Differences between POE 802.3af and 802.3at

- Aug 09, 2017-

PoE (Power over Ethernet) is a local area network technology, through twisted pair to provide DC power equipment, has been widely used in enterprise and industrial applications.

According to statistics, 2006, Ethernet power delivery of 32 million ports, by 2011, delivery will grow to 145 million ports, the annual growth rate will exceed 30%. The standard used by the POE industry is the IEEE 802.3af, which specifies that the power supply can be powered by an Ethernet power device under 13W. This is enough for traditional IP telephony and webcams to meet demand, however, with the advent of high power applications such as dual-band access, video phone, PTZ video surveillance system, 13W power supply is obviously not enough to meet the demand, so the IEEE began to develop new POE standard in 802.3at(PoE Plus) to enhance the power of POE.

Compared with 802.3af, 802.3at can output more than 2 times the power, the output power of each port can be more than 30W, so can greatly broaden the PoE applications.

Contrast with 802.3at. Although the current 802.3ats has not yet officially launched, but the industry manufacturers to begin to comply with pre-IEEE802.3at standard devices.

802.3af(PoE)802.3at(PoE Plus)
Classification0~34 only and layer 2
Volt Number44~57V DC50~57V DC
CableUnstructuredCAT-5 or better
Number of lines22
Power of PD 13W30W
Electric Current350mA720mA

Online telephone(3-7W)

WLAN access Point(8-12W)

Video Network Phone(1000-20W)

PTZ video surveillance system(20W)

WiMAX and 802.11n Receiver(8-45W)


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