PoE Power Sourcing Equipment (PSE) FAQs

Andy Chen

To enhance comprehension of the PoE network system, it is essential to become acquainted with the PoE devices, as the initially published IEEE802.3af standard categorized Power over Ethernet (PoE) technology into two primary types of power devices: power sourcing equipment (PSE), which supplies power over the Ethernet cable, and powered devices (PD), which receive the power. Presented below is an introduction to power sourcing equipment and a selection of frequently asked questions.

Q: What Is PoE PSE?

A: PoE PSE, an acronym for Power Sourcing Equipment in Power over Ethernet (PoE) systems, represents the equipment responsible for delivering power to PoE PDs (Powered Devices). PoE PSEs detect and categorize the connected PoE devices, monitor power consumption, and allocate power to the devices based on their specific power requirements.

Q: What Are the Differences Between PoE PD and PoE PSE?

A: In a Power over Ethernet (PoE) system, two fundamental elements exist: PoE PD (Powered Device) and PoE PSE (Power Sourcing Equipment).

  • PoE PSE (Power Sourcing Equipment): PoE PSE denotes the equipment supplying power to PoE PDs. It can take the form of a PoE switch or a PoE injector. The PoE PSE injects power into the Ethernet cable, alongside data signals, enabling connected PoE PDs to receive both power and data through a single cable. It serves as the power source for PoE devices.

  • PoE PD (Powered Device): PoE PD refers to the device that draws power from the PoE network infrastructure. It encompasses various device types, such as IP phones, wireless access points, IP cameras, and network switches. The PoE PD consumes power from the PoE PSE, allowing it to operate without the need for a separate power source. Typically, it features an Ethernet input for data communication and a power input to receive power from the PoE PSE.

Q: What Are the Common PoE PSEs?

A: PoE PSE (Power Sourcing Equipment) is vital for providing power to PoE-enabled devices in a network. Although the variety of PoE PSE devices is more limited compared to the diverse range of PoE PDs, there are several commonly deployed types in modern PoE networks. These include PoE switches, PoE injectors, PoE NVRs (Network Video Recorders), and PoE media converters. Here is an overview of these commonly used PoE PSE devices:


  • PoE Switch: The PoE network switch integrates PoE injection, allowing it to transmit both data and power over a single Ethernet cable directly to the connected PD.

  • PoE Injector: PoE injector is used to add PoE capability to regular non-PoE network connections. It injects power into the data stream originating from a non-PoE switch and delivers both power and data to the PD via an Ethernet cable.

  • PoE NVR: PoE NVR (Network Video Recorder) incorporates built-in PoE injection. It is commonly employed in IP video surveillance systems, responsible for encoding and processing video data from IP cameras and recording it for storage and remote viewing. The PoE NVR can also supply power to IP cameras via Ethernet cables.

  • PoE Media Converter: PoE media converter facilitates the connection between fiber cabling and a copper network while concurrently providing PoE power to PoE PDs like IP cameras and VoIP phones.

  • PoE Splitter: The PoE splitter is capable of delivering power, but its primary function is to provide power to non-PoE terminal devices. It accomplishes this by splitting power from the data stream and delivering it to the non-PoE device through a separate power supply cable. PoE splitters are advantageous for deploying remote non-PoE devices without nearby AC outlets.

Q: Do I Still Need A PoE Injector if I Have a PoE Switch?

A: If you have a PoE switch, there is no requirement for a PoE injector. When utilizing a standard PoE switch, the power connection is already included, rendering the use of an injector unnecessary. However, if you are utilizing a non-PoE switch, a PoE injector becomes essential for supplying power to PoE PDs like IP cameras, as non-PoE switches do not provide power to PoE devices. It is worth noting that PoE injectors are typically suitable for smaller-scale PoE networks with only a few PDs. For networks with a larger number of PDs, opting for a PoE switch is a more advantageous choice.

Q: Can I Use A PoE Switch with NVR?

A: Yes, you can. A PoE switch not only functions as a hub but also has the capability to provide power to an NVR (Network Video Recorder) without requiring an external power source or additional power cables. This feature significantly reduces installation costs and simplifies cabling complexity, as both power and video can be transmitted over a single Cat5 cable.

Q: Can I Use a Media Converter with PoE Switch?

A: Certainly. It is true that PoE switches have a distance limitation of 100 meters for Ethernet cables. However, when we need to extend beyond this limit, a PoE media converter becomes an excellent solution. A PoE media converter addresses the distance challenge by providing a copper-to-fiber connectivity solution. It serves as the PoE PSE on the copper side, enabling the powering of PDs while extending the network over fiber optic cables to reach greater distances. This allows us to overcome the 100-meter limitation of PoE switches.

Q: Can I Use a PoE Splitter as a PoE Injector?

A: No, PoE splitters and PoE injectors are distinct types of PoE devices that can often lead to confusion. As mentioned earlier, PoE injectors are utilized with non-PoE switches to provide power to PoE devices connected to them. On the other hand, PoE splitters are used in conjunction with PoE PSEs (Power Sourcing Equipment) and separate the data and power signals onto separate cables for non-PoE devices.

To provide a clearer understanding, please refer to the accompanying figure which illustrates the typical applications of PoE splitters and PoE injectors:


With the increasing need for streamlined installations and the recent adoption of standards to support a broader range of smart devices, the adoption of Power over Ethernet (PoE) technology is anticipated to witness significant growth in the future. Consequently, it becomes crucial for us to gain a comprehensive understanding of the aforementioned PoE PSE devices, particularly when making purchasing decisions for establishing PoE networks. This knowledge will enable us to make informed choices and effectively build PoE infrastructure to meet our requirements.