User`s manual

12
6. Installation Guide & Application Note
6.1 Note for PoE Network Construction
PoE+ Extender Switch is a plug-and-play device. No any configuration
or setup is necessary. Because of some PoE spec limitation, please
follow the following application note for installation.
The key limitation of PoE application is the “maximum power delivering
limit”. For 802.3at, it could be up to 30W/port. For 802.3af, it could be
up to 15.4W/port. For a PoE switch, it also has total power budget limit.
If those limit are overload, the following problems could happen ...
1. If power request is over the power allocation on port, the power
delivering will stop because of overload. And the PD will be power
down and stop working.
2. If total power allocation is over system budget, some PoE connection
will not allocate power from the switch. And the PD will not work.
So, “power budget planning” is very important for PoE network
construction. That can prevent any device stop working because of
power limit issue.
“Cable power loss” also needs to be considered for power budget
planning. It depends on the cable quality, cable length and the
delivering power.
- If 802.3af 15.4W power is delivered on a 100 meters Cat5 cable, it
could be up to about 1.4W power loss on cable.
- If 802.3at 30W power is delivered on a 100 meters Cat5 cable, it could
be up to about 4.5W power loss on cable.
- Less power being delivered, shorter cable length, and better cable
quality can reduce power loss on cable.
6.2 Basic of the PoE+ Extender Switch
The PoE+ Extender Switch can receive power from a PoE connection on
Uplink port, or from a power adapter. And deliver power on Port 1~4.
It is a 4-port PoE switch with PoE extender function on uplink.