Significant progress has been made in optical fiber cable signal transmission distance

Optical fibre cable  is a communication cable consisting of two or more glass or plastic optical fiber cores located in a protective coating and covered by a plastic PVC outer sleeve. The signal transmission along the internal optical fiber generally uses infrared rays. In January 2013, Cuba carried out communications reforms, opening fiber optic cables and increasing foreign channels to attract attention.
The difference between PV wire and ordinary cable
First: There is a difference in material. Cables use metal materials (mostly copper, aluminum) as conductors; optical fibers use glass fibers as conductors.
Second: There is a difference in the transmission signal. The cable transmits electrical signals. Optical fiber transmits optical signals.
Third: There are differences in the scope of application. Cables are now mostly used for energy transmission and low-end data information transmission (such as telephone). Optical fiber is mostly used for data transmission.
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.

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The research was funded by the British Engineering and Physical Sciences Research Council, and the 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.
They 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, researchers plan to test new methods of dense super channels that are commonly used in digital cable television (64QAM), cable 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 fiber optic 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 commercial 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.”

Development of high flexible fireproof cable

With the development of society, the scale of the city has been expanding, high-rise buildings have been emerging, and the number of important buildings has been increasing. The fire caused by the electric line, especially the huge fire accident, endangers the safety of life and property, and some fatal and huge fire, often causes a series of social problems and accountability. Once the fire happens, rescue is very important, fire pump, fire smoke exhaust, emergency lighting, fire elevator and other rescue equipment become the protection of people's escape, and these protection "lifeline" is the fire-proof cable. Due to the frequent occurrence and serious consequences of fire, more and more attention has been paid to the performance and testing of fire-resistant cables. Table 1 gives examples of the structure and standard test conditions of fire-resistant cables in some countries and regions, from Table 1, we can see the different requirements of GB, IEC, BS, AS for the test performance of fire-proof cable. China fire-resistant cables mainly implement the national standards, fire resistance requirements through BS 6387 or BS8491 fire-resistant + vibration + spray fire test.

At present, the fire-proof cables on the market are mainly divided into two categories from insulating materials, namely, magnesium oxide insulated fire-proof cables and mica-mineral compound insulated fire-proof cables, the common custom is respectively called the rigid fireproof cable and the flexible fireproof cable. Because of the difference of structure design and material technology, the two kinds of cables have their own characteristics and need to be improved. As a rigid fireproof cable, it has many advantages, such as high temperature resistance, radiation resistance, long life and good earthing, etc. . The other category is flexible fireproof cable with twisted conductor + mineral composite insulation + Metal Sheath or fireproof mud composite sheath, theoretically speaking, tubular metal or metal sheathed fireproof cable after mechanical deformation through rolling, the flexibility is mainly relative to solid conductors, and the flexibility of fireproof cables with fireproof mud insulation is limited by the hardness of the fireproof mud. Compared with conventional cables, these fireproof cables need special accessories and technology in connection, and it is more difficult to realize pre-branching. Their branch joints are often connected by branch boxes, except for complicated installation, construction strength, fire performance, joint performance and sealing moisture performance is also uneven.

We study the structure and material of the fireproof cable deeply, and take the flexibility, fireproof safety and construction convenience as the research direction, develop a kind of flexible fireproof cable, it has passed GB, IEC, BS and AS tests, and is a kind of truly flexible fireproof cable. On this basis, we developed the prefabricated branch type environmental protection fireproof cable. This prefabricated branch type fireproof cable has low manufacturing cost and not only retains the advantages of the traditional fireproof cable, the utility model also overcomes the problems of moisture absorption of the fire-proof layer of the general fire-proof cable and the poor flexibility of the cable, and is convenient to install and lay.

Why should the length of power cable be reserved?

It is very difficult to repair and replace600V 90°C XLPE ACWU90 AC90 Cable, especially when the middle section is in trouble, because the cable is laid in the open, the bridge, the buried, the cable trench and the pipe. So in the cable laying is required to reserve. Not only in the cable trench in the feeder, but also to reserve the end; if it is tube or cable trench laying, in the middle of the maintenance wells to reserve a certain length.

Advantages: When the power cable is connected to the feeder circuit or equipment, the copper nose needs to be pressed and the outer protective layer of the cable needs to be removed And the distribution cabinet, control cabinet itself is also relatively easy to affect the cable, so the cable in both ends need to reserve a certain length to deal with the subsequent maintenance.

Otherwise, it will be difficult to deal with the problem in the figure below. The advantage of the reserved maintenance well: When the power cable is laid secretly, a maintenance well must be set up at a certain distance, which is mainly used to deal with the inspection and repair of the fault in the middle part ofPVC XLPE Insulated Power Cable 25mm² ~ 400mm². If a section is damaged by external forces or problems, the amount reserved in the manhole can be used nearby, making maintenance convenient and time-saving. Otherwise, it is very difficult to deal with the following problem.

Other benefits: due to the general cable laying path is generally more complex, often need to turn bend, calculation of cable length can not be accurate, appropriate length can also be reserved for laying a variety of special circumstances.

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.

Misunderstandings in the process of wire installation meeting (2)

Power cables bring light to the home, add all kinds of fun to life and meet the needs of family life. However, if negligence in the process of wire installation, it is easy to cause various hidden dangers in the home environment.

Misunderstanding 3: The wires are buried directly without casing
Some irresponsible construction workers buried the wires directly on the wall during the construction process, the wires were not covered by the insulating tube, and the wire connectors were directly exposed. This may cause hidden dangers and is a typical cut corner. In the future life, the wires lack protection, are easy to be bitten by rats or suffer external damage, and the wires are short-circuited, the wiring specifications of the wires are clear, they need to be protected with insulating sleeves, and the connectors cannot be exposed. Therefore, during the construction supervision period, the owner needs to supervise Whether the construction party performs construction as required.


Misunderstanding 4: Install socket cables at will
The power cord needs to use a copper wire cross-section. If you live in an old house, you need to replace the original aluminum wire with copper wire. Because the aluminum wire is easily oxidized, the connector is easy to catch fire. An investigation shows that the incidence of electrical fires in residential buildings usingAerial Bundled Cable (ABC) ASTM B231 Standard is dozens of times that of copper wires. In addition, for aesthetics, many households will use slotted buried wires and buried pipe laying methods, and wiring needs to be followed. “The live wire is inserted into the switch, and the neutral wire enters the lamp holder” and the principle that there is a leakage protection device on the socket.

Home circuit safety

Overload is also called “overload”. For example, the load capacity of a certain type of car is 4 tons, and the load exceeding the stipulation is “overload”, which is easy to damage the car, and the electric wire also has its load regulation. The current passing through the wire will heat the wire, which is normal. However, if it is overloaded and the thin wire passes a large current, it is easy to cause a fire.Install the bare wires indoors, the ambient temperature should not be higher than 35c, choose the wire in the safe current of the wire, the wire will not overheat. However, when the power consumption exceeds the current carrying capacity of the wire, the wire will generate heat. The heat of the wire is proportional to the square of the current intensity. If the current intensity is increased by 2 times, the heat generation will increase by 4 times compared to the original, which will cause the wire to overheat and easily cause a fire.

Misunderstandings in the process of power cable installation meeting (1)

Power cables bring light to the home, add all kinds of fun to life and meet the needs of family life. However, if negligence in the process of wire installation, it is easy to cause various hidden dangers in the home environment.
Misunderstanding 1: Strong and weak electricity sharing
AC power is usually used in our homes. In order to facilitate the construction, some construction teams directly store the wires together. Power cords, network cables, telephone lines, etc. are all placed in the same base, which will cause interference between the wires and unstable signals. It will also bury the hidden dangers of home fires. Strong current and weak current should be wired separately. Strong current and weak current sharing tube and bottom box are strictly prohibited. The parallel spacing of the strong current should be no less than 3cm, no less than 50cm, and the intersections should be at right angles.


Misunderstanding 2: Duplicate wiring
In order to make the pipes look clearer, some construction workers use a pipe for each wire, so many pipes are buried in the wall. It is difficult to find the location of the problematic pipe or most of the wall needs to be damaged when repairing in the future. And the structure of the ground can find the problem. Generally speaking, the pipeline should be made into a “live line”, in the case of less than 40% of the pipeline capacity, put Aerial Bundled Cable (ABC) HD 626 S1 Standard in the same direction in the pipe, which is economical and avoids the trouble of future maintenance.

 

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.

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.