In this four-part series, Charles Knuffke, Systems VP & Evangelist, Wattstopper/Legrand, North and Central America and past chair of the Lighting Controls Association provides a crash Lighting Controls 101 class for lighting practitioners. Originally published as the Controls Column in LD+A Magazine in 2023. Reprinted with permission.
In the past, lighting controls were often regarded as something to be added onto the nearly completed project design, but times have changed. Lighting controls are now more integrated than ever in lighting design. Because every good lighting design therefore includes a good lighting control design, it is essential that all lighting professionals—new to the business and veterans alike—have a solid foundation of controls, from which they can explore product lines, satisfy energy codes, solve problems, and overall furnish an optimal integrated design or solution. Thinking about this, I thought it worthwhile to switch things up in this column by visiting some very important fundamentals—things every lighting professional should know.
A general attempt to classify systems
Looking at controls from a high vantage point, there are two system distinctions that should be recognized—choices each manufacturer makes that determine the fundamental nature of their specific systems. These choices define how the system’s devices will communicate between each other and the overall type of system.
These distinctions could be called 1) system architecture and 2) device-to-device communication method. All control systems—regardless of their overall function—are collections of inputs and outputs. What these two choices define is 1) where the programming that defines these interactions is stored and 2) how the components communicate between each other.
System architecture
When we talk about the architecture of the system intelligence, we’re defining where the programming resides that defines the interactions between the inputs and outputs.
For some systems, the control logic is stored in a single frontend device (think of a computer server sending output to remote terminals), and for other systems the control logic might be stored in the individual devices themselves (often called a “distributed intelligence” system). Both architectures have their pros and cons, which is why different selections have been made by the lighting control manufacturers.
It’s also important to recognize that this choice of architecture isn’t a purely binary distinction. Some manufacturers may use distributed intelligence for simple setup of some of the devices in a room but may keep other operational parameters—say, time of day schedules—in a central frontend device separately from the room devices. For example, this would allow a single schedule for lighting loads to be programmed once instead of for each individual room of devices.
Device-to-device communication
The second item in the list is usually much more obvious and often readily apparent by looking at the product’s cut sheets. When referring to communication method used between devices, the first distinction is whether it is a wired or a wireless approach. Once that distinction is made, there are many variations.
When a system declares it uses a wired method (twisted pair with or without a shield, Cat 5e or 6 cable, or some other conductor), you still would want to understand what communication protocol is used—whether it is proprietary or open serial RS232 protocol, serial RS485, Power over Ethernet, or something else. If it’s wireless communication, you want to determine which wireless protocol or protocols are used, such as ZigBee, 6LoWPAN, WiFi, Bluetooth Low Energy, or other.
The reason for looking deeper than just the basic wired versus wireless distinction is that the manufacturer’s choice will dictate other characteristics of the communication. For example, with wireless, it should 1) indicate whether it configures in a mesh or other topology and 2) define whether other products might be able to interact with devices in the room or negatively impact the communication between devices.
The protocol used also has direct design implications that the manufacturer should let you know about. For example, the type of wired protocol would dictate what wiring topologies are allowed or are required, the distance between devices or the total wire length allowed in a room or on a trunk between rooms, possibly the quantity of devices or loads that are allowed to be connected to the wire, or whether any additional wiring requirements are called for (e.g., adding an “end of line” resistor). For wireless, the protocol used might also indicate distances allowed between devices, the number of devices that can communicate on the wireless network, and whether the devices can create a self-forming network or require the use of an additional device to manage the communication between them.
“Panelized” architecture
While not one of the two major distinctions, it’s worth noting whether the loads in a system are “panelized” (i.e., whether individual load devices with one or more outputs are mounted together in a single enclosure) or are distributed in the space.
The benefit for a panelized approach to a lighting control system is that it allows large number of loads to mounted inside an electrical closet or other central location, which may allow the electrician or facility engineer to make future wiring changes with little impact to the occupants in the space. A panelized approach is helpful on projects where entire circuits from a circuit breaker need to be controlled or where remote mounting of the load control devices might be difficult, such as hard lid ceilings for instance or in a prison. Those who have ever worked on architectural dimming systems with phase-dimming requirements understand that this approach is helpful.
Currently, some manufacturers offer both a panelized approach for some load types—On/Off, 0-10V, or the previously mentioned phase dimming—but not others. Even with dimmable lighting now a common requirement for new projects, an On/Off panel combined with a time-of-day sequence of operation may be the design choice to handle plug load circuits in open office areas. It certainly helps to understand the location and mounting restrictions to allow the selection of the most appropriate system for a project.
With the discussion of system architecture and device-to-device communication out of the way, we can proceed in the next column into a discussion around selecting room devices for a project such as occupancy sensors, manual controls, timeclocks, and so on.
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