PoE or Power Over Ethernet is a technology where you can save money and time at the same time by using the same Ethernet cables both for Data as well as power. To convert the power over ethernet, you need to find a proper PoE, PoE+, or PoE++ switch.  But wait! what do you know about these switches? What are the differences between them and how to choose the right switch as per your need? PoE PoE technology was defined by the IEEE 802.3af standard back in 2003. Under this standard, the PoE allows a powered device (PD) like CCTV Cameras or VoIP phones to receive up to 12.95W PoE wattage, it utilizes 2 Pairs out of four twisted pairs in Ethernet cabling. PoE Switch It’s a device that works as a kind of power sourcing equipment (PSE), a PoE switch can supply power to powered devices 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 where as the Powered devices connected to this should have voltage ratings between 37V to 57V. PoE+ PoE+ technology (IEEE 802.3at standard) is an upgraded form of PoE technology, which was published in 2009. Some powered devices with more wattage requirement was the reason of this upgrade like wireless access points that require PoE wattage more than 12.95W to work normally. To tackle this the PoE plus technology was introduces, which can support high power consumption products. PoE+ Switch Similar to a PoE network switches, the PoE plus switch also supplies power over two pairs, but it adds an additional power class that is able to deliver more power up to 25.5W for a powered device 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. PoE++ With the increasing demand of power the IEEE 802.3 Standard launched PoE++ technology which is IEEE 802.3bt standard. The main reason was to support the broader range of power consuming devices that consumes more power. They introduced two different types this time which can be classified as Type-3 & Type-4 respectively. By the way, here it is very important to mention that the previous two types are Type-1 (PoE) and Type-2 (PoE+). In Type-3 two or all four twisted pairs of a pure copper conductor cable can be used to transfer the power to a device up to 51W Max. In Type-4 the power is up to 71W at a Powered device over four twisted pairs in a pure copper Ethernet cable. By the way, Cisco’s proprietary technology UPoE (universal Power over Ethernet) works similarly to the PoE++ Type 3, which extends the IEEE PoE+ standard to double the power to a Powered device to 51 watts. PoE++ is also called UPoE sometimes. Similarly, with the upgrade of PoE technologies their switches also upgraded to meet the need of the IEEE standards. PoE++ switches can deliver up to 60W on each PoE port under the Type-3 and up to 100W under the Type-4. Choosing the Right Switch Below is the simple comparison chart, which is based on the above introduction and would definitely be helpful in understanding the specs more clearly and this table will lead you to choose the best switch for your need.
  PoE PoE+ PoE++ / UPoE
IEEE Standards IEEE 802.3af IEEE 802.3at IEEE 802.3bt
PoE Types Type-1 IEEE 802.3at Type-2 IEEE 802.3at Type-3 IEEE 802.3bt Type-4 IEEE 802.3bt
Power available at PD (Powered Device) 12.95 W 25.50 W 51 W 71 W
Maximum power delivered by PSE (Power Source Equipment) 15.40 W 30 W 60 W 100 W
Twisted Pairs Used 2-Pairs 2-Pairs 2-Pairs ; 4 Pairs 4-Pairs
Voltage range (at PD) 37.0–57.0 V 42.5–57.0 V 42.5–57.0 V 41.1–57.0 V
Voltage range (at PSE) 44.0–57.0 V 50.0–57.0 V 50.0–57.0 V 52.0–57.0 V
Maximum current Imax 350 mA 600 mA 600 mA per Pair 960 mA per Pair
Maximum cable resistance per pair-set 20 Ω (Cat3 Cable) 12.5 Ω (Cat5 Cable) 12.5 Ω 12.5 Ω
Min Supported cabling Cat3 and better Cat5 and better Cat5 and better Cat5 and better
Examples of PD’s VoIP Phones Access Points Sensors Static CCTV Cameras Video IP Phones Alarm Systems Pan/Tilt/Zoom Cameras Laptop’s TV’s LCD Monitors
Preferred Supported Conductor Type 100% Solid Copper Conductor
Note : The presented figures are just valuable in theory. In fact, PoE series switches often oversubscribe the total power capacity of a switch with more ports. That is because many devices will use 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 switch and select corresponding patch cables for your PoE design.

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