What is Power over Ethernet (PoE)?
Power over Ethernet or PoE is a technology that makes it possible to transport both data and power over a single UTP / network cable. This makes an external power adapter superfluous. This makes it possible to mount cameras in places where there is no power supply.
Standard with or without PoE
Modern ip cameras are available with and without built-in PoE function. Cameras with a built-in PoE function can be connected directly to a PoE recorder. A camera without PoE cannot use the power supply from the PoE recorder and will have to be equipped with an external 12V adapter.
It is also possible to combine ip cameras with and without PoE on a recorder with PoE.
Technology of Power or Ethernet
Earlier we briefly explained what Power or Ethernet content. The technology is also known as IEEE 802.3af. A standard UTP cable has 8 cores, however only 4 of them are used. The other 4 cores are therefore free and can be used for PoE to deliver power in pairs. This includes a specific protocol, which first measures whether a PoE device is connected, what power is needed and only then will the necessary voltage be offered on the line. This is very important, as some devices short-circuit the unused cores. This process is fully automatic and you will not notice.
In general, the available power per wire pair is 16 watts. With 4 available cores, the maximum is about 32 watts. During the transfer through the cable there is a small loss of power due to resistance, so the realistic power is around 30 watts.
Application of Power or Ethernet
PoE's technology is used to power network equipment such as cameras, recorders, VoIP phones, switches, antennas for wireless networks, small computers and tablets. This makes an external power supply superfluous. Given the limited power a network cable can transmit, this technology is not suitable for heavier consumers such as computers or servers.