Why is the cable hot?

In recent years, various types of electrical appliances often catch fire in our daily lives. Therefore, when using electrical appliances, the cables need to be protected. However, I don’t know if you find that the cable will heat up during operation. Is it a manifestation ofAerial Bundled Cable (ABC) HD 626 S1 Standardquality problems? Or is it a normal phenomenon of cable use? What is the cause of the cable heating during operation? How should we deal with the heating of cables?
If the cable becomes hot during operation, this does not mean that there is a problem with the cable quality, but the normal operation of the cable. As long as the cable passes a certain load current, it will definitely heat up, and as the load current increases, the surface temperature of the cable will be higher. Therefore, it is basically normal to control the surface temperature of the wire below 60 degrees.


The reasons for the cable heating during operation are as follows:
1. The cable conductor resistance does not meet the requirements, causing the cable to generate heat during operation.
2. Inappropriate cable selection, for example: the conductor cross section of the cable is too small, and overload occurs during operation. The heat dissipation and heat dissipation of the cable are unbalanced after long-term use, causing the cable to heat up.
3. When the cables are installed too densely, the ventilation and heat dissipation effect is not good. OrAerial Bundled Cable (ABC) SANS 1418 Standard is too close to other heat sources, which will affect the normal heat dissipation of the cable, and may also cause the cable to heat up.
4. The manufacturing process of the cable joint is not good and the crimping is not tight. If the contact resistance at the joint is too large, it will also cause the cable to heat up.


5. The insulation performance between the phases of the cable is not good, which leads to low insulation resistance and heat generation during operation.
6. Part of the sheath of the armored cable is damaged. After the water enters, it will slowly damage the insulation performance. As a result, the insulation resistance will gradually decrease, and it will also cause heat during the operation of the cable.
After the cable heats up, if the cause is not found, the fault should be eliminated in time, and the continuous power operation will continue. The insulation thermal breakdown phenomenon will occur, causing the cable to short circuit and trip between the phases, which may cause a serious fire.
So, how to deal with the heating of the cable? Since the cable heats up when there is current passing through it, we cannot cool the cable in cold water because this will cause water to enter the cable and affect the use of the cable. Therefore, when using the cable, we can only pay attention to the use time of the cable and distribute the power reasonably. The cables should be checked regularly to see if they are old or damaged. If this is the case, the cable should be replaced in time to avoid causing the cable to catch fire.

How to find the fault point after the ACSR cable is short-circuited?

Generally speaking, when the ACSR conductor has a short-circuit fault, the air switch cannot be closed, which will not only cause a small-scale power failure, but if it is not handled properly, it may sometimes expand the scope of the fault and even cause an electric shock accident. Therefore, if the short-circuit fault is not eliminated, illegal power transmission is absolutely not allowed.

When dealing with a short-circuit fault of a cable, try not to break the cable destructively. In that case, it will damage the cable insulation, reduce the insulation strength of the cable, and cause electric shock. So, how to find the short-circuit point quickly and effectively when the cable has a short-circuit fault?

 

 

The main methods are as follows:

1. The place where the cable has a connector is the frequent occurrence point of cable short-circuit faults. When searching, the main search object is the cable connector.

ASTM 477 MCM ACSR Cable

2. If ASTM 477 MCM ACSR Cable is erected for a long distance, and there is a short circuit in the middle or at the end of the cable, the tripping time of the air switch may be delayed. This is because the short-circuit point is far from the air switch and there are A certain resistance value reduces the short-circuit current. If this is the case, the section of cable from the short-circuit point to the circuit breaker will definitely heat up and be higher than the temperature of the human body, and the rubber sheath will become soft or even bulge. At this time, touch the hot cable with your hand until it suddenly becomes cold. The place where you feel the cable hot is the short-circuit point.

3. If it is a two-core lighting cable, the light bulb from the short-circuit point to the power circuit breaker will emit light, but due to insufficient voltage, the light will be dim, and the light bulb after the short-circuit point will not light up at all.

What effect does the cable sheath have on the PVC Sheath Flexible Cable ?

The sheath is the “skin” of the wire and cable and the appearance that people look directly at. It must be smooth and round, uniform in color, not eccentric, not damaged, free of impurities, free of bubbles, and not flattened, twisted, etc., except In addition to being unsightly, the thickness of the sheath also has a certain impact on the quality of H05VV-F H03VV-F PVC Insulated cable.

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  1. Reduce service life
    After the cable is laid, it will be energized for a long time, which will generate heat. The allowable working temperature of the conductor is 70℃. The long-term use temperature of polyvinyl chloride should not exceed 65℃. If it is summer, the working temperature will rise, and these temperatures will pass outside. When the sheath is emitted, the thickness of the sheath increases, and the heat energy is difficult to dissipate, which will affect the service life of the cable. Due to the heat of PVC, the insulation layer will undergo a series of physical and chemical changes and lose its original excellent performance. , Resulting in a significant decrease in insulation performance, and even a short circuit, affecting the normal operation of the unit.
  2. Material performance defects
    The performance of the material is not reflected by the thickness. According to the requirements of the GB8815-2002 standard, if one of its indicators does not meet the standard, the flame-retardant PVC material, its oxygen index is lower than 30.
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  1. There are problems with the cable structure
    Conductor, insulation layer, and braid density are strictly controlled in accordance with the requirements of the standard. If the outer diameter of the cable is normal but the sheath is too thick, it is very likely that other structures are cutting corners.
  2. Increase the difficulty of cable laying
    At present, cable laying is mainly based on bridges or pipes. Many companies are implementing tight cable requirements and small outer diameters. There can be gaps during the laying process to dissipate heat and ensure that the outer sheath of PVC cable is not damaged. Otherwise, the construction unit and Cable laying brings difficulties.
    To sum up, the thickness of the sheath should be strictly controlled in accordance with the standard, which not only saves resources, reduces material consumption, and increases profits for the enterprise, but also ensures the quality of the cable and creates high-quality and low-cost products.

Analysis of commonly used PVC materials for wire and cable sheath

Commonly used plastics for wires and cables include polyethylene, cross-linked polyethylene, polyvinyl chloride, polypropylene, polyolefin, fluoroplastics, nylon, etc.
Polyethylene is currently the most widely used plastic with the largest consumption. From the data in the table, it can be seen that polyethylene has low meson loss, high resistivity, high breakdown field strength, good weather resistance and manufacturability. It is currently the best electrical Insulation Materials. However, due to its low operating temperature, it is mainly used as insulation for communication cables. Medium-density and high-density polyethylene have high strength and hardness, and their water permeability is low, and they are mostly used as cable sheaths. However, polyethylene has the biggest disadvantage, that is, it is easy to burn and has strong black smoke, so its application brings many hidden dangers to the environment.
Cross-linked polyethylene is an excellent thermosetting insulating material formed by adding a cross-linking agent to low-density polyethylene. On the basis of inheriting many excellent properties of polyethylene, it has improved mechanical properties, weather resistance and allowable working temperature, thus becoming the best insulation material for power cables.
Due to the different crosslinking agents added, different crosslinking processes are formed. At present, there are three kinds of chemical crosslinking, warm water crosslinking, and radiation crosslinking that are most used. Chemical crosslinking is mainly used for medium and high voltage cables (such as 10KV and above); warm water crosslinking and radiation crosslinking are mainly used for low voltage cables (1kV and below).
The insulation conductor performance of cross-linked polyethylene is closely related to its purity. The insulation of high-voltage and ultra-high voltage cables above 35KV must be made of ultra-clean cross-linked polyethylene, which not only requires high purity of raw materials, but also requires high cleanliness of cross-linking process equipment and environment, and the process is stable and reliable.
It should be particularly pointed out that the insulation properties of polyethylene and cross-linked polyethylene have a “quirk”, that is, they are suitable for AC insulation, not DC insulation, especially DC high voltage will reduce their insulation life. Therefore, the insulation of DC cables is mostly rubber insulation or oil-paper insulation. Furthermore, polyethylene and cross-linked polyethylene insulation have “waterphobia”, and their breakdown is often related to the presence of water, that is, “water branches” are formed under high voltage, leading to insulation damage. Therefore, when polyethylene and cross-linked polyethylene are used for the insulation of high-voltage and ultra-high-voltage cables, they are particularly “water-proof” during their processing, storage and transportation, and insulation extrusion, and there should be a water-blocking structure outside the cable insulation shield, such as metal jacket.
Compared with polyethylene, polyvinyl chloride and paper insulation, one of the biggest advantages of cross-linked polyethylene insulation is that the working temperature is increased by 20°C, which improves the safety of the cable and reduces the input cost of the cable. For example, when the line flow is the same (such as 300A), the cross-sectional area of ​​the copper conductor of the polyethylene or PVC insulated cable (such as the YV type or VV type) needs 120mm2, while the cross-linked polyethylene insulation tape male basketball copper conductor cross-sectional area only needs 70mm2 is sufficient. It can be seen how remarkable the advantages of cross-linked polyethylene insulated cables are.
Polyvinyl chloride has good physical and mechanical properties and excellent process performance. It is the most used plastic in the 20th century. It is also the main insulation material and sheath material for low-voltage wires and cables. But entering the 21st century, PVC will gradually shrink or even fade out in the cable market. There are two reasons for this. On the one hand, people’s safety awareness has increased and they hope to adopt halogen-free materials, so many halogen-free materials have emerged. There is no doubt that it will become the new favorite of the 21st century cable industry and squeeze the market. On the other hand, PVC has five weaknesses: one is its high density, which is about 1.5 times that of cross-linked polyethylene, and its insulation cost is high; the other is its low working temperature; and the third is its higher dielectric loss than cross-linked polyethylene. One hundred times higher; fourth, poor cold resistance (brittle at -15 degrees); fifth, toxic gas (HCL) is released during combustion. In recent years, the mechanical properties, electrical heating properties, and insulation resistance of cross-linked polyvinyl chloride developed in recent years have been greatly improved. Some small cross-section cables have been introduced into the market by irradiation technology, and they have been used in equipment and installation wires, high-voltage lead wires, automotive wires and building wiring. Application, but its shortcoming of halogen cannot be changed.
Fluoroplastics are widely used in wires and cables due to their high working temperature, small medium, insulation, weather resistance, acid and alkali resistance, oil resistance, and good flame retardancy. Among them, polyperfluoroethylene propylene is particularly popular due to its good manufacturability. But it is expensive, and users have to think twice.
Low-smoke halogen-free polyolefin is a new type of cable sheathing material that has not been developed in the 20th century. Its greatest advantage is its flame retardancy, low smoke and non-toxic gas during combustion, and it is increasingly widely used in important public buildings.

Introduction to ABC Cable

1. The main features of overhead insulated conductors (ABC cables) have good insulation performance.
Overhead insulated conductors have an extra layer of insulation and have superior insulation performance than bare conductors, which can reduce the distance between lines, reduce the insulation requirements for line supports, and increase the number of circuits erected on the same pole. Overhead insulated (ABC) cable uses and characteristics-Jianzhenda Cable|Jianzhenda Wire and Cable|Jianzhenda-Jianzhenda Cable has good insulation performance. Overhead insulated conductors have an extra layer of insulation and have superior insulation performance than bare conductors, which can reduce the distance between lines, reduce the insulation requirements for line supports, and increase the number of circuits erected on the same pole. Good corrosion resistance.
2. The specification core of the overhead insulated wire. There are two types of overhead insulated wires: aluminum core and copper core. In the distribution network, aluminum core applications are more, mainly because aluminum is lighter and cheaper, and has low requirements for line connectors and support parts. In addition, the original distribution lines are mainly steel core aluminum stranded wires. The aluminum core wire is used to facilitate the connection with the original network. In actual use, aluminum core wires are often used. Copper core wire is mainly used as the down conductor of transformers and switchgear. Insulation Materials. There are two types of insulation protection layers for overhead insulated wires: thick insulation (3.4mm) and thin insulation (2.5mm). The thick insulation allows frequent contact with trees during operation, and the thin insulation allows only short-term contact with trees. The insulating protective layer is divided into cross-linked polyethylene and light polyethylene, and the insulating properties of cross-linked polyethylene are better.
3. The laying method of overhead insulated wires is a single conventional laying method.
This erection method is to use the current conventional cement poles, iron accessories and ceramic insulator accessories with bare conductors, and erect according to the bare conductor erection method, which is more suitable for the area where the old line is reconstructed and the corridor is sufficient. A special insulating bracket is used to suspend the wires for single laying. This method can increase the number of circuits erected, save the line corridors, and reduce the cost of the line unit.
4. The application area of ​​overhead insulated wires is suitable for places with many trees.
Lines erected by bare conductors are often shielded by the erection and maintenance of lines and greening and forestry in areas with many trees. The use of overhead insulated wires can reduce tree felling (early erection and operation and maintenance stages), solve many problems, and reduce conflicts with greening and forestry departments, protect the ecological environment, beautify the city, and reduce the line Ground Fault. Used in areas where there is a lot of metal dust and pollution. In old industrial areas, metal processing companies often have metal dust flying in the wind due to environmental protection failures. In polluted areas of thermal power plants and chemical plants, short circuits and ground faults in overhead distribution lines have been caused. The use of overhead insulated wires is a better way to prevent short-circuit grounding of 10 kV distribution lines. Suitable for salt spray areas. The salt spray corrodes the bare wires very seriously, which greatly reduces the tensile strength of the bare wires. In the event of wind and rain, the wires will break, causing short circuit grounding accidents and shortening the service life of the wires. The use of overhead insulated wires can better prevent salt spray corrosion.
5. Design and construction of ABC conductors. The insulated wires and the steel core aluminum stranded wires are in the same specification, and the current carrying capacity of the insulated wires is smaller than that of the bare wires. After the insulated wire is added with the insulating layer, the heat dissipation of the wire is poor, and its current-carrying capacity is almost a grade lower than that of the bare wire. Therefore, when designing and selecting, the insulated wire should be selected a larger gear. At the same time, the strain clamp is directly clamped on the wire insulator. In order to prevent excessive wire tension from cracking or peeling of the insulation layer, the maximum working stress of generally insulated wires is about 41N/mm2. Wire arrangement and pitch. The conductor arrangement of overhead insulated lines is basically the same as that of bare conductor lines, which can be divided into: triangular, vertical, horizontal, and multi-loop erection on the same pole. The span of overhead insulated lines should be controlled at 50m. The distance between phases of insulated wires. Due to the good insulation performance of overhead insulated wires, the distance between phases is smaller than that of bare conductor lines, but the distance between vertical and triangular arrangements is not less than 0.3m; the distance between horizontal arrangements is not less than 0.4m. The vertical and horizontal distances of two circuit lines erected on the same pole shall not be less than 0.5m. The clearance distance between the jumper, the down conductor and the adjacent lead wire and low-voltage line, and the clearance distance between the overhead insulated wire and the pole wire or frame shall not be less than 0.2m. Connection of insulated wires. The connection of the insulated wire is not allowed to be twisted, and the insulated wire should not be connected within the span as much as possible. It can be connected when the tension rod is jumper. If you really want to connect within the span, within a span, each wire cannot exceed one socket, and the distance between the connector and the fixed point of the wire should not be less than 0.5m. Insulated wires of different metals, different specifications, and different twisting directions are strictly forbidden to make load-bearing connections within the pitch. The connection point of the insulated wire should be wrapped with an insulating cover or self-adhesive insulating tape. Sag of insulated wire. After the conductor is erected, considering the influence of plastic elongation on sag, the sag reduction method should be used to compensate. The percentage of sag reduction is 20% for aluminum or aluminum alloy core insulated wires and 7% to 8% for copper core insulated wires. When the wire is tightened, the insulated wire should not be overdrawn. After the wire is tightened, the sag of each phase wire in the same gear should be consistent. Fixing of insulated wires. Insulated wire and insulator are fixed with insulated wire. For pin-type or rod-type insulators, the straight rod adopts the top groove tying method, and the direct angle rod adopts the side groove tying method, which is tied to the side groove of the outer corner of the line. The screw-type insulator is bound in the side groove, and the insulating wire and the contact part of the insulator should be wound with insulating self-adhesive tape. Construction and erection of insulated wires. The construction and erection of insulated wires is different from overhead bare wires. It does not allow the wires to damage the insulation layer during the construction process. Pay attention to the protection of the insulation layer during construction, and try to avoid contact and friction between the wire insulation layer and the ground and tower accessories. Overlap of insulated conductors and drop wires. The connection of jumper wires and drop wires of insulated wires is different from that of bare wires, because insulated wires need special wire strippers to strip the insulation layer. The process is more complicated and the requirements are stricter. The jumper connection can be connected by a parallel groove clamp or a connecting pipe. The lead wire can be connected with a parallel groove clamp or a T-shaped clamp. At the same time, wrap the interface with an insulating cover or insulating self-adhesive tape. Coordination of ordinary fittings and insulated wires. Overhead insulated wires have special line fittings, which can insulate the entire line. Considering the cost of the circuit, ordinary accessories can also be combined to reduce the cost of the circuit. Since the insulated wire has an extra layer of insulation, the wire diameter is larger than that of the bare wire. When using ordinary fittings, the wire fixing fittings and connecting fittings should be enlarged. The tension clamp should be clamped together with the protective layer of the wire to prevent the overhead insulated wire from peeling off, which affects its mechanical and insulation properties.
The use of insulated wires instead of bare wires is a technological advancement measure to achieve insulation of distribution lines, which can better improve the reliability, stability and safety of power supply, save line maintenance and management costs, and help improve the economic benefits of power supply enterprises. Compared with overhead bare wires, overhead insulated conductors have better performance, and the cost is not too high. In rural power grids, depending on local conditions, it is beneficial to use overhead insulated conductors in some areas.

What are the functions of ACSR cables?

There are too many types and specifications of cables, and if you explain them carefully, it will be very cumbersome. Therefore, today we mainly understand one of them: “flexible fireproof cable”. If you are not a professional, this may sound strange. But it is obvious from the name that this is a flexible cable. This kind of cable has the function of fire prevention; also known as mineral insulated cable, it has the advantages of good flexibility, excellent shielding performance, corrosion resistance, strong practicability, and long service life. It is widely used in demanding occasions.
Flexible fireproof cable function
1. Good flexibility: the cable can be coiled on the cable tray with a bending radius ≤ 20D (D is the outer diameter of ACSR  cable).
2. Large cross-section: the cross-section of single-core cable can reach 1000mm, and the cross-section of multi-core cable can reach 240mm.
3. Long continuous length: Whether it is a single-core cable or a multi-core cable, its length can meet the requirements of the power supply length, and each continuous length can reach 1000m.
4. Corrosion resistance: Organic insulated fire-resistant cables sometimes need to wear plastic pipes or iron pipes, plastic pipes are easy to become brittle, iron pipes are easy to rust, fire-resistant cables with copper sleeves do not need to wear pipes, and copper sleeves have good corrosion resistance此图像的alt属性为空;文件名为abc-cable-full-form.jpg
5. Good shielding performance: Put the fireproof cable on the same shaft as the information cable and control cable. Under the shield of the copper sheath, it will not interfere with the information transmitted by the signal cable and control cable.
6. Excellent fire resistance: its fire resistance not only meets the requirements of the national standard GB12666.6 A 950℃ and 90min, but also meets the test requirements of A grade 650℃ 3h, B grade 750℃ 3h and C grade 950℃ British bs6387-1994 3 hours specified in At the same time, it can withstand the water spray and mechanical shock during the combustion process.
7. Safe and reliable: fireproof cables can usually supply power in flames, reducing fire losses, especially for personal safety, which is particularly reliable. Its copper sheath is an excellent conductor and is the best grounding PE wire. Continuous use within the range improves the sensitivity and reliability of grounding protection.
8. Long service life: Inorganic insulating materials are resistant to high temperatures and not easy to age. Its service life is many times that of organic insulated cables.
Each side of the flexible fireproof cable has a relatively large advantage, and it will also have a higher utilization rate for different environments. If you need to use cables and wires in your life, you can look at one of the advantages of flexible fire-resistant cables and see if they can be used and needed. Of course, we must also grasp the comprehensive consideration of psychological choices when buying, the most appropriate is the best.

Is it better to buy ACSR Cable online or in physical stores?

I don’t know whether to buy ASTM 477 MCM ACSR Cable online or in physical stores. It mainly depends on which part of the demand you need to meet. For users with higher quality requirements, you can buy them in physical stores. After all, you can get in touch with the real thing. , Specifications, voltage, etc. to prevent errors.


Those users who are more price sensitive can order directly online; the advantage of online purchase is that the price is much cheaper than offline, because it can save the cost of site rent increase and other costs, especially the one-stop supply of ACSR Cable online. Manufacturers have special supply channels and direct sales at factory prices, which is very cost-effective.


For users who are unsure about the quality of the wire purchased online, this is actually unnecessary. We can identify the quality of the product through the sample map. Users in the same city can also directly check the production workshop; and the manufacturer has spent so much money to make the website online, it is not necessary For the sake of a single order, the previous efforts have been broken, so it is still very reliable to place an order online, provided that you must look for a more formal wire and cable website.
Yu Zheng is entangled in whether the cable is bought online or bought in a physical store. Jinhaotai suggests that you can first consult the product price online, then go to the physical store to check the quality in the same city, and then decide where to buy. After all, the advantages of online and physical stores have their own advantages.

Corrosion resistance of aluminum alloy conductors

Aluminum alloy power conductor is a new type of material power cable that uses AA8030 series aluminum alloy material as the conductor and adopts special roll forming wire stranding production technology and annealing treatment. Alloy power cables make up for the shortcomings of pure aluminum cables in the past. Although the electrical conductivity of the cable is not improved, the bending performance, creep resistance and corrosion resistance are greatly improved, which can ensure that the cable remains continuous during long-term overload and overheating. The performance is stable. The use of AA-8030 series aluminum alloy conductors can greatly improve the conductivity and high temperature resistance of the aluminum alloy cable, while solving the problems of pure aluminum conductors and creep. The electrical conductivity of aluminum alloy is 61.8% of the most commonly used benchmark material copper IACS, and the current carrying capacity is 79% of copper, which is better than the pure aluminum standard. But under the same volume, the actual weight of aluminum alloy is about one-third of copper. Therefore, the weight of the aluminum alloy cable is about half of the copper cable at the same current carrying capacity. The use of aluminum alloy cables instead of copper cables can reduce the weight of the cable, reduce the installation cost, reduce the wear of the equipment and the cable, and make the installation work easier.


The inherent anti-corrosion performance of aluminum comes from the formation of a thin and strong oxide layer when the AAAC Conductor surface is in contact with air. This oxide layer is particularly resistant to various forms of corrosion. The rare earth elements added to the alloy can further improve the corrosion resistance of the aluminum alloy, especially the electrochemical corrosion. Aluminum’s ability to withstand harsh environments makes it widely used as conductors for cables in trays, as well as many industrial components and containers. Corrosion is usually related to the connection of different metals in a humid environment. Corresponding protective measures can be used to prevent corrosion, such as the use of lubricants, antioxidants and protective coatings. Alkaline soil and certain types of acidic soil environments are more corrosive to aluminum, so directly buried aluminum conductors should use insulating layers or molded sheaths to prevent corrosion. In sulfur-containing environments, such as railway tunnels and other similar places, the corrosion resistance of aluminum alloy is much better than that of copper.
flexibility
Aluminum alloy has very good bending properties, and its unique alloy formula and processing technology greatly improve flexibility. Aluminum alloy is 30% more flexible than copper and has a 40% lower resilience than copper. Generally, the bending radius of copper cables is 10-20 times the outer diameter, while the bending radius of aluminum alloy cables is only 7 times the outer diameter, making it easier to connect terminals.
Armor characteristics
Commonly used armored cables are mostly armored with steel tape, with low security level. When subjected to external destructive forces, their resistance is poor, which is easy to cause breakdown, and the weight is heavy, the installation cost is quite high, and the corrosion resistance is poor. The life is not long. The metal interlocking armored cable we developed according to American standards uses aluminum alloy tape interlocking armor. The interlocking structure between layers ensures that the cable can withstand the powerful destructive force from the outside, even if the cable is subjected to greater pressure The cable is not easy to be punctured under the impact force, which improves the safety performance. At the same time, the armored structure isolates the cable from the outside world. Even in the event of a fire, the armored layer improves the flame-retardant and fire-resistant level of the cable and reduces the risk of fire. Compared with the steel tape armored structure, the aluminum alloy tape armored structure is lighter in weight, convenient to lay, and can be installed without bridges, which can reduce installation costs by 20% to 40%. According to the different places of use, different outer sheath layers can be selected, which makes the use of armored cables more extensive.

Graphene: Let AAAC cables also “voice control”

The new material we are going to talk about this time may bring new changes to the material field of aluminum alloy cables. It is magic angle graphene. Some people say, isn’t it just graphene? I already knew it.
In fact, it is really not. The magic angle graphene we are going to talk about is not the graphene you understand. Different from graphene, magic angle graphene has a feature, that is, insulation and superconductivity will appear on the same material. We don’t know what this material can do in the field of cables, but it may open a sea of ​​unknowns to the cable industry.


Let’s get to know it now.
The “Magic Horn” is indeed like a magical angle. Graphene is originally a material with better conductivity than metal, but when two layers of graphene are stacked together, at a special angle, they suddenly become insulators.
According to our general understanding, insulators and superconductors are two extreme materials. The resistance of the insulator is very high, while the resistance of the superconductor is zero. However, when the two layers of graphene are at a special angle, they can easily bridge the gap between these two extremes. You can imagine that one day, the insulation of the cable you make is a conductor, and the conductor is also insulation, and you can change it at will. Anyone who makes materials knows that it takes time and effort to find new materials with certain characteristics. Because there is almost only one way to do this work, which is to keep sifting through a large number of materials. Whether you can find it is almost pure luck.
But the study of magic angle graphene has opened up new ideas for materials science. It makes scientists realize that materials science can accurately predict the performance of materials in advance and reduce a lot of work. Even materials science can construct new materials based on the underlying logic of material properties.


In early May 2020, Chinese young scientist Cao Yuan published two articles in the same issue of Nature, introducing some new discoveries of his team on “Magic Angle Graphene”.
To talk about this new hairstyle, we have to start with graphene. Graphene is a material with a thickness of only one carbon atom. More specifically, the carbon atoms will first form a hexagonal unit, and then spread out on the plane like a tile. If you compare it, it looks like a mosquito net. Common mosquito nets are covered with hexagonal holes, and each hole is like a unit of six carbon atoms in graphene.
If we randomly stack two layers of mosquito nets together, it is difficult to completely overlap the hexagonal holes, and there will always be a certain angle of misalignment. For graphene stacked in two layers, this angle will bring about a surprising change: at a special angle, graphene that has better conductivity than metal will suddenly become an insulator.
This special angle is the “magic angle”. When two or more layers of graphene are stacked at this angle, it is called “magic angle graphene.”
In fact, as early as 2011, some scientists discovered through theoretical predictions that when the angle between two layers of graphene is at a certain angle, the electrical properties of graphene will suddenly change. But at the time, there was only theory, no experiments.
In 2018, experiments appeared. The Pablo Jarillo-Herrero team of the Massachusetts Institute of Technology in the United States published a paper in the journal “Nature” and used experiments to prove that this prediction was valid. Chinese scientist Cao Yuan was the first author.
They twisted the stacked graphene at a very low temperature and found that when the angle between the two graphene layers is 1.08 degrees, there will be a sudden change in prediction, and the originally conductive graphene will suddenly become Insulator.
What is even more amazing is that as long as a small electric field is applied, the insulator will turn into a superconductor. This experimental result exceeds the original theoretical prediction.
In May 2020, Cao Yuan’s team made some new discoveries.
In one of his papers, it can be seen that on the original basis, they have studied three different angles of double-layer graphene, the three angles are 0.84 degrees, 1.09 degrees and 1.23 degrees.
After studying double-layer graphene stacked at these angles, Cao Yuan’s team came to an important conclusion. They revealed that magic-angle graphene is “tunable.” This is a proper term in a subject, but don’t worry, it’s not hard to understand.
For example, the voice-activated lights in the corridor will light up when there is a sound. But in the beginning, no one knew the connection between sound and light. Cao Yuan’s work in 2018 is like discovering a phenomenon, that is, shouting at the voice-activated light from a specific angle, and the voice-activated light can be switched between “on” and “off” freely.
Of course, there is no such phenomenon in real life, but it happens in the world of graphene, so it is very eye-catching.
In his work in 2020, Cao Yuan further discovered that the lighting is very sensitive to angle changes still near this angle. You still shout, but when you shook your head slightly to the left or right, the light can not only switch between “on” and “off,” it can also change into various colors. This is the so-called “tunability”.
Using this “tunability”, maybe one day our AAAC cables will become “voice-activated”.

Optical fiber cable signal error-free transmission distance increased to 5890 kilometers

Recently, researchers from University College London demonstrated a new method of processing optical fiber cable signals. Researchers claim that this method can double the error-free transmission distance of signals through submarine fiber optic cables. Because the new method does not need to strengthen the signal, it has the potential to cut the cost of long-distance optical fiber communications.

This research, funded by the British Engineering and Physical Sciences Research Council, improves the transmission distance by eliminating the interaction between different optical channels via a fiber optic cable.

Research leader Robert Maher said: “By eliminating the interaction between optical channels, we can double the error-free signal transmission distance from 3190 kilometers to 5890 kilometers. This is also the largest distance increase reported in the system architecture. .”
“The challenge is to design a technology that can simultaneously capture a group of optical channels with a single receiver, called a super channel.” Maher added.

Researchers use a 16QAM (quadrature amplitude modulation) super channel, which contains a set of frequencies. These frequencies can be encoded using amplitude, phase, and frequency to create a high-capacity optical signal. Utilizing a high-speed super receiver and a new signal processing technology developed by the team that can receive all channels without errors, the super channels can then be detected.

Now, the researchers plan to test new methods for dense super channels that are commonly used in digital cable television (64QAM), wired modems (256QAM), and Ethernet connections (1024QAM).

Polina Bayve, Professor of Optical Communications and Networking, added: “We are very pleased to report this important discovery, which will improve PV wire communications. Our method can greatly increase the efficiency of data transmission, almost double the signal transmission distance, which may greatly reduce the existing The cost of business systems. One of the biggest global challenges we face is how to maintain communications under the prosperous Internet demand. Overcoming the capacity limitations of fiber optic cables is the key to solving the problem.”