2. Peeling off the skin to see the line pairs inside, the colors of genuine line pairs are clearly printed, while the colors of inferior line pairs are likely to be blurred or even discolored;
3. Untie the wire pair and fold the wire core at will to see if the wire core has recovered greatly. If so, the wires will not work well. It is estimated that the copper core is thin and plastic. A good network cable can be used for
It is meaningful and not easy to break.
Generally, through these three points and the comparison with the genuine network cable, it can be basically identified.
How to judge the quality of network cable? You want to make a box of 1000m network cable with a standard of about 300m and a box of1000 m. And in the construction, you have to follow the 1000m cable transmission regulations. If you want to pull1000 m, the direct fiber rubber sleeve will be finished.
How to judge the quality of network cable? If 1000m network is to be built, it can be judged by cable sheaths such as Cat.5, Cat.5e and cat.6.. The complete CAT-5e cable is printed with words similar to "24awg/4puttia/EIA 568-a 5e LAN cable". 5 is100M, 5e is 250M, and 6 is.
How to judge the quality of home network cable? The network cable that can be connected is a good network cable. Network cables are all of the same quality and material. There is no difference.
How to judge the quality of an online shop? What we are seeing now is the experience after the success of the store. Maybe they won't say how bitter it is. Of course, this is the result. Everyone has to find a good shop to promote and manage by themselves. Copying it may not be suitable for your own store. The most important thing is that they have their own experiences. Maybe after mastering the method, they will be more experienced and more handy! And if you want to, you can solve it now, even if you start late. Now you can rent out this idle high-end old shop and go directly to Aipu to buy rent or transfer one. There are many ways, but it is impossible to get a return without paying.
How to judge the quality of online lending platform depends on the background of the platform. If the platform is supported by well-funded entities, the staff of the platform have long-term experience in bank credit, and the risk is relatively reduced. If you have the conditions, you'd better choose a formal financial institution, and don't be greedy and cheap.
In online loans, we should pay attention to several matters:
1. First of all, formal loans do not need to pay deposit or interest in advance, and withholding interest is also against relevant laws and regulations;
2. When choosing an online lending platform, if the other party directly or in disguised form requests to pay the "pre-loan fee", which does not meet the relevant regulations, be vigilant;
3. Secondly, regular small loan companies generally do not engage in cross-regional loans;
4. In addition, it is best to know the real situation of small loan companies behind the platform before lending to prevent being deceived.
How to judge the quality of cylinder dividing line? The resistance of cylinder pipeline can be measured by multimeter.
Reference value: (long line) 5.0K；; (short-term) 2.4k
If the error between the actual measured value and the reference value is greater than 10%, it can be determined that it is damaged.
The high-voltage line of a car is neither iron nor copper. Its outer skin is high insulating rubber and its inner core is mostly carbon material. An excellent set of high-voltage lines must have minimum current loss to avoid electromagnetic interference caused by high-voltage power transmission. Therefore, the high-voltage ignition wire is designed with resistance, and the circuit is scientifically called damping resistance. The resistance of high-voltage lines varies according to the design of various high-voltage output systems, some are only a few hundred ohms, and some are above 10k.
How to judge the quality of GPS antenna? GPS antenna is small in size and weak in signal voltage, which cannot be measured by general instruments. The best way is to try a new antenna, or plug the GPS antenna into other available navigators for testing.
How to judge the quality of network cable? 1, test the ductility of the cover.
Considering that the network cable often needs to be bent when wiring, many regular manufacturers leave some ductility to the skin when making the network cable to ensure that the network cable is not damaged when bending. Therefore, when you pull the regular network cable with both hands, you find that the skin can be extended. If the sheath of the cable is forcibly pulled off, or the sheath cracks under the action of external force, it indicates that there is something wrong with the cable quality.
Looking at the network cable from the outside, the skin should be thick, the handwriting should be clear, the regular brand network cable is full and tight, and the network cable is basically twisted into a regular line shape, while the inferior network cable has a smooth skin without any lines.
2. Check the flexibility of the network cable
A good network cable will take into account the possible bending of the network cable during network construction, and try to reduce the impact on data transmission efficiency when the network cable is bent due to unchangeable environmental factors. Moreover, a good protective layer of network cable is flexible and will not break due to bending. It is recommended to test the network cable after repeated bending or even folding.
Fold the line 180 degrees, and then skim it back to see how the skin resists folding. Good quality network cable, no matter how the skin is folded, will not be too obvious whitening. It is obviously white after staying. The network cable with good sheath is not easy to break during construction.
A good quality network cable is designed with the convenience of wiring in mind, as flexible as possible, convenient no matter how it is bent, and not easy to break. At present, many profiteers in the market add other cheap metal components to the original pure copper network cable in order to obtain high sales profits, which will reduce the cost of the network cable, but the quality and efficiency of the network cable itself are quite different. The phenomenon is that the texture of the network cable is no longer so soft and the transmission speed of the network cable is greatly reduced. If such a network cable is bent repeatedly in the wiring process, the copper cable inside the network cable may break. Of course, if you find that the network cable is too soft, you should also pay attention to the possibility that it is a fake and shoddy product.
3. Test the winding distance of the network cable
As we all know, ordinary twisted pair is made up of four groups of intertwined network cables. The so-called winding distance of network cable is actually the length of a network cable. Usually, people use the winding distance to indicate the tightness of each pair of wires, but in order to minimize the crosstalk between each pair of wires, each pair of wires is often tightly wound counterclockwise, and the winding distance adopted by each pair of wires should not be the same. However, in order to reduce production links and process costs, many profiteers who produce network cables often wind four pairs of wires at the same winding distance, and even many inferior network cables have a winding distance as high as several centimeters, which greatly increases the crosstalk between pairs and seriously affects the use efficiency of network cables.
After pulling out the sheath of the cable, we will see four pairs of wires. In a conventional cable, these four pairs of wires will be twisted counterclockwise or clockwise, the colors of the four pairs of wires are standard, and the twisted wires are arranged evenly. And the lay lengths are different, but the lay lengths of each pair of wires are very uniform. In order to save trouble, four pairs of wires are wound in the same direction or even the same winding distance, and some of them are not wound at all, so the signal crosstalk between each pair of wires is very large, which seriously affects the efficiency of signal transmission.
4. in-line conductor
The worst wire is not only thin, but also the iron core (copper plating on the surface). The easiest way is to test with a magnet.
Copper core is generally used as transmission medium in regular network cables, and there are strict regulations on the thickness and coating of copper core. In this contrast, all inferior network cables are wires as thin as hair. (In the picture, blue is the inferior network cable, and gray is the qualified network cable. )
The finished network cable can be observed from the crystal head.
5. Test the flammability of the network cable.
Generally speaking, the material that constitutes the network cable must be flame retardant, otherwise there will be a fire or something, which will cause heavy losses. Therefore, when you choose the network cable, you must check the flammability of the network cable skin to distinguish the authenticity. In the specific test, you can cut the cable sheath about 2 cm long with scissors, and then burn it with a lighter. The skin of genuine cable will gradually melt and deform under the barbecue of fireworks, but the skin will certainly not burn by itself; If you find that the skin of the network cable can't stand the test of fire and burns at all, you should give up the choice no matter how high the transmission speed of the network cable is. After all, such a network cable is very unsafe in the wiring project, and it will leave great security risks when used. The author once found a genuine network cable and a fake network cable and lit them with a lighter. The results show that after 6 seconds, the genuine network cable only emits white smoke, which gradually melts and deforms with time, while the fake network cable is easily ignited in less than 2 seconds, accompanied by a lot of black smoke.
6. Test the temperature resistance of network cable.
Temperature will also affect the speed at which the network cable transmits data. The temperature difference between high and low that a good quality network cable can bear will be much greater than that of a poor quality network cable, and some poor quality network cables will obviously reduce their transmission speed in a high-temperature computer room.
In the wiring engineering, the requirements for the network cable to resist external temperature changes are quite high, not to mention any environmental changes, at least the network cable can not soften or freeze crack in high and low temperature environment. In order to ensure that the performance of the network cable is not affected in the high temperature environment, the skin material used in the genuine network cable can withstand the high temperature test of about 50 degrees, and there will be no similar phenomenon that the network cable becomes soft or deformed. If you take a short piece of cable sheath and put it next to the stove for a period of time, it is found that the sheath is softer than the normal sheath, which means that the quality of the cable will definitely not be too hard.
7, network cable test
All identification methods can not correctly judge the quality of network cable 100%, and the most scientific method is detection. According to the related test standard of TIA Cat5e (Super Class 5 568B), the test was carried out with FLUK-TX 1800.