More Power to You
IEEE802.3bt provides more versatility and cost efficiency
- By Ronnie Pennington
- Dec 01, 2019
Many of you may remember the show “Home Improvement”
from the 1990s with Tim the Tool
Man, who was played by comedian Tim Allen.
In most episodes, Tim pursued his continual
quest to supplement everyday appliances with
“more power” often with reckless abandonment, but always in a
humorous and almost slapstick manner. Today’s professional security
industry seems to have adopted the “more power” mantra
by taking a much more pragmatic approach, as edge devices continue
to become more complex and are pushed to new physical
distances to extend the reach of security, access and surveillance
networks. The adoption of the new IEEE802.3bt PoE standard
clearly supports this on-going trend.
Now often referred to as 4PPoE or 4-Pair PoE, IEEE802.3bt
provides up to 90W over all four pairs of wire in a structured
cable to evenly distribute power. This allows IEEE802.3bt to be
deployed for two distinct types of installation applications. The
first is to power new PoE products with bigger features, faster motors
and more capabilities. The second, and perhaps more significant,
is to provide 12VDC and 24VDC to non-PoE compatible
devices, such as maglocks or strikes, using new PoE-driven power
supply solutions.
802.3BT Midspan/Injectors
Pave the Way
We are already starting to see more manufacturers explore the
use of 802.3bt beyond LED lighting for a variety of access and
surveillance devices.
In preparation for these next generation products, new PoE
injectors, such as Altronix NetWay 802.3BT (4PPoE) Series Managed
Midspans, are already available. Capable of delivering up
to 90W per port (480W total on 4 port models), these new midspans
provide power for the latest power-hungry illuminators
and multi-sensor PTZ cameras that conform to the new IEEE
standard.
New PoE Driven Power Supplies
Using IEEE802.3bt injectors/midspans to provide power to PoEdriven
power supplies is a game changer as it significantly reduces
the overall cost to deploy access control and myriad security devices
by eliminating the need for a licensed electrician.
One immediate mainstream application is deploying electrified
locks and strikes. New PoE-driven power supplies like the
Tango1B from Altronix allows for a PoE input of 15.4W, 30W, or
the new 4PPoE 90W and converts it to a useable 75W of available
power. While there are PoE adapters that convert to 12VDC or
24VDC, the available power is limited. With 75W available, an
installer can have the ability to power an entire access control system,
including the panels, locks, readers, request to exits devices
and charging batteries all with a single Cat 6 cable.
For example, based on calculations using Mercury controllers,
75W can potentially power a conventional eight-door access
control system. If the 75W capacity is too close for comfort and
you prefer to have reserve power built into the system, you can
reduce power consumption by installing a midspan injector or
PoE switch that has battery backup.
This eliminates the need for battery backup on the PoE-driven
power supply and alleviates 10W. If that is not the route you
want to take, limit the PoE-driven power supply to 4-6 doors, and
use two PoE-driven power supplies with 12VDC devices on one
power supply and the 24VDC devices on the other. The cost to
add the second PoE-driven power supply will certainly be much
less than the cost of an electrician to provide power at the installation
location.
This method of powering an access control system will eliminate
the need to schedule a certified electrician to wire the power
supply, and run a dedicated conduit to the electrical panel. It also
makes installation and system maintenance easier. The category
cable used for power can run in the same cable trays and paths as
other network cabling as well as the access control cable.
When servicing the system, there would be no high voltage
inside the enclosure making it safe to unplug the Ethernet cable
from the PoE driven power supply. Once the cable is plugged back
in, the handshake is performed with the midspan/injector and
802.3bt PoE is sent back to power the system.
The new IEEE802.3bt 4PPoE standard provides a host of
benefits and allows for a new generation of high-powered security
and surveillance devices to be deployed with
extreme efficiency at the edge. More power to
all of the system designers, integrators and endusers
out there.
This article originally appeared in the November/December 2019 issue of Security Today.
About the Author
Ronnie Pennington is the national sales engineer at Altronix Corp.