PoE Power Over Ethernet ¿Qué es PoE? Diferentes tipos de PoE

There are several common techniques for transmitting power over Ethernet cabling. Three of them have been standardized by the IEEE 802.3 standard of the Institute of Electrical and Electronics Engineers (IEEE) since 2003.

The three techniques are:

Alternative A, which uses the same two of the four signal pairs that use 10BASE-T and 100BASE-TX for data on typical Cat 5 cabling.
Alternative B, which separates the data and power conductors for 10BASE-T/100BASE-TX, making troubleshooting easier.
4PPoE, which uses the four twisted pairs in parallel, increasing the achievable power.

Alternative A transmits power over the same cables as data for the 10 and 100 Mbit/s Ethernet variants. This is similar to the phantom power technique commonly used to power condenser microphones. Power is transmitted through the data conductors by applying a common voltage to each pair. Because twisted pair Ethernet uses differential signaling, this does not interfere with data transmission. The common mode voltage is easily extracted using the center tap of the standard Ethernet pulse transformer. For Gigabit Ethernet and faster, both alternatives A and B transmit power on pairs of cables that are also used for data, since all four pairs are used for data transmission at these speeds.

4PPoE provides power using all four pairs of a twisted pair cable. This allows for greater power for applications such as pan-tilt-zoom (PTZ) cameras, high-performance WAPs, or even charging laptop batteries.

In addition to standardizing existing practices for spare pair (Alternative B), common mode data pair power (Alternative A), and 4-pair transmission (4PPoE), the IEEE PoE standards provide signaling between power supply equipment (Alternative A). PSE) and powered device (PD). This signaling allows the power source to detect the presence of a compliant device and allows the device and source to negotiate the amount of power required or available while preventing damage to non-compliant devices.

Two- and four-pair Ethernet
The original IEEE 802.3af-2003 [1] PoE standard provides up to 15.4 W of DC power (minimum 44 VDC and 350 mA) [2] [3] on each port. [4] Only 12.95W is guaranteed to be available on the powered device as some of the power is dissipated in the cable. [5]

The IEEE 802.3at-2009 PoE standard [6], also known as PoE+ or PoE plus, provides up to 25.5 W of power for Type 2 devices. [7] The 2009 standard prohibits a powered device from using all four pairs as a power source. [8] Both standards have since been incorporated into the IEEE publication 802.3-2012. [9]

The IEEE 802.3bt-2018 standard further expands the power capabilities of 802.3at. It is also known as PoE++ or 4PPoE. The standard introduces two additional power types: up to 51 W of delivered power (Type 3) and up to 71.3 W of delivered power (Type 4), optionally using all four pairs for power. [10] Each pair of twisted pairs needs to handle a current of up to 600 mA (Type 3) or 960 mA (Type 4). [11] Additionally, support for 2.5GBASE-T, 5GBASE-T and 10GBASE-T is included. [12] This development opens the door to new applications and expands the use of applications such as high-performance wireless access points and surveillance cameras.

Single Pair Ethernet
The IEEE 802.3bu-2016 amendment introduced power over single-pair data lines (PoDL) for the 100BASE-T1 and 1000BASE-T1 single-pair Ethernet standards intended for industrial and automotive applications. In two- or four-pair standards, the same supply voltage is applied to each conductor in the pair, so that within each pair there is no differential voltage other than that representing the transmitted data. With single-pair Ethernet, power is transmitted in parallel to data. PoDL initially defined ten power classes, ranging from 0.5 to 50 W (in PD).

PoDL was later added to the 10BASE-T1, 2.5GBASE-T1, 5GBASE-T1 and 10GBASE-T1 single-pair variants and, as of 2021, includes a total of 15 power classes with additional intermediate voltage and voltage levels. power.

Examples of PoE powered devices include:

VoIP phones
IP cameras, including PTZ
WAP
IP television decoders (IPTV)
Network routers
A mini network switch installed in distant rooms to support a small group of Ethernet ports from an uplink cable. PoE power is fed to the PD port (or PoE input). These switches can, in turn, power remote PoE devices using the PoE passthrough.
Intercom and public address systems and power amplifiers