Factors restricting the development of the cable industry

The cable industry has developed to now, and the overall size is very large, with a large number of companies. China has surpassed the United States to become the world’s largest cable manufacturer. However, in this rapid development process, many problems have gradually been exposed.
The first problem is that there are few large domestic cable companies, and they lack competitiveness with foreign cable companies in high-end products. Even in 2018 or so, the annual output value of the top ten companies in  ACSR cable production scale is not as good as the total output value of the industry. 20% of the total, which is in sharp contrast with developed countries. However, it is roughly the same as my country’s current economic structure, and it is basically the same as that of other industries.


The second problem is that the homogeneity of products is serious and the market competition is fierce. There are a large number of cable companies in China, most of which are small and medium-sized enterprises. The operation mode, management and technical level of these companies present serious homogeneity problems. The problem of homogenization has aggravated overcapacity. In a homogeneous product market, users are mainly concerned with price, and competition is almost entirely concentrated on price. The greater the surplus of homogenized production capacity, the fiercer the price competition, the thinner the profit, and the more difficult it is for a company to survive.


The third problem is that the pressure of funds is huge. The xlpe cable industry is a typical heavy-material and light-industry industry and a capital-intensive industry. Therefore, the cable industry is always facing the pressure of the capital chain. The most significant phenomenon is the application of many companies. The total amount of money collected accounts for a high percentage of annual revenue, many of which are 30%. This also leads to financial difficulties for companies, and China’s cable industry is mostly small and medium-sized enterprises, so these companies are generally facing financial pressures. The problems of difficult financing, expensive financing, and high financing costs have sharply increased the risks in the capital chain of enterprises. In the past two years, due to the tightening of the entire financial system, many companies have found it difficult to cope and shut down and revert.

Ingenious use of aluminum alloy cables for photovoltaic systems(2)

In the era of low-cost Internet access, the cost of the control system is critical. In the past ten years, the prices of modules and inverters have fallen by 90%, which has contributed greatly to the overall cost reduction of photovoltaic systems, but the cost of cables has not been reduced. In large-scale projects, cables account for 10% of the system, which is even higher than that of inverters. In fact, as long as the design and installation are proper, under the premise of ensuring the normal operation and safety of the system, some AC cables are made of aluminum alloy cables, which can reduce part of the cost.
Rare earth aluminum alloy cable uses high elongation aluminum alloy material. By adding boron and other rare earth trace element materials to pure aluminum, and processed by rolling technology and special annealing process, the cable has good flexibility. When the surface is in contact with air, a thin and strong oxide layer can be formed, which can withstand various corrosions. Even when overloaded or overheated for a long time, the stability of the connection can be guaranteed, and the cost is slightly higher than that of ordinary aluminum alloy cables by about 10%.
The application range of aluminum cables: long-distance overhead lines, underground cable trenches with a relatively large space, and places with reliable fixed bridges, aluminum cables may be considered.


Precautions for the use of aluminum cables:
The melting point of copper is 1080°C, while the melting point of aluminum and aluminum alloy is 660°C, so copper conductors are a better choice for fire-resistant cables. Now some aluminum alloy cable manufacturers claim that they can produce fire-resistant aluminum alloy cables and have passed the relevant national standard tests, but there is no difference between aluminum alloy cables and aluminum cables in this respect. No matter what kind of heat insulation measures the cable adopts, the cable will melt in a short time and lose its conductive function. Therefore, aluminum alloy is not suitable for fire-resistant cable conductors, nor is it suitable for use in densely populated urban distribution networks, buildings, factories and mines.


Compared with the aluminum core cable, the copper core is flexible, the allowable bend radius is small, and it is not easy to break after repeated bending. Therefore, the aluminum cable is not suitable for the occasions with many turns, more pipes, or complicated lines.
Since the terminals of the electrical switch equipment are all made of copper, the copper and aluminum are directly connected, and the chemical reaction of the galvanic battery will occur after power on: the more active aluminum will accelerate the oxidation, resulting in higher resistance at the joints and current carrying capacity. Therefore, some measures need to be taken when the copper and aluminum are connected, such as the use of copper-aluminum transition terminals or copper-aluminum transition terminals to eliminate electrochemical reactions.

Ingenious use of AAAC Conductors for photovoltaic systems(1)

In the era of low-cost Internet access, the cost of the control system is critical. In the past ten years, the prices of modules and inverters have fallen by 90%, which has contributed greatly to the overall cost reduction of photovoltaic systems, but the cost of cables has not been reduced. In large-scale projects, cables account for 10% of the system, which is even higher than that of inverters. In fact, as long as the design and installation are proper, under the premise of ensuring the normal operation and safety of the system, some AC cables are made of aluminum alloy cables, which can reduce part of the cost.


The cables of the power station are divided into DC cables and AC cables. Among them, the DC cables between the components and the DC cables between the components and the inverter are generally required to use photovoltaic special DC cables, and from the inverter to the AC distribution There is no requirement for cables between electric cabinets and cables between distribution cabinets and transformers.
What is aluminum alloy cable: Aluminum alloy cconductor is a new material power cable with AA8030 series aluminum alloy material as the conductor. The resistivity of aluminum alloy is between aluminum and copper, higher than copper, and slightly lower than aluminum. Under the premise of the same current carrying capacity, the weight of the aluminum alloy conductor of the same length is only half of that of copper.
In terms of service life: after the metal surface reacts with oxygen, different metal oxides are formed. Aluminum oxide can form a dense surface protective film with a certain hardness. Copper oxide, commonly known as patina, is between the above two and is a toxic substance.


The cost of aluminum alloy cable is about 25% to 50% of that of copper core cable, and the cost advantage of using aaac cable is relatively large. We can make a comparison. In a 400kW village-level poverty alleviation power station, the distance from the AC distribution cabinet to the step-up transformer is 1500 meters, and the maximum output current of the 400kW power station is 580A. If copper cables are used, two cables are required for each phase. 150 square meters, 3 phases need 6 pieces, the total length is 9000 meters, the price is 864,000; if you use aluminum alloy with two 240 square meters, the total length is also 9,000 meters, the price is 450,000, you can save 414,000 yuan, and 240 A square aluminum wire has lower loss than a 150 square copper wire.

Industry Standard for high-strength aluminum alloy conductor overhead insulated cables

Aluminum power cable is a new type of power cable, which is made of AA8030 series aluminum alloy material and adopts the advanced technology such as special roll-forming wire stranding and annealing treatment. The alloy power cable makes up the deficiency of the traditional pure aluminum cable. Although the electric conductivity of the cable has not been improved, the bending, creep and corrosion resistance of the cable have been greatly improved, the AA-8030 series aluminum alloy conductor can improve the electric conductivity and high temperature resistance of the aluminum alloy cable, at the same time, the problems of pure aluminum conductor and creep are solved.

The electrical conductivity of aluminum alloy is 61.8% of copper IACS, and the current carrying capacity is 79% of copper, which is superior to pure aluminum standard. But at the same volume, aluminum alloys actually weigh about a third as much as copper. Therefore, at the same ampacity, the weight of the aluminum alloy cable is about half that of the copper cable. Using aluminum alloy cable instead of copper cable can reduce cable weight, reduce installation cost, reduce equipment and cable wear, make installation work easier. The new standard specifies the terms and definitions, specifications, technical requirements, test methods, inspection rules, marking, packaging, transportation and storage of medium strength aluminum alloy core insulated overhead cables. The Standard Product is suitable for the aluminum alloy conductor overhead insulated cables with rated AC voltage of 20kV or less for fixed overhead laying in cities, forests, scenic spots and other power distribution fields. The main technical contents include medium strength aluminum alloy conductor structure, conductor DC resistance, insulation thickness, AC voltage level and test items and methods. The medium strength aluminum alloy conductor overhead insulated cable has the characteristics of light weight, large breaking force and low resistance. It is a kind of overhead insulated cable with excellent comprehensive performance and better economical operation in the whole life cycle. The establishment of the industry standard further promotes the progress of this technology, and unifies the structural design and manufacturing process of Medium Strength Aluminum Alloy conductors, which is of great significance to the development and application of medium strength aluminum alloy core overhead insulated cables, on the basis of this, international standards can be formed to promote China technological progress, promote industrial transformation, and substantially participate in international standard activities.

Do you know what are the advantages of superconducting cables

At present, the long-distance large-capacity power transmission generally uses overhead bare aluminum cable and wires, and the power transmission in large cities generally uses underground cables, and the conductors are copper wires or aluminum wires. Using these traditional wires or cables, electrical energy will lose 5% to 10% during the transmission process. In order to reduce the loss of electric energy during the transmission process, the voltage should be increased as much as possible during long-distance transmission, such as using 500kV or 750kV and above ultra-high voltage lines. UHV lines have very high requirements on the insulating porcelain bottles of transmission towers and the use of space, especially the materials and production technology requirements of line terminal accessories, which greatly increase the construction cost of UHV lines. At present, my country cannot produce terminal accessories for ultra-high voltage lines, and imported ultra-high voltage line terminal accessories are very expensive.

If a superconducting cable is used, its AC impedance is only 1/10 of that of a conventional aerial bundled cable ASTM B231 standard, which can reduce the line loss of the power grid by about 50%; the application of superconducting cable will also reduce the system voltage for long-distance transmission, and the overall cost of other equipment in the system will follow It is reduced.In the long run, the application of superconducting cables also makes long-distance DC transmission technology easy and economical. For direct current transmission, superconducting cables will reduce the power grid line loss by more than 70%, showing better economic benefits. Since the power transmission capacity of superconducting cables is 3 to 5 times that of traditional conventional cables, the use of superconducting cables can also save the area and space of the power transmission system, save a lot of valuable land resources, and protect the ecological environment accordingly.

The smooth grid-connected operation of China’s first group of practical superconducting cables indicates that the technology of my country’s superconducting cables has become mature and has a profound impact on the development of my country’s power system. The application of superconducting cables in the main lines of my country’s power grids and transmission bottlenecks will help improve the safety and reliability of the power grid. In the long-distance and large-capacity transmission, superconducting cables have incomparable advantages in the overall performance of the system, and will fundamentally solve the problem of long-distance and large-capacity transmission such as my country’s “West-to-East Power Transmission” in the long run. In the near future, high-temperature superconducting cables may soon show advantages in the following aspects:

(1) In dense urban residential areas, skyscrapers, conventional cable capacity is insufficient, and there is no room for aerial bundled cables BS 7870;

(2) High current, short distance, and small space applications such as metal smelting equipment;

(3) High-current transmission bus in power stations and substations;

(4) In large cities with rapidly developing power demand, the required power supply capacity is constantly expanding. Due to the congestion of the city and the high cost of excavation, it is impossible to expand the scope of cable laying. With the help of superconducting cables, it can be replaced in the original pipeline to increase the power supply capacity. Increase 3-5 times.

Selection of power cables for home use

The decoration of the new house has many small and large details, and every detail needs to be taken seriously. This is because many decorative details are related to the comfort and safety of the house. However, there are many decorative materials on the market. Therefore, many friends do not know how to choose when choosing materials. Among them, everyone is more entangled. The question of material selection is: Should power cables be flexible wire? Or should I choose a hard line! What is the difference between hard wire and soft wire? Below, I will give you a brief explanation.
Before choosing hard wire or soft wire, we must first know what is hard wire? What kind of wire is a flexible wire?
The so-called flexible wire refers to strands of conductive solid wires with a diameter less than 1mm twisted together, that is, multiple strands of copper wires are twisted together. Therefore, the flexible cord is also called “sheathed cord”. Hard wire refers to a hard wire composed of several thick copper cores. Generally, hard wires of less than 10 square meters are single stranded.


So, what are the advantages and disadvantages of soft and hard wires? The details are as follows.
From the point of view of the service life of the wire, because the hard wire is thicker, it is not easy to oxidize; the flexible wire is composed of multiple thin copper wires, which are easily oxidized by the air, so the service life of the hard wire is much longer than that of the flexible wire From the perspective of the cost of the wire, since the flexible wire is relatively soft, it must be wound many times before use; the hard wire has only one copper wire, which can be passed directly. Therefore, compared with flexible wires, hard aaac conducors have less processing and are much cheaper; from the perspective of current-carrying capacity, flexible wires are composed of multiple strands of copper wire, and their current-carrying capacity is greater than that of a single copper wire. , But when it is suddenly loaded, the capacity of the current-carrying hard wire is greater than the capacity of the flexible wire; therefore, if it is used in general household appliances and the current does not exceed 100 A, single-stranded wire can be used.


2. From the perspective of the working process of the wire, use a soft wire at the connection of the hot tin or iron wire end, otherwise the multi-stranded wire may rise and connect with the next wire, which is very dangerous; and the hardness of the hard wire Very strong, its safety performance is relatively strong, from the perspective of whether it is convenient to repair the wire; although the hard wire is more difficult to replace, it can be completely pulled out of the threaded tube; if necessary, you can also replace the threading; but The cord is different, because the cord is prone to aging and breaks easily, so when the cord is replaced, the wire is likely to be damaged.
Generally, hard wires are more suitable for household use. However, it is worth noting that not all household wires need to use hard wires, and some places are more suitable for flexible wires. Therefore, when choosing wires, you should choose according to the location of the wires and the needs of your own home.

Model of mobile rubber sheathed flexible cable

Mine cable is a general term for flame retardant cables for coal mines

Working voltage of mobile flexible cables for coal mines:

The rated current is indicated by U0/U, and the enterprise is kV. U0 indicates the effective value of the voltage between any main insulated conductor and the “ground” (metal material shielded, metal material sheath or surrounding material); U is the middle of a multi-core cable or a single-core cable system software. The effective value of the voltage.

In an AC system, the rated voltage of the cable should be at least equal to the nominal voltage of the system to which the cable is applied. This standard is applicable to both U0 and U values.

Shenyang coal mine mobile rubber sheathed flexible cable

Naming standards for mobile flexible cables:

The name of the mobile flexible cable is composed of seven parts: among them: the first, second, third, fourth, and fifth parts constitute the model specifications of the cable; the sixth, seventh, and eighth parts The specifications and models that make up the cable.

The first part: use English capital letter M to indicate the serial product number of cables for coal mines.

The second part: application application feature number, reflecting the place where the cable is applied,

C: For coal mining machine, D, for ultra-low temperature natural environment, M: for cap lamp, Y: for coal mining machinery and equipment (mobile), Z: for electric drill.

The third part: the characteristic number of the cable, B: manual braided lifting; J monitoring or auxiliary copper core cable; P: non-metallic material shielded; PT: metal material shielded; Q: light-shaped; R: wrapping and lifting.

The fourth part is the characteristic number of the raw material. Use E to indicate that the insulation layer or the sheath is made of polyurethane elastomer. This part is omitted when vulcanized rubber is used for both the insulating layer and the wire sheath. E, polyurethane elastomer raw materials

The fifth part: Indicate the rated current U0/U, the enterprise is KV (kV).

Part 6: Indicate the number of cores of the driving force * tolerance cross section, and the two are connected by “×”. Tolerance cross-section enterprise is square millimeter (mm2)

Part 7: Indicate the number of grounding wire cores*tolerable cross-section, and the two are connected by “×”. The tolerance cross-section enterprise is square millimeter (mm2).

The eighth part: Indicate the number of bisector cores*tolerable cross section, with “×” between them

Join. The tolerance cross-section enterprise is cubic millimeter (mm2).

The fourth part and the fifth part are connected by “-”; the sixth part, the seventh part, and the eighth part are connected by a “+”.

Mobile flexible cable core specifications: 1, 1.5, 2.5, 4, 6, 10, 16, 25, 35, 50, 70, 95, 120, 150, 185, 240, 300, 400,

MYPTJ — — -Mining mobile shielded metal material monitoring rubber sheathed flexible cable

MYP — — — -Mining mobile shielded rubber sheathed cable (0.66/1.14)

MCP — — — — Special cable for mining shearer (shearer shielded rubber sheathed flexible cable)

MYJV22 — — — -Mining polyethylene insulation layer HDPE sheathed double steel chain armored cable

Shenyang coal mine mobile rubber sheathed flexible cable

The use of ACSR conductor 

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Rubber sheathed cables are widely used in various electrical equipment, such as portable power cords for household appliances, electrical machinery, electrical equipment and appliances, and can be used in indoor or outdoor environmental conditions. According to the mechanical external force of the cable, the product structure is divided into three types: light, medium and heavy, and there is also an appropriate connection in the section. Generally, light-duty rubber-sheathed cables are used in household electrical appliances and small electric equipment, requiring softness, lightness, and good bending performance. In addition to industrial use, medium-duty rubber-sheathed cables are widely used in agricultural electrification, and heavy-duty cables are used in port machinery, searchlights, Large-scale hydraulic irrigation and drainage stations in the family business. This type of product has good versatility, complete series specifications, good performance and stability.

Waterproof rubber sheathed cables and AAC conductor for submersible pumps are mainly used for submersible motors. The model is JHS, JHSB.

For cables for radio devices, currently two types of acsr conductor (one shielded and one unshielded) are mainly produced, which can basically meet the requirements. The model is WYHD, WYHDP.

Photographic cable products, in line with the development of new light sources, have a small structure and good performance, while meeting the needs of indoor and outdoor work, and gradually replace some old products with heavy weight and poor heat resistance.

Rubber cable model

Rubber sheathed cables are divided into heavy rubber sheathed flexible cables (YC cables, YCW cables), medium-sized rubber sheathed flexible cables (YZ cables, YZW cables), light rubber sheathed flexible cables (YQ cables, YQW cables), and waterproof rubber sheathed flexible cables ( JHS cable, JHSB cable), welding machine cable (YH cable, YHF cable) and YHD cable are tin-plated power cables for field use.

Talk about the common misunderstandings of those wires and cables

Nowadays, there are many kinds of wires and cables, and their performances are diverse. When buying All Aluminum Alloy Cable

, many people choose to learn about the various parameters and evaluations of the cables on the network, but because the information on the network is too complicated, it is difficult to distinguish between true and false. , Some wrong viewpoints will cause misunderstandings to many people who browse and watch, so many misunderstandings about wires and cables are formed. Here is a summary of several common misunderstandings.

Misunderstanding 1: There is radiation in wires and cables

Many people have seen on the Internet that wires and cables have radiation. To be honest, there is radiation, but those who have a little knowledge of physics should know that everything that uses electricity has radiation. Even an electric fan has radiation. Except for those high-risk radiation products, the amount of radiation from ordinary wires and cables is negligible and basically negligible.

And what you may not know is that the radiation of wires and AAAC cables is even weaker than that of the mobile phones we carry around every day, so those who are afraid of radiation from wires and cables, the first thing to do is not to stay away from wires and cables, but Throw away the phone quickly.

There are also some people who worry about the magnetic field generated by wires and cables, and think that this kind of magnetic field has an unhealthy effect on the human body. If they are worried about the magnetic field, it is even more nonsense, because everyone knows that our earth has a natural geomagnetic field , And it has a larger range and stronger power. If the magnetic field is not good for the human body, the entire earth is no longer suitable for human habitation. Our Mars immigration plan can only be started in advance, so we are worried about the radiation magnetic field of wires and cables.

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.

Requirements for power cable use

Power cables are usually rope-like cables formed by twisting several or several groups of wires. Each group of wires is insulated from each other and is often twisted around a center. The entire outer layer has a highly insulating coating. They are mostly erected in the air, underground, or underwater for telecommunications or power transmission. Cables can be divided into power cables, communication cables and control cables according to their uses. So are there any safety requirements when using the cable? Let’s look at it in detail next.

1. When the cables cross each other, the high-voltage cables should be under the low-voltage cables. If one of the cables is protected by a pipe or separated by a partition within 1m before and after the intersection, the smaller allowable distance is 0.25m.

2. When the cable is close to or crossing the heating pipe, if heat insulation measures are provided, the smaller distance between parallel and crossing is 0.5m and 0.25m respectively.

 

 

3. When the ACSR conductor crosses the railway or road, it should be protected by a pipe. The protective pipe should extend 2m beyond the track or road.

4. The distance between the cable and the foundation of the building should be able to ensure that the cable is buried outside the building’s scattered water; when the cable is introduced into the building, it should be protected by a pipe, and the protective pipe should also exceed the building’s scattered water.

 

5. The distance between the cables directly buried in the ground and the grounding of the general grounding device should be 0.25~0.5m; the buried depth of the cables directly buried in the ground should generally not be less than 0.7m, and should be buried under the frozen soil layer.

The above is about the safe use of wires and cables. When using wires and cables, they must be in accordance with the standards to prevent the wires and cables from causing losses.