Tripp Lite NGI-S08C2POE8, Owner'S Manual

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4.3. Power Over Ethernet (PoE)
Power over Ethernet or PoE technology describes a system to pass electrical power safely,
along with data, on Ethernet cabling. PoE requires category 5 cable or higher for high power
levels, but can operate with category 3 cable for low power levels. Power can come from a
power supply within a PoE-enabled networking device such as an Ethernet switch or can be
injected into a cable run with a mid-span power supply.
The original IEEE 802.3af-2003 PoE standard provides up to 15.4W of DC power (minimum
44V DC and 350mA) to each device. Only 12.95W is assured to be available at the powered
device as some power is dissipated in the cable.
The updated IEEE 802.3at-2009 PoE standard (also known as PoE+ or PoE plus) provides up
to 25.5W of power. Some vendors have announced products that claim to comply with the
802.3at standard and offer up to 51 W of power over a single cable by utilizing all four pairs in
the Cat5 cable. Numerous non-standard schemes had been used prior to PoE standardization to
provide power over Ethernet cabling. Some are still in active use.
PSE : Power sourcing equipment (PSE) is a device such as a switch that provides ("sources")
power on the Ethernet cable.
PD : A powered device (PD) is a device such as an access point or a switch, that supports PoE
(Power over Ethernet) so that it can receive power from another device through a 10/100 Mbps
Ethernet port.
Total PoE power budget 128W
Vin (Power Input) 24~57V DC
Vout (PoE Output) 50V DC
Standard PoE parameters and comparison
Property
802.3af (802.3at Type 1) 802.3at Type 2
Power available at PD 12.95W 25.50W per mode
Maximum power delivered
by PSE
15.40W 30.00W per mode
Voltage range (at PSE) 44.0 - 57.0V 50.0 - 57.0V
Voltage range (at PD) 37.0 - 57.0V 42.5 - 57.0V
Maximum current 350mA 600mA per mode
Maximum cable resistance 20 Ω (Category 3) 12.5 Ω (Category 5)
Power management
Three power class levels
negotiated at initial
connection
Four power class levels negotiated
at initial connection or 0.1 W steps
negotiated continuously
Dreading of maximum
cable ambient operating
temperature
None
5°C with one mode (two pairs)
active, 10°C with two modes (four
pairs) simultaneously active
Supported cabling Category 3 and Category 5 Category 5
Supported modes
Mode A (end span), Mode B
(mid-span)
Mode A, Mode B, Mode A and
Mode B operating simultaneously