What is POE
What is PoE Power?
PoE (Power over Ethernet) is a method of providing power and data at the same time using a single UTP (twisted pair) cable for a wide range of devices, ranging from office telephones, through antennas, switches, routers and ending with CCTV devices.
Due to the different energy demand, several PoE standards have been created, and some manufacturers have gone a step further and, based on the very idea of PoE, have created their own variations.
Colloquially speaking about PoE, we mean generally accepted standards, 802.af and 802.at, where powered devices require 48V voltage. PoE cameras and Zintronic PoE recorders work in these standards.
Differentiation of standards
The PoE 802.af standard was developed in 2003, according to a standard power supply device (PoE NVR, PoE Switch) should supply approx. 44~57V at the power supply port at 350mA, which gives us more or less 15W for a given port; while the powered device (e.g. PoE camera) should receive approx. 37~57V at 13W. With the 802.af standard, we can use UTP Cat.3 and Cat.5 cabling to provide power, however, due to the requirement to transmit quite a large amount of data between CCTV devices - a Cat.5e twisted pair cable is required.
The PoE 802.at standard (so-called PoE+) was developed in 2009, according to a standard power supply device (PoE NVR, PoE Switch) should supply approx. 50~57V at the power supply port at 600mA, which gives us more or less 30W for a given port; while the powered device (e.g. PoE camera) should receive approx. 42~57V at 25W. With the 802.at standard, we can only use UTP Cat.5 and Cat.6 cabling to provide power, due to the requirement to transfer quite a large amount of data between CCTV devices - a twisted pair cable of at least Cat.5e category is required.
In both standards, we distinguish two methods (modes) of making a twisted pair - A and B. This is important because each of the modes uses different pairs of wires for data and power transmission. Zintronic devices operate in both T568A and T568B modes.
As I mentioned earlier - some manufacturers of CCTV devices use their own standards in accordance with the PoE idea, these are not generally accepted standards, however, having contact with this type of equipment - it is worth mentioning:
A large part of Ubiquiti devices is powered by 24V, colloquially we call this type Half-PoE (half PoE).
There are also PoE cameras powered by 12V, this type of equipment is widely available and advertised as 'PoE', especially on websites offering cheap electronics from China.
NOTE: Always make sure that your PoE power device and the PoE powered device are working in the same standard and in the same mode. Non-compliance with power standards can lead to permanent equipment damage.
Passive PoE - This is the use of a UTP cable to supply power to devices that do not support PoE power (e.g. ordinary network cameras). In this case, we inject the 12V power supply (from the camera's power supply) onto the free wires of the UTP cable using the PoE Splitter on the switch / router side, and using the same PoE Splitter we separate the power supply and data transmission for the camera connections.
Semi-Active PoE - This is the use of a PoE power supply device (switch, NVR) to power a device (camera) that does not support PoE power supply. In this case, we lead a single UTP cable from the PoE power supply device and at its end we connect a PoE stabilizer that will reduce the voltage from 48V to 12V and distribute the power and data supplied via the UTP cable to the DC and RJ45 terminals; only we connect the camera to the PoE Stabilizer.
Advantages and disadvantages of PoE
An undoubted advantage of PoE devices is the reduction of the amount of cabling needed to operate the devices. Due to the need to run only one cable for data and power over quite large distances, you can afford to install the cameras in places where it is not possible to connect devices to the mains power supply. This type of solution helps to reduce installation costs, despite the slightly higher initial price of PoE devices.
The disadvantage of PoE power supply is the need to use devices of the same standard, the initial cost of PoE devices is also relatively higher compared to devices not equipped with this power standard. The biggest disadvantage, however, is the need to replace / service the entire PoE power device at the time of failure; if we use a PoE recorder and it fails - you will have to disconnect the recorder from the monitoring network and send it to the Service.