peo power supply

The principle of the last POE power supply via cable, many friends asked me privately what is the power supply method of PoE equipment? Today, let's talk about the power supply method of PoE equipment!

According to the definition of the 802.3af / at standard, the PoE power supply system includes two types of equipment, PSE and PD.

PSE

(1) Definition of PSE equipment:

PSE (power-sourcing equipment) is mainly used to supply power to other equipment.

(2) Classification of PSE equipment:

It can be divided into two types,

Midspan equipment: PoE function is outside the switch or other network equipment.

Endpoint equipment: PoE functionality is integrated into switches or other network equipment.

2. PD

(1) Definition of PD equipment:

PD (Powered Device), a device used to receive power in a PoE power supply system.

(2) Types of PD equipment:

Wireless AP equipment;

IPPHONE device: camera;

3. Power supply mode:

At the same time, the 802.3af / at standard also defines PI (Power Interface: interface between PSE / PD and network cable).

â‘  Classification of PI:

Alternative A (AlternativeA): Network cable 12, 36 pair power supply, that is: signal line power supply;

Alternative B (AlternativeB): Network cable 45, 78 pair power supply, that is: idle line power supply.

â‘¡ Safety / reliability description of PoE power supply:

Because DC current and data frequency do not interfere with each other, current and data can be transmitted on the same pair of wires at the same time. In fact, it can be regarded as a kind of "multiplexing" for cables.

The voltage provided by PoE is below 57V, which is a "safe voltage" and meets the safety requirements.