A new white paper from CommScope recaps the finer points of the IEEE 802.3at DTE power standard for Power over Ethernet (PoE) applications. The document's premise is as follows:
Enterprise distribution networks can be used to supply power to application equipment located in different parts of a network, including ISDN, building automation systems (BAS), security/alarm systems, and other systems complaint to the IEEE 802.3af remote power to data terminal equipment (DTE) standard, which facilitates the connection of low power devices to local area networks (LANs). The IEEE 802.3at DTE power application project is an extension of the IEEE 802.3af standard that provides additional power and flexibility either from a switch or an adjunct power source to IEEE 802.3 10Base-T, 100Base-T, and 1000Base-T devices.
IEEE 802.3at DTE permits the transmission of DC power using structured cabling for low voltage applications. The requirements provided in the standard can be used to support a wide variety of low voltage power limited applications that will benefit from using remote power supplied over balanced twisted pair cabling. The application of power is done by power sourcing equipment (PSE) that is located either at the end of a structured cabling channel (end point) or within the extents of structured cabling (mid-span).
Notably, the new white paper includes sections on: IEEE 802.3at backward compatibility to IEEE 802.3af; powering options; temperature rise and current capacity; UTP vs. FTP for temperature rise; components of an IEEE 802.3at network; and design considerations.