Information about planning and application
System Manual 2CKA000073B9795
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5.2.3
PoE planning (Ethernet, WLAN)
Functioning
The necessary Ethernet cable can also be used for the energy supply of network devices. Aside
from the data, it can also transmit current, which cancels a separate power supply.
The network devices can be sub-divided into supplying (PSE: Power Source Equipment) and
supplied (PD: Powered Devices) devices.
This mechanism is already integrated in many devices. To upgrade devices without PoE
functionality, additional devices can be used as power supply system (PoE injectors) and intake
(PoE splitter).
Devices as power supply system (Endspan/Switch, Midspan)
For the PoE power supply system, the availability of the power supply, any PSE device can be
used. It must only be ensured that the necessary performance class is supported.
PSE devices are usually Endspan devices such as PoE switches. For the later integration of
PoE loads into existing networks, Midspan devices such as PoE injectors are often used.
The voltage is fed in from the last device before the load. It can not be distributed by
conventional switches.
Performance classes / Consumption
PoE exists in two different versions.
Designation
802.3af (PoE)
802.3at (PoE+)
Supply voltage
48 V
48 V
Maximum power consumption
350 mA
600 mA
Maximum power output
15.4 W
25.5 W
Table 6: PoE rerformance classes
Version 802.3at is the successor of 802.3af. It is downward compatible to 802.3af, i.e. all
802.3at PSE devices can also supply power to 802.3af PD devices. For operating ABB-
Welcome IP devices the performance of 802.3af is already fully adequate.
