The power cable is used to transmit and distribute the large-functional power in the main line of the power system, and the control cable transfers the power directly from the power distribution point of the power system to the power connection lines of various appliances and appliances. The rated voltage of the power cable is generally 0.6/1kV and above, and the control cable is mainly 450/750V. When power cables and control cables of the same specifications are manufactured, the insulation and sheath thickness of power cables is thicker than that of control cables.
First of all, the control cable belongs to the cable for electrical equipment, and the power cable is two of the five categories of cable.
The standard for control cables is 9330 and the standard for power cables is GB12706
The color of the insulated cable core of the control cable is generally black and white, and the low voltage of the power cable is generally color separation.
The cross section of the control cable generally does not exceed 10 square meters. The power cable is mainly used for power transmission and generally has a large section.
Due to the reasons mentioned above, the specifications of power cables can generally be larger, as large as 500 square meters (range that conventional manufacturers can produce), and relatively few manufacturers can do as large cross-sections as possible, and the cross-section of control cables is generally small. Smaller, the maximum is generally not more than 10 square. From the perspective of the number of cable cores, the power cable is generally up to 5 cores according to the grid requirements, while the control cable transmits control signals with a higher number of cores. According to the standard, there are more than 61 cores, but it can also be produced according to user requirements. .
Network transmission media - three kinds of cables in the network hardware, there is a category can not be ignored is the network transmission media, we usually called the network cable. At present, the more common network cables are fine coaxial cables, coarse coaxial cables, twisted pairs, and optical fiber cables.
1. Coaxial <br> <br> Coaxial cable is more familiar with many friends for a class of transmission medium, which is wrapped around the cable center conductor by a layer of copper of insulated wire, its most important feature is interference With good capabilities, stable data transmission, and low prices, it was once widely used, such as closed-circuit television lines. However, more coaxial cables were used in the past, mainly because the cost of the bus structure network composed of coaxial cables is low, but the damage of a single cable may cause the entire network to collapse, and the maintenance is also difficult. This is its biggest drawback. Coaxial cables in Ethernet applications are mainly classified into coarse coaxial cables (10Base5) and fine coaxial cables (10Base2). Rough coaxial cables are not used much now, and there are still some markets for fine coaxial cables. Fine coaxial cable market price of a few yuan a meter in general, is not too expensive. In addition, the coaxial cable is used to connect with the BNC head. The coaxial cable sold on the market is generally a finished product that has been connected to the BNC head.
2. <br> <br> twisted-pair twisted-pair cable is a flexible communications, contains a pair of insulated copper wire, which is characterized by cheap, so widely used, such as our common telephone lines, etc. . According to the maximum transmission rate, twisted pair can be divided into 3 categories, 5 categories and 5 categories. The speed of Category 3 twisted pair is 10Mb/s, Category 5 is up to 100Mb/s, and Super Category 5 is up to 155Mb/s or more, which can be suitable for future multimedia data transmission needs. Therefore, it is recommended to use 5 types or even 5 types of double Stranded wire. Twisted pair can also be divided into shielded twisted pair (STP) and unshielded twisted pair (UTP). Although the STP twisted pair has a low speed (only 4Mb/s), the anti-interference is stronger than the UTP twisted pair, so the price is much more expensive. Now such a twisted pair is cheaper, a few dollars a meter, and you may be ten. A few dollars or more can buy one meter. In contrast, UTP twisted-pair prices are generally around one meter one yuan, which is relatively low. In addition, popular 10M and 100M unshielded twisted pair is popularly known as 10Base-T and 100Base-T, which are often seen in the market. The RJ45 crystal head is also used for the twisted-pair cable. It is used to make the joint between the twisted-pair cable and the RJ45 interface of the network card. The quality is directly related to the stability of the entire network and cannot be ignored.
3. <br> <br> fiber optic cable fiber optic cable is a new generation of transmission media, compared to copper media, optical fiber both in terms of safety, reliability or network performance has greatly improved. In addition, the bandwidth of optical fiber transmission exceeds that of copper cables, and the maximum connection distance it supports is more than two kilometers. This is an inevitable choice for building larger networks. Because fiber optic cable has the advantages of good anti-electromagnetic interference, strong confidentiality, high speed, and large transmission capacity, its price is also relatively expensive, and it is rarely used in home use. At present, there are two different types of optical fiber, which are single-mode fiber and multi-mode fiber (so-called "mode" refers to a beam of light that enters the fiber at a certain angle). Multimode fibers are generally used for network connections in the same office building or in relatively close areas. While single-mode fiber delivers higher quality data and longer transmission distances, it is often used to connect office buildings or geographically dispersed networks. If optical fiber cables are used as the network transmission medium, the shielding of the equipment such as the optical transceiver must be added. The outermost layer of the wire and cable is generally a rubber or rubber composite sleeve. The role of this layer is insulation, and it also protects the cable from being used. The effect of injury.
The cable is divided into high-voltage and low-voltage cables. If it is high pressure, there will be a layer of resin-like filler inside. This is an insulation. In high-voltage cables, this layer is the most important part of insulation. There is no such thing as low pressure. Then there will be something like a ribbon wrapped inside, this is to fix every cable core, fill the gaps in the middle.
As for the shielding layer, there are two cases in which the role of the shielding layer of the power cable is as follows:
1, because the power cable through the current is relatively large, the current around the magnetic field will be generated, in order not to affect other components, so add shielding layer can shield this electromagnetic field in the cable.
2, can play a certain degree of grounding protection, if there is damage inside the cable core, leakage of current can be along the shielding of laminar flow such as grounding network, play a role in security protection.
If it is a control cable, there is no difference, but in many places, especially the control cable of a computer system, the shielding layer here is used to shield external influences, because the current itself is very weak, and it is very afraid of the influence of the external electromagnetic field.
Polyvinyl chloride, polyethylene, cross-linked polyethylene, the difference between the three polyethylene English referred to as PE, which is ethylene polymer, non-toxic. Easy to color, good chemical stability, cold resistance, radiation resistance, good electrical insulation. It is suitable for food and drug packaging materials, production of food utensils, medical equipment, but also to do the insulation of the electronics industry. Such as: Intrinsically safe computer shielded cable (or intrinsically safe DCS system cable) PVC English abbreviation PVC, vinyl chloride polymer. It is chemically stable and resistant to acids, alkalis and some chemicals. It is resistant to moisture, aging and flame. When it is used, the temperature cannot exceed 60°C and it will harden at low temperatures. Polyvinyl chloride is divided into soft plastic and hard plastic. The soft main film is used for packaging materials, rain protection products, agricultural breeding films, etc. It can also be used for insulation of cables and wires, artificial leather products. Hard, generally made pipes and plates are used as pipes and pipes for conveying corrosion-resistant fluids. The plates are used as linings and floors for various tanks. Such as: 0.6/1kv PVC insulated power cable cross-linked polyethylene English abbreviation XLPE, is an important technology to improve PE performance. Cross-linked modified PE can greatly improve its performance, not only significantly improve the mechanical properties of PE, resistance to environmental stress cracking resistance, chemical corrosion resistance, creep resistance and electrical properties and other comprehensive performance, but also The temperature rating of the PE is obviously improved, and the heat-resistant temperature of the PE can be increased from 70°C to 90°C, which greatly broadens the application range of the PE. At present, cross-linked polyethylene (XLPE) has been widely used in pipes, films, cable materials and foam products. Such as: 35kv and the following cross-linked polyethylene insulated power cable wire and cable classification application and basic structure 1. Classification The wire products used to transmit electricity (magnetic) energy, information and achieve electromagnetic energy conversion are collectively referred to as wire and cable. According to different uses, wire and cable can be divided into five categories:
Bare wires: Products that have conductors but no insulating layer, such as ACSR, Al-strand, and Cu-strand. Products are mainly used in suburbs, rural areas, user main lines, switchgear, etc.
Winding wire (magnet wire): In the form of windings in the magnetic field cutting magnetic line induced current, or through the current generated by the magnetic field of the wire, mainly for a variety of motors, instruments and meters. Such as enameled wire.
Power cable: A cable product that is used to transmit and distribute high-power electrical energy in the backbone of a power system, such as cross-linked polyethylene insulated power cables. The products are mainly used in the transmission of electricity, electricity, electricity, electricity, electricity, and electricity in high-voltage transmission lines, with large currents (tens of amps to several thousand amps) and high voltages (220 V to 500 kV and above).
Communication cables and optical cables: cables, optical cables, etc. that transmit telephone, telegraph, television, radio, fax, data, and other telecommunication information.
Wire and cable for electrical equipment: Wires and cables used to transmit power directly from the power distribution point of the power system to the power supply connection lines of various electrical equipment and appliances. Such as control cables, cloth wires, etc.
2, wire and cable applications <br> <br> power system: The system uses a power wire and cable products mainly overhead bare wires, bus (bus), a power cable (plastic cable, power cable greaseproof paper (plastic power cable is substantially Instead of, rubber cables, overhead insulated cables), branch cables, electromagnetic wires, and electrical equipment, electrical wires and cables.
Information transmission system: Wire and cable used for information transmission system mainly includes local telephone cable, television cable, electronic cable, radio frequency cable, optical cable, data cable, magnet wire, power communication or other composite cables.
Mechanical equipment, instrumentation systems: Except for overhead bare wires, almost all other products have applications, but mainly power cables, electromagnetic wires, data cables, instrumentation cables, etc.
3, the basic structure of a conductor wire and cable <br> <br>: conduction current object, wire and cable specifications are indicated by the conductor cross section.
Insulation: The insulation material is coated with a different thickness on the outside of the conductor according to the requirements of its withstand voltage level.
Protective layer: The part that protects the cable.
Why should cables be armored and twisted? Armored cable means a cable with a metal armored protective layer. The purpose of the cable plus the armored layer is not only to enhance the mechanical protection such as tensile strength and compressive strength, but also to extend the service life. Shield protection improves cable interference performance.
The commonly used armouring materials include steel belts, steel wires, aluminum belts, and aluminum tubes. Among them, steel belts and wire armored layers have a high magnetic permeability and have a good magnetic shielding effect. They can be used for anti-low frequency interference and enable The cable is laid directly buried to avoid wearing the tube and it is cheap and practical.
Different sizes of copper wires are twisted together according to a certain arrangement order and twisting distance, and they become larger diameter conductors. Such twisted large-diameter stranded conductors are larger than the same diameter. The copper wire is more flexible, and the wire bending performance is good. It is not easy to break when the swing test is performed. It is easier to meet the requirements for some soft wire materials (such as medical grade wires).
According to the electrical performance, after the conductor is energized, the resistor will generate heat due to power consumption. As the temperature rises, the performance life of the insulating layer and the protective layer material will be affected. In order to make the cable operate efficiently, the conductor cross section should be increased, but the large cross-section single conductor Inconvenient to bend, poor flexibility, it is not conducive to the production of transport and installation of laying. From the mechanical properties and requirements of flexibility, reliability, multiple single twisted twisted together, you can solve the problem.
First of all, the control cable belongs to the cable for electrical equipment, and the power cable is two of the five categories of cable.
The standard for control cables is 9330 and the standard for power cables is GB12706
The color of the insulated cable core of the control cable is generally black and white, and the low voltage of the power cable is generally color separation.
The cross section of the control cable generally does not exceed 10 square meters. The power cable is mainly used for power transmission and generally has a large section.
Due to the reasons mentioned above, the specifications of power cables can generally be larger, as large as 500 square meters (range that conventional manufacturers can produce), and relatively few manufacturers can do as large cross-sections as possible, and the cross-section of control cables is generally small. Smaller, the maximum is generally not more than 10 square. From the perspective of the number of cable cores, the power cable is generally up to 5 cores according to the grid requirements, while the control cable transmits control signals with a higher number of cores. According to the standard, there are more than 61 cores, but it can also be produced according to user requirements. .
Network transmission media - three kinds of cables in the network hardware, there is a category can not be ignored is the network transmission media, we usually called the network cable. At present, the more common network cables are fine coaxial cables, coarse coaxial cables, twisted pairs, and optical fiber cables.
1. Coaxial <br> <br> Coaxial cable is more familiar with many friends for a class of transmission medium, which is wrapped around the cable center conductor by a layer of copper of insulated wire, its most important feature is interference With good capabilities, stable data transmission, and low prices, it was once widely used, such as closed-circuit television lines. However, more coaxial cables were used in the past, mainly because the cost of the bus structure network composed of coaxial cables is low, but the damage of a single cable may cause the entire network to collapse, and the maintenance is also difficult. This is its biggest drawback. Coaxial cables in Ethernet applications are mainly classified into coarse coaxial cables (10Base5) and fine coaxial cables (10Base2). Rough coaxial cables are not used much now, and there are still some markets for fine coaxial cables. Fine coaxial cable market price of a few yuan a meter in general, is not too expensive. In addition, the coaxial cable is used to connect with the BNC head. The coaxial cable sold on the market is generally a finished product that has been connected to the BNC head.
2. <br> <br> twisted-pair twisted-pair cable is a flexible communications, contains a pair of insulated copper wire, which is characterized by cheap, so widely used, such as our common telephone lines, etc. . According to the maximum transmission rate, twisted pair can be divided into 3 categories, 5 categories and 5 categories. The speed of Category 3 twisted pair is 10Mb/s, Category 5 is up to 100Mb/s, and Super Category 5 is up to 155Mb/s or more, which can be suitable for future multimedia data transmission needs. Therefore, it is recommended to use 5 types or even 5 types of double Stranded wire. Twisted pair can also be divided into shielded twisted pair (STP) and unshielded twisted pair (UTP). Although the STP twisted pair has a low speed (only 4Mb/s), the anti-interference is stronger than the UTP twisted pair, so the price is much more expensive. Now such a twisted pair is cheaper, a few dollars a meter, and you may be ten. A few dollars or more can buy one meter. In contrast, UTP twisted-pair prices are generally around one meter one yuan, which is relatively low. In addition, popular 10M and 100M unshielded twisted pair is popularly known as 10Base-T and 100Base-T, which are often seen in the market. The RJ45 crystal head is also used for the twisted-pair cable. It is used to make the joint between the twisted-pair cable and the RJ45 interface of the network card. The quality is directly related to the stability of the entire network and cannot be ignored.
3. <br> <br> fiber optic cable fiber optic cable is a new generation of transmission media, compared to copper media, optical fiber both in terms of safety, reliability or network performance has greatly improved. In addition, the bandwidth of optical fiber transmission exceeds that of copper cables, and the maximum connection distance it supports is more than two kilometers. This is an inevitable choice for building larger networks. Because fiber optic cable has the advantages of good anti-electromagnetic interference, strong confidentiality, high speed, and large transmission capacity, its price is also relatively expensive, and it is rarely used in home use. At present, there are two different types of optical fiber, which are single-mode fiber and multi-mode fiber (so-called "mode" refers to a beam of light that enters the fiber at a certain angle). Multimode fibers are generally used for network connections in the same office building or in relatively close areas. While single-mode fiber delivers higher quality data and longer transmission distances, it is often used to connect office buildings or geographically dispersed networks. If optical fiber cables are used as the network transmission medium, the shielding of the equipment such as the optical transceiver must be added. The outermost layer of the wire and cable is generally a rubber or rubber composite sleeve. The role of this layer is insulation, and it also protects the cable from being used. The effect of injury.
The cable is divided into high-voltage and low-voltage cables. If it is high pressure, there will be a layer of resin-like filler inside. This is an insulation. In high-voltage cables, this layer is the most important part of insulation. There is no such thing as low pressure. Then there will be something like a ribbon wrapped inside, this is to fix every cable core, fill the gaps in the middle.
As for the shielding layer, there are two cases in which the role of the shielding layer of the power cable is as follows:
1, because the power cable through the current is relatively large, the current around the magnetic field will be generated, in order not to affect other components, so add shielding layer can shield this electromagnetic field in the cable.
2, can play a certain degree of grounding protection, if there is damage inside the cable core, leakage of current can be along the shielding of laminar flow such as grounding network, play a role in security protection.
If it is a control cable, there is no difference, but in many places, especially the control cable of a computer system, the shielding layer here is used to shield external influences, because the current itself is very weak, and it is very afraid of the influence of the external electromagnetic field.
Polyvinyl chloride, polyethylene, cross-linked polyethylene, the difference between the three polyethylene English referred to as PE, which is ethylene polymer, non-toxic. Easy to color, good chemical stability, cold resistance, radiation resistance, good electrical insulation. It is suitable for food and drug packaging materials, production of food utensils, medical equipment, but also to do the insulation of the electronics industry. Such as: Intrinsically safe computer shielded cable (or intrinsically safe DCS system cable) PVC English abbreviation PVC, vinyl chloride polymer. It is chemically stable and resistant to acids, alkalis and some chemicals. It is resistant to moisture, aging and flame. When it is used, the temperature cannot exceed 60°C and it will harden at low temperatures. Polyvinyl chloride is divided into soft plastic and hard plastic. The soft main film is used for packaging materials, rain protection products, agricultural breeding films, etc. It can also be used for insulation of cables and wires, artificial leather products. Hard, generally made pipes and plates are used as pipes and pipes for conveying corrosion-resistant fluids. The plates are used as linings and floors for various tanks. Such as: 0.6/1kv PVC insulated power cable cross-linked polyethylene English abbreviation XLPE, is an important technology to improve PE performance. Cross-linked modified PE can greatly improve its performance, not only significantly improve the mechanical properties of PE, resistance to environmental stress cracking resistance, chemical corrosion resistance, creep resistance and electrical properties and other comprehensive performance, but also The temperature rating of the PE is obviously improved, and the heat-resistant temperature of the PE can be increased from 70°C to 90°C, which greatly broadens the application range of the PE. At present, cross-linked polyethylene (XLPE) has been widely used in pipes, films, cable materials and foam products. Such as: 35kv and the following cross-linked polyethylene insulated power cable wire and cable classification application and basic structure 1. Classification The wire products used to transmit electricity (magnetic) energy, information and achieve electromagnetic energy conversion are collectively referred to as wire and cable. According to different uses, wire and cable can be divided into five categories:
Bare wires: Products that have conductors but no insulating layer, such as ACSR, Al-strand, and Cu-strand. Products are mainly used in suburbs, rural areas, user main lines, switchgear, etc.
Winding wire (magnet wire): In the form of windings in the magnetic field cutting magnetic line induced current, or through the current generated by the magnetic field of the wire, mainly for a variety of motors, instruments and meters. Such as enameled wire.
Power cable: A cable product that is used to transmit and distribute high-power electrical energy in the backbone of a power system, such as cross-linked polyethylene insulated power cables. The products are mainly used in the transmission of electricity, electricity, electricity, electricity, electricity, and electricity in high-voltage transmission lines, with large currents (tens of amps to several thousand amps) and high voltages (220 V to 500 kV and above).
Communication cables and optical cables: cables, optical cables, etc. that transmit telephone, telegraph, television, radio, fax, data, and other telecommunication information.
Wire and cable for electrical equipment: Wires and cables used to transmit power directly from the power distribution point of the power system to the power supply connection lines of various electrical equipment and appliances. Such as control cables, cloth wires, etc.
2, wire and cable applications <br> <br> power system: The system uses a power wire and cable products mainly overhead bare wires, bus (bus), a power cable (plastic cable, power cable greaseproof paper (plastic power cable is substantially Instead of, rubber cables, overhead insulated cables), branch cables, electromagnetic wires, and electrical equipment, electrical wires and cables.
Information transmission system: Wire and cable used for information transmission system mainly includes local telephone cable, television cable, electronic cable, radio frequency cable, optical cable, data cable, magnet wire, power communication or other composite cables.
Mechanical equipment, instrumentation systems: Except for overhead bare wires, almost all other products have applications, but mainly power cables, electromagnetic wires, data cables, instrumentation cables, etc.
3, the basic structure of a conductor wire and cable <br> <br>: conduction current object, wire and cable specifications are indicated by the conductor cross section.
Insulation: The insulation material is coated with a different thickness on the outside of the conductor according to the requirements of its withstand voltage level.
Protective layer: The part that protects the cable.
Why should cables be armored and twisted? Armored cable means a cable with a metal armored protective layer. The purpose of the cable plus the armored layer is not only to enhance the mechanical protection such as tensile strength and compressive strength, but also to extend the service life. Shield protection improves cable interference performance.
The commonly used armouring materials include steel belts, steel wires, aluminum belts, and aluminum tubes. Among them, steel belts and wire armored layers have a high magnetic permeability and have a good magnetic shielding effect. They can be used for anti-low frequency interference and enable The cable is laid directly buried to avoid wearing the tube and it is cheap and practical.
Different sizes of copper wires are twisted together according to a certain arrangement order and twisting distance, and they become larger diameter conductors. Such twisted large-diameter stranded conductors are larger than the same diameter. The copper wire is more flexible, and the wire bending performance is good. It is not easy to break when the swing test is performed. It is easier to meet the requirements for some soft wire materials (such as medical grade wires).
According to the electrical performance, after the conductor is energized, the resistor will generate heat due to power consumption. As the temperature rises, the performance life of the insulating layer and the protective layer material will be affected. In order to make the cable operate efficiently, the conductor cross section should be increased, but the large cross-section single conductor Inconvenient to bend, poor flexibility, it is not conducive to the production of transport and installation of laying. From the mechanical properties and requirements of flexibility, reliability, multiple single twisted twisted together, you can solve the problem.
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