How far is the power supply distance of the industrial PoE switch

Industrial-grade PoE switch analyzes how far the POE power supply distance is

　　 Industrial-grade PoE switch is a switch with power supply function. PoE switch is widely used in the field of security monitoring and wireless coverage, which can save the cumbersome power supply wiring for camera and wireless AP. So how far is its POE power supply distance?

The Ethernet standard stipulates that the maximum transmission distance is 100 meters, which means that the PoE switch uses a standard network cable for power supply. The maximum transmission distance is 100 meters. When using a Category 5 or Category 6 oxygen-free copper network cable, data delays and packet loss may occur if more than 100 meters. And other phenomena. In fact, the PoE power supply distance is determined by the transmission distance of the data signal. Pure electricity supports long-distance transmission when the circuit is normal, but the transmission distance of the data signal is determined by the network cable, while the transmission distance of the ordinary Category 5 cable data signal is about 100 meters. In order to ensure the construction quality, Generally take 80-90 meters.

　　 1. The influence of the network cable on the power supply distance:

　　 First, let’s look at the requirements for Cat5e network cables in the IEEE802.af and IEEE802.3at standards:

　　 Generally, the equivalent impedance IEEE802.3at of a 100-meter cat5e network cable must be less than 12.5 ohms, and IEEE802.3af must be less than 20 ohms.

　　PoE power supply distance is closely related to the network cable. The lower the impedance of the network cable, the longer the transmission distance. Everything about the PoE power supply distance apart from the network cable is empty talk. If you want to supply power far enough, you must first buy a genuine network cable.

　　 Two, IEEE802.3af/at standard for PoE power supply voltage requirements:

　　1. PoE output voltage range 44-57V, PD receiving voltage range 36-57V, 802.3af/at standard; reference is as follows:

　　PoE power supply distance is long, and the output voltage must be high. If the PoE power supply distance is long enough, the network cable must meet the standard, and the output voltage of the PoE power supply product should be as high as possible within the standard (44-57V).

　　2. How to treat the 150m long-distance transmission of a POE switch with a distance of 250m correctly

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 The cost of use, even so, if the internal circuit of the POE switch uses a very common network switching chip and a POE power supply management chip, it is impossible to achieve 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 OK. 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 inconvenient for the smooth transmission of high-definition monitoring images.