Power over Ethernet

What is Power over Ethernet (PoE)?

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• published: 02 Feb 2012
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http://www.fiberoptics4sale.com/wordpress/what-is-power-over-ethernet-poe/ http://www.fiberoptics4sale.com Power over Ethernet technology is a system that passes DC electrical power safely, along with data, on Ethernet cabling. Power over Ethernet eliminates the need to run 110 or 220V AC power to Wireless Access Points and other network devices on a wired LAN. The network installers only need to run a single CAT5 Ethernet cable that carries both power and data to each device. This allows greater flexibility in the locating of access points and network devices. This process begins with a CAT5 "injector" that inserts a DC Voltage onto the CAT5 cable. As shown in this picture, a Power over Ethernet midspan hub injects DC voltage onto the Cat 5 cables and provides both power and data to the Voice over IP phone, the wireless access point, the network camera, over a single cat5 cable. The main reason to use Power over Ethernet is cost, and easy of installation. Here is the an example. It can cost between $100 and $200 to run an Ethernet cable to a wireless access point. But it can costs a further $400 to run an electrical conduit to power that access point. Power over Ethernet technology removes the need to run expensive electrical conduit and saves this $400. Now think about that the quantity of IP security cameras can run from tens to hundreds, then you know that Power over Ethernet can save big money. PoE is presently deployed in applications where USB is unsuitable and where AC power would be inconvenient, expensive or infeasible to supply. Currently there are already a lot of Power over Ethernet network devices on the market. Such as IP telephones, wireless LAN access points, IP security cameras, Access control and help-points, such as intercoms, entry cards, and more. This slide shows two typical configurations for Power over Ethernet application. Some network devices accept the injected DC power directly from the CAT5 cable through their RJ45 jack. These devices are called "PoE-Compatible". These devices are powered directly by the Power over Ethernet cable as shown in the top picture. Other network devices including most legacy products are not "PoE Compatible", which means they cannot directly use the DC power from the cable. In this case, you need a DC picker, also called a splitter, as shown in the bottom picture. The DC picker picks off the DC voltage from the Power over Ethernet cable and makes it available to the non-PoE-compatible device through the regular DC power jack. There are two versions of Power over Ethernet standard made by IEEE. The original IEEE 802.3af-2003 PoE standard provides up to 15.4 W of DC power (minimum 44 V DC and 350 mA) to each device. The updated IEEE 802.3at-2009 PoE standard, also known as PoE+, provides up to 25.5 W of power. So there you have it. Please leave your comment below if you'd like to see other topics. Don't forget to visit fo4sale.com for more free fiber optic tutorials. I will see you in the next video!