How does a POE Injector work?
In situations where Ethernet switches or other devices lack PoE functionality but require support for Powered Devices (PDs) such as PoE IP cameras, PoE wireless access points (WAPs), PoE lighting, and more, a PoE injector can provide a solution for transmitting power and data up to 100 meters. A PoE injector typically converts alternating current into direct current to serve as a power source for low-voltage PoE devices.
PoE Injector Varieties
Active vs. Passive PoE Injectors
PoE injectors are designed to follow the IEEE802.3af, IEEE802.3at, or IEEE802.3bt PoE standards – this is known as active PoE. The standard mandates a communication handshake between the power sending and receiving devices, so an 802.3af/at/bt injector will only provide power if it receives the proper acknowledgement from the receiving device. The PoE injector will verify the incoming power and only activate if it meets the device’s power requirements, ensuring the PoE device’s safety. Typically, 802.3af/at/bt PoE voltage will range from 44 to 57 volts DC.
In contrast, passive PoE injectors utilize PoE technology that does not comply with the 802.3af, 802.3at, or 802.3bt standard. Passive PoE devices typically operate on 18 to 48 volts DC, and using the wrong voltage could lead to permanent electrical damage.
12V vs. 24V vs. 48V PoE Injectors
PoE injectors are generally categorized based on the output power voltage they can provide, with 12V, 24V, and 48V being the most common options. When purchasing a PoE injector, it’s important to match the voltage of the injector to the voltage standard required by the PoE device that needs to be powered.
Aside from the above categories, PoE injectors can also be grouped according to the number of ports they have, such as single-port PoE injectors, 8-port PoE injectors, and so on.