All about POE ( Power Over Ethernet) to Power IP Devices

PoE is the most suitable technology made for network-connected devices. PoE is a short form of Power over Ethernet and is widely used to power IP-based devices through a single Ethernet cable. Power over Ethernet allows both data and power transmission over one cable, making it ideal for VoIP phones, IP security cameras, IP paging speakers, Wi-Fi access points, and other PoE-enabled devices. As a trusted Patton Electronics supplier in US, Spogmey offers a wide range of networking brands and enterprise-grade solutions to help businesses choose the right PoE products based on their infrastructure needs and performance goals.

How does PoE power work?

PoE works by having a PoE power source drive power to a connected PoE-enabled device through an Ethernet cable. 

The device providing the power is known as the PSE: Power Sourcing Endpoint. The device being powered is referred to as a PD: Powered Devices. There are two PSEs used for a PoE: a PoE switch and PoE injectors. 

What are PoE Injectors?

PoE injectors are used with Ethernet cables that don’t have power running through them. You connect the unpowered cable to a PoE injector, which then “injects” power into cables. A standard power supply powers the injector. Then you run another cable from the injector to the PoE-enabled device. PoE injectors are also known as PoE midspans, because you use them between a switch and a device. You might also see them referred to as PoE adapters sometimes.

What are PoE Switches?

PoE switches are network switches that support PoE; that is, they can power connected PoE-enabled devices. They also act as standard network switches: You don’t need separate PoE switches and network switches. You might see them mentioned as PoE end spans.

One thing you need to be careful about is that each PSE, whether it’s a PoE switch or PoE injector, has a limit to how much power is provided. They will support different PoE standards. We get into these standards in just a second. 

Another device you need to look out for is PoE extenders. Power on over Ethernet can travel a maximum distance of 100 meters (328 feet) via Ethernet cable. PoE extenders let you push power for longer distances. What happens is that you lose roughly 5W of power for each extender, so you’ll need to take into account the increased power requirements.

What are the different Power Over Ethernet Types?

Types of POE ( Power Over Ethernet) to Power IP Devices differ by how much power they can give.  PoE standards are found under section 802.3 of the IEEE 802 LAM/MAN standards. That means that it’s an industry standard for computer networks. Section 802.3 gives standards for Ethernet, so PoE is part of that section. These standards are well-established, extremely dependable, and very widely used across the industry. 

Power over Ethernet was first standardized in the year 2003. It has later added to, which is why it is a set of standards. They specify how the power should be provided as well as the quantity of power a PSE provides to a PD. We will see how much power a PD (power devices) has available to it (input power) rather than how much power a PSE delivers (output power). Due to attrition in the cable, a PSE pushes more power than a PD receives. 

Here are the three PoE standards in POE ( Power Over Ethernet) to Power IP Devices you should know: 

• 802.3af-2003 provides for input power of up to 12.95 W. It is known as PoE. 
• 802.3at-2009 provides for input power up to 25.50 W. It is known as PoE Plus or PoE+.
• 802.3bt-2018 provides for input power up to 71.3 W. It is known as 4PPoE or PoE++.

In case you are wondering about the name of 802.3 bit as (4PPoE). This is short for “Four-Pair Power Over Ethernet”. Ethernet cables are arranged in pairs of circuits; for better electromagnetic compatibility, they are twisted together. The first two PoE standards only drive power through two pairs, while 802.3bt lets power be driven through four pairs of circuits in a cable.

Power over Ethernet Classes

The amounts of power are further broken down into types and classes. There are four different types of PoE, these are:

1. PoE Type 1: refers to the 802.3 af standard with up to 12.95W of input power. 
2. PoE Type 2: refers to the 802.3at standard with up to 25.50 W of input power.
3. PoE Type 3: refers to the 802.3bt standard with up to 51W of input power. 
4. PoE Type 4: refers to the 802.3bt standard with up to 71.3W of input power. Type 4 is unknown, High PoE or Hi-PoE.

These types explained above have further classes, POE ( Power Over Ethernet) to Power IP Devices, starting from 0 to 8, these are:

• PoE class 0 is the default and provides input power up to 12.94 W.
• PoE class 1 provides input power up to 3.84 W. 
• PoE class 2 power over ethernet poe class 2 provides input power up to 6.49 W.
• PoE class 3 power over Ethernet class 3 provides input power up to 12.95 W.
• PoE class 4 power over Ethernet class 4 provides input power up to 25.50 W.
• PoE class 5 provides input power up to 40 W.
• PoE class 6 provides input power up to 51 W.
• PoE class 7 provides input power up to 62 W.
• PoE class 8 provides input power up to 71.3 W.

In short, classes from 0 to 3 are described in 802.3af. Class 4 is described in 802.3at. And classes from 5 to 8 are specified in 802.3bt. 

PSEs support specific standards. And not every PoE switch can handle PoE++. For example, if you need a type 4 class 8 Poe over for a PTZ security camera, then make sure your switch can handle it.

Passive Power Over Ethernet

Ever heard of passive power over Ethernet?. Well, Passive power over Ethernet is basically a non-standardized, always-on method of delivering electric power and data over Ethernet cables to devices like cameras and APs. Opposite to active PoE (IEEE802.3af/at), it doesn’t control voltage, which means it continuously sends power (usually 24V or 28V) directly, which can damage incompatible devices in case of a mismatch. 

One final standard you need to be aware of is IEEE802.3az, which is known as Energy-Efficient Ethernet (EEE). Basically, EEE reduces the amount of power being driven when data activity is low, which in theory can add up to a significant reduction of power consumption without harming functionality.  

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