PoE PSE Introduction and FAQs

The initially published IEEE802.3af standard has divided Power over Ethernet (PoE) technology into two main power device types: power sourcing equipment (PSE) that provides power on the Ethernet cable and powered device (PD) that accepts the power. To get a better understanding of the PoE network system, it is necessary to get familiar with the PoE devices. This post will focus on the common PoE PSE devices and clarify their applicable scenarios.

PoE PD vs PSE: What Is PoE PSE?

As mentioned above, PoE PDs are PoE devices that can get powered in a PoE network system. The common PoE PDs include numerous terminal devices such as IP phones, IP cameras, wireless access points (WAPs), etc. The PoE PSE, which supplies power, however, is limited to fewer products when comparing PoE PD vs PSE. The main PSE types in use today are PoE switch, PoE injector, PoE NVR, and PoE media converter. The concrete PoE PSE type in a network is chosen based on the infrastructure and the number of PDs which will be connected to. In addition, PoE splitter is also commonly used as an intermediary device to supply power in the PoE network even though it does not belong to the PoE PSE device.

PoE PSE Introduction

• PoE Switch: PoE network switch is a network switch that has PoE injection built-in. Therefore, it can transmit both data and power over one Ethernet cable to the PD directly connected to it. Learn more about PoE switch at What Is a PoE Switch and How Does It Work?

• PoE Injector: For adding PoE to regular non-PoE network links, a PoE injector is used. It injects power to data that is coming from a non-PoE switch and delivers both the power and data to the PD through an Ethernet cable. Learn more about PoE injector at What Is a PoE Injector and How to Use It?

• PoE NVR(PoE network video recorder): PoE NVR has PoE injection built-in. Mostly used in the IP video surveillance system, it is responsible for encoding and processing the video data on IP video cameras, and recording it for storage and remote viewing. PoE NVR can also deliver power to IP video cameras through Ethernet cables. Learn more here: Setting Up NVR for IP Cameras with or Without PoE Switch?

• PoE Media Converter: PoE media converter is a device that not only connects fiber cabling to a copper network but also provides PoE power to PoE PD such as IP cameras and VoIP phones. Learn more at Understanding Power Over Ethernet (PoE) Media Converter.

• PoE Splitter: The PoE splitter can also supply power, but it delivers power to a non-PoE terminal device by splitting power from the data and feeding it to the non-PoE device through its power supply cable. It is used for deploying remote non-PoE devices with no nearby AC outlets. Learn more about PoE splitter at What Is PoE Splitter and How Does It Work?

Frequently Asked Questions About PoE PSE

Do I Still Need a PoE Injector if I Have a PoE Switch?

No, you don't need a PoE injector when you have a PoE switch. When you are running through a standard PoE switch, you will not need the power connection. In this case, no injector is needed. But if you have a non-PoE switch, you will need a PoE injector to power the PoE PD such as IP cameras, because non-PoE switches do not deliver power to PoE devices. However, it should be noted that PoE injectors are only suitable for PoE networks with only a few PDs. If there are dozens of PDs, the PoE switch is a better choice.

Can I Use a PoE Switch with NVR?

Yes, you can. A PoE switch will act as a hub but can also supply power to NVR, without the need for an external power source or extra power wires. This makes for less installation cost and cabling complexity – you can handle your power and video over a single Cat5 cable.

Can I Use a Media Converter with PoE Switch?

Yes. As we know, the PoE switch restricts Ethernet cable distances to 100m. Then how do we get beyond the 100m limit? A PoE media converter is an ideal product to overcome the distance challenge by offering a copper to fiber connectivity solution and acts as the PoE PSE on the copper side to power up PDs at the same time.

Can You Use a PoE Splitter as a PoE Injector?

No, you can't. PoE splitters and PoE injectors are two types of PoE devices that confuse people a lot. As mentioned above, PoE injectors are used with non-PoE switches to power terminal PoE devices. PoE splitters, on the contrary, are used with PoE PSE and separate the data and power onto two different cables for non-PoE devices. The following figure illustrates common applications of the PoE splitter and PoE injector:

Conclusion

Power over Ethernet (PoE) technology is expected to expand in the future due to the demand for ease of installation and newly ratified standards designed to support more smart devices. Therefore, it is necessary for us to have a better understanding of all the above PoE PSE devices and the PoE splitter, especially when we need to select and buy products for building up PoE networks.

Related Articles: Understanding IEEE 802.3bt High Power PoE (Hi-PoE)