POE stands for Power over Ethernet, which refers to a technology that can provide DC power while transmitting data signals to some IP-based end devices without changing the existing Ethernet cabling infrastructure.
A complete PoE system includes two parts: the power supply device (PSE) and the power receiving device (PD). PSE is the device that powers Ethernet client devices, such as PoE routers, PoE switches, etc.; PDs are PSE loads that receive power, such as wireless APs, IP phones, surveillance cameras, etc.
The main standards for PoE technology are IEEE 802.3af, IEEE 802.3at, and IEEE 802.3bt. Among them, the IEEE 802.3af standard requires PSE to achieve an output power of 15.4W, and the power to reach the powered equipment is 12.95W; The IEEE 802.3at standard requires PSE to achieve an output power of 30W, and the power to reach the powered device is 25.5W; The IEEE 802.3bt standard requires PSE to achieve an output power of 60W or 90W and 51-60W or 71-90W to the powered device, respectively.
| Standard | Year | Maximum Output Power (PSE) | Device Available Power (PD) | Power supply line pair | Common applications |
| IEEE 802.3af (PoE) | 2003 | 15.4 W | 12.95 W | 2 pairs | VoIP phones, regular APs, basic cameras |
| IEEE 802.3at (PoE+) | 2009 | 30 W | 25.5 W | 2 pairs | Gigabit APs, PTZ cameras, video terminals |
| IEEE 802.3bt (PoE++) | 2018 | 90-100 W | 71-90 W | 4 pairs | Wi-Fi 6/7 AP, large camera, industrial control equipment, LED lighting |
