PoE-powered LED lighting: Advantages beyond efficiency are more attractive

LED lighting is now a mainstream technology, gradually replacing incandescent, halogen and compact fluorescent lamps (CFL) in commercial, industrial and residential areas. The benefits of LEDs are well known, including longer life, higher energy efficiency and very small lamp size.

Although the benefits of using LED lighting are well known, the way to efficiently power them remains controversial. Using modern Power over Ethernet (PoE) technology to provide DC power to LEDs is comparable to traditional AC lighting power systems. However, if the lights are networked using a local area network (LAN) to achieve the added benefit, PoE technology wins out, and LEDs have lower maintenance costs.

LEDs are essentially low-voltage DC devices. To ensure compatibility with traditional AC power supplies, most LED drivers for lighting use AC/DC converters to convert AC power to a lower DC voltage. This conversion process reduces system efficiency, so designers have proposed DC-based power systems. The efficiency comparison between PoE systems and AC systems will depend on the lighting requirements of the specific application. If the individual output power is kept low and the length of Cat 5 or Cat 6 cables is short, PoE power efficiency will always be better than AC systems. Therefore, the more sophisticated the lighting requirements are compared to AC power, the higher the efficiency of PoE-powered LEDs.

Beyond efficiency ‍

When powered by PoE, each LED lighting fixture can be a standard RJ-45 connector plug-and-play device with its own independently addressable IP address. Furthermore, adding sensors to LED fixtures can transform them from simple lighting devices to smart LED hubs. With this configuration, each "smart" LED hub can collect information about ambient light, temperature, humidity, and anonymous occupancy and transmit it back to the controller. For example, occupancy detection can ensure that lighting is turned on when someone enters a room and turned off when the room is empty ( Figure 1 ). Ambient light sensors also support daylight collection and adjust LED lighting to maintain a constant brightness when there is no daylight. ‍

Figure 1. Networked lighting and sensor hubs can provide new functionality to areas where lighting is used and turn off lighting when it is not needed.

PoE is well suited for powering, connecting and controlling smart LED concentrators over a LAN. In this way, the LED lighting system becomes part of the IT network; its services are extended beyond the vicinity of the user through any networked device (e.g., phone, tablet, PC) to other building services. Then, users can use the system's proximity detection sensors to find the nearest free conference room. It can even bring greater benefits to facility owners and managers, enabling them to gain an overall understanding of the facility's energy usage. By implementing measurement, monitoring and control of all nodes of the network (including heating and ventilation), managers can identify opportunities to improve energy utilization and operational efficiency. With this information, managers can adjust temperature, lighting and cleaning plans based on historical user behavior data.

Another benefit is that PoE LED networks are adaptable to future growth. LED lighting fixtures (and associated smart sensor concentrators) are already installed where needed, and power and data are already connected to most useful locations. So, new sensors or communication modules, such as distributed short-range wireless access points, can be added now with low marginal costs and relatively low labor ( Figure 2 ). ‍

Figure 2. With LED lighting systems integrated with sensors, smart network concentrators can provide useful data to improve energy utilization and operational efficiency.

What does this mean for us? Clearly, using PoE reduces the cost of deploying and installing IP-enabled devices, whether they are sensors or LED lights. Cabling costs are reduced because data and power share the same cable; installation costs are reduced because a qualified electrician is not required to install the network cable; and the installation process is safer because PoE DC voltage is much less dangerous than 110VAC (or 220VAC). PoE networks support better overall network power management: both discrete control of power to connected devices and the ability to provide power backup during power outages using only the network connection.

In summary, powering and controlling LED lights through PoE networks creates new opportunities for using LED lights. Since PoE-powered LED lighting networks are easily integrated with other components, such as sensors and wireless communication modules, they provide a way to adapt to future developments and easily support new technologies and new features that continue to emerge in IoT.

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