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”.

Summary of power cable knowledge (two)

Conductor shielding layer (also called inner shielding layer, inner semi-conductive layer)

①Conductor shielding layer is a non-metallic layer squeezed on the cable conductor, and is equipotential with the conductor, and the volume resistivity is 100~1000Ω•m. Equipotential with conductor.

② Generally, low-voltage cables of 3kV and below have no conductor shielding layer, and medium- and high-voltage cables of 6kV and above must have conductor shielding layer.

③The main function of the conductor shielding layer: eliminate potholes on the surface of the conductor; eliminate the tip effect on the surface of the conductor; eliminate the pores between the conductor and the insulation; make close contact between the conductor and the insulation; improve the electric field distribution around the conductor; The cable conductor shielding layer also has the function of inhibiting the growth of electrical trees and heat shielding.

Insulation layer (also called main insulation)

①The main insulation of the aaac conductor  has the specific function of withstanding the system voltage. During the service life of the cable, it has to withstand the rated voltage and the overvoltage of the system failure, lightning impulse voltage for a long time, and ensure that no phase-to-earth or phase-to-phase interaction occurs under the working heat state. Breakdown short circuit. Therefore, the main insulation material is the key to the quality of the cable.

②Cross-linked polyethylene is a good insulating material and is now widely used. Its color is bluish white and translucent. Its characteristics are: higher insulation resistance; able to withstand higher power frequency and pulse electric field breakdown strength; lower dielectric loss tangent value; stable chemical performance; good heat resistance, long-term allowable operating temperature of 90℃; Good mechanical properties, easy to process and process.

Insulation shielding layer (also called outer shielding layer, outer semi-conductive layer)

① The insulating shielding layer is a non-metallic layer extruded on the main insulation of the cable. Its material is also a cross-linked material, which is semi-conductive and has a volume resistivity of 500-1000Ω•m. Equipotential with ground protection.

② Generally, low-voltage cables of 3kV and below have no insulation shielding layer, and medium- and high-voltage cables of 6kV and above must have insulation shielding layer.

③The role of the insulating shielding layer: the transition between the main insulation of the cable and the grounded metal shield, so that there is close contact, eliminates the pores between the insulation and the acsr conductor; eliminates the tip effect on the surface of the grounded copper strip; improves the insulation around the surface Electric field distribution.

④Insulation shielding is divided into peelable type and non-peelable type according to the process. Generally, medium voltage cables use peelable type for 35kV and below. A good peelable insulating shield has good adhesion and no semi-conductive particles remain after peeling. 110kV and above adopt non-peelable type. The non-peelable shielding layer is more closely integrated with the main insulation, and the construction process requirements are higher.

 

Metal shield

①The metal shielding layer is wrapped outside the insulating shielding layer. The metal shielding layer is generally made of copper tape or copper wire. It is a key structure to limit the electric field inside the cable and protect personal safety. It is also a grounding shield that protects the cable from external electrical interference.

②In the event of a grounding or short-circuit fault in the system, the metal shielding layer is the channel for short-circuit grounding current. Its cross-sectional area should be calculated and determined according to the short-circuit capacity of the system and the neutral grounding method. Generally, the cross-sectional area of ​​the shielding layer calculated for a 10kV system is recommended to be no less than 25 square meters. Mm.

③The metal shielding layer in the cable line of 110kV and above is composed of a metal sheath, which has the function of electric field shielding and waterproof sealing, as well as mechanical protection.

④The material and structure of the metal sheath generally adopt corrugated aluminum sheath; corrugated copper sheath; corrugated stainless steel sheath; lead sheath, etc. In addition, there is a composite sheath, which is a structure in which aluminum foil is affixed to the PVC and PE sheaths, and is used more in European and American products.

Armor layer

① A metal armor layer is wound around the inner lining layer, generally double-layer galvanized steel tape armor. Its function is to protect the inside of the cable and prevent damage to the cable by mechanical external forces during construction and operation. It also has the function of grounding protection.

②The armor layer has a variety of structures, such as steel wire armor, stainless steel armor, non-metal armor, etc., which are used for special cable structures.

Outer sheath

①This is the outermost protection of the acsr conductor chart. Generally, polyvinyl chloride (PVC) polyethylene (PE) is used, which are all insulating materials and are formed by extrusion. According to technical requirements, flame-retardant polyvinyl chloride (PVC) is generally used. Adapt to the requirements of cold winter and hot summer without cracking or softening.

②The main function of the outer sheath is to seal to prevent moisture intrusion, protect the armor layer from corrosion, and prevent the expansion of fire caused by cable failure.

③The characteristic information of the cable is also printed on the outer sheath, such as specification, model, production year, manufacturer, continuous meter length, etc.

ACSR Conductor Packing

Since the beginning of the 1990s, China’s contribution to aluminum-cored steel reinforced Conductor (ACSR ) has increased significantly, and at the same time, the export volume has also soared.As the main electrical material for long-distance transmission, AAAC conductor will also face major development. The wire has the advantages of good flexibility, good reliability and high strength, and can be designed and manufactured according to different needs. A variety of products with different performances can be designed and manufactured. It has greater advantages than the half wire and has been widely used. However, due to the current carry capacity of ACSR  conductors , The metal surface of the wires is directly exposed outside, unlike ordinary cables that are protected by an outer sheath. Therefore, more attention should be paid to their packaging.

The choice of packaging tray 1.1 The choice of structure type my country’s current wire and cable coiling tools, from the material used, the wire and cable delivery tray Song uses all wood steel wood and all steel and other materials. All wood refers to the side plate of the wire and cable packaging tray And Jianjing are made of wood. The whole wooden plate has the longest history of use. Although it has the advantages of low price and light weight, it has poor strength and rigidity, and is easily affected by the atmosphere. Although sometimes measures such as anti-corrosion and termite prevention are used, it is used in tropical and subtropical rainy areas The service life of the wooden disc is still very short, and it is easy to scratch the wire because there are hundreds or even thousands of nails on the wooden disc. When stored for a long time, the corrosion and deformation of the wood often cause the nails to loosen, and the nails often occur when the wire is installed. It is not easy to choose the whole wooden plate as the packaging plate of the steel core aluminum stranded wire because of the scratching of the wire. The use of the all-steel plate means that the side plate and the simple diameter of the wire and cable packaging plate are made of steel.


There are two basic structural forms of all-steel packaging trays, namely, profile steel plus pu steel plate all-steel structure and corrugated all-steel structure; the former profile steel is the first frame of the side plate of the wire and cable packaging tray, on which a thin plate is welded, and the simplified Steel composition. The two are fastened with bolts or welded together, the latter is the skeleton of the wire and cable shipping tray, and the side plates are welded by corrugated steel plates. The simplified form is composed of all steel. The two are welded by electric welding. These two kinds of all-steel structure cable packaging have the advantages of high strength and long service life, but they are expensive, and they are easy to scratch the surface of the wire, and it is not easy to be used for steel core aluminum stranded wire packaging. The steel-wood hybrid structure packaging tray is used, which refers to the wire. The side plate of the cable packing reel and the skeleton of the cylinder are welded with profiled steel, and the yoke-shaped plate on the side plate and the diameter slats on the wire and cable diameter are made of wood, and the two are fastened and connected by bolts. The cable reel of this structure not only saves part of the wood, but also is cheaper than the all-steel structure wire and cable packaging, convenient for construction, and lighter in weight. Although it is less strong than the all-steel structure wire and cable packaging reel, its cost is low and only all steel About 40% of the structure packaging tray, and there is no nail. Therefore, there is no disadvantage of wire scratches and scratches. In short, no matter from the protection effect of the conductor or from the economic point of view, it is appropriate for Zhu to use the steel-wood mixed structure packaging tray to package the steel core aluminum stranded wire.

Seamless corrugated aluminum sleeve

The biggest advantage of corrugated aluminum sheathed cross-linked cables is light weight and large short-circuit thermal stability. In a system with a slightly longer short-circuit current, the standard thickness of the aluminum sleeve can meet the requirements. For example, when the thermal stability is not enough in the calculation, the aluminum sleeve can be thicker to meet the technical requirements. There is no need to increase copper wire shielding. The lead set is simple. The mechanical properties and tightness of the aluminum sleeve extruded by the aluminum press are very good.
The weight of aluminum sheathed cables is much lighter than that of lead sheaths. How to use manual labor to move, lift, carry and move the cables is less labor-intensive than lead sheathed cables, which is very popular with laying workers.

The corrugated aluminum sleeve structure was developed in the 1960s and 1970s. At that time, high-voltage cables were mainly oil-filled aerial bundled cables 7870 standard. The use of corrugated aluminum sleeve in oil-filled cable design has many advantages: the radial reinforcement of the lead sleeve is omitted; the spiral corrugation forms the outer oil passage to significantly reduce the transient pressure drop of the oil-filled cable, which can be released in the circuit design. The length of the fuel supply section can reduce the number of plug joints; the price of aluminum at that time was much lower than the current price, and it was much cheaper than the price of lead and copper. Therefore, corrugated aluminum sleeves have been used to replace lead sleeves in land-based oil-filled cables in some countries, which has great economic and technical benefits. However, the spiral corrugations of the corrugated aluminum sheathed cross-linked cable make the cable do not have the longitudinal water blocking function. In the wire design, if it can also longitudinally block the water and reduce the gap, the electrical performance will be reduced, which seems to outweigh the gain.

The atomic number of aluminum in the periodict able is 13, while lead is 82. Aluminum is a chemically active metal. When encountering external force damage during operation, the outer protective layer is damaged or the outer protective layer is broken on the support, and the aluminum sleeve will soon be corroded and perforated, causing water ingress.

The melting point of aluminum is 658°C, and the mold base temperature is about 500°C when the aluminum press is extruded. The extrusion temperature of the lead sleeve is much higher than that of the lead sleeve. For this reason, there should be a copper wire braided glass ribbon or a semi-conductive resistance hose in the aluminum sleeve to prevent the insulation shield from being burned. There are two types of aluminum pressing machines: continuous pressing and discontinuous pressing. It is not very beneficial to cross-linked cable core to stop for a period of time when adding aluminum ingots discontinuously. Although the new and old aluminum ingots can be combined into one body in the aluminum press, there are still visible seams on the surface of the aluminum sleeve, but it has no effect on the resistance strength of the aluminum sleeve. It should be said that continuous is better than discontinuous.

The aluminum press system is a precision equipment with a high cost, and the production process and process of the aluminum press are also more complicated. The aluminum press has a higher energy consumption and labor consumption to produce the aluminum cover, and the production cost of the metal cover is also higher.

The allowable side pressure of the aerial bundled cable(abc)1418 is related to the type of insulation, not the type of metal sheath. The data recommended in some foreign authoritative manuals are shown in the table below. Although the compressive strength of the corrugated aluminum pipe is higher than that of the lead pipe, the tension of the cable during laying is on the conductor core. The lateral pressure at the bend is transmitted from the conductor to the insulation, metal sheath and sheath, and the corner pulley bears the thrust . Among them, the most susceptible to mechanical force is insulation. It is reasonable to determine the lateral pressure of the cable by the insulation resistance.

The impact of “anti-dumping” on the domestic optical fiber and cable industry

Recently, the optical communications section is relatively hot. In the process of communicating with friends, it seems that many people are very concerned about the impact of the Ministry of Commerce on the impact of the anti-dumping of optical fiber preforms from US and Japanese manufacturers on domestic enterprises, especially worried about the implementation deadline of August 19, 2017 After the expiration, the domestic optical fiber and aerial bundled cable  b231 business situation came to an abrupt end.

So what is the reason for this “anti-dumping”, what is the specific content, and what impact will its implementation and future expiration have on the domestic optical fiber and cable market?

1. The whole story of the “anti-dumping” case concerning optical fiber preforms in the United States and Japan.

—On May 18, 2015, the Ministry of Commerce issued Announcement No. 15 of 2015, announcing the preliminary ruling of the anti-dumping investigation on imported optical fiber preforms originating in Japan and the United States: to determine the existence of imported light rod products from the United States, Japan and other countries Anti-dumping behavior. From the side, it shows the state’s attitude to support the development of domestic optical communication enterprises.

—On August 19, 2015, the Ministry of Commerce issued Announcement No. 25, announcing the final decision on the anti-dumping case against imported optical fiber preforms originating in Japan and the United States. The Ministry of Commerce determined that there was dumping of imported optical fiber preforms originating in Japan and the United States, China’s domestic industry was threatened with material damage, and there was a causal relationship between dumping and the threat of material damage, and decided to implement anti-dumping measures on the product.

—On March 6, 2015, the Ministry of Commerce issued an announcement that in view of the special aerial bundled cable (abc)  and complicated anti-dumping investigation of imported optical fiber preforms originating in Japan and the United States, the Ministry of Commerce decided to extend the investigation period of this case by 5 months , That is, the deadline is August 19, 2015. This makes the anti-dumping investigation of optical fiber preforms that have been controversial when they first emerged, once again in a halo.

—On May 18, 2015, the Ministry of Commerce issued Announcement No. 15 of 2015, announcing the preliminary ruling of the anti-dumping investigation on imported optical fiber preforms originating in Japan and the United States: to determine the existence of imported light rod products from the United States, Japan and other countries Anti-dumping behavior. From the side, it shows the state’s attitude to support the development of domestic optical communication enterprises.

—On August 19, 2015, the Ministry of Commerce issued Announcement No. 25, announcing the final decision on the anti-dumping case against imported optical fiber preforms originating in Japan and the United States. The Ministry of Commerce determined that there was dumping of imported optical fiber preforms originating in Japan and the United States, China’s domestic industry was threatened with material damage, and there was a causal relationship between dumping and the threat of material damage, and decided to implement anti-dumping measures on the product.

What are the common types of aluminum alloy cables

Aluminum alloy cable (abbreviation: alloy cable) is different from the traditional copper core cable. This aluminum alloy cable uses high elongation aluminum alloy material. The pure aluminum is added with iron and other materials, and undergoes a compact stranding process and special Annealing treatment can “squeeze” the voids in the alloy aluminum to reduce the cross-sectional area, so that the cable has better flexibility. The safety performance of this kind of aluminum alloy cable is also better than that of copper core cable. When its surface is in contact with air, it can form a thin and strong oxide layer, which can withstand various corrosions. Even when overloaded or overheated for a long time, the stability of the connection can be guaranteed. To achieve the same electrical performance, the direct purchase cost of aluminum alloy cables is 40% lower than that of copper cables, and the general construction and installation costs can be saved by more than 20%.

1.Aluminum alloy (STABILOY) non-armored AC-XLPE insulated PVC sheathed cable:
AC-XLPE insulated PVC sheathed cable, aluminum alloy non-armoured cable is made of conductor, the cross-section specification is from 10mm² to 400mm², the core is grade compressed strand type, which fully complies with CSA C22.2 NO.38 about ACM alloy conductor Standards, also in line with the latest editions of GB 12706.1 and IEC 60502.1.
Aluminum alloy (non-armoured cables use cross-linked polyethylene insulation with a working temperature of 90℃ and black PVC outer sheath, which have a very wide range of applications where no armored mechanical protection is required. They can be used in non-combustible buildings, such as Feeder lines for lighting, sockets and other equipment in office buildings, hotels, shopping malls and factories.

Aluminum alloy cable is an aluminum alloy conductor specially developed for construction application cables. The safety performance, electrical performance, and mechanical performance of aluminum alloy cables have been tested by the China Quality Certification Center and the National Wire and Cable Quality Supervision and Inspection Center, and all meet the requirements of China’s National Standards (GB). Aluminum alloy cables have been successfully used in North America for more than 30 years and are advanced and mature technologies and products.

2.Self-locking armored cable:
ACWU90 is a highly flexible self-locking aluminum armored, PVC outer sheath, 90℃ cross-linked polyethylene waterproof insulated single-core or multi-core cable, with an equipotential bonding bare conductor. Because of the FT4 grade PVC outer sheath, ACWU90 can be directly laid and buried in the ground, and is suitable for corrosive environments and non-combustible buildings. ACWU90 reduces the construction difficulty and labor cost caused by pipeline wiring.


The alloy cable has been assembled in the factory with a highly flexible self-locking armor and a sealed PVC outer sheath. There is no need for pipelines and accessories and manual procedures such as intensive drawing, buckling and pipe threading. ACWU90 has passed the CSA certification and can be used in open or dark wiring in dry and humid environments, as well as in the first-level hazardous environment in zone 1 and 2, as well as the second and third-level hazardous environments. Laying method: Brackets, ladders, trays and cable clamps can be used for indoor laying. Outdoors can be directly buried, cable trench, cable tunnel and other methods. ACWU90 is equipped with calibration marks per meter to accurately determine the cable length.


Aluminum alloy cable, ACWU90 multi-core cable is made of conductor, and the cross-section specification ranges from 10mm² to 400mm². It is fully compliant with IEC 60502.1 and GB 12706.1 standards, and can also provide various specifications of low-smoke and halogen-free products according to customer requirements. Both AC90 and ACWU90 can be used as user incoming cables. The self-locking armored technology used makes the cables more flexible and easier to install than conventional armored cables. In fixed installation, the bending radius of the self-locking armored cable can be only 6 times the outer diameter of the cable.

3AC90 type multi-core aluminum alloy self-locking armored aluminum alloy cable:
AC90 is a highly flexible self-locking aluminum armored, 90℃ cross-linked polyethylene insulated single-core or multi-core cable, with an equipotential bonding bare conductor. The AC90 cable is assembled in the factory with high-flexibility self-locking armor, without the need for pipelines and accessories, and manual procedures such as intensive drawing, buckling and pipe threading.
AC90 type has been used in non-combustible buildings, such as office buildings, hotels, shopping malls and factories in the lighting, sockets and other equipment feeder lines, can be used as users on the ground and in dry environments as the incoming cable. AC90 can be installed on the cable tray (perforated tray, non-perforated tray and ladder frame), and can also be laid along the wall and the top by using a bracket or a cable clamp.
AC90 multi-core cables are made of conductors, with cross-sectional specifications ranging from 10mm² to 400mm². It has passed CSA certification and can be used for open or dark wiring in a non-humid environment, and has the same performance as pipeline laying. AC90 is a flame-retardant Class A, low-smoke and halogen-free type, which fully complies with the standards of IEC 60754, GB17650.1 and IEC 60502.1\GB 12706.1.

 

What should we pay attention to when installing cables?

Matters needing attention in Electrical cable installation:

1. Keep a distance of 2m when the mine cable is installed in parallel with the heating pipeline, and keep 0.5m when crossing.
2. When the cable is installed in parallel or across other pipes, a distance of 0.5m must be maintained.
3. When the cable is directly buried, the depth of the 1-35kV cable should not be less than 0.7m.
4. When the cables of 10kV and below are installed in parallel, the mutual clear distance is not less than 0.1m, the 10-35kV is not less than 0.25m, and the distance when crossing is not less than 0.5m.
5. The minimum bending radius of the cable must not be less than 15D for multi-core cables and 20D for single-core cables (D is the outer diameter of the cable).


6. Cable joints of 6kv and above.
A. When installing the cable terminal head, the semi-conductive shielding layer must be stripped off, and the insulation must not be damaged during operation. Knife marks and unevenness should be avoided, and sandpaper should be used to smooth it if necessary; the shielding end should be flat and graphite The layer (carbon particles) is removed.
B. The copper shield and steel armor of the plastic insulated cable end must be well grounded. This principle should also be followed for short circuits to avoid induced electromotive force at the end of the steel armor during unbalanced operation of three-phase, or even “fire” and burn the sheath Wait for the accident. The grounding lead wire should be tinned braided copper wire, and soldering iron should be used when connecting with the copper tape of the cable. It is not suitable to use a blowtorch to seal and solder, so as to avoid burning insulation.
C. The three-phase copper shield should be connected to the ground wire separately. Note that the shield ground wire and the steel armor ground wire should be led out separately and insulated from each other. The position of the welding ground wire should be as low as possible.
7. The basic requirements for cable ends and intermediate joints: a. Good conductor connection; b. Reliable insulation, it is recommended to use radiation cross-linked heat-shrinkable silicone rubber insulating materials; c. Good sealing; d. Sufficient mechanical strength, Can adapt to various operating conditions.


8. Electrical Power Cable end must be waterproof and corroded by other corrosive materials to prevent breakdown due to aging of the insulation layer caused by water trees.
9. Cable loading and unloading must use cranes or forklifts. Horizontal transportation or laying flat is prohibited. When installing large cables, cable cars must be used to prevent cables from being damaged by external forces or scratching the insulation layer due to manual dragging.
10. If the cable cannot be laid in time for some reason, it should be stored in a dry place to prevent sun exposure and water ingress into the cable end.

Precautions for testing cross-linked cables

In recent years, silane cross-linked polyethylene cable material (hereinafter referred to as XLPE) has become the leading material for low-voltage cross-linked cable insulation because of its simple manufacturing equipment, mature technology, convenient operation, and low overall cost.

At present, the commonly used XLPE is the two-step XLPE. When the cable factory produces the insulated core, the polyethylene (PE) grafted with silane and the catalyst masterbatch are mixed in a certain proportion and extruded in a common extruder. Then complete the cross-linking in hot water or steam; the other one-step method XLPE is made by the cable material manufacturer, which mixes all the raw materials together by a special method according to the ratio, and the cable factory directly completes the grafting and grafting in one step in the extruder. Extrude the insulated core, and then complete the cross-linking under natural conditions. The common point of these two types of XLPE is that no special extrusion equipment is needed and the cross-linking process is relatively simple. As long as the raw materials and process conditions meet the requirements, it can be made into an insoluble and infusible thermosetting plastic. Compared with thermoplastic PE, its heat-resistant deformation and mechanical properties at high temperature, environmental stress cracking, aging resistance, chemical resistance, etc. have been improved or improved, while the electrical properties remain basically unchanged, and the long-term work of the cable The temperature is increased from the original 70°C to 90°C, thereby improving the short-term current withstand capability of the cable. In summary, XLPE low-voltage cables have become the main products of cable manufacturers in recent years.

As a third-party inspection agency, this type of cable is also increasing year by year. How to accurately provide the test results of the thermal extension and aging performance of this type of product? Inspectors are faced with some special circumstances. The following is an analysis:

First, the problem of abnormal thermal extension of XLPE insulation. When testing, the author often finds that the elongation rate of XLPE cable insulation under load in the 200℃ thermal extension test greatly exceeds the requirements specified in the standard, or the sample is put into the oven and melted in a short time. If the test is repeated immediately with the original sample, The reproducibility of the results is very good. According to the routine, as long as the test method is correct and the sampling is correct, a conclusion can be drawn based on the test results. However, for XLPE, this may be a great risk. Because the cross-linking process of ACWU90 AC90 Cable is a slow chemical change process related to temperature, humidity, time, insulation thickness and other factors, especially the naturally cross-linked XLPE insulation material is affected by the above factors to complete the cross-linking. There will be a big difference in time, and it is entirely possible that the natural cross-linking has not been completed within the prescribed test period. Once the natural cross-linking is completed over time, its performance may meet the requirements of national standards. For such situations, the author believes that under the premise of reflecting the current situation of the sample, we should not rush to determine, but should provide the sample with a condition to promote crosslinking-soaking in hot water at 90°C±2°C Do the hot extension test after 4 to 5 hours. Practice has proved that the test results at this time can be used as a basis for judgment. It is worth mentioning that individual manufacturers are pursuing commercial profits one-sidedly, using the similar characteristics of PE and XLPE to pretend to be XLPE, and PE will not produce cross-linking changes no matter what conditions are provided to promote cross-linking. In terms of performance, it does not meet the requirements of XLPE at all, which is the same as the fact that stones cannot hatch chicks. This requires inspectors to have the ability to identify true and false, good and bad XLPE. In fact, through observation and work accumulation, we can distinguish whether the tested sample is under-crosslinked, inferior XLPE, or PE is used according to the fusing time and fusing point after the sample is placed in the oven. However, as a third-party inspector, you cannot draw conclusions based on experience alone, and must make judgments based on real data.

Second, the problem of the change rate of XLPE heat aging test exceeding the standard. When testing, if you get the sample, prepare it immediately, and put it in the oven for aging as usual, the tensile strength and elongation at break will often exceed the standard after aging, and you must be cautious in judging this result. This phenomenon is not entirely caused by poor aging performance, it may be because XLPE has not been completely cross-linked (from the time curve of XLPE cable material thermal extension with warm water placement, it can be seen that when the thermal extension is qualified, it does not represent the sample Completely cross-linked), and after being placed in the aging box, XLPE is still completing its cross-linking process, which leads to an increase in tensile strength, a decrease in elongation at break, and the final rate of change exceeds the standard. Due to the long time to complete the aging, it will be troublesome to discover the problem once the test is over. Therefore, it is necessary to thoroughly crosslink the sample before performing the aging test.

In summary, it can be seen that special factors should be considered to determine the thermal elongation and thermal aging performance of XLPE. Personnel engaged in third-party inspections can neither make a hasty conclusion on the results of the test, because doing so involves the risk of misjudging qualified products as unqualified; nor can they avoid these two tests because it is difficult to draw conclusions. This may cause substandard products or counterfeit products to be missed. Therefore, it is necessary to exclude the possibility that the sample has not been cross-linked or completely cross-linked before performing the above two tests. We advocate the use of scientific and reasonable test methods to provide fair and reliable test results.