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As a industry standard, this technology have been used for many years in all type of IP projects. See below the list of its benefits:
Since running extra cable to power devices is no longer necessary, it's possible to save money by cutting investments on expensive power cables, outlets and all the infrastructure equipment related to electric installation.
PoE has simplified network installation while improving energy efficiency and reducing specialized technical labor costs with electricians.
In some large IP camera installation, the savings with infrastructure are estimated to up to 50%
Running only one network cable from a PoE switch to a device such as an IP camera is much simpler than run extra cable just to power the device.
A a PoE switch can be installed in a central location and power all the devices at once, it's also possible to monitor how much power each device is using by simply looking at the switch PoE management interface.
Before power up IP device, is necessary to check the total power required to make it run properly. After you find out that information you can use the correct type of switch or power injector that will meet your needs.
See below the standard based on power that can be used by the devices:
|
Properties |
Type 1: IEEE 802.3af |
Type 2: IEEE 802.3at |
|---|---|---|
|
Power available at powered device |
12.95W |
25.50W |
|
Maximum power delivered |
15.40W |
34.20W |
|
Voltage range at powered source |
44.0-57.0V |
50.0-57.0V |
|
Voltage range at powered device |
37.0-57.0V |
42.5-57.0V |
|
Maximum current |
350mA |
600mA |
|
Maximum cable resistance |
20 Ohms |
12.5Ohms |
So, when you buy an IP camera, just check the datasheet or manual to make sure its specification complies with the *IEEE 802.3af or 802.3at standard.
OK, it's time to learn more about PoE switches for IP cameras. There a lot of different options in the market and you need to understand which one is better for your IP CCTV project.
Old IP camera projects use two cables to send power and data to the camera, while modern IP camera projects uses only cable to send data en power.
A PoE switch is very useful for IP CCTV project, because it allows easy power management from a central location such as a surveillance room.
Small projects require simple solution and the use of good quality networkPoE switch can make everything simple, inexpensive and easy to manage.
A power injector is a device that can be installed between a regular network switch and a device that will be powered, such an the IP camera.
For projects that already have the network infrastructure in place, sometimes is too expensive to replace all the regular network switches and for that case, it's possible to use power injectors as shown in the picture below:
Let's see an example of a IP camera project that uses PoE switches.
Suppose there's a project to install 24 IP cameras and you want to power all of them by using a PoE switch. The first thing you need to consider is how much power each camera will consume and multiple by 24.
The picture below shows the IP camera information. Note that the camera consumes a maximum of 12W when using PoE Class 3.
So, doing the math: 24 x 12W equals 288W. That's the total power necessary for all the IP cameras that will be installed
The PoE switch catalog informs that IEEE 802.3af is supported on all ports.
As long as the switch total PoE power is equal or higher than 288W, that will enough for the project. So you must check that information with the dealer before buy the PoE switch.
Source: LearnCCTV.com
