The TP-POE-1824G is a unique Power over Ethernet adapter which converts an 802.3af/at 48VDC PoE input into an 18V or 24VDC regulated passive PoE output. The PoE output voltage is an 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.