POE system composition: poe power supply a complete POE system including the power supply side of the device (PSE, Power Sourcing Equipment) and the receiving end of the device (PD, Powered Device) two parts. PSE equipment is the Ethernet client device power supply equipment, but also the entire POE Ethernet power supply process manager.

The PD device is to receive power from the PSE load, that is, the POE system client devices, such as IP phones, network security cameras, APs, intelligent embedded IOT serial servers and many other Ethernet devices. Based on the IEEE 802.3af, IEEE 802.3at, IEEE 802.3bt (draft) standards, both of them establish the information link about the connection, device type, power consumption level, etc. of the PDs at the receiving end of the devices, and use this as the basis for the PSE to supply power to the PDs via Ethernet.

What Is PoE and PoE Switch?

What is PoE? PoE technology was defined by the IEEE 802.3af standard in 2003. Under this standard, the PoE allows a PD (powered device) like VoIP phone to receive up to 12.95W PoE wattage, utilizing just two of the available four twisted pairs in Ethernet cabling.

Then what is a PoE switch? PoE switch refers to an application of PoE technology. Functioning as a kind of PSE (power sourcing equipment), a PoE switch can supply power to PDs via Ethernet cables to realize network connectivity. Generally, an 802.3af switch supports max power consumption of up to 15.4W per PoE port with a voltage range between 44V and 57V. And the voltage range of PDs, connected with the PoE switch, is from 37V to 57V.

What Is PoE+ and PoE+ Switch?

PoE+ technology (IEEE 802.3at standard) is an upgrade of PoE technology, which was published in 2009. PDs in the market tend to require more wattage, like wireless access points that require PoE wattage of more than 12.95W to work normally. To solve that, here comes the PoE plus technology, which can support high power consumption.

Similar to a PoE network switch, the PoE plus switch also supplies power over two pairs, but it adds an additional power class that is able to deliver power up to 25.5W for a PD with a voltage range from 42.5V to 57V. The max power delivered by each port of a PoE+ switch is 30W, along with a voltage range from 50V to 57V.

What Is PoE++ and PoE++ Switch?

In the pursuit of adding more power to broader device applications, the IEEE 802.3 standard once again is required to upgrade its PoE+ technology to PoE++ (IEEE 802.3bt standard) in 2018. PoE++ can be classified into two types: Type 3 and Type 4. Type 3 enables two or all four twisted pairs in a copper cable to deliver power at a PD of up to 51W. Type 4 is up to 71W at a PD over four twisted pairs in an Ethernet cable.

PoE++ network switch is the next generation of PoE+ technology. PoE++ switch supports up to 60 watts of power to each port under Type 3 and offers the highest level of power for Power over Ethernet switches -- up to 100W on each PoE port under Type 4.

PoE vs. PoE+ vs. PoE++ Switch: Which to Choose?

As choosing a PoE switch should depend on different requirements, this part offers the information for making the optimal choice of four types of Power over Ethernet switches from two aspects: specifications and applications.

Specifications of PoE vs. PoE+ vs. PoE++ Switch

Based on the above-mentioned introduction, a reference chart that summarizes detailed specifications among PoE vs PoE+ vs PoE++ switches is presented below.

Note: the presented figures are just valuable in theory, while the total power capacity of PoE series switches in the application will be oversubscribed with more ports for many devices using less than maximum power. For instance, if you have a switch with all PoE++ Type 4 ports, it does not mean you will use all of them at maximum load 24×7. Consequently, you need to calculate the power requirements for all the powered devices that you plan to connect to the switch and select corresponding patch cables for your PoE design.

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