Non standard cable material market mainly copper clad steel, copper clad aluminum, copper coated iron wire, the resistance is large, is not suitable for the POE power supply, POE IEEE 802.3af standard PSE output power output port for 15.4W or 15.5W transmission 100 meters after PD equipment power acceptance shall not be less than 12.95W. According to the 350mA value for the calculation of 802.3af typical current, resistance wire must be 100 m (15.4-12.95W) /350ma = 7 ohms (15.5-12.95) or /350ma = 7.29 ohms, while the standard cable is natural to meet this requirement, because the IEEE 802.3af Poe standard power supply is in itself a standard cable set. The reason why the POE power line is required is that many of the network lines on the market are non-standard network lines, not strictly in line with the requirements of the standard network cable. So the question is, how do you choose the POE power grid? Professional network line manufacturer Orwell to answer for you:
The POE power supply must use the wire of the oxygen free copper material, that is, the standard net.
The cable must be connected according to the 568A or 568B standard cable must be connected to 8 lines, and 100 meters in length. The better the quality of the network cable is, the higher the transmission stability. At least is the super five kinds of network cable. If the budget cost is enough, we can choose the 6 kinds of network lines that have far distance and better effect.
Super five kinds of lines: Super 5 kinds of lines have the advantages of less attenuation, less crosstalk, and higher attenuation crosstalk ratio (ACR), signal-to-noise ratio (StructuralReturnLoss) and smaller delay error. The ultra 5 lines are mainly used in Gigabit Ethernet (1000Mbps).
The six kind of line: the transmission frequency of this kind of cable is 1MHz to 250MHz, and the six class cabling system has a larger margin when the 200MHz is at the time of 200MHz, and it provides 2 times the bandwidth of over five classes. The transmission performance of the six types of cabling is far higher than that of the super five standard, which is most suitable for the application with the transmission rate higher than the 1Gbps.
Another important difference between the six class and the super five class is that:
Six kinds of lines improve the performance in crosstalk and return loss. For the new generation of full duplex high-speed network applications, excellent return loss performance is very important. At the same time, the basic link model is cancelled in the six kinds of standards. The star topology is adopted in the wiring standard. The required link distance is not more than 90m, and the channel length can not exceed 100m.
How to identify the true and false of the net?
1. Look at the material
2. Look at the logo of the net
3. Look at the feeling of hand
In addition to looking at the way you can feel the difference between the 5 types of true and false / Super 5 lines on the material. True 5 types / Super 5 lines are soft in texture, which is mainly to meet the needs of different network environments. Twisted pair cable usually uses copper wire as conductor core, which is relatively soft, because some network environment may need small angle bending with wire mesh. If wire rod is hard, it will easily cause circuit breakage. While some illegal manufacturers add other metal elements to copper in order to reduce costs, they are hard to produce, and are not easy to bend.
4. Cut with a knife
Use scissors to remove the outside a small section of plastic wrapping, to expose the 4 pairs of core wires, watch these core wire. The true 5 class / Super 5 kinds of lines, 4 pairs of core lines, the white ones should not be pure white, but the white with the pair of pairs of core wires. This is mainly for the convenience of users to distinguish the line pairs when making crystal heads. And the fake is usually pure white or the color is not obvious.
The core wire winding density of 4 and 5 in class / Super 5 lines are also different, really 5 / 5 lines around the line of moderate density, direction is counterclockwise; false line density is usually very small, the direction may also be clockwise (less), because the fake in the production line is simple, so the process is rough.
5. Fire with fire
Can be twisted put in a high temperature environment test, take a look at 35 to 40 DEG C, outside of the cable will become soft rubber cable is not really, soft, fake is not necessarily true; another cable out of the plastic is flame retardant, and some are not fake is flame retardant, no comply with safety standards, you may wish to try to buy.