Principle and advantage of Power over Ethernet (PoE)

PoE (Power over Ethernet, also known as remote Power supply), the PoE Power supply device will add Power to the network line, through the network line simultaneously transmission data and Power, to achieve the first line dual use. When it comes to PoE systems, PSE and PD are inseparable.

PSE：（Power Sourcing Equipment）It refers to the power supply terminal equipment, and is also the administrator of the power supply process of PoE Ethernet. Such as a PoE switch.

PD：（Power Device）It refers to devices that receive electricity from PSE, such as PoE network cameras, wireless AP and so on. Based on IEEE 802.3 af/ats standard, both for the electric equipments of PD connectivity, the types of equipment, power consumption level and other aspects of information, based on, PSE PD power supply via the Ethernet.

The standard five types of network cables consist of four pairs of double stranded wires with a total of 8 core wires, of which 1, 2, 3 and 6 are data cables and 4, 5, 7 and 8 are idle wires. IEEE802.3af allows two linear power supply methods. 1. Power supply of idle line: transfer current on idle line 4, 5, 7 and 8 cores, and transfer data on line 1, 2, 3 and 6 cores. 2. Power supply of data line: transmit data and current simultaneously on data line 1, 2, 3 and 6.

The PoE system works as follows：

1. Detection：PSE devices output a small voltage at the port until it detects a connection to the cable terminal that supports the IEEE 802.3af standard.

2.  Classification：When PSE detects the required PD device, the output voltage will be further increased to grade the PD device. Different levels correspond to different working power.

3. Power Supply：After confirming the classification, PSE equipment began to supply power to PD equipment from low voltage until it provided stable and reliable direct current power for PD equipment.

4. power supply management：It provides stable and reliable direct current for PD equipment, and is also a process of continuous monitoring of PoE power supply.

5.  blackout：If the PD power receiving device is disconnected from the network line, PSE power supply device will quickly stop power supply and re-check whether the cable terminal is connected to the receiving device.

The advantages of POE technology：

1. easy construction：The PoE system only needs network wiring and does not need to lay power cord, which not only solves the inconvenient problem of engineering power wiring, but also greatly saves the time and energy required to deploy the power supply system.

2. High security: no need for strong electricity distribution, construction safety is greatly improved, and there is no strong power interference.

3. Simple to install: just connect PSE and PD devices via a network cable.

4. Simple debugging: PoE IPC and PoE switch, plug and play, no tedious configuration operation, power on automatically have a picture。

5.Cost saving: save the cost of equipment such as power cord, power adapter, etc.

6. Low maintenance cost: less topological nodes, no need to maintain the power adapter, power cord, power socket and other intermediate link equipment, and low maintenance rate and simple maintenance cost.

7. Energy conservation and environmental protection: the power identification function of PoE equipment is generally provided in the hooking power module, which can realize the power source adaptation without causing power waste and achieving effective energy saving.

8.Centralized power supply: PSE power supply, centralized power supply scope, easy to manage stability

Beautiful: the installation is simple, do not need to deal with the power adapter separately and set waterproof box and other equipment that affect the appearance