Must know information for PoE Switch

What’s PoE Technology?

Power over Ethernet is the abbreviation of PoE, it’s new technology to offer 48V DC power through a single Ethernet cable. The standard PoE system contains two main devices, one is Power sourcing equipment (PSE), which is LAN switch or passive power supply, the other one is Powered device (PD), which is the terminal device to receive power from cable and use it.

What’s the advantage for PoE technology?

PoE technology enables devices receive power supply over single Ethernet cable, also reduced the budget for both equipment cost and installation. Utilizing PoE solution will eliminate the necessary to install wall power supply for terminal devices, which mean increased flexibility for installation, making it possible to install network connected devices in places where local power supply deploy is difficult.

PoE switch

What’s the PoE Smart power management?

PoE smart power management is a function provided by smart PoE switch, which can achieve the optimization and controlling of power supply. This feature can permit customer to manage power supply effectively which prevent problems of power overuse. This feature including it can predefine power distribution for each port, and reset electricity distribution for ports that do not have electricity, also offering prioritization function which can avoid power exhaust of PoE switch. Smart power supply management also call LAN switch automatically recognize connected devices, and manage power for each compatible connected devices. Smart power supply management is based on IEEE power classification features, it can can make sure the actual power demand of compatible PD devices, rather than only adopt power level.

What’s IEEE electrical classification?

The Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) is an organization within IEEE that develops global standards in a broad range of industries. IEEE electrical classification is a select-able standard in IEEE802.3af standard. LAN Switch or Powered devices manufacturers do not need to execute this class, however, it’s very important to provide flexibility and compatibility for devices.

What’s contents do select-able electrical classification feature include?

On the basis of electrical output of power sourcing equipment (PSE), this select-able IEEE802.3af standard can defines 3 different types of electrical classification level and 1 is default mode. Besides, it also defines the maximum electrical output for each level.

IEEE types PSE max electric output PD max electric output
0 15.4W 0.44-12.95W
1 4W 0.44-3.84W
2 7W 3.84-6.49W
3 15.4W 6.49-12.95W

Why is there difference between the PSE power output and power PD input?

We know, power transmission through cable will cause voltage drop or power loss. In IEEE802.3af standard, PD device must provide no more than 15.4W power, where on the end of cable, only 12.9W is needed in this standard, it’s same case from power supply to physical PD port.

Does PoE switch provide protection?

Yes, majority of PoE switch has adopted the multiply protection, including over current and short-circuit protection. For example, each port of rated current is 250mA, if the current reaches over 400mA and time lasts for 75ms, the switch will cut off the current. If the low-resistant short-circuit cases happen, then it can be checked within 1ms and the current will be cut off at once, after each port restore to normal status, each port will re-start work automatically from over current and short-circuit. Each port has independent protection detection, which means the fault of one port will not affect the working of rest of other ports.

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Tags: PoE, PoE Switch