For beginners, wires and cables are always a bit silly and unclear ~ Wires refer to wires that conduct current, which can effectively conduct current and are the carrier used for conducting electrical energy. Cables are wire products used to transmit (magnetic) energy, information and realize electromagnetic energy conversion. They are usually composed of several or several groups of wires, which are divided into: power cables, control cables, compensation cables, shielded cables, Computer cables, signal cables, coaxial cables, fire-resistant cables, marine cables, mining cables, aluminum alloy cables, etc. What is the difference between the two? What types of wires and cables are there? Where are they used? This editor will take you into the world of wires and cables.
What is the difference between wire and cable?
1. The wire is composed of one or several soft conductors, which are covered with a light and soft sheath; the cable is composed of one or several insulated conductors, which are then covered with tough metal or rubber. outer layer. Cables and wires are generally composed of three parts: core wire, insulating sheath and protective sheath. In fact, there are no strict boundaries between "wire" and "cable". Usually, products with few cores, small product diameter and simple structure are called wires, those without insulation are called bare wires, and others are called cables. The conductor with a larger cross-sectional area (greater than 6 square millimeters) is called a large wire, the smaller one (less than or equal to 6 square millimeters) is called a small wire, and the insulated wire is also called a cloth wire.
2. The cable generally has more than 2 layers of insulation, most of which are multi-core structures, which are wound on the cable reel, and the length is generally greater than 100 meters. The wire is generally single-layer insulated, single-core, 100 meters in a roll, and has a wireless reel.
3. The smaller diameter is called "line"; the larger diameter is called "cable".
4. The simple structure is called "line"; the complex structure is called "cable".
However, with the expansion of the scope of use, many varieties of "cable in cable" and "cable in cable". So there is no need to strictly distinguish. In daily habits, people call household wires as wires, and power cables as cables for short.
What types of wires are there? Where are they used?
1. BLX type, BLV type: aluminum core wire, due to its light weight, is usually used for overhead lines, especially long-distance transmission lines.
2. BX type, BV type: copper core wires are widely used in electromechanical engineering and are suitable for the fixed laying of power units of 450/750V and below. The BV type of wire is complex, and some chemical components in the rubber-insulated insulation will have a chemical effect on copper. Although this effect is slight, it is still a defect, so it is basically used in mechanical and electrical engineering. PVC insulated wire BV type alternative.
3. RV type, RX type: The copper core soft wire is mainly used in the movable parts that need flexible connection. RV type is suitable for household appliances, small electric tools, instruments and meters of 450/750V and below, and the allowable working temperature for a long time should not exceed 65°C. RX type is suitable for indoor lighting fixtures, household appliances and tools of 300/500V and below, and the allowable operating temperature should not exceed 70°C.
4. BVV type: multi-core flat or round plastic wire, which can be used for wiring in electrical equipment, and is often seen in fixed wiring in household appliances, but the model is not the BVV hard wire used for conventional lines, and It is RW, which is a copper core plastic insulated plastic sheathed multi-core flexible cord. For example, BV-type or BX-type PVC insulated or rubber-insulated copper core wires are usually used as power connection wires for general home and office lighting; RV-type PVC insulation is often used for the connection between electric welding machines and welding tongs in mechanical and electrical engineering sites. Copper core flexible wire, this is because the welding position is not fixed and moves more.
What types of cables are there? Where are they used?
1. VV type, YJV type: PVC type power cable, XLPE type power cable, can not be affected by mechanical external force, suitable for indoor and tunnel bridge and pipeline laying. For example, the cross-Huangpu River power cable laid in the Dalian Road Tunnel in Pudong New Area uses YJV copper core XLPE insulated PVC sheathed cable, because the cable will not be subjected to mechanical external force in the tunnel, nor does it require withstand great tension.
2. VV22 type, YJV22 type: inner steel tape armored power cable, which can withstand certain mechanical external force, but cannot withstand large tensile force. The long-term allowable high temperature of XLPE insulated power cable YJV22 is 90°C, and its aging resistance and environmental resistance are higher than that of PVC insulated cable VV22, and it is light in weight, simple in structure, easy to use, and not limited by drop. . Such as in high-rise buildings, hospitals, subways, nuclear power plants, power plants, mines, petroleum, chemical and other laying indoors, tunnels, cable trenches and direct buried underground laying.
3. ZR-YJFE type, NH-YJFE type: flame-retardant, fire-resistant and other special irradiation cross-linked power cables, the long-term allowable working temperature of the cable can reach 125°C, and it can be laid in the ceiling and the cable shaft of high-rise buildings inside, and suitable for wet places. Flame retardant cables should have flame retardant properties. In order to extinguish, reduce or inhibit the burning of materials, 11 kinds of common materials and engineering equipment need to be added to the materials or processed. Usually, flame retardants are added to the materials to make the materials It has the properties of preventing or delaying the spread of flame when burning. That is, it burns on an open flame and goes out automatically after a period of time after leaving the fire. At present, there are four grades A, B, C, and D, and the C grade is generally used.
The characteristics of fire-resistant cables are that they still have the ability to conduct electricity when the cables are burned or even for a period of time after burning. They are mostly used in relatively important working environments, such as warships. Fire-resistant cables can have flame-retardant properties at the same time, but flame-retardant cables do not have fire-resistant properties.