PoE Powered Smart Building – Part 1


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What Power over Ethernet (PoE) is exactly what the name says: It provides power using the cable used to transmit data. This type of technology can be widely found in smart buildings where, thanks to the lower voltages involved, normal electrical safety rules do not apply. This is exactly why PoE looks interesting because it is able to significantly reduce costs with installation and compliance. Since many office buildings already have flooded Ethernet throughout the structure, with battery-assisted uninterruptible power supplies (UPS) installed, robust systems can be easily implemented. Adding PoE equipment retroactively could take advantage of the same cables that have already been deployed, to also provide power for applications such as lighting and security cameras. Power can be delivered via an Ethernet cable to devices that are up to 100 meters away from PoE-enabled Ethernet equipment. Benefits of Powering Smart Buildings with PoE One of the obvious benefits of adopting PoE is that it enables DC power to run over your existing Ethernet. Although you still need to update your network adapters with ports that support PoE, the cost benefit associated with not having to run additional copper wires for the powered device can be significant. The price of copper rose from $0.65 per pound in 2000 to $4.05 per pound in 2021 (source: Macro Trends). In addition, further cost savings can be achieved by not implementing AC-to-DC conversion in the powered device. PoE also provides greater flexibility when locating powered devices. Most major AC outlets are located near the floor, which is not an ideal location for Wi-FI® access points (APs), femtocells, picocells, and cameras. In order to maximize coverage, it is advisable to avoid placing such devices near obstacles, which means that it is better to place them at ceiling height. Unlike backbone networks, Ethernet cables are often routed through voids created by suspended ceilings, removing another barrier to adoption. The power and data mating of PoE enables 24/7 smart monitoring and control of a variety of applications including lighting, security cameras and digital signage. Centralized PoE networks equipped with battery-powered UPSs ensure continuous operation of critical equipment during power outages. Figure 1: Smart Building Benefits in PoE Smart Building Applications and PoE Standards The original PoE standard (IEEE 802.3af) was certified in 2003 and offers up to 15 watts of power. It was widely adopted in applications such as IP telephony, building access control, and operating early distributed Wi-Fi access points. Subsequent revisions to the standard, including IEEE 802.3at (30 W/2009) and IEEE 802.3bt (90 W/2018), have increased the power provided to enable more demanding applications, such as faster Wi-Fi networks, security cameras, amplifiers, and POS ( POS), LED lighting, and more. Figure 2: PoE standards and applications. PoE topology Figure 3 shows a typical PoE topology. The PoE switch is called Power Source Equipment (PSE) and this provides DC power to customers, it is called Powered Device (PD). The specification requires that the PSE be able to deliver power to the PD via a maximum of 100 meters of Ethernet cable (typically CAT5/6). Figure 3: Typical PoE Topology (Source: Ethernet Alliance) Because an Ethernet cable can reach 100m, there is some dissipation at this distance, so under worse conditions, the power to PD is less than that provided by PSE. This is included in specifications such as 13 watts for 802.3af, 25.5 watts for 802.3at, and 71.3 watts for 802.3bt. The DC voltage can range from 42 to 57 volts [RB2]In PD for “bt” standard. Networked devices that do not support PoE can still be connected at their input and use a PoE splitter to separate data and DC power. This can also reduce the need for AC/DC converters and locating equipment near an AC outlet. PoE Powered PTZ Cameras Current security systems generally use cameras that incorporate small motors to enable them to move in three axes, or pan, tilt and zoom (PTZ), and typically feature high-resolution digital cameras. These cameras can be controlled manually via a wired connection such as Ethernet, or programmed to automatically pan and zoom when objects are detected in the selected window of interest or across the entire field of view. Some cameras may also be configured to scan a scene by performing a continuous rotation from 0° to 360° and tilting from 0° to 180°, while zooming can be performed using optical or digital techniques. The power needed for these security and surveillance cameras can now be supplied using PoE based on the IEEE 802.3at standard. PoE powered wireless networks Wi-Fi access points and routers are also common implementations of PoE. The power consumption of both is often a function of the speed and number of supported streams. Modern networks increase range and throughput by using technologies such as MIMO (Multiple Input, Multiple Output). Implementation of an AP/router that supports Wi-Fi 6 (IEEE 802.11ax) speeds will set the PoE standards as: Synchronous Band: 802.3at/bt Wi-Fi 6, 4×4 Tri-Band Synchronous: 802.3at/bt Although Wi-Fi routers/access points are equipped with AC/DC power, they can also be powered with PoE distributor. In contrast, products like the Cisco MerakiTM MR56 Wi-Fi 6 (802.11ax, 8 streams) access point now support 802.3at, which means the RJ45 port can connect directly to a PoE-enabled PSE switch to power the device. PoE powered Picocells, Femtocells and femtocells are used to extend or increase cellular coverage, particularly in crowded areas such as indoors, offices, shopping malls and stadiums. In contrast to a normal cell, the range of a picocyll cell is small at about 200 m or less, while that of a femtocell cell can be up to 10 m. These small devices are ideal candidates for PoE, as one of the examples below demonstrates: ApexTM 4G/LTE 3.5GHz Outdoor Picocell (35W): 802.3bt PoE Powered Digital Signage LED TVs are a very efficient form of connectivity. They can display dynamic and customized digital signage in a variety of areas including corporate office space, smart retail, hotels and government municipalities. Like Wi-Fi, digital signage is only as good as its location. For example, larger screens usually hang from the ceiling so that the audience can view the content easily. In contrast, smart kiosk or Point of Sale (PoS) applications take advantage of smaller screens – some with touch screens for a more personal and interactive user experience. LED TV power consumption varies greatly. The Samsung® 55″ LED TV listed below has a typical power consumption of 69 Watts, while another of the same size and manufacturer requires 120 Watts. It is important to ensure that the power of the LED TV does not exceed the power of the PD. With the 802.bt standard, this can range from 90 watts to 71.3 watts depending on the length of the Ethernet cable between the PSE and the LED TV (PD). Several signage TVs with PoE are also available on the market. It will be interesting to see if LED TV makers start incorporating 802.bt into larger LED TVs, for the growing digital signage market. 55″, Samsung 4K LED TV (#Q70T) 69W (Type): 802.3bt (PoE splitter required) 46″, HD with touchscreen from Thinlabs, Inc: 802.3bt (PoE Splitter not required) 10″, digital signage from Samsung ( DB10E-TPOE) 802.3at (PoE Splitter Not Required) 48″, Samsung (DH48E) Digital Signage 44W (Type) 802.3bt (PoE Splitter Required) 40″, Samsung (H40B) Digital Signage 44W (Type) ) 802.3bt (PoE splitter required) 16 inch TV medTV® PDI-P16TV-GB2-P (25 Watts) 802.3at (PoE splitter not required) PoE Smart Connected Lighting PoE and LED lighting normally fit as LEDs consume DC power, PoE provides DC power. This allows you to eliminate the cost of converting AC to DC power when powering LEDs with PoE. A great example of how PoE for smart buildings can enhance the connected lighting platform ON Semiconductor® (Fig. 4). This platform is based on a modular design, capable of providing 7000 lumens to two series of 16 LEDs, driven by dual FL7760 LED drivers. The PoE module based on the NCP1096802.3bt controller delivers up to 90W of DC power to the LED driver. Meanwhile, a second connector on the LED driver unit accepts an RSL10 Bluetooth® 5 radio for wireless connection to the smartphone gateway, enabling cloud connectivity. Now that’s smart lighting. Figure 4: Lighting platform connected with PoE business phones PoE Module (VoIP) Voice over Internet Protocol (VoIP) is probably the most common implementation of PoE. VoIP digitizes low-frequency analogue voice signals into packets of data using the Ethernet protocol over a wide area network. From there, it will pass through switches and routers to the cloud, to its destination. VoIP only consumes 4-7 watts, so it is very compatible with the 802.3af PoE standard. Modern VoIP phones with an RJ45 connector are designed to receive both data and power over an Ethernet cable, so an external PoE hub is not required. Conclusion The convenience of connecting power and data delivery over the same cable is compelling; We just need to consider how USB has become a ubiquitous power source for many consumer devices. The same is true for PoE in commercial and industrial applications. It advances the concept of single cable solutions by targeting applications that can directly benefit from the simplicity they provide. With solid experience in both digital communications and energy management, ON Semiconductor is well positioned to deliver PoE solutions. As more manufacturers discover its benefits, end users will start ordering PoE. It’s time to start transitioning to a smarter, more integrated energy/data mix. All the brands are owned by their owners. ON Semiconductor is a trademark of Semiconductor Components Industries, LLC dba ON Semiconductor or its affiliates in the United States and/or other countries. Wi-Fi is a registered trademark of Wi-Fi Alliance®. Cisco Meraki is a trademark of Cisco Systems, Inc. and/or its affiliates in the United States and certain other countries. Apex is a trademark of Casa Systems, Inc. Samsung is a trademark of Samsung Electronics Co., Ltd.. medTV is a registered trademark of PDi Communication Systems, Inc. The Bluetooth mark and logos are registered trademarks owned by the Bluetooth SIG, Inc. Written by Bob Card, Americas Marketing Director, Advanced Solutions Group, EN Semiconductor.


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