Cable wiring is the industry's leading Belden CDT launch of the new Brilliance®, the cable is not shielded twisted-pair cable (UTPs), support high-definition video transmission and accurate data transmission and KVM (keyboard, monitor and mouse) technology, is the best solution for professional video and data applications, at the same time for the component video application provides the excellent performance of low migration, accord with the standard and suitable for TIA/EIA.
Common sense of choose and buy
1. Check the certification mark of CCC. Cable products, therefore, is a national mandatory product safety certification, all production enterprise must obtain the Chinese electrical product certification board certification "CCC" certification, won the "CCC" certification marks, and on the certificate of approval or product "CCC" certification marks.
2. Inspection report. As a product that affects the safety of person and property, the cable line has been listed as the key point of government supervision and inspection, and the regular manufacturers have been inspected by the supervision department according to the cycle. Therefore, the seller should be able to provide the inspection report of the quality inspection department, otherwise, the quality of the cable product is not good or bad.
3. Focus on packaging. The packaging of wire and cable products is the same as that of other products, and the production of products that meet the national standards requires large and medium-sized enterprises. Pay attention to the packaging should be fine, printing should be clear, type specification, factory name, site and so on.
4. Looking outward, the product looks smooth and round, and its color is even. Products meet the requirements of the national standard cable enterprises, in order to improve the quality of products, ensure that products meet the national standard requirements, the raw materials, production equipment and production technology of choose and buy strictly controlled. Therefore, the product appearance of the production wire and cable product meets the standard requirements: smooth and round, the color is even. The appearance of the fake cable is rough and dull. And for the rubber insulated soft cable, requires the appearance of the round, sheath, insulation, the conductor close not easy to peel off. And fake inferior product appearance is rough, the elliptical degree is big, protect sleeve insulation strength is low, use hand can tear off.
5. Look at the conductor, the conductor has the luster, the dc resistance, the conductor structure dimension and so on meet the national standard requirements. To meet the requirements of national standard of wire and cable products, aluminum conductor, or copper conductors are light, no pollution, thus the dc resistance of conductors in full compliance with national standards, has the good electrical conductivity, high safety.
Measure cable length. Length is the main intuitive way to distinguish between national standard requirements and fake products. When the choose and buy, must not covet is cheap, 90 m or 80 m of choose and buy, not even the length of the wire and cable identification, length must conform to the requirements of the 100 + / - 0.5 m standard, namely on the basis of 100 meters, margin of error of 0.5 meters).
Traverse area and load flow calculation
The safety load flow of a normal copper wire carrying wire is determined according to the maximum temperature, cooling conditions and laying conditions of the allowable core. The safe load flow of the copper conductor is 5~ 8A/mm2, and the safety load flow of the aluminum conductor is 3~ 5A/mm2. The safe load flow of the normal copper conductor is 5~ 8A/mm2, and the safety load of the aluminum conductor is 3~ 5A/mm2. For example, the recommended value of the safe load flow of the 2.5mm2 BVV copper conductor is 2.5x8a/mm2 =20A 4 mm2 BVV copper conductor safe load flow recommended value of 4 x 8A/mm2=32A
Second, the calculation of copper wire cross-sectional area using the recommended values of the safety of the copper wires carrying capacity 5 ~ 8 A/was, calculate the selected copper wire cross-sectional area S fluctuation range: S = < I/(5 ~ 8) > = 0.125 ~ 0.2 I (was) I S -- -- -- -- -- copper wire cross-sectional area (was) I -- -- -- -- -- load current (A)
Three, the power calculates general load (also can be used electric appliance, such as point lamp, freezer and so on) fall into two kinds, one kind of resistive sex load, one kind is inductive load. The calculation formula of resistive load: P=UI for the calculation formula of fluorescent lamp load: P=UIcos phi, where the power factor of the fluorescent lamp load is equal to 0.5. Different inductive load power factors can be used to calculate the power factor cosine of 0.8. All that is to say if A household electrical appliances and total power of 6000 w, the maximum current is I = P/Ucos ф = 6000/220 * 0.8 = 34 (A) but, in general, home appliances may not use at the same time, so with A common factor, general utility coefficient of 0.5. So, the above calculation should be rewritten to be I=P* public factor/Ucos phi =6000*0.5/220*0.8=17 (A), which means that the total current value of the family is 17A. The total brake air switch cannot use 16A, should be greater than 17A.