The TP-POE-1824G is a unique Power over Ethernet adapter which converts an 802.3af/at 48VDC PoE input into a 18V or 24VDC regulated passive PoE output. The PoE output voltage is external jumper selectable and capable of up to 25W power output.
This part is 10/100/1000MB compatible and has a 24W output.
They accept data-in and 802.3af/at PoE to a shielded RJ45 Jack and provide data-out and 18V or 24V PoE on the shielded RJ45 output jack. They work by supplying power to the remote device on the unused Ethernet pins 4,5(V+) and 7,8(V-). The Ethernet spec supports distances up to 100m (328 feet). They have various protections for surge, short circuit, overload and overvoltage.