PoE认证的目的

PoE is the driver behind emerging technology and applications like smart buildings and Internet of Things (IoT). Through a single PoE cable, data and electricity are provided to PoE-capable devices. Because they no longer need to be located near electrical outlets, this opens new doors in terms of where you can place devices like wireless access points, surveillance cameras with PTZ features, LED lighting fixtures and large display screens.

PoE Requirements are Increasing

Today’s devices are requiring higher power levels for operation. For this reason, IEEE 802.3bt – the 100W Power over Ethernet (PoE) standard – was approved last year. It’s backward compatible with all PoE devices.

IEEE 802.3bt calls for two power variants: Type 3 (60W) and Type 4 (100W). This means that close to 100W of electricity can be carried over a single cable to power devices.

Potential PoE Problems

With PoE’s popularity, some products and providers are now using the term without following PoE standards. So why is this an issue? And how can you avoid it?

Because of lack of interoperability, products labeled as “PoE capable” from different manufacturers won’t work together. In many cases, this is because manufacturing shortcuts were taken – or because one product employs a proprietary PoE solution vs. a standards-based PoE solution.

Case in point: Many inexpensive PoE injectors that lack IEEE standardized features have been brought to market. By placing permanent voltage that is not IEEE standardized voltage on “idle” pairs, the current in these injectors exceeds specifications. In these cases, device or cable damage may occur – or systems may malfunction. Although these devices are marketed as “PoE” injectors, they don’t follow IEEE 802.3 standards. Other products marketed as “PoE compatible” or “PoE capable” may bypass detection protections. Some may be designed to specific portions of IEEE 802.3 but not to the entire standard.

To minimize frustration and performance issues – and emphasize the use of standards-based vs. proprietary PoE solutions – the Ethernet Alliance launched a PoE Certification Program in 2017. This certification identifies products that are designed to the latest IEEE 802.3 PoE standards.

PoE certification may be given at the system or component level to:

• Power sourcing equipment (PSE) like switches, adapters and power injectors
• Powered devices (PDs) like surveillance cameras, VoIP phones, wireless access points, digital signage screens and lighting fixtures

The intent is that, with this PoE certification end-users will be confident in knowing which PSEs and PDs will work together without any issues, regardless of the manufacturer. The total number of products certified at this point is small (a group of about 40).

Of course, there are many products manufactured in accordance with IEEE 802.3 standards that are fully compatible but don’t carry the label. Just because a product doesn’t feature the PoE certification doesn’t mean it isn’t designed to the latest standards. But the certification label ensures that you won’t suffer from PoE performance problems when you invest in devices.

The best thing you can do to ensure reliable PoE performance? Make sure the cables you use are designed to support PoE – and make sure the devices you install are designed in accordance with IEEE 802.3 standards vs. proprietary solutions.

Have more questions about Power over Ethernet? Our experts are here to help!