FAQ
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QHow to identify good quality cable or poor quality cable?A1. Check printed label carefully, whether the printing is illegible. It means to see printed words on the label and the insulated sheath, if there are typos or printed shades, vague words, you need to pay attention. 2. Twist insulation sheath with hand, check whether it fades or lose word. Twist insulation sheath with your fingers, insulation sheath of poor quality cable is easy to fade, especially red insulation sheath and printed word is easy to rub away. 3. Scratch or nip insulation sheath of cable with nails. it is poor quality cable if you can pinch off the insulation sheath. 4. Bend insulation sheath repeatedly, and check whether it will break after three to four times. If break, it is poor quality cable because its insulation sheath is very bad. 5. Fire the insulation sheath of cable, check whether it will self-ignite when fire off. If it will self-ignite, it is poor quality cable. 6. Check the conductor. The conductor of cable is common aluminum and copper if the conductor color is dark and no metallic luster, it is poor quality cable. 7. Measure inner diameters and outer diameters, and then weigh the cable. Measure the inner and outer diameters of cable insulation sheath the tolerance is ±10%. If it exceeds the tolerance it is poor quality cable.
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QWhy flexible mine insulated fire resistant cable have good fire resistance performance?ASuperior high temperature resistance and fire resistance performance. General wire and cable insulation due to the use of organic polymer materials are therefore highly carbonized under fire conditions and thus lose insulation Flexible mine insulated fire resistant cable main materials is mineral compounds, which in itself does not cause a fire, can not burn or support combustion. These materials generally have a higher melting point above 1500 C, so even for fire resistant cable under fire conditions can also play a normal transmission function, it is a real fire cable sense. And through the BS6387 C, W, Z test. Strong overload Flexible mine insulated fire resistant cable ampacity is large, and has a strong circuit overload, according to the relevant electrical design requirements that cable surface temperature is usually not higher than 70℃, if there isn’t combustibles around, Flexible mine insulated fire resistant cable long-term working temperature can reach overload 250℃.
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QHow to choose right cross-section of low voltage overhead cable conductor?A1. According to the conductor permissive current, When low voltage overhead cable conductor passes the maximum permissible continuous load current, conductor wire core heat does not exceed the allowable temperature. 2. According to the permissive voltage loss. voltage loss is generated by low voltage overhead cable conductor continuously pass the normal maximum load current not exceed the permitted range, to ensure the normal operation of electrical equipment. 3. According to the mechanical strength, low voltage cable conductors should be prevented from breakage during installation or operation. Low voltage overhead cable conductor cross-section, AAC and AAAC are required not less than 25mm2, ACSR is not less than 25mm2, copper bare conductor voltage overhead cable diameter is not less than 4mm. When you select a larger conductor cross-section should consider according to the economic current density to minimize power consumption and operating costs of the line.
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Q4 tips for power cable laying constructionA1. High current power cables cause eddy current problems. Power cables in the construction some use steel bracket some use steel protection tube and some use strain relief clamp and overhead cable laying. all in the vicinity of power cables formed of steel (iron)of a closed loop. it is likely to form a vortex, especially in high current power cable system, the eddy current is greater. When the power cable laying construction, measures must be taken so that the cable can not be formed closed loop around the steel(iron), prevent power cable causing eddy current. 2. Mechanical damage problems caused by power cable bending Due to the large diameter of power cable, transportation and laying is more difficult, the power cable to bending radius requirements is more stringent. When power cables is in laying construction, if the bending angle is too large, it may make the internal conductor subjected to mechanical damage, and cause mechanical damage cable insulation strength decline, until break down. In power cable construction process, we should minimize the torque cable suffered, when cable turning and obligate power cable, we should let the cable in a natural bent, prevent the power cable internal mechanical damage. 3. Power cable moistureproof problem. Operating experience shows that most of medium voltage power cable and low voltage power cable faults are occurred at the middle connector or terminal head of the cable, and the middle joints, and terminations head failure is largely due to poor sealing moisture intrusion caused dielectric strength decreased, while the medium voltage power cable and low voltage power cable net are usually use dendritic power supply, a larger number of cable terminal head. So to ensure that the cable head end and middle joints plugging seal i to ensure safe and reliable operation of the cable one of the important measures. 4. Medium voltage power cable and low voltage power cable grounding problems. In public medium voltage power cables net, since the three-phase load are not equal, so if using a metal sheath of the cable, the metal sheath grounded problem must be considered, and to ensure that at any point of non-ground metal protective layer normal induction voltage shall not exceed 100V.
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Q5 measures to prevent electric cable insulation breakdownA1. The conductor must be smooth and free of burrs, and the insulating material should not contain impurities. 2. The three-layer co-extrusion is strictly implemented in accordance with the production process to avoid scorching and aging. 3. Safe operation at the construction site to avoid damage to the cables 4. Safe use of electricity and avoid overload. 5. Regular maintenance Line to ensure safe electricity use.
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QThe differences between communication cable and optical fiber cableAThe core of optical fiber cable is a communication line which is composited of a certain number of optical fibers in a certain way, with outer jacket and outer sheath, for effecting optical signal transmission. Optical fiber cable has a larger transmission capacity than copper cable, long-distance relay, small size, light weight, no elctromagnetic inteference. Since 1976, optical fiber cable has developed into the main wire transmission line for long haul line. the city relay, coastal and transoceanic submarine communications. LAN, as well as private network . And begin to spread to areas of city subscriber loop distribution network, provide a transmission line for FTTH and B-ISDN. Communication cable is usually made of a few or several groups of wires [each at least two] twisted together like rope cable, insulated from each other between each group wire, and often twisted around a center, there is the whole package outside highly insulating cover layer, especially a submarine cable. Firstly, different material. Communication cable uses metal(mostly copper or aluminum) as conductor, optical fiber cable uses glassy fiber as conductor. Secondly, different transmission signals. Communication cable transmission is electrical signal. Optical fiber cable transmission is optical signal. Thirdly, different applications. Communication cable is used for energy transmission and low-end data transmission (eg. telephone). Optical fiber cable is used for data transmission.