Detailed Explanation Of Common Problems Of PoE Network Camera

- Jul 25, 2019-

With the changes of the times and people's increasing security awareness, the installation scale and radiation area of video surveillance are becoming larger and larger. Its project scope covers the whole city, with tens of thousands of cameras. Large-scale network monitoring has led to a large number of applications and popularization of PoE switches, and the use of PoE switches has indeed brought a lot of convenience to the monitoring project. PoE switches have been used for so long, but do you know the reasons why PoE network cameras are not normally powered in use?

Answer: When using the PoE network camera, we should carefully check the camera and its corresponding PoE protocol, and choose the right cable and POE power supply equipment or switch. When the PoE network camera can not work properly, there may be several reasons in power supply:

1) Selection of Standard PoE Power Switch or Power Supply Equipment

At present, there are two kinds of common PoE standards for web cameras: PoE and PoE+, and PoE+ is compatible with PoE.

PoE meets the standard of 802.3af, providing 48V, power not exceeding 15.4W.

PoE + meets the standard of 802.3at, providing 48-57V power supply with power less than 30W.

When choosing switch or power supply equipment, the corresponding switch or power supply equipment should be selected according to the performance of PoE network switch. If the camera adapts to PoE (802.3af), then it must be the corresponding power supply equipment or switch that adapts to PoE or PoE+function, while the ordinary switch can not provide power to the remote camera. Source: If the network camera adapts to PoE+ (802.3at) and needs larger power supply, then the switch or power supply equipment must also adapt to the PoE+ protocol to provide enough power supply, while the ordinary switch or only the PoE switch can not meet the requirements.

2) The quality of network cables and the power supply modes of mid-span and end-span of PoE switches

Four pairs of UTP type 5 cables usually use only 1,2 and 3,6 pairs of wires when transmitting network signals (4,5 and 7,8 pairs of wires are also used in Gigabit networks). Therefore, some cable manufacturers use copper wires in order to save wire, 1,2 and 3,6 pairs of wires, while 4,5 and 7,8 pairs of wires use copper-clad iron or iron wires. In this way, in the application of PoE network power supply, in the use of cross and end power supply mode, because the quality of the network will be different, the power supply effect will be quite different.

PoE power supply by mid-end cross connection method is to use the other two pairs of lines of UTP cable to transmit data signals, that is, 1, 2 and 3, 6 pairs of lines to transmit network signals, while 4, 5 and 7, 8 pairs of transmission power supply; the end cross connection method is to load the power supply on the transmission network line to transmit, through the separation of data and power supply to achieve power transmission. Transmission, that is, network signals and power are transmitted through pairs of 1, 2 and 3, 6 lines.


Therefore, the terminal crossover method can avoid the bad condition of UTP wires and realize the power supply of network PoE, especially the cables that have been laid down. The selection of terminal crossover method can reduce the risk of construction and improve the utilization rate of cables.

3) Are there any other devices in the middle that cause the PoE camera to fail to function properly?

In order to prevent thunder and surge, some cameras add network surge protector on transmission line. If it is network surge protection equipment, the transmission of PoE power supply will be reduced or blocked, so that the normal power supply to the PoE camera can not be provided. Therefore, in choosing surge protector, it is also necessary to select the corresponding PoE surge protector; it is not recommended to connect other devices on the transmission line, which will also have an impact on the power supply of PoE.

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