802.3at: Ultimate Power Solution

Power over Ethernet (PoE) technology allows network cables to deliver both power and data, enabling convenient deployment of devices like wireless access points, IP phones, and security cameras without the need for proximity to power outlets. 802.3at represents the most advanced and powerful PoE standard available today, providing capabilities far beyond previous standards. In this article, we will take a deeper look at 802.3at PoE and how it sets a new bar for performance.

Overview of 802.3at

802.3at, also referred to as PoE+ or PoE Plus is a PoE standard that was introduced in 2009. It provides up to 25.5W of power, a significant increase from the 15.4W provided by the previous 802.3af standard. Now, you know what is 802.3at.

The key benefit of IEEE 802.3at is its ability to deliver adequate power for devices that require more power input than what 802.3af can provide. Devices such as pan-tilt-zoom security cameras, video phones, and thin clients can operate effectively with 802.3at, whereas 802.3af may not be sufficient.

The 802.3at standard utilizes all four pairs of wires in an Ethernet cable for power transmission. This allows delivery of higher power compared to 802.3af, which only uses two pairs. Overall, 802.3at enables a wider range of powered devices to be deployed in networks efficiently.

802.3at Specifications

Here are some key specifications of the 802.3at PoE standard:

• Voltage: 802.3at operates at a maximum DC voltage of 57V compared to 48V for 802.3af. The higher 802.3at voltage allows more power to be transmitted.
• Power: 802.3at can deliver up to 25.5W of 802.3at power to a powered device, over 10W more than the 15.4W delivered by 802.3af.
• PSE: The Power Sourcing Equipment (PSE) must be 802.3at compliant to deliver the higher voltage and power. PSE includes switches, routers, and midspan injectors.
• Compatibility: 802.3at is backward compatible with 802.3af. An 802.3at PSE can automatically detect and deliver appropriate power levels to either 802.3at or 802.3af-powered devices when connected.

In summary, the main specifications of 802.3at are 57V DC delivery, 25.5W power level, and backward compatibility with 802.3af devices. These capabilities make it highly useful for powering equipment with higher demands.

Understanding 802.3at PoE Technology

802.3at PoE, also known as PoE+, builds upon the previous 802.3af PoE standard but offers substantially more power capacity. It provides up to 25.5W to powered devices compared to just 15.4W from 802.3af.

This higher power capacity enables 802.3at PoE+ to support a wider range of powered devices that have higher power requirements. Devices such as VoIP phones, pan-tilt-zoom security cameras, wireless LAN access points, and thin clients can be powered reliably and efficiently by 802.3at.

To achieve the increase in power delivery, 802.3at makes use of all four pairs of wires in an Ethernet cable. In contrast, 802.3af only uses two pairs. By utilizing all four pairs, 802.3at can safely deliver up to 25.5W to powered devices.

Additionally, 802.3at operates at a higher voltage of up to 57V DC compared to 48V for 802.3af. This higher operating voltage also contributes to increased power capacity.

Overall, PoE+ 802.3at technology enables greater flexibility, efficiency and simplicity in network power delivery through its high power output. It eliminates the need for local power supplies and outlets for a diverse range of network endpoints.

802.3at PoE Injector and Its Functionality

A PoE injector is a device used to add PoE capabilities to network switches or routers that lack built-in PoE. An 802.3at PoE injector specifically supplies power per the 802.3at standard.
The key functions of a PoE 802.3at injector are:

• Converts AC power from a wall outlet to DC power for PoE output. It allows a non-PoE switch to supply power to PoE devices.
• Provides PoE power up to the 802.3at limit of 25.5W to connected devices. An 802.3at injector can power equipment with higher demands compared to 802.3af injectors limited to 15.4W.
• It also maintains backward compatibility to power 802.3af or lower PoE devices if connected. The injector will automatically detect the connected device and provide suitable power levels.
• Supports passive 24/48V PoE devices that lack PoE negotiation protocols. The injector can be configured to provide continuous power to such equipment.
• May offer additional ports to connect multiple PoE devices for power sourcing. The total PoE budget across ports is limited to the injector's max capacity, typically 130W or more.

In summary, 802.3at injectors greatly simplify deploying PoE devices in existing networks by delivering high PoE power safely and reliably. They are an economical solution compared to upgrading switches for 802.3at support.

802.3af vs. 802.3at: What's the Difference?

The key difference between the 802.3at vs 802.3af PoE standards is the maximum power delivered to connected devices. 802.3at provides up to 25.5W of power compared to 15.4W for 802.3af. Here are the differences between 802.3af vs 802.3at:

Power Output

The substantially higher power capacity of 802.3at enables it to support more types of powered devices. 802.3af is limited primarily to smaller devices with lower power needs, such as VoIP phones and wireless access points.

In contrast, 802.3at can power larger devices like PTZ security cameras, video conferencing equipment, thin clients, and even powering LCD monitors. The extra power makes 802.3at much more versatile.

Voltage and Current

802.3at operates at voltages up to 57V DC, which is higher than the 48V DC used by 802.3af. This allows 802.3at to deliver more power safely over Ethernet cabling.

The maximum current for 802.3at is specified at 600mA across all four wire pairs. 802.3af is limited to 350mA on two wire pairs only.

Applications

The high power delivery of 802.3at makes it suitable for enterprise usage, where the greater power capacity is beneficial. 802.3af finds more use in small office and home office settings with lower power demand.

Compatibility

A key strength of 802.3at is its backward compatibility with 802.3af. An 802.3at powered device can be connected to an 802.3af PSE and still receive power safely, albeit at reduced levels. This provides flexibility in slowly transitioning networks over to 802.3at as needed. Powered devices can work on either standard.

For example, before using a PoE security camera, such as the Reolink Duo 3 PoE, you need to check its compatibility with PoE injectors and switches. The Duo 3 PoE is a dual-lens security camera with 16MP resolution. It allows you to see every finer detail in different outdoor or indoor spaces.

FAQs

Is PoE+ the same as 802.3at?

Yes, PoE+ and 802.3at refer to the same PoE standard. 802.3at is the official name used in the IEEE standard. PoE+ is a commonly used shorthand referring to the same standard.

What is the IEEE 802.3at PoE+ standard?

The IEEE 802.3at standard, also known as PoE+, provides up to 25.5W of power over Ethernet cabling. It allows powering of equipment with higher demands compared to the older 802.3af PoE standard that has a 15.4W limit. Key aspects of 802.3at are higher voltage (up to 57V DC) and usage of all four cable pairs for power.

Can I use 802.3at instead of 802.3af?

Yes, 802.3at is fully backward compatible with 802.3af. An 802.3at PSE will automatically detect and deliver the appropriate power for either 802.3at or 802.3af-powered devices when connected. Replacing 802.3af with 802.3at will allow powering a wider range of devices.

Conclusion

802.3at represents the pinnacle of PoE performance and capabilities. By massively upgrading the power delivery from 15.4W per port to a stunning 25.5W, 802.3at enables a new generation of powered devices with substantial power appetites.

What do you think of this article? Do you understand the 802.3at now? Share your thoughts in the comment section below! Let's discuss them together!