Tenda PoE injector, like the PoE30G-AT, is a device that provides power and data over a single Ethernet cable to devices like wireless access points or security cameras. It allows for extended power reach, up to 100 meters, and supports the IEEE 802.3at/af standards for compatibility with various PoE-enabled devices. These injectors are often used to simplify network deployments by reducing the need for separate power outlets and cabling.