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67
BY
IAN
MILLNER
(PoE). This is power delivered over
Category 5 cabling or, even better,
Category 6.
The Standards continue to evolve, and
they are getting to a point where they
can deliver up to 70W of power on Cat 5
or better cable.
The first Standard was IEEE 802.3af,
which supported 15.4W. Then came IEEE
802.3at, which supported up to 30W.
The benefit of the technology is that
you can start to power devices such
as IP phones; IP cameras; a range of
devices for security, fire detection and
environmental monitoring; aged and
assisted living; and home health.
Structured cabling brings it all back
to a central location where you locate
the patch panel and all the essential
communications equipment – the
broadband NTD and/or modem, the
gateway, the security system and
monitoring systems.
This means you can install one UPS to
support everything at one central point.
Figure 1 shows an installation
without PoE, and you can see that
every device needs to be connected to a
240V AC socket.
Figure 2 shows an installation with a
PoE switch. Now power to the phone,
CCTV camera and home gateway can
come from that switch.
How does PoE work? It’s simple. The
Ethernet port in the gateway/switch
injects a DC voltage into two or more
pairs of the Ethernet port.
This means that if you need to provide
back-up to the DSL modem and the CCTV
camera only, you could install a UPS next
to the telecommunications equipment
then connect the DSL modem and the
PoE switch to the UPS.
All other devices can now be
connected to the PoE switch, which
provides networking access and power.
You can then program the PoE switch to
power only certain ports during a mains
power failure.
So far we are only seeing the
beginning, but one thing you can be sure
of is that PoE is here to stay and will
cause disruption in areas you may not
have considered.
You can do one of two things – ignore
it or embrace it.
A final word: several manufacturers
use PoE technology for lighting systems,
so think very carefully about the choices
you make.