Power over Ethernet (PoE) is a revolutionary technology that enables the transmission of electrical power over standard Ethernet cables alongside data, eliminating the need for separate power cables. Originally emerging in Voice over IP (VoIP) communication systems during the transition from analog to digital phone systems, PoE has now found its place in IP intercom systems and beyond.

By delivering power over Ethernet infrastructure, PoE simplifies the deployment of connected devices, particularly in locations where traditional power sources are inaccessible. Additionally, PoE-enabled devices can be centrally powered, facilitating remote device management and reducing overall energy consumption/service costs.

One of the significant advantages of PoE is that power transmission is entirely separated from data communications. This provides great flexibility to adapt to the ever-changing transmission speeds of Ethernet. Furthermore, adding a device is as simple as connecting an Ethernet cable.

Key Components of PoE Deployment: PD and PSE

PoE deployment requires two key components:

1. Powered Device (PD): this refers to any equipment or device capable of receiving both power and data over the Ethernet cable using PoE technology. PDs are designed to operate under PoE standards defined by IEEE 802.3af, 802.3, or 803.3bt, which determine the maximum power it can receive and operating mode.
2. Power Source Equipment (PSE): PSE supplies electrical power to the PD devices over the Ethernet cable. It is responsible for providing DC power to Ethernet cables while simultaneously transmitting data.

PDs encompass any networked devices connected through Ethernet cable that require power to operate, such as IP phones/cameras, wireless access points, and wired Internet of Things (IoT) devices. There are two main types of PSE equipment: PoE-enabled network switches and PoE injectors. PoE switches integrate both power and data transmission, directly powering and communicating with PD devices via Ethernet cables. Also known as Midspans, PoE injectors are standalone devices that add PoE functionality to non-PoE-enabled network switches and deliver DC power directly to PoE-enabled devices.

Evolution of PoE Standards

PoE standards have evolved over the years to accommodate increasing power demands for connected devices. The main PoE standards developed by IEEE are (Figure 1):

1. IEEE802.3af (PoE): Introduced in 2003, this standard delivers a maximum of 15.4W to power PD devices over two pairs of wires from the Ethernet cable. It can operate in Mode A (power delivered via the data pairs) or Mode B (power delivered on the spare pairs).
2. IEEE802.3at (PoE+): Introduced in 2009, this standard increases power delivery up to 30W. It operates on CAT 5 or higher Ethernet cables, delivering DC power over two pairs of wires. Similar to the earlier standard, it offers the option to run on data or spare pairs (Mode A and Mode B, respectively).
3. IEEE802.3BT (PoE++): The latest standard introduced in 2018 provides even higher power delivery, up to 60W in Type 3 and a maximum of 100W in Type 4. Also known as "PoE++," this standard requires all four pairs of wires to deliver power.

All three PoE standards specify requirements for power, voltage, current levels, and cable types for proper implementation. Both PSE and PD must comply with these specifications to ensure compatibility. Thanks to backward compatibility, it is possible to use a mix of old and new PoE, PoE+, or PoE++ devices as long as their power requirements fall within the supported range.

PoE's Expanding Role in IoT Device Deployment

Today, PoE devices are found in various environments and industries, extending far beyond their original designs. They play a significant role in the growth of IoT device deployments. The ability to deliver power and data simultaneously over a single Ethernet cable simplifies the installation process, allowing for much more flexible device placement without being limited by the availability of power sources.

PoE eliminates the need for separate electrical power infrastructure, such as power outlets, wiring, and additional materials, thereby reducing installation costs. This technology proves extremely beneficial for outdoor deployments where power sources are inaccessible, such as surveillance cameras, digital signage, wireless access points, and IoT sensor networks.

Moreover, PoE facilitates centralized management through Ethernet data communication. Each device on the network can be individually controlled, allowing for precise power allocation, device maintenance, and troubleshooting. This centralized management, combined with the reliability of wired connections, makes PoE the perfect choice for mission-critical device operations.

Overall, PoE technology significantly enhances the efficiency, reliability, and scalability of IoT deployments, simplifying installation processes and reducing overall costs. Embracing PoE is a smart move for businesses and industries looking to make the most of their connected devices and networks.

Are you ready to unlock the Potential of PoE in your IoT deployment? Our seasoned team of Applications Engineers possess in-depth knowledge and experience in PoE, IoT, IIoT, and wireless device and can provide guidance and support to achieve your connected goal. Consultation is free and available throughout your design cycle. Contact Symmetry Electronics today!