High temperature superconducting cable

High temperature superconducting cable is a kind of power facility that adopts unimpeded superconducting material that can transmit high current density as the conductor and can transmit large current. It has the advantages of small volume, light weight, low loss and large transmission capacity, and can realize low loss, high efficiency and large capacity transmission. HTS cables will first be used for short distance power transmission (e.g., generator to transformer, substation to substation, underground substation to urban grid port) and short distance power transmission of large current, such as electroplate plant, power plant and substation, as well as large or super-large city power transmission.

The transmission loss of HTS cables is only 0.5% of the transmission power, much lower than the 5-8% loss of conventional cables. Under the same weight and size, compared with the conventional power cable, the capacity of HTS cable can be increased by 3-5 times and the loss reduced by 60%, which can obviously save the occupied area and space and precious land resources. Retrofitting existing underground cable systems with HTS cables would not only increase transmission capacity by more than three times, but also reduce total costs by 20%. The use of HTS cable can also change the traditional transmission mode, using low voltage and high current to transmit electric energy. Therefore, HTS cable can greatly reduce the loss of power system, improve the total efficiency of power system, and have considerable economic benefits.

The global market for superconducting applications is forecast to reach $244 billion (1516.4 billion yuan) by 2020, with HTS cables accounting for about 5 percent of the total. The world’s existing underground cables with a total length of about 130,000 kilometers will probably be replaced by HTS power cables. Therefore, the market prospect of HTS cable is very broad.

European cable standard and IEC standard

European countries such as Britain, Germany, and France are highly developed countries. The requirements of their cable standards are generally higher than IEC standards. However, these standards are now being integrated with each other to form an absolutely authoritative standard system, that is, the European standard.
In charge of European cable standards is the European Electrotechnical Association: CENELEC, whose members include Austria, Belgium, Czech Republic, Denmark, Finland, France, Germany, Spain, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands, Norway, Portugal, Spain , Sweden, Switzerland and the UK’s national electrical associations.
CENELEC members are obliged to implement the CEN/CENELEC international agreement, which stipulates: This European Standard shall be implemented in accordance with national standards and no changes shall be made. Once a European standard is promulgated, all members must announce it according to the level of the national standard within 6 months after the European promulgation, and implement the European standard according to the national standard within one year after the European promulgation. And within the next 5 years, the original national standard that conflicts with the European standard will be abolished.
In addition, the European Electrotechnical Association has also issued a coordination document that has the same effect as the European standard, namely the HD document. HD documents also supersede the national standards of member countries within the period specified above.
In fact, European countries often replace their corresponding national standards with European standards in a short period of time. For example, the European standard for cable bundle burning test, namely EN50266, its promulgation date is 2001, but Britain, Germany and other countries In 2003, similar national standards BS4066 and DIN VDE0472-804 have been abolished.
The number of the European standard is directly included in the national standards of various countries without change. For example, the national standard numbers of EN50306 in Britain, Germany, France and other countries are BS EN50306, DIN EN5050306 and NF EN50306. HD files are numbered separately.
The European standard also integrates certain standards in IEC and ISO, such as IEC60811, whose European standard number is EN 60811, and the national standards are BS EN60811, NF EN 60811, etc.
The European standard converted from the IEC standard, the first digit of the standard number should be “6”.
France, Germany and other countries are the most active supporters of European standards. Nowadays, some important cable standards of France, Germany and other countries have been integrated into HD files. Currently, about half of the national cable standards in France are European standards.

The most commonly used low-voltage cable standards in France, Germany and other countries, namely the series standards for rubber cables and PVC cables (DIN VDE 0282, NF C32-102 and DIN VDE 0281 and or NF C32-201), have been integrated into HD22 and HD21.
The IEC and ISO standards are the most widely used standards in the world, while the European standards are the standards used by most developed countries. To connect our products with the world, we must first implement standard integration. In fact, many countries with underdeveloped industries often adopt the standards of advanced countries such as BS.
The advanced nature of European standards exceeds the IEC standard, and the authority is higher than the national standards of Britain, Germany, France and other countries. Compared with American standards, European standards are closer to Chinese standards.

What is the basic structure of the cable?

One is the conductor structure.The conductor of cable is usually made of high purity copper or aluminum of certain toughness and strength with good electrical conductivity. Conductor sections are commonly used in circles and sectors. A conductor with a smaller section (less than 16 square meters) is made of a single copper wire, while a conductor with a larger section (16 square meters or more) is made of several copper wires twisted in fractional layers. When twisted, the twisted direction of the two adjacent layers is opposite.Cable structure


The second is the insulation layer of the cable.The insulation layer of cable is used to make the multi-core conductor and conductor and sheath mutually isolated, and to ensure a certain electrical compressive strength, it should have a certain heat resistance and stable insulation quality.
The thickness of the insulating layer is related to the working voltage. Generally speaking, the higher the voltage level is, the thicker the insulation layer will be, but not in direct proportion.Cable structure


Third, cable sheath.So that the cable insulation is not damaged, and to meet the requirements of various use conditions and environment, divided into inner sheath and outer sheath.Inner sheath is a protective covering covering the cable insulation to prevent the insulation from being affected by moisture, mechanical damage, light and chemical corrosive media, etc., and can also flow through short-circuit current. Common inner protective layer has non-metallic polyethylene sheath, polyvinyl chloride sheath, metal corrugated aluminum sheath and so on.Outer sheath is the protective covering layer outside the inner sheath of the cable, which mainly plays the role of mechanical strengthening and anti-corrosion. The outer sheath is usually composed of metal tape armor or wire armor plus polyvinyl chloride or polyethylene sheath.Cable structure

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What are the advantages of environmental friendly cables?

What are the advantages of environmentally friendly cables compared to other traditional cables? Compared with ordinary cables, environmentally friendly cables have the following advantages:

The first is to have high flame retardancy. We all know that the flame retardant performance of the cable is very important. It fully ensures the safety and fire resistance of the cable. The cable is not easy to burn and catch fire, and can prevent the flame from expanding.

The second is halogen free, green insulation, special oxygen barrier material, not only has good electrical performance, mechanical properties, and to ensure that the product does not contain halogen, to prevent the formation of traditional PVC wire burning in the combustion process to produce cancer-causing dioxins British materials to prevent secondary pollution.

The third is a new environment-friendly coated wire and cable material that is free of odor and corrosive odor, does not contain hydrochloric acid and other toxic gases, and produces no pollution to the environment. It will not produce or emit very little during the use and combustion. Acidic gas, to ensure the safety of personnel and reduce environmental protection features such as equipment damage.

The fourth one is high light transmittance. The smoke produced by burning environmentally friendly cables is very thin, which is helpful for evacuation and fire fighting. The light transmittance of the product is greater than 40%, much higher than that of the traditional flame-retardant cable and the light transmittance is lower than 20% or even higher.

The last one is the environmental protection type cable waterproof and ultraviolet protection performance, environmental protection type wire and cable special molecular structure, to ensure the production of ultra-low water absorption . Special ultraviolet absorber makes the product have good anti-ultraviolet performance。