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1. The PoE transmission distance is the same as the transmission distance of the network cable using PoE. They are all 100 meters. In general, PoE uses the 4/5 and 7/8 pairs of cables in the network cable for power supply. Therefore, when using PoE, try to use a good quality 8-core copper wire (standard network cable).
2. Power supply, voltage PoE power supply has two standards, one is IEEE802.3af and the other is IEEE802.3at.
IEEE802.3af: Supply voltage 44~57V, supply current 10~350mA, maximum supply power 15.4W, maximum received power 12.95W.
IEEE802.3at: The power supply voltage is 50~57V, the power supply current is 10~600mA, the maximum power supply is 30W, and the maximum power is 25.5W.
Why is the voltage 40V and 50V so large that it won't burn the device? Of course not. PoE-powered cameras have PoE modules that can convert 40V and 50V to the voltage required by the device.
What is the power supply and received power? The power supply is the output voltage from the switch or video recorder port, and the received power is the voltage received by the camera. It is calculated by attenuating the 100-meter CAT-3 cable.
25.5W power is too large, will the camera burn? No, the PoE module will perform “AC†to determine the power of the power supply and it will not necessarily output at maximum power.
3, power supply process detection: Before the power supply, the power supply will output a very small voltage to detect whether the powered device supports PoE, if not, it does not supply power, if it is supported, proceed to the next step.
Classification: After confirming that the power-receiving party supports PoE, the power-supplying party will conduct further tests to determine the power required by the power-receiving party and classify the power-receiving party.
Start supplying power and continue to provide a stable power supply.
4, PoE question answer af and at can be common? Can not be universal, but at can be backward compatible with af. In other words, if the switch supports the at-standard, it can provide up to 30W of power, so it can fully power the camera that supports the af standard and needs 7W. However, if the camera supports at, 20 W of power is required. Only the switch that supports af cannot supply power to this camera normally.
Can PoE switches exchange two levels? PoE only solves the power supply problem and does not affect the signal. If you want to use a multi-layer switch, you only need to let the switch closest to the camera power the camera, and the switch behind does not need to have any connection with PoE.
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