1.Definition:
A Power over Ethernet (PoE) injector provides data and DC power over a twisted pair [Cat5e and Cat6] cable to the remote devices.
There are two types of PoE injector, passive PoE injector and active PoE injector.
2.Passive injector
In the common “passive” PoE system, 2 twisted pairs (4 wires) in Ethernet cable are simply merged into two wires to transport the electric power from an external power adapter.
3.Active injector
While active injector is integrated with power source with the voltage and wattage are determined by the injector.
In addition to, active PoE injector also divides into standard and non-standard type. What’s the difference is whether the injector and the powered device have some protocols in common or not. The standard PoE injector complies with three standards, namely, IEEE 802.3af, IEEE 802.3at or IEEE 802.3bt power negotiation protocols while non-standard PoE injector transmits power to the powered device without negotiation of its required voltage or wattage from remote ip devices, and merely supplies power at all times, that is why it is also known as “always ON”.
4.Typical PoE injector
(1)30W 802.3at PoE+ Midspan Injector
(2) 90/95W Power Over Ethernet Injector
(3) 8 Port Managed PoE Injector