With a PoE injector, a PoE terminal, e.g. an IP camera, can be connected to a switch without PoE ports. Connected at its input to the switch via patch cable, it offers a standard PoE port at its output.
A PoE splitter separates the incoming PoE connection into data (RJ45) and power (V+, V-). This allows 12/24 VDC devices to be supplied with up to 48W at remote locations.
PoE extenders increase the maximum Ethernet range from 100m by default to another 100m or, depending on the model, up to 2.4km via UTP or coaxial cable. As a Powered Device (PD), the Extenders do not need their own power supply, but take it from the incoming PoE connection. At their output, they offer one or more PoE ports for connecting Ethernet devices with or without PoE.