Talking about the view of POE Switch

- Dec 11, 2017-

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POE (power over Ethernet) refers to the transmission of data signals for some ip-based terminals (such as IP telephones, wireless LAN access point APS, network cameras, etc.) while the existing Ethernet CAT.5 cabling infrastructure is not altered. It can also provide direct current technology for such equipment. It is a switch that supports Ethernet power.

1. Power Supply Standard

International standards: POE switch port support output power up to 15.4W or 30W, in line with the IEEE802.3AF/802.3AT standard, through the cable power supply to the standard Poe Terminal equipment power, eliminating the additional power wiring; IEEE The 802.3AF standard is a new standard of Poe based on the Ethernet power supply system, which increases the standard of direct power supply through the network cable on the basis of IEEE 802.3, and it is the extension of the existing Ethernet standard, and also the first international standard on the distribution. The IEEE 802.3AT Standard was developed in 2005 and promulgated in 2009. 802.3AT standard output power of up to 30W, by the power available to the end of 25.5W.

2. POE switch working process:

A, Testing: At first, the Poe switch outputs a very small voltage at the port until it detects that the cable terminal is connected to a IEEE802.3AF-compliant, electrically-terminated device.

B, PD Equipment classification: When the device PD is detected, the POE switch may classify the PD device and assess the power loss required for the PD device.

C, Start the power supply: in a configurable time (generally less than 15μs) start-up period, the Poe switch started from low voltage to PD equipment power supply until 48V DC power supply.

D, Power supply: for PD equipment to provide stable and reliable 48V DC power, to meet the PD equipment does not cross 15.4W power consumption.

E, Power off: If the PD device disconnects from the network, the Poe switch will quickly (generally within 300~400ms) stop powering the PD device and repeat the detection process to detect whether the cable terminal is connected to the PD device.

3. What is the difference between the POE switch and the traditional switch?

In general, the POE switch not only has the transfer function of ordinary switch, but also provides power for the terminal (such as AP, digital camera, etc.).

For example, a digital surveillance camera (which requires power to function properly), no power to connect, but a cable connected to a common switch, in which case the camera is not working. If the camera is not connected to the power supply, but his transmission network cable to the POE switch, the camera will be able to work properly. (assuming that the camera needs to be a support for Poe's camera, if not, you need to use the separator box)

4. Advantages of POE Switch:

The advantages of the POE switch do not have to repeat one by one: simple wiring, no need for power cord, while cost savings (wire costs, manual wiring costs), late fault maintenance is simple and so on.

PS: The POE switch in the market is divided into standard and non-standard: The standard POE switch supports IEEE802.3AF/802.3AT standard, the Poe switch mentioned in the former is the reference to the standard Poe switch, it detects whether the connected network device has a Poe's electrical end. If there is a power supply, if there is no power supply, only to provide data transmission; For example, OPTFOCUS's POE switch, there are many types, in addition to the number of switch ports, there can be superimposed on the optical port (to do the optical transceiver use), At the same time there is a web-managed POE switch (power supply port can be set separately switch, output power, priority, etc.).

Non-standard Poe switches are actually defined by each company, mandatory power supply, whether the front-end equipment is required, will be forced to provide current, can damage the equipment, so when the purchase of Poe switch, you need to consult the type of Poe switch, port output power, the total power of the Poe switch, back plate bandwidth and so on.

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