Needless to say, security devices need power to operate. In this regard, devices can use power-over-Ethernet (PoE), which provides power to various networked systems, including video surveillance, access control and PA.
Needless to say, security devices need power to operate. In this regard, devices can use power-over-Ethernet
(PoE), which provides power to various networked systems, including video surveillance
, access control and PA.
PoE provides power over the standard Ethernet cable, making installation easier as there’s no need to run a separate electric cable to power up a networked security device, be it a CCTV camera or a door access control controller.
In fact, PoE demands prompt growth for the technology in the years to come. According to a report by MarketsandMarkets, the global PoE solutions market was valued at US$451.1 million in 2015 and is estimated to reach $1 billion by 2022, at a compound annual growth rate of 12.56 percent during the forecast period.
In a typical PoE setup, there is usually a power supplier, for example a PoE-based network switch, and power devices like the ones mentioned above. During the security design process, it is ideal to calculate the total power budget, or the power needed for the security system at a particular site, before choosing which network switch or other power supplier to purchase.
The IEEE specifies various PoE standards, which include 802.3af that provides up to 15.4 watts of DC power on each port. IEEE 802.3at, also known as PoE+, provides up to 25.5 W of power. Now, at a particular site, if there are eight 15.4W cameras and two 25.5W cameras, then the total budget will be 174W. The user therefore needs to get a 10-port PoE switch capable of supplying that much amount of power.
With the introduction of new technologies and devices, IEEE has drafted new PoE standards to meet the power demand. IEEE 802.3bt, for example, introduces two additional power types: up to 55W and up to 90 to 100W.
Typically, PoE can benefit various security systems, which are summarized as follows.
Almost all IP cameras
are made to receive power from PoE. In most cases, the 15.4W of power provided by each port on the switch is ample enough for an IP camera.
But it’s also important to realize that there are cameras that consume more power than allowed by the IEEE 802.3af, or even IEEE 802.3at, standard. Some cameras, for example, have heaters/blowers inside to keep them either cool or warm in specific conditions. When turned on, they can draw more power than the current standards allow. To meet this requirement, the user may need to purchase Ethernet switches with 55W ports.
More and more, access control systems are becoming IP-based. In a typical setup, the system includes a controller, or a reader-controller, which receives power from PoE and delivers power to the electric lock.
“The IP readers and controllers are powered over the network (PoE) and supply 12 VDC to power electric locks. Electric strikes require less power than magnetic locks. The magnetic locks also cause current surges as they are energized. This power surge requires a higher rated relay. Door access controllers that include reed-relays can support the mag locks,” said a recent blogpost
by Kintronics. “Some access control readers require a power splitter. The network is connected to one side of the splitter and the other side includes a standard network connection and a separate power plug that splits off the power for the reader-controller.”
IP paging and intercoms
Network-attached PA systems and intercoms use PoE to simplify installation as well. “Small amplifiers can be placed wherever you have a network drop. There’s no need for long speaker wire connections from a large central amplifier. Intercoms
allow you to communicate to a specific room, or any location you have a network connection,” the post said.