A wire and cable square number and diameter conversion method knowledge
Wire specifications are commonly used in the international community, there are three standards: American (AWG), British (SWG) and our (CWG).
How many squares is a nominal value specified by the national standard, how many squares is the user according to the load of the wire and cable to choose the wire and cable. Wire square number is a verbal term in the renovation of plumbing and electrical construction, often said a few square wires are not added units, that is, square millimeters. The square of the wire is actually marked as the cross-sectional area of the wire, that is, the area of the circular cross-section of the wire, the unit is square millimeters. Generally speaking, the empirical load capacity is when the grid voltage is 220V, each square of wire experience load capacity is about one kilowatt. Copper wire can carry 1-1.5 kW per square, and aluminum wire can carry 0.6-1 kW per square. Therefore an appliance with a power of one kilowatt requires only one square of copper wire. Specific to the current, short distance power supply general copper wire per square can carry 3A to 5A current. Heat dissipation conditions are good to take 5A / square millimeter, not good to take 3A / square millimeter.
Conversion method: know the square of the wire, calculate the radius of the wire with the circular area of the formula: the number of square wires (square millimeters) = circumference (3.14) × wire radius (millimeters) of the square to know the square of the wire, calculating the diameter of the line is also the same way, such as: 2.5 square wires of the wire diameter: 2.5 ÷ 3.14 = 0.8, and then open the square to arrive at the 0.9 millimeters, so the 2.5 square wire of line diameter is: 2 × 0.9 mm = 1.8 mm. Know the diameter of the wire, the calculation of the square of the wire is also used to find the circular area of the formula to calculate: the square of the wire = circumference (3.14) × line diameter of the square / 4 cable size is also nominalized by the square, multi-stranded wire is the sum of the cross-sectional area of each wire. The formula for calculating the cross-sectional area of the cable: 0.7854 × wire radius (mm) of the square × number of shares such as 48 shares (0.2 mm radius of each share of the wire) 1.5 square line: 0.785 × (0.2 × 0.2) × 48 = 1.5 square
Second, commonly used small-size cable knowledge
RVVP: copper core PVC insulated shielded PVC sheathed flexible cable, voltage 300V/300V 2-24 cores. Main quality indicators: wire diameter (including the core wire and braided wire, not the thicker the better, with impurity copper to achieve resistance standards and do very thick), copper core purity, braiding density, stranding distance. Use: instruments, meters, intercom, monitoring, control installation.
RG: physical foaming polyethylene insulated access network cable for coaxial fiber optic hybrid network (HFC) in the transmission of data analog signals, this is the U.S. standard, approximately equivalent to the national standard SYWV series. Main quality indicators: copper core wire diameter, insulation thickness, braiding materials (the market is mostly aluminum-magnesium wire braid, good quality should be tinned copper), braiding density. UTP: LAN cable Use: transmission of telephone, computer data, fire and burglary prevention security systems, intelligent building information network. Commonly used UTP CAT 5, UTP CAT 5E with shielding model STP
KVVP: PVC sheathed braided shielded cable Usage: Signal transmission, control and measurement of electrical appliances, instruments and power distribution devices.
SYWV (Y), SYKV cable structure for cable TV, broadband network: (coaxial cable) a single oxygen-free round copper wire + physical foaming polyethylene (insulation) + (tinned wire + aluminum) + PVC (polyethylene), (equivalent to the U.S. standard RG-6, RG-59). Nowadays, the market is mostly braided with aluminum-magnesium wire (can’t be welded, easy to oxidize), and the core wire is made of copper-clad aluminum and copper-clad steel, so much so that many people think that SYWV wire is cheaper than SYV wire, but the fact is that it’s not so.
RVV (227IEC52/53) PVC insulated flexible cable (cross-sectional area: 0.5-6.0 number of cores 1-24) Uses: power lines, signal lines, household appliances, small power tools, instruments and power lighting. This specification line as long as the national standard is in line with the price difference is not great, but there is no shortage of impurity copper in the market, wire diameter is not enough, short meters, straight discharge (core copper wire is not stranded or core wire is not stranded, so that tensile capacity is greatly reduced, increased resistance) to fill the number of cases. Derived from the model: RVVS: this type of core wire stranding distance encryption, generally used in broadcasting systems.
AVVR Polyvinyl chloride sheath installation with flexible cable (cross-sectional area: 0.12-0.5 Number of cores 1-24) Use: signal, control. Such as access control signals, control, PTZ control.
HYV, HYA data communication cable (indoor, outdoor) (core diameter of 0.5mm, the number of cores 2, 4, 8, etc.) that is, the telephone line, used for telephone communications and radio equipment connections and telephone wiring network distribution box wiring, etc.. The general market core diameter is 0.4 mm, there are almost with steel wire or copper-aluminum alloy. Another telephone line is generally not enough meters.
RV, RVP PVC insulated cable, PVC shielded cable, mainly used for equipment.
RVS, RVB for household appliances, small power tools, instruments, meters and power lighting connection cable, RVS can also be used for broadcasting lines or instead of RVV line.RVB in the case of low requirements can replace the gold and silver wire.
BV, BVR polyvinyl chloride insulated cable Usage: suitable for electrical instrumentation equipment and power lighting fixed wiring, affordable low resistance. In many occasions to connect the power supply can be considered.
RIB speaker connection line (audiophile line, gold and silver wire) some audio line model labeling often have “6N”, “7N” words, the meaning of which is used to indicate the use of metal materials made of audiophile line purity of the high and low. For example, “99.9999%”, you can use “6N”, that is, its purity is 6 9, the larger the number in front of the N shows that the purity of the audio line is higher. Home theater audio equipment whether you need to use higher quality audio cable, the key is to grasp the practicality, according to ability.