什么是以太网供电（PoE）电缆解决方案？(请参照英文内容)

Power over Ethernet (POE) is a technology whereby a limited amount of electrical D.C. power is transmitted over the structured cabling whilst the cables simultaneously transmit data over the non-powered pairs .

In 2003 the Institute of Electrical and Electronics Engineer (IEEE) approved the first PoE standard (IEEE 802.af) which delivered 12.95Watts of DC power using 2 of the pairs within the 4 pair cable structure. Emerging applications demanded more power therefore in 2009 the IEEE delivered a new standard (IEEE 802.3at) which realized a 25Watt DC power delivery over 2 pairs within the cable structure. The new 25Watt PoE solution is sometimes designated as PoE+.

IEEE 802.3bt is being developed in anticipation of future applications such as Thin Clients, Building Automation including Security, Hospitality and Next Generation Wireless Access Points and LED Lighting (see Fig.3).

It is anticipated that during early 2017 the IEEE will standardize IEEE 802.3bt. This standard will introduce 2 new PoE applications which utilize all 4 pairs within the cable structure. For these new applications, power and data will simultaneously be transmitted along the cable channel. The two new 4 pair applications will be described as Type 3 and Type 4 and thus formalize the power delivery structure within LAN cabling (See Table 1).

In developing PoE solutions for 100W applications the IEEE has remained cognizant of the fact that any solution has to be Energy Efficient.