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PoE in Networking Explained: PoE Standards, Voltage and Types

PoE in Networking Explained: PoE Standards, Voltage and Types

Black Box Explains

What Is PoE (Power over Ethernet) In Networking?

Power over Ethernet delivers electrical power to PoE-enabled devices using your CATx network cables. Because you don’t need to run electrical wiring, PoE saves money in materials and installation time. It’s also flexible, especially for remote applications, since it doesn’t require a nearby electrical outlet. These and other benefits have led to a sharp increase in PoE’s popularity in recent years. However, the limiting factor has always been power.

How Does PoE Work?

The way it works is simple. Ethernet cable that meets CATx standards consists of four twisted pairs of cable, and PoE sends power over these pairs to PoE-enabled devices. In one method, two wire pairs are used to transmit data, and the remaining two pairs are used for power. In the other method, power and data are sent over the same pair.

When the same pair is used for both power and data, the power and data transmissions don’t interfere with each other. Because electricity and data function at opposite ends of the frequency spectrum, they can travel over the same cable. Electricity has a low frequency of 60 Hz or less, and data transmissions have frequencies that can range from 10 million to 100 million Hz.

Power over Ethernet Application Example

What Is The Current 802.3 AT PoE Standard?

For the last years, the main PoE standard has been the IEEE 802.3at which allows for up to 30W of power at the source. That’s sufficient power for devices such as VoIP phones, wireless access points, and security cameras. But it’s not enough for technology like flat screen displays, LED lighting, or retail POS terminals.

What is the 802.3 BT PoE Standard And Its Voltage?

To meet the demand for higher power, the IEEE is set to release a new PoE standard to significantly increase capacity. IEEE 802.3bt will allow for up to 60W to 100W of power at the source by providing power over four pairs of wires (compared to the previous technology’s ability to power over just two pairs). The IEEE 802.3at PoE standard supplies up to 25W to larger, more power-hungry devices. This increase in power allows you to use PoE for a greater range devices and applications. As an added benefit, the new standard will boost energy efficiency by minimizing power loss in the cable—potentially cutting power loss in half.

Speeds Supported

The new standard will include support for 2.5GBASE-T, 5GBASE-T and 10GBASE-T, while existing standards have a maximum speed of 1 gigabit. This new support will create intermediate data speeds between existing standards. Even though the new standard has not yet been ratified by the IEEE, Type 3- and Type 4-compatible products are already on the market.

PoE Types And Voltage

PoE 3 and PoE Type 4

Previous PoE technology included Type 1 and Type 2 powered devices and power source equipment. With the new standard come two new options: Type 3 and Type 4 (known as 4-pair PoE, 4PPoE, or PoE++). Type 3 provides 60W of power at the source and is ideal for video conferencing equipment and building management devices. Type 4 offers the highest power capabilities—potentially up to 100W—and can support flat screens and workstations.In 2014, Cisco released a proprietary solution in advance of the new standard that could deliver up to 60W of power over all four pairs of wires after negotiation. This technology, called Universal Power over Ethernet (UPOE), will likely remain an option even after 802.3bt is approved.

PoE Applications And Benefits

  • Use one set of twisted-pair wires for both data and low-wattage appliances.
  • In addition to the applications noted above, PoE also works well for video surveillance, building management, retail video kiosks, smart signs, vending machines, and retail point-of-information systems.
  • Save money by eliminating the need to run electrical wiring.
  • Easily move an appliance with minimal disruption.
  • If your LAN is protected from power failure by a UPS, the PoE devices connected to your LAN are also protected from power failure.
POE Application: Security Cameras

Black Box offers a wide range of PoE products that allow you to take advantage of higher-power capabilities of PoE such as the following:

PoE Ethernet Switches

PoE Ethernet Switches bring PoE into a Gigabit Network by detecting PoE devices and injecting power into PoE devices such as wireless access points and security cameras. Find more about PoE Ethernet Switches.

PoE Splitters

PoE Splitters work by bringing PoE power to non-PoE devices, Spliting a PoE or PoE+ signal into separate power and data sources. Find more about PoE Splitters.

PoE Repeaters/ PoE Extenders

Enable extension of PoE connections beyond the 100-meter limit to access faraway PoE devices such as access points, cameras, and VoIP phones. Find more about PoE Repeaters / Extenders.

PoE Media Converters

PoE Media Converters are the ideal way to extend your network over fiber or copper and also provide power to remote PoE devices to long-distance data links. Find more about PoE Media Converters.

PoE Injectors

PoE injectors carry data and power simultaneously over a single Ethernet cable. These type of Injectors power various VoIP phones, security system cameras, wireless network access points, Bluetooth® access points, and other 802.3af-compatible equipment. With it, you avoid the cost and hassle of installing AC power at remote cameras, access point, or thin client. Move equipment from room to room without costly, time-consuming rewiring. Find more about PoE Injectors.


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