What is PoE or Power Over Ethernet?

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Power Over Ethernet, abbreviated as PoE

If Ethernet already carries electrical power, why is it considered a feature? Since it is a set of copper cables distributed in twisted pairs and sends electrical impulses of +/- 2.5V, can we say that there is already an electrical supply or not?


While electrons flow through a network cable, which can be measured as a voltage potential, they are used for communication rather than power supply. In other words, devices connected in a network don’t typically use that voltage to provide power but to “read” that energy and interpret it as information.

However, why not utilize the copper pairs to not only transmit information but also deliver sufficient voltage that can serve as “power” to turn on a device, in addition to receiving communication, eliminating the need for conventional electrical contacts.

Conventional electrical contacts have a potential of 110 to 220 volts and their medium of transport is alternating current that flows between positive and negative flows. However, modern computers do not require that voltage and operate based on direct current that needs to be stable to transmit electrical “pulses.” Therefore, almost all computer equipment converts alternating current to direct current using a transformer, typically ranging from 5V to 48V depending on the application and hardware requirements.

Small devices that consume low electrical power, such as Wi-Fi antennas, surveillance cameras, or IP phones, require low voltage to operate. Connecting them to a conventional electrical contact, aside from being inefficient, could entail significant electrical wiring expenses. Therefore, using low voltages through Ethernet cables to “power” or provide voltage to computer equipment makes economic sense, as well as being simple and efficient.




Therefore, PoE or Power Over Ethernet indicates the ability of devices to either provide or be powered by energy through an Ethernet communication cable.

In the case of providing power, the devices used for this function are PoE-enabled Switches, which must have special power sources for this task. It is important to validate their power supply capacity, as exceeding it may result in insufficient power to energize the connected devices.

There are also Power Injectors that receive communication through an Ethernet cable but are connected to a conventional power supply to provide direct current to the PoE-enabled Ethernet output.

On the other hand, devices capable of turning on and operating through Ethernet must specify in their technical specifications whether they can receive PoE through their network interface card.

Power over Ethernet technology (PoE) simplifies network designs by addressing the electrical aspect in many cases. As more devices become more efficient in terms of the required voltage to operate, we will see new applications, such as LED lamps that can now be powered by PoE, gradually reducing the need for conventional electrical contacts.


Conoce más sobre los Distintos Tipos de PoE 802.3af 802.3bt

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