Explain why the Power Supply Distance of PoE Powered Switch is only 100 meters, can't it be further?


It is believed that many engineers have encountered such problems in network planning. The distance between poe powered switch is only about 100 meters, but the farthest wireless AP (camera, etc.) on the fourth floor is just over 100 meters from the weak motor room on the second floor. So, many people wonder why the power supply distance of poe powered switch is only 100 meters, can't it be further?

In fact, pure power in the normal state of the circuit is to support long-distance transmission, but the use of ethernet power Poe also need to transmit data signals, and data signals in physical media (such as twisted pair) transmission must have attenuation and distortion. When the signal attenuation or distortion reaches a certain degree, it will affect the effective and stable transmission of the the signal.

That is to say, the power supply distance of Poe is determined by the transmission distance of data signal. But the power supply distance of poe power switch is 100m, which is the longest distance that data signal can transmit before sending a minimum frame at 100Mbps.

However, with the development of power supply technology, some manufacturers in the market claim that there are more than 200 meters of long-distance power supply switches, so can the power supply distance of poe powered switch break through the 100 meters limit and reach 200 meters? To understand this ultra-long-distance power supply, we have to mention a standard protocol of poe powered supply: 802bt is a secondary enhanced ethernet power supply standard, also known as poe++. This technology reduces the network rate from 1000M/100M to 10M, and then increases the voltage amplitude of RJ45 port of poe powered switch from 0.98V to 2.2V, so as to drive the data signal transmission to the farthest distance beyond 200 meters! Based on this implementation principle, it is easy to understand that ultra-long distance transmission is actually achieved at the cost of reducing ethernet ports to lower broadband (down to 10M bandwidth).