Powering Access Control
New standard allows manufacturers to design products with bigger features
- By Ronnie Pennington
- Feb 01, 2020
The new IEEE802.3bt PoE standard, also often referred
to as PPoE or 4-Pair PoE, is a game-changing
solution for powering 12VDC and 24VDC
access control and related devices. IEEE802.3bt
introduces two new types of PoE; one providing
up to 55W and the other up to 75W. Unlike Hi-PoE (60W),
IEEE802.3bt uses all four pairs of wire in a structured cable to
evenly distribute power. This new standard allows manufacturers
of powered devices to design new products with bigger features,
faster motors and more capabilities.
To date, there are few products on the market that have already
adopted the 802.3bt standard. Aside from PoE lighting,
there are some infrared illuminators that adhere to 4PPoE, but
now that this standard has been ratified, manufacturers are looking
to take advantage of this standard for new products.
There are several sources for PoE injectors that supply 802.3bt
up to Type 4. For example, Altronix NetWay Midspans are available
in single or multi-port options with larger wattage power
supplies to cut down on the number of injectors for larger projects.
And just recently, Altronix introduced switches offering
4PPoE outputs. This is a good indicator that we will see a lot
more devices demanding more power.
When we think of power supplies, they normally have a high
voltage input such as 115VAC that is converted into 24VAC or
12/24VDC. There are other power supplies that accept a 24VAC
input and convert to 12VDC or lower. For example, when a simple
burglar alarm panel requires 16.5VAC input, the panel converts
this to 12VDC. This 12VDC will also power the keypad and
charge a battery for backup. Though the video surveillance world
is going mostly IP and using PoE for power, HD analog cameras
for the most part still require 12VDC.
A big application using power supplies hardwired with high
voltage is for the deployment of electrified locks. These power
supplies generally take 115VAC power input and reduce this to a
12VDC or 24VDC output. That single output is then connected
to a distribution board where the electrified magnetic locks or
strikes are connected. Most jurisdictions require that this power
input be hardwired with a dedicated circuit. Due to the high voltage,
a certified electrician must wire this type of installation.
While some security integrators do have certified electricians
on staff, the use of high voltage still adds to the cost of any installation.
In large cities like Chicago, Boston, or New York, electricians
have offices in the same building as the access control system.
This limits contracting your own electrician to do the work.
The installation also requires dedicated conduit runs as well as
expensive large gauge copper and a dedicated circuit breaker. The
new 802.3bt 4PPoE standard helps curtail this costly practice.
4PPoE delivers up to 75W of total power. Using new solutions
like Tango PoE driven power supplies from Altronix, we can
harness the IEEE 802.3bt standard. Tango solutions allows for a
PoE input of 15.4W, 30W, or the new 4PPoE 100W and converts
it to a useable 75W of available power. With 75W available, the
flexibility to power an entire access control system is a reality.
Here is the breakdown using Mercury boards, one of the most widely used platforms in access control.
Based on this data, you can see that 75W can potentially
power an entire 8 door system. If these levels are too close for
comfort, there are ways you can save power: use a midspan injector
or PoE switch that has battery backup. This would eliminate
the battery backup on the PoE driven power supply and
alleviate 10W. You can also limit the PoE driven power supply
to 4-6 doors and use 2 power supplies, putting the 12VDC devices
on one power supply and the 24VDC devices on the other.
The cost for the second power supply will certainly be less than
using an electrician.
Additionally, the access control manufacturer you are working
with may draw less power on the panels. Keep in mind that
this method of powering your access control system will eliminate
the need to schedule a certified electrician to wire up the
power supply. The category cable used for power can run in the
same cable trays and paths as other network cabling.
When servicing the system, unplugging the Ethernet cable
from the PoE driven power supply is safe with no voltage present.
Once the cable is back in, the handshake is performed with the
power source and 802.3bt PoE is sent back to power the system.
IEEE802.3bt 4PPoE has made its way into our world of security
and we can take full advantage of its characteristics to save
money, labor and make our installations much safer to work with
innovative PoE driven power supplies like Tango from Altronix.
Take a look at a recent access control project
you installed, and calculate how much you
would have saved using 4PPoE and a PoEdriven
Power Supply. You may be surprised at
the savings.
This article originally appeared in the January / February 2020 issue of Security Today.