1. The basic concept of electric wires
Electric wires are carriers for transmitting electrical energy, thermal energy, and signals
In 1744, German scientist J. Winkler realized the remote transmission of electrical energy through electric wires. The first electric wire came out. We generally refer to electrical equipment. The cable industry is a particularly complete industry segment. Industrial cables. Consumer cables are just a big category, as well as special cables.
2. The distinction between wires and cables:
In fact, "wire" and cable "do not have strict boundaries. Generally, products with few cores, small product diameters, and simple structures are called wires. Those without insulation are called bare wires. Others are called cables. The conductor cross-sectional area is relatively large The larger (greater than 6 mm2) is called a large cable, the smaller (less than or equal to 6 mm2) is called a small cable, and the insulated cable is also called a wiring wire.
3. Structure of the wire
The conductors are generally: copper wire, aluminum wire, copper-clad steel, iron wire, copper foil wire (Tinsel), etc .;
Insulation generally includes: PVC, PE, PP, TEFLON, TPU, TPE, FPE, etc .;
Sheaths generally include: PVC, PU, PA, neoprene, mica tape, ceramics, etc .;
Protective layer: armor (steel pipe), ceramic, polyester fiber, woven mesh, etc.
4. Requirements for copper wires
Copper wire generally includes: Strand, single wire, tinned wire, aluminum wire, enameled wire, twisted wire first, copper wire (Tinsel);
Multi-stranded wire: The most commonly used, most wire rods use multi-stranded wire for the following reasons:
■ Easily extruded and processed to make the wire soft;
■ Increase heat dissipation area;
■ Increase tensile strength and flexural strength;
■ Reduce the loss; (do not split the conductor in the large-section power cable, the current resistance of the cable will increase due to the skin effect and the proximity effect, and the current carrying capacity will decrease)
Common copper wire code meaning:
■ Bare copper wire BA.AS or CU;
■ Tinned wire TAS, TCU or TS;
■ Twisting first and then plating wire TC-T;
■ Copper foil wire (TSL);
■ Clad copper CCS, tinned copper clad steel CP;
■ Copper-clad aluminum CCA, copper-clad aluminum magnesium CCAM, etc.
■ Silver-plated copper wire SC ﹔
■ SCCS silver-plated copper-clad steel;
5. Insulation jacket and outer cover
Insulation and outer quilt mainly play a protective role. Plasticizers, flame retardants, antioxidants, coupling agents, anti-aging agents, and anti-ultraviolet agents are added to PVC to make the outer quilts bear different functions.
With different insulation thickness, the withstand voltage level is different: (1mil = 1 / 1000inch = 0.0254mm)
■ Thickness is less than 15mil, for use below 150V, such as UL1571
■ Thickness less than 30mil, for use below 300V such as UL1007
■ Thickness is less than 45mil, for use below 600V, such as UL1015
The heat resistance level is used to guide the body to heat up to a certain temperature, and the temperature tolerated within a certain period of time does not mean resistance to ambient temperature. Temperature 80'C (such as UL1007, UL2464, etc.), 105'C (such as UL1015, UL1672, etc.) can be achieved after adding flame retardants
When the insulation is XLPVC (crosslinked polyvinyl chloride), it can reach 105'C-125'C, such as UL1430, UL1431;
When the insulation is XLPE (crosslinked polyethylene), it can reach 125′C, such as UL3271, UL3266, etc .;
When the insulation is silicone rubber, it can reach 150′C, such as UL3122, UL3135, etc .;
Insulation is Teflon, which can reach 200’C ~ 260’C, such as 1330;
MI cable (mineral insulated cable), which is made of copper core, copper sheath, and magnesium oxide insulation processing, has good fire resistance, and can work for a long time below 250'C;
The above wires are temperature-resistant wires, but they cannot be burned in fire. Some special wires are covered with a layer of mica tape and can work at temperatures above 800'C for 90 minutes. They are called true fire-resistant cables.
Flame retardant grade of plastic:
How are HB, V-2, V-1 and V-0 defined? Plastic flame retardant grades are gradually increased from HB, V2, V1 to VO
HB: UL94 and CSA C22.2 No 0.17 lowest flame retardant grade. It is required that for samples of 3 ~ 13mm, the burning speed is less than 40mm / min; for samples less than 3mm, the burning speed is less than 70mm / min; or it is extinguished before the 100mm mark;
V-2: The flame was extinguished within 60 seconds after the sample was subjected to two 10-second burn tests. May have combustibles falling off;
V-1: After two 10-second fire tests on the sample, the flame extinguished within 60 seconds. No burning matter should fall off;
V-0: After two 10-second fire tests on the sample, the flame extinguished within 30 seconds. No burning matter should fall off;
Click to view: Introduction to UL Flame Retardant