INS_CWGE10FX2TX8MSPOE 02/19/21 PAGE 98
INSTALLATION AND OPERATION MANUAL
CWGE10FX2TX8MSPOE
TECH SUPPORT: 1.888.678.9427
Power over Ethernet (PoE)
PoE
Introduction
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 midspan power supply.
The original IEEE 802.3af-2003PoE standard provides up to 15.4 W of DC power (minimum 44 V
DC and 350 mA) to each device. Only 12.95 W is assured to be available at the powered device as
some power is dissipated in the cable.
The updated IEEE 802.3at-2009PoE standard also known as PoE+ or PoE plus, provides up to
25.5 W 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 Cat.5
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.
Standard PoE parameters and comparison
Property
802.3af (802.3at Type 1)
802.3at Type 2
Power available at PD
12.95 W
25.50 W per mode
Maximum power delivered by PSE 15.40 W
30.00 W per mode
Voltage range (at PSE)
44.0 - 57.0 V
50.0 - 57.0 V
Voltage range (at PD)
37.0 - 57.0 V
42.5 - 57.0 V
Maximum current
350 mA
600 mA 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 (endspan), Mode B
(midspan)
Mode A, Mode B, Mode A and
Mode B operating simultaneously