What You Need to Know About PoE PSE (Power Sourcing Equipment)？

PoE is a network function defined by the IEEE 802.3af and IEEE 802.3at standards. PoE powers network devices through the Ethernet cables used for existing data connections. And a complete PoE system consists of two parts: PSE (Power Sourcing Equipment) and PD (Power Device). This article will focus on Power Sourcing Equipment and list common PSE devices to help you make wise PoE device choices.

What Does PSE Stand for?

PoE PSE is the acronym for PoE Power Sourcing Equipment. It is an important part of the Power over Ethernet system and is also the manager of the entire PoE power supply process. Common PSEs include PoE switches and PoE routers. They power connected devices through Ethernet and provide detection, analysis, and intelligent power management functions. By integrating PSE into devices such as network switches, data and power can be transmitted over the same cable, simplifying installation and eliminating the need for a separate power supply.

PoE PD vs PoE PSE, What's the Difference?

The main difference between PoE PD (Powered Device) and PSE (Power Sourcing Equipment) is their different functions in the PoE system. PD is a device like IP cameras, wireless access points, VoIP phones, etc., that receives power through Ethernet cables, while PSE is a device that provides power to these devices. PSE is not only responsible for transmitting data through the network cable but also actively detects whether the connected device needs power and provides the right amount of power based on demand. At the same time, PD can only receive power and cannot power other devices. Therefore, in the entire PoE system, PSE undertakes the dual tasks of power supply and data transmission, while PD accepts power from PSE to work normally.

How Does Power over Ethernet PSE Work?

Detection

This process is mainly to detect PD. PSE periodically outputs a small voltage at the port to detect the powered device, which is called voltage pulse detection. If an effective resistance of a specified value is detected, it means that the cable terminal is connected to a powered device that supports the IEEE 802.3af standard or the IEEE 802.3at standard.

Classification

Since there are many types of powered devices and the power they require is also different, after the power supply device correctly detects the powered device, it is necessary to detect the power level of the peer PD device. Powered devices are divided into different levels according to the power they require. When the PD is connected to the PSE, it provides its level to the PSE so that the PSE can provide it with the correct power.

Power Delivery

After classification and determining the power requirements, the PSE will supply power to the PD by applying the appropriate voltage on the Ethernet cable. During this process, if the powered device is overloaded or short-circuited, the PSE will stop supplying power to it and enter the detection phase again.

What Are the Common PoE Power Sourcing Equipments?

PoE Switch

A PoE switch is a network switch with PoE function. It can transmit data while supplying power. The main function of an ordinary switch is only to transmit data, and it does not have the function of supplying power. A PoE switch is more suitable for scenarios with special power supply requirements and the desire to simplify wiring, such as monitoring systems and wireless coverage. Suppose a small office needs to install a surveillance camera. If a PoE network switch is selected, data transmission and power supply can be achieved on one network cable simultaneously, which is convenient and fast.

PoE Injector

PoE injector, also known as midspan, PoE charger or PoE adapter, combines data and power. When non-Poe equipment needs to support PoE PDs, PoE injectors can power and transmit data to these PDs. Typically, PoE injectors convert AC to DC to power low-voltage PoE devices. This PoE equipment is typically used where low-power end devices need to be installed but lack power from electrical outlets.

PoE Splitter

PoE splitters are the opposite of the PoE injectors mentioned above. PoE injectors combine data signals and power, but the working process of PoE splitters is to separate data signals and power. There are two output lines on one side of the PoE splitter, one for data and the other for power. PoE splitters are used in conjunction with PSE to power network devices such as wireless APs and wireless routers in network environments that lack power cables or are far away from power sockets. In many monitoring situations, the best location for monitoring may not be very convenient for equipment to get power. The emergence of PoE splitters facilitates the integration of devices that do not support PoE power supply into PoE networks, and monitoring equipment does not have to sacrifice the best installation location to take into account the distance from the socket.

PoE NVR

NVR stands for Network Video Recorder. Its core function is to store and forward video streams in network video surveillance systems. When it is integrated with the PoE transmission protocol, it becomes a PoE NVR. PoE NVR can transmit data and power through a single Ethernet cable. No additional PoE switch is required, which theoretically reduces the cost of the equipment. It is very suitable for users with minimal network management experience and is commonly used in homes and small businesses.

PoE Media Converter

A PoE media converter is a converter with PoE functions. It can power IP cameras, wireless devices and VoIP phones through network cables, eliminating the trouble of installing power cables separately. PoE media converter has two functions, one is optical-to-electric conversion, and the other is to transmit DC power to devices through network cables. PoE media converters can be widely used in various data communication fields, such as security monitoring, conference systems, and intelligent building projects.

Conclusion 

PoE PSE provides a simplified power solution, enabling network devices to achieve data transmission and power supply through a single Ethernet cable. PoE PSE and PoE PD form the Power over Ethernet (PoE) technology. In addition, different types of PSE devices such as PoE switches, injectors, splitters, NVRs and media converters have their own characteristics to meet the special needs of various network environments. In the future, with the continuous development of network technology, the application of PoE PSE (Power Sourcing Equipment) will be more extensive, realizing a flexible and efficient network architecture.