Ordinary network cable does not meet the PoE power supply requirements. Using ordinary network cables to transmit signals may cause instability or even blockage.
POE power supply provides network power supply to remote powered terminals through POE switches. The POE power supply system requires 4 cores to send and receive power. 4 cores are used for power supply, so POE power supply first The most important point is to choose an 8-core network cable.
POE power supply has relatively high requirements for network cables. The transmission distance of POE power supply is decisively related to the effective transmission distance of the network cable. If the resistance of the network cable is too high, the signal transmission There will be instability or even blockage.
Ordinary all-copper network cables are bronze network cables. The purity of copper is not high. The resistance of the network cable itself is very high, and the transmission distance will be relatively short. In an ordinary network transmission environment, the transmission distance of all-copper network cables is about 80 meters. The POE power supply system has high requirements for network cables, and all copper does not meet the transmission requirements of POE power supply. It is recommended to choose oxygen-free copper network cable as the transmission medium.
The oxygen-free copper network cable has low resistance, long transmission distance, and relatively stable transmission effect. When used as a POE power supply transmission medium, transmission problems are not prone to occur. The transmission of data signals is determined by network cables. Good quality network cables can naturally transmit farther. The transmission distance of ordinary Category 5 cables for data signals is about 100 meters. However, in order to ensure the construction quality during the project, it is usually About 80 meters to 90 meters.
The POE standard defines two methods for transmitting DC power to POE-compatible devices using Ethernet transmission cables:
Intermediate bridging method
One is called "intermediate "Mid-Span" method uses independent PoE power supply equipment to connect between the switch and the terminal device with PoE function. It usually uses the unused idle wire pairs in the Ethernet cable to transmit DC power. Midspan PSE is a specialized power management device, usually placed together with the switch. It has two RJ45 jacks corresponding to each port, one is connected to the switch with a short line (here refers to a traditional switch without PoE function), and the other is connected to the remote device.
End-Span Method
Another method is the "End-Span" method, which integrates the power supply equipment at the signal outlet of the switch. This type of integrated connection Generally, "dual" power supply function for idle line pairs and data line pairs is provided. The data line pair uses a signal isolation transformer and uses a center tap to realize DC power supply. It is foreseeable that End-Span will be popularized rapidly. This is because Ethernet data and power transmission use common line pairs, thus eliminating the need to set up dedicated lines for independent power transmission. This is for only 8-core cables and matching standard RJ The -45 socket is of particular significance.
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