appropriate lighting, rather than spending valuable time raising and lowering dimmers on a multi-gang switch plate to achieve the desired effect. Plus, energy savings can be achieved by incorporating occupancy sensors into such a lighting control network, because they automatically turn lights off if occupants forget, or keep the lights off if enough natural sunlight exists to sufficiently illuminate the room.
Following is an overview of these devices, along with two common system topology types — distributed or centralized — and the overall ramifications for contractors.
Input and output devices
The inherent value of these devices is simple — upon arrival at an illuminated keypad or touch screen, the user can immediately identify the room's lighting options. For example, keypads with a backlit LCD screen are available that can display text showing which load the button actually controls or what lighting scene will be activated. For example, one label might read "Presentation." Press it, and a pre-set lighting scene perfect for a computer-based presentation activates. Other types of keypads incorporate LEDs built into the buttons to easily indicate on/off status.
From one location, touch screens can control a single room, such as a classroom with multiple lighting scenes and audio/visual requirements, or a building's entire lighting control network. Activating lighting scenes throughout the building is as simple as a few screen taps. Colorized and black-and-white screens make it easy to search for functions, and can replace large multi-gang switches or dimmer plates that clutter walls in hallways and conference rooms.
Creating the perfect lighting scene can't be done without output devices like dimmers and relays, and significant technological progress has been made in this area as well.
Dimmers, for instance, are available for nearly every lamp type, including fluorescent and HID types. Relays suitable for switching sub-circuit loads are becoming increasingly popular as energy building codes dictate more granular control of small spaces. Such devices are increasingly found distributed throughout a facility rather than in centralized cabinets in an electrical room.
But none of the conveniences that keypads and touch screens provide would be possible without a robust network behind the walls facilitating commands from end users. Two common topologies available today are distributed and centralized, and both begin with the usual lighting panelboard, but take different routes from there to achieve the same effect.
Control topologies
A centralized topology means a controller is present, typically mounted in an equipment room. This traditional lighting control technology relies on communication cables that are fed from the controller to the various input devices in either a radial or loop fashion. Additional wiring from the controller to output devices is also required. Sometimes both the controller and output devices are housed in the same enclosure.
In a distributed topology, control functionality is built into each input and output device itself, thus eliminating the need for a centralized controller. Communications wiring between input and output devices is typically made in a free topology arrangement that does not depend on daisy chain loops or radial feeds.
Contractors have plenty to consider when installing a lighting control system, which is why a distributed topology is of growing interest. For example, the type of cable can be a major factor. In some traditional systems, proprietary wiring from the lighting system manufacturer is required. This can create cost and availability issues, because a contractor has to maintain adequate supplies of that type of cable in order to complete a job. Plus, if there is a last-minute change that requires extra cable, and stock is depleted, a new purchase order has to be generated, and it takes time to receive the delivery of merchandise.
Many distributed systems are now available that use standard Cat-5 wiring, of which most contractors keep an abundant supply. That makes it easier to attend to last-minute changes, and it also means contractors shouldn't have to wonder if they have enough stock to complete a job.
That's not the only convenience issue worth considering. In a distributed system, it's much easier to add new devices, because processing power is built into each unit, increasing flexibility to accommodate new devices if there are last-minute project changes. Adding a new device in a centralized system may create problems for a controller that is not adequately sized to accommodate future needs. A centralized controller is limited in the amount of input and output devices it can handle. Exceed that amount by even one, and a contractor needs to add either another controller or a larger one, which increases costs. In a distributed system, there is virtually no limit to the number of devices that can be added.
But perhaps the most important consideration is this: Because each input device in a distributed topology works independently of the others, if one fails, others will not. If the centralized controller goes down, the entire system will go down as well.
Making the choice
Most contractors are concerned about controlling costs and proper allocation of their labor force. With the anticipated growth of lighting control systems featuring input devices like keypads with LCD labeling and touch screens, contractors will have to weigh cost and labor concerns when assuming jobs involving these systems. A better understanding of the available options, especially when it comes to system topology, will not only benefit the contractor, but also the customer.
Scott Jordan is Product Marketing Manager for Square D/Schneider Electric, a market-leading brand of electrical distribution and industrial control products, systems and services. Learn more at www.squared.com.
In Brief
Overview of two common lighting control system topologies—distributed or centralized.
Related Products: Dynamic Lighting Keypads; Touch Screens; Occupancy Sensors; Dimmers; Relays.
author: By Scott Jordan, Square D/Schneider Electric




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