Some customers asked, there are POE switches on the market that claim to be able to transmit 150 meters or even 250 meters, is it true or false?

First of all, we need to understand what POE is. POE is the abbreviation of Power over Ethernet, which means that without any changes to the existing Ethernet Cat.5 cabling infrastructure, it can be used for some IP-based terminals (such as IP phones). The technology that can provide DC power to such devices while transmitting data signals, such as wireless LAN access points, APs, and network cameras, is a switch that supports Power over Ethernet.

The Ethernet standard stipulates that the maximum transmission distance is 100 meters, and data delay and packet loss may occur if the distance exceeds 100 meters.
But not all network cables are limited to 100 meters. In actual operation, the network cable can also effectively transmit more than 100 meters, and the quality can reach about 120 meters, that is, oxygen-free copper Cat.5 network cable, or category 6 network cable.

Many PoE manufacturers are now launching 150-meter, long-distance, 250-meter power supply, and even 500-meter transmission distance POE switches. Doesn’t it mean that the transmission distance of standard POE switches is 100 meters, and it is best to control the distance within 80 meters in actual use. What’s the matter?

We all know that the PoE power supply distance is determined by the transmission distance of the data signal. Pure electricity can be transmitted very far, but the transmission distance of the data signal is determined by the network cable. The transmission distance of the ordinary category 5 cable data signal is about About 100 meters. In order to ensure the quality of construction, it is generally 80-90 meters. Please note that the transmission distance here refers to the maximum rate, such as 100M.
Many manufacturers have marked that the transmission distance of their POE switches can reach 150 meters, but in actual applications, if ordinary POE switches want to achieve a transmission distance of 150 meters, they have strict requirements on the quality of the network cable. They must use more than category 6 cables, which increases Even so, if the internal circuit of the POE switch adopts a very common network switching chip and a POE power supply management chip, it is impossible to reach a network of 100M and a transmission distance of 150 meters, even if a high-quality network cable is used. It will increase the power consumption, exceed the power consumption of the PoE power supply, and be very unstable, with serious packet drops, severe transmission bandwidth and signal attenuation, resulting in signal instability, aging of PoE switch equipment, and difficulty in subsequent maintenance.

Even a high-performance POE switch with 100M full load and stable transmission can only reach 150 meters. What is the transmission distance of 250 meters? In fact, there are ways. If the rate is reduced to 10M, that is, the transmission bandwidth is 10M, the transmission distance is fine. Extending to 250 meters (depending on the quality of the network cable), this technology does not provide high bandwidth. The bandwidth is compressed from 100M to 10M, which is not convenient for the smooth transmission of high-definition monitoring images.
Many manufacturers, while promoting their products to support 250-meter transmission, do not mention the drop to 10M bandwidth, and are suspected of deliberately concealing the bandwidth from customers.

Moreover, not all POE switches can easily transmit 250 meters as long as the bandwidth is reduced to 10M. This also depends on the quality of the switch. If the internal switching chip adaptability of the switch is too poor and the power chip management ability is not strong, even if 10M is forced Transmission, also cannot guarantee the stable transmission of 250 meters, even 150 meters can not reach.

Therefore, in theory, to achieve a transmission of 250 meters, it is necessary to adopt a high-power design for POE, and the POE power chip adopts imported high-quality industrial-grade chips. The power management module can intelligently and automatically recognize the IEEE802.3af/at standard, automatically adjust the power, and use 8 cores at the same time. Intelligent power supply technology, to achieve such a function, using built-in power supply, the advantage of using built-in power supply is that it can optimize specific design, automatically measure the power demand of the receiving end and the cable transmission impedance and other parameters, which are analyzed and calculated by the intelligent power management module and issued Instruct the internal power supply circuit to adjust the linear voltage input to match the automatic power output to the end-powered equipment.