What’s The Difference Between ACSR and AAAC cable ?

Following are some Q&A people interested about wire and cables :

1. What types of commonly used wires and cables are classified by purpose?
Answer: According to the purpose, it can be divided into bare conductors , insulated wires, heat-resistant wires, shielded wires, power cables, control cables, communication cables, radio frequency cables, etc.

2.What is the difference between ACSR cable and AAAC cable ?
AAAC:This bare concentric-lay-stranded conductor, made from round aluminum alloy 6201 -T81 wires, is constructed with a central core surrounded by one or more layers of helically laid wires.
it provide better corrosion resistance than the one produced by the aluminum conductor steel reinforced(ACSR).
ACSR: This bare concentric-lay-stranded conductor is made from round aluminum 1350-H19 (extra hard) wires and round zinc-coated or aluminum-coated steel core wire(s) to be used as overhead electrical conductors.it provides better strength than AAAC cable.

3. What kinds of insulated wires are there?
Answer: There are the following types of insulated wires: PVC insulated wires, PVC insulated cords, nitrile and polyvinyl chloride compound insulated cords, rubber insulated wires, direct buried aluminum core plastic insulated wires for agricultural use, and rubber insulated cotton yarn Textile cords, PVC insulated nylon sheathed wires, PVC insulated cords for power and lighting, etc.

4. What kind of occasion is the cable tray suitable for?
Answer: The cable tray is suitable for the overhead laying of power cables and control cables indoors and outdoors in general industrial and mining enterprises, and can also be used for indoor and outdoor installations in telecommunications, radio and television departments.

5. What are the cable accessories?
Answer: Commonly used electrical accessories include cable terminal junction box, cable intermediate junction box, connecting pipe and terminal block, steel plate junction box, cable tray, etc.

6. What is the cable middle connector?
Answer: The device that connects the cable and the cable’s conductor, insulation shielding layer and protective layer to connect the cable line is called the cable intermediate joint.

7. What is electrical main wiring?
Answer: The electrical main wiring is the connection method of the main electrical equipment and the bus in power plants and substations, including the connection of the main bus and the auxiliary power system according to certain functional requirements.

8.When choosing the cross section of the power cable, which regulations should be followed?
Answer: The selection of power cables should follow the following principles:
(1) The rated voltage of the cable should be greater than or equal to the rated voltage of the power supply system at the installation point;
(2) The continuous allowable current of the cable should be equal to or greater than the maximum continuous current of the power supply load;
(3) The cross-section of the core must meet the requirements of stability of the power supply system when it is short-circuited;
(4) Check whether the voltage drop meets the requirements according to the cable length;
(5) The minimum short-circuit current at the end of the line should enable the protection device to operate reliably.

9. What are the advantages of XLPE cables and oil-paper cables?
Answer: (1) Easy to install, because it allows a small minimum bending radius and light weight;
(2) Not restricted by line drop;
(3) Good thermal performance, high allowable working temperature and large transmission capacity;
(4) The cable accessories are simple and all are dry structure;
(5) Simple operation and maintenance, no oil leakage problem;
(6) The price is lower;
(7) High reliability and low failure rate;
(8) There are few manufacturing procedures, simple process and remarkable economic benefits.

 

Stranded and twisted prefabricated branch cable

With the acceptance of prefabricated branch cables by the majority of users, a variety of prefabricated branch cables have entered the market under the situation of rapid increase in usage. This situation has brought a certain degree of selection to building electrical designers. difficult. The choice of stranded type, also called twisted type, branch cable is introduced below.

1. Defects of twisted type
The so-called twisted type and twisted type are multiple single-core power cables twisted together. For the core wires of power cables, the purpose of twisting multiple copper cable or aluminum wires is to increase the cross-section of the wires. Because they are all in the same phase and the same electromagnetic angle, there will be no problems with the distribution and change of capacitance and inductance due to any difference in electromagnetic phase angle. However, the influence of heat dissipation and the decrease of current-carrying value have also appeared. Therefore, the larger the cross-section, the lower the unit current intercept value. And it is still on the special equipment, according to the specified pitch and twisting force, the whole strip is finished at one time. This kind of twisting is consistent in terms of torque, pitch and uniformity, and there will be no change in pitch or uneven elasticity. The following only takes the round conductive core as an example, and the stranding rules are as follows:
(1). The center is generally a single wire, and the second layer has six single wires. In the future, each layer will increase by six more than the original number of the inner layer. The single wire adopts the same wire diameter;
(2). The stranding direction of each layer of single wires should be opposite to the previous layer, and generally the outermost layer is twisted to the left.
Stranded and twisted prefabricated branch cables, that is, multiple single-core power cables are twisted and used as three-phase three-wire, three-phase four-wire or three-phase five-wire power supply circuits. First of all, let’s start with “stranding”. This kind of “stranding”, whether in the production plant of prefabricated branch cables or the completion of the “stranding” process at the construction and installation site, is a special “stranding” equipment that has neither specialized , There is no corresponding pitch, strength, tightness, and uniformity regulations or requirements to follow. What is even more difficult to deal with is the branch cables and branch connectors of various sizes and locations with no rules, which are enough to determine the “multi-core cable” after the “stranding”, whether it is in terms of torque, pitch, density, The tightness, uniformity, and external dimensions will all be unknown. Therefore, it is determined that this “stranded” “multi-core cable” has become the most basic parameters and indicators in terms of the distribution of inductance and capacitance, and the electromagnetic theory of electromagnetic vibration, attraction and repulsion. The chaotic “Brownian motion”.

In the actual operation after construction and installation, first, the distribution, pitch, and tightness of inductance  and capacitance are chaotic, which will inevitably lead to chaos in the entire power supply circuit and some local heat dissipation and temperature rise. Even for several power cables without branches and without branch connectors, the power cables that are twisted under the conditions of strict control of their twisting strength, tightness, and pitch, are affected by heat dissipation and temperature rise. The actual allowable current carrying capacity cannot be compared with single-core power cables laid horizontally or vertically in accordance with the specifications.

Secondly, under the operating state of balanced or unbalanced current, when the load current, temperature, environment change or influence, the resistance between each cable and each cable itself in terms of absorption, repulsion, extension, contraction, up and down, etc. Irregularities in force and movement. This phenomenon is extremely detrimental to the stability and reliability of the entire power supply loop, and it may even cause damage to the sheath and insulation at the location where the cable is installed and tightened, which may cause an accident.

Thirdly, this kind of “twisted” power cables in a chaotic manner is really unsightly when placed in cable wells or cable channels. At the same time, it will also bring a defect in the design and construction of electrical system drawings, electrical system construction and engineering quality that fail to comply with the “horizontal, horizontal and vertical” regulations.

2. Relevant regulations in the electrical design code for civil buildings

2.1 Regulations for parallel laying of cables
When cables with the same voltage in the “Code for Electrical Design of Civil Buildings” promulgated and implemented by the Ministry of Construction in 1993, the net distance of the cable should not be less than 35 mm and should not be less than the outer diameter of the cable. It is stipulated in the article that when cables are laid side by side, a certain distance should be kept between cables to ensure the safe operation of the cables and the needs of maintenance and overhaul, so as to avoid the burning of adjacent cables when the cables fail. Reduce current carrying capacity, affect maintenance and cause mechanical damage. In addition, the distribution and influence of inductance and capacitance are also important reasons for increasing operating temperature and decreasing current carrying capacity. Obviously, “twisted type” and “twisted type” cannot meet the requirements of this article.

2.2 Regulations for cable selection
The electrical design code of civil buildings stipulates: “The power cable used in the three-phase four-wire system should be a four-core cable.” In the article description, it is stipulated in the three-phase four-wire system that an additional three-core cable is used. Conductor or single-core cable is used as the neutral line. When the three-phase system is unbalanced, it is equivalent to the operating state of single-core cable, which is easy to cause power frequency interference. For bare armored cables, it will also accelerate the corrosion of the metal sheath and armor layer, so four-core cables are required. “This article explains that although the distribution and change of inductance and capacitance are not clearly raised, it also indirectly pointed out their influence. It is not possible for a three-core power cable to be used as a neutral line, let alone four or five single cables. “Twisted” and “twisted” of core power cables? Obviously, “twisted” and “twisted” types cannot meet the requirements of this article.

2.3 Regulations for laying of power cables
The laying of power cables, whether indoor or outdoor, whether it is in the “Code for Electrical Design of Buildings”, “Code for Construction of Electrical Construction”, the “Codes” for the design and construction of various power systems, and whether it is the “Codes” of China or IEC standards, NEC “regulations”, Japanese standards, and standards of other countries all have a clear stipulation: whether it is installed vertically or horizontally, it must meet the requirements of “horizontal, horizontal and vertical” in order to ensure the acceptance of the project quality. Obviously, “twisted type” and “twisted type” can not meet the requirements of this regulation.

Throughout the development history of power cables, from the advent of single-core power cables to the present, we have fully realized in theoretical research and use practice: “twisting” and “twisting” four or five single-core power cables together , As a three-phase four-wire, three-phase five-wire system power supply circuit inside the building facilities, it is not advisable, nor feasible. my country has always followed the practice and regulations of parallel laying, which is based on its theory and practice. If in order to reduce or compress its laying and use space, just “twisting” or “twisting” can meet all requirements from theory to practice, then there is no need for multi-core power cables to come out. Throughout the domestic and international “standards”, “standards”, “regulations” and examples of outstanding well-known buildings, there are no regulations or allow four or five single-core power cables to be “twisted” or “twisted” as Precedents for the use of three-phase three-wire, three-phase four-wire, and three-phase five-wire power supply circuits. In irregular, small and sporadic construction facilities, use “twisted” or “twisted” multiple single-core power cables as three-phase three-wire, three-phase four-wire, three-phase five-wire power supply circuits exception.

In foreign power supply circuits embedded in the soil, it is allowed to use three single-core power cables twisted and embedded. Its purpose is: the twisted cable has a certain degree of flexibility, and it can play a certain buffering role when the cable is damaged or impacted by the local changes and land subsidence. But it must be twisted in strict accordance with the specified pitch and strength inside the factory, and no branches are allowed.

Single-core Parallel Type and Multi-core Twisted Type Cable

The advent of power cables has greatly improved the safety of power generation, transmission, transformation, supply, distribution, and use of electricity. Single-core power cables appeared first. As there are more and more occasions for three-phase four-wire power supply, three-phase five-wire power supply and multi-loop power supply in actual use, the requirements for occupied space and laying occasions are also getting higher and higher. When multiple and multi-layer laying are required, and the space occupied and laying conditions are limited, single-core power cables cannot be used conveniently. Therefore, multi-core power cables have been developed and quickly entered the field of power applications, and are accepted and used by the majority of users.

1.Busway
With the rapid growth of power cable usage, even if single-core power cables are used in actual use, the joints and branches shall be stripped and insulated on site, and the branches or joints shall be crimped before using epoxy resin insulation The method of material encapsulation treatment still has disadvantages such as large site occupation, long construction time, high cost, multiple equipment, high technical requirements, and high difficulty, especially the joints or branches after the completion of the on-site construction, and their insulation Strength, reliability, and consistency are difficult to guarantee. Therefore, the busway was developed, and after the development was put into the market, it was quickly accepted and used by a large number of users.
With the increase in user usage, it is found that the bus duct also has some defects, such as too many parts connected by * screws, complicated installation and construction, and large maintenance and high maintenance costs. In the process of operation, it often encounters the influence of electromagnetic vibration, thermal expansion and contraction, expansion coefficient, external force and other factors, which will cause the loosening of the screw. If a screw is loose, there will be heat and high temperature at the fault point, which will affect the stability of the entire bus duct. In particular, the improper use of the five-wire bus duct will also cause the contact resistance of the PE wire to increase. It violates the basic requirements for the continuity of the PE wire that is clearly stipulated in the building electrical design code and construction code. However, bus ducts still have their own advantages in the case of large capacity. Because when the current reaches thousands of amperes, if a cable is used, even a single-core cable must be laid in multiple, otherwise the corresponding large current capacity will not be reached, and the busway will show its own advantages at this time.

2. Prefabricated branch cable
With the development of technology and the increasing market demand, prefabricated branch cables have been developed and developed from single-core prefabricated branch cables to multi-core prefabricated branch cables, which also include flame-retardant, fire-resistant, and armored prefabricated branch cables. That is, in the factory, in accordance with the cable specifications, models, cross-sections and specific locations of the branches specified in the architectural design drawings, special production equipment and molds are used on the professional production line, which can be completed in one time. Its advantage lies in the high insulation strength, the encapsulated injection-molded branch joint connector and the outer insulating sheath of the cable are tightly bonded together, and it has excellent water tightness and air tightness. Because it is made of factory-specific equipment and molds, It has excellent reliability and consistency, and it is extremely convenient for users to install and use. When installing vertically, only the main cable can be evenly fastened to the corresponding bracket. In horizontal, pre-buried, overhead, tunnel, airport runway, port Construction and installation under environmental conditions such as docks, mines, and modern industrial plants are simpler and more convenient. The requirements for site, equipment, technical level of construction personnel, and costs during the installation and construction process are much lower than those for handling cable branches or cables at the construction site. Busway: It saves a lot of maintenance costs during operation and reduces the power outage time. In some cases, it can achieve the effect of maintenance-free. In the case of small cable shafts and cable channels, it can show its unique advantages. Therefore, branch cables are ideal products to replace bus ducts in medium and small capacity power supply occasions.

3. Stranded and twisted prefabricated branch cables
With the acceptance of prefabricated branch cables by the majority of users, a variety of prefabricated branch cables have entered the market under the situation of rapid increase in usage. This situation has brought a certain degree of selection to building electrical designers. difficult. The choice of stranded type, also called twisted type, branch cable is introduced below.

4. Multi-core prefabricated branch cable
The multi-core power cable is the core wire conductors are individually insulated, and are collectively and parallelly enclosed in the same outer sheath. Inside the outer sheath of the entire power cable, whether it is armored or unarmored, all power cable core wires that have been independently insulated and encapsulated are parallel and tightly encapsulated in the outer insulation. Set of interior. During the entire encapsulation process of the outer insulating sheath, no part or any power cable is allowed to “cross”, “displace”, or “twist” inside the sheath. Of course, “twisting” is not allowed. If any of the above phenomena occurs, the entire power cable will be judged as “unqualified” and not allowed to leave the factory. Therefore, the multi-core power cable itself is a qualified product that uses special production equipment in a professional production plant and strictly follows the relevant standards. Regardless of the distribution of inductance and capacitance and the basic requirement that the vector sum of any part is equal to zero, good consistency can be guaranteed. This cannot be achieved by any “stranded conductor type” or “twisted type”, and is a basic requirement that must be guaranteed on the power distribution circuit. Therefore, prefabricated multi-core branch cables made of qualified multi-core power cables can ensure that various technical parameters and basic requirements will not be destroyed, and can ensure the stability and reliability of operation. Of course, compared with single-core prefabricated branch cables, multi-core prefabricated branch cables are much more complicated and difficult regardless of the required technical level, the complexity of the manufacturing process, and the production equipment and investment.

Conclusion
In summary, the use of “twisted” or “twisted” prefabricated branch cables in the three-phase three-wire, three-phase four-wire, and three-phase five-wire power supply loops is used as the power supply loop to ensure the safety of its operation. And stability are extremely disadvantageous. The author also consulted related materials, regulations, specifications, standards such as IEC, NEC, etc., which clearly stipulated the distance between cables and cables when laying in parallel, and the correction coefficient of the current carrying capacity of cables at various distances. The author believes: This is also enough to explain the use of power cables. The series of processes from design to laying must fully consider the distribution of capacitance and inductance during operation, electromagnetic attraction, repulsion, vibration, etc.; the temperature rise during operation (capacitance And the distribution of inductance, electromagnetic attraction, repulsion, vibration, etc. are all part of the’temperature rise’) and heat dissipation environment and conditions. Therefore, only stipulating the different correction factors for the ampacity at different distances is sufficient to explain the nature and essence of the problem. What’s more, these are facts proved by theory and practice

Power Cable Fire Protection Technology

According to incomplete statistics, there have been more than 100 major accidents caused by cable fires spreading across the country in the past ten years, and more than 320,000 meters of cables have been burned. The restoration and reconstruction work is expensive and time-consuming, and the loss of power supply alone amounts to more than 100. 100 million yuan. The cable fire accident has its special hazards, that is, the failure of the control circuit causes the accident to expand and even damage the main equipment, and it is difficult to repair, and production cannot be resumed for a long time.

Power cables are an important part of the normal operation of power plants and substations. The widespread distribution of cables in power plants and substations, the flammability of cables, the serial ductility of cable fires, and the seriousness of the consequences of cable fires make the fire protection of cables highly valued by power departments, firefighting agencies and scientific research institutions. In view of the frequent occurrence of cable fire accidents, it is necessary to discuss the fire safety measures for cables.

1. Create a good operating environment to avoid accelerated aging and damage of cable insulation
Cable trenches and cable tunnels must have good drainage facilities, such as shallow drainage ditches and water collection wells, and can effectively hold water. If necessary, install automatic start and stop pumping devices to prevent water accumulation and keep the interior dry. The longitudinal drainage slope of cable trenches and tunnels should not be less than 1% to 2%, and should be at least greater than 0.5% to prevent water, corrosive gas or liquid, and flammable liquid or gas from entering. Cable trench, cable tunnel. The cable tunnel should be naturally ventilated, but when the normal load of the cable causes the air temperature in the tunnel to be higher than 40℃~50℃, a combination of natural exhaust and mechanical exhaust can be used for ventilation. The fan of the ventilation system should be interlocked with the fire detector to ensure that the air supply can be automatically stopped in the event of a fire in the tunnel. The cable tunnel shall not be used as the air inlet of the ventilation system.

 

Avoid placing the cable fire door in a normally closed state, using a fire barrier to completely seal the cable, and filling and sealing all gaps in the cable trench cover, which affect the ventilation and heat dissipation of the cable. Moreover, completely enclosing the cable also makes normal inspection of the cable impossible, and the cable failure cannot be found in time.

In addition, there must be complete facilities for preventing the intrusion of rats and snakes to prevent small animals from destroying the insulation cable and causing accidents.

2. Strengthen the preventive test of cables
The preventive test of cables should not only look at the qualified and unqualified test data, but also compare and analyze the data. It can be compared with the test data of the same cable or with the historical test data of this cable to explore the law of the test data. For example, when the DC withstand voltage test is performed, if the measured leakage current value rises faster with the increase of the test voltage value or the increase of the pressure time, or the value increases more than the same cable, or if the The measured data shows an obvious upward trend, or the leakage current imbalance coefficient between the three is relatively large, etc., which should be carefully analyzed. If it is not caused by improper test method, the test voltage can be appropriately increased or the test time can be extended to determine whether the cable meets the conditions for continued operation.

3. It is necessary to strengthen the management and operation monitoring of the production quality of cable heads
According to statistics, cable fire and explosion accidents caused by cable head failure account for about 70% of the total cable accidents. Therefore, it is necessary to strictly control the quality of the materials and workmanship of the cable head. It is required that the service life of the made cable head should not be less than the service life of the cable. The rated voltage level and insulation level of the connector shall not be lower than the rated voltage level and insulation level of the connected cable. The withstand voltage between the insulation pads on both sides of the insulation head shall not be less than 2 times the insulation level of the cable sheath. The form of the connector should be compatible with the environmental conditions set, and should not affect the flow capacity of the cable. Within the range of 2 to 3 meters on both sides of the cable head, fire-resistant tapes shall be used for fire-resisting and flame-retardant cable treatment.

Generally speaking, the cable head is the weak link of the cable insulation, so strengthening the monitoring and management of the cable head is an important part of cable fire protection. The terminal cable head must not be placed in the cable trench, cable tunnel, cable trough box, or cable interlayer. The intermediate cable heads placed in the cable trenches, cable tunnels, cable trough boxes, and cable interlayers must be registered and monitored using a variety of monitoring equipment. When the cable head is found to have abnormal temperature rise or smell or smoke, exit the operation as soon as possible to avoid the cable head from catching fire during operation.

There should be sufficient safety length between the middle cable heads. Two or more cable heads should not be placed in the same position. Tight sealing measures should be taken between the cable heads and other cables.

4. Prevent other equipment from catching fire and igniting the cable
Oil-filled electrical equipment, coal conveying, pulverizing systems, and steam engine oil systems can be ignited by cables. Corresponding measures must be taken for them; the cable trench cover near the oil-filled electrical equipment should be sealed to prevent the oil from flowing into the cable trench to ignite the cable when the equipment fails and catches fire. The dust accumulation on the electric blanket near the coal conveying and pulverizing system should be cleaned regularly to prevent the spontaneous combustion of the pulverized coal from igniting the cable. The cables facing the explosion-proof door of the pulverizing system must be packed in a fire-proof box to prevent the fire-proof door from igniting the cable. The cables under the head of the turbine should be packed in a fire-proof trough box.

5. Use measures such as sealing, blocking, coating, isolation, and wrapping to prevent the cable from spreading

Fire-retardant paint has the characteristics of thin coating, does not affect normal heat dissipation, and can play a good heat insulation and flame retardant effect, but it also has many defects.
Therefore, it is not advisable to apply a large number of fire-retardant coatings to the cable to be flame-retardant. Instead, a large number of methods of sealing, blocking and isolation should be used. When using sealing, blocking, and isolation methods, the following issues should be noted:

(1). Use the methods of sealing, blocking and separating to ensure that the fire of a single cable does not extend to multiple cables. Cables enter cable trenches, cable tunnels, and cable trough boxes; the nozzles of the cable interlayer should be tightly fireproofed to prevent a single cable or a small number of cables from igniting a large number of cables. A fire wall and fire door shall be installed every 60 to 100 meters in cable trenches and cable tunnels. Fire barriers shall be arranged in layers in the shafts. Fire barriers shall be arranged between power cables and control cables. The control cables shall be fully fireproofed. Flame-retardant cables are used to ensure that the main equipment can safely stop running in any emergency. Important cable channels should be equipped with automatic alarm and automatic fire extinguishing devices, such as water spray and water mist fire extinguishing devices, to achieve early detection and early fire fighting.

(2). The tightness and thickness of the fire-proof sealing must be guaranteed. If the fire-proof sealing is not tight, the sealing effect will be lost, especially where the cables are concentrated, it is best to use soft blocking materials to ensure tight sealing. During maintenance and inspection, the damaged blockage should be restored in time. The thickness of the blocking material is not enough, and the fire will pass through the blocking material and burn after the cable catches fire. The thickness of the plugging material should be proportional to the number of cables on the plugging surface, the more the number of cables, the thicker the plugging. The fire door should have a device that automatically closes after a fire occurs.

(3). The fire blocking layer must have sufficient mechanical strength. Because the cable catches fire, especially the electrical short circuit, it will cause the rapid expansion of the air to produce a certain impulse, destroy the fireproof sealing layer with low mechanical strength, and make the fireproof sealing useless.

Explore Future Trends of Fire Retardant Cable Market

In our lives, electrical fire accidents caused by short circuits and spontaneous combustion caused by the aging of cables frequently occur, and the losses caused are countless. With the continuous acceleration of domestic economic construction and the heating of urbanization speed, the number of various large-scale industrial facilities, high-rise commercial buildings, underground buildings and residential houses has suddenly increased. At the same time, it has also driven the large-scale cable use. This inevitably leads to another problem: the safety of the cable.

The fire-retardant and flame-retardant cable market continues to ferment. What is its future trend?
The use of high-performance, efficient and safe special power cable products has become the common voice of the entire society. This also makes people deeply aware that in addition to enhancing awareness of fire safety in daily life, strict standards for related types should also be formulated to vigorously promote various flame-retardant cable products.

Standardized products will gradually move towards standardization
Industry standards are an important cornerstone for the development of industries and enterprises, and product technical standards are an effective guarantee for determining product quality. With the development and maturity of China’s cabling industry, the national competent authority is also vigorously promoting the standardization process of the cabling industry. At present, the formulation of technical standards for fire-retardant and flame-retardant cable products has been included in the work plan for the next stage. We believe that with the joint efforts of the government, industry and enterprises, the production and quality assurance of fire-retardant and flame-retardant cable products will be standardized, and the technology and application of fire-retardant and flame-retardant cables will be more reliable and professional. The field of chemistry is advancing rapidly.

Up-and-coming leaders will occupy the mainstream market
After decades of development, China’s integrated wiring industry has formed a certain scale. Driven by global economic integration, leading companies among different products in the industry will inevitably emerge, and industry concentration will continue to rise. Only in this way can the entire industry form a common development concept and avoid low-quality and low-end unfair competition. At present, the domestic leader in the fire and flame retardant industry has begun to take shape. The domestic fire and flame retardant cable market has formed a number of mainstream companies. These companies have continued to extend their products and channels through continuous improvement in corporate management and team building. , Whether in terms of brand influence, overall improvement of product quality, and service standards, it has been increasingly accepted and affirmed by the industry and users. Therefore, the trend of leading companies to occupy the mainstream market will be unstoppable.

Pay attention to service and enhance the safety awareness of the whole people
Cable products bear important data, images and other information transmission tasks in buildings and engineering safety systems. Because users or engineering companies do not pay enough attention to the purchase of cable products, especially fire-resistant and flame-retardant cable products, problems often endanger life and property safety. These painful lessons have made more and more users and engineering companies pay attention to the selection and correct use of cable types, and gradually changed the idea that the price dominates the purchase of wiring and cable products in engineering use. The important role of fire-retardant and flame-retardant cables in engineering use is becoming more and more recognized by everyone. In the future, the fire-retardant and flame-retardant cable manufacturing enterprises will not only provide products in a simple sense at this stage, but will also strengthen the service concept while continuously extending the product chain, providing users with a full line of compatible products, and ensuring that the products are correct. Reasonable use provides a full range of technical support and services, which will surely become the market development trend of the fire-retardant cable wiring industry.

Go abroad to build an international brand
“Being the world’s cable manufacturer and building an international national brand in China’s cabling industry” has become the development goal and corporate mission of outstanding companies in the industry. Under the guidance of this belief, China’s cable products have been widely penetrated into multiple fields in various industries. Fire-retardant and flame-retardant cables have also been increasing with everyone’s attention to safety and the demand for international trends. International cooperation between enterprises and enterprises in advanced developed countries has been carried out in all directions. At present, several of the strongest domestic cable companies have also followed the international trend of market development and extensively promoted special cables such as fireproof and flame retardant. And invested a large amount of funds for independent research and development. A few years ago, it has begun to formulate and launch a global development strategy. Through extensive cooperation and exchanges in technology, capital, management, etc., the introduction of advanced technology and management concepts from foreign companies has made the company Strength has been rapidly improved and developed. And actively go abroad, seek international markets, increase product exports, and now a large number of fire-retardant cable products are exported to all parts of the world.

With the rapid development of China’s wire and cable industry, people’s safety requirements have increased, and awareness of fire and flame retardant has continued to increase, which has greatly improved the overall technical level of the flame retardant cable industry. Many wiring companies and governments continue to promote and promote fire-retardant cables, which have contributed to our further understanding of the application and technology of flame-retardant cables. The problem of cable fire-retardant and flame retardant will undoubtedly receive more and more attention. Flame-retardant cables will also get more applications in actual projects, bringing opportunities for information security and personal safety in data centers. The cable selection of the majority of users when wiring is related to the fast, convenient and safe future data transmission, and it also provides a strong guarantee for the safety of life and property.

At the same time, only high quality can be recognized by customers to a higher degree. High quality and good reputation are the true value of the brand and the foundation for the survival of brand enterprises. The rise of fire-resistant and flame-retardant cables in China is not an unrealistic fantasy, but the call of the integrated wiring market.

General Rubber Plastic Wire Structural Characteristics

Requirements of General rubber plastic wire:
1. Scope of application: connection and internal installation of power, lighting, electrical equipment, instrumentation and telecommunication equipment with AC rated voltage of 450/750V low voltage cable and below.
2. Laying occasions and methods: indoor open laying and communication channels, along the wall or overhead laying in tunnels; outdoor overhead laying, laying through iron pipes or plastic pipes, electrical equipment, meters and radio installations, all fixed laying; plastic The sheathed wire can be directly buried in the soil.
3. General requirements: economical and durable, simple structure.
4. Special requirements:
1) When laying outdoors, due to the influence of sunlight, rain and freezing conditions, it is required to be resistant to the atmosphere, especially sunlight aging; cold resistance requirements are required in severe cold areas;

2) In use, it is easy to be damaged by external force or flammable, and it should be worn in the occasions where it is in contact with oil. When the pipe is worn, the wire is subject to greater tension and may be scratched, so lubrication measures should be taken;
3) When used internally for electrical equipment, when the installation location is small, it should have a certain degree of flexibility, and require clear color separation of the insulated wire core, and should be matched with the corresponding connector terminals and plugs to make the connection convenient and reliable; for occasions with electromagnetic protection requirements , Shielded wires should be used;

4) For high ambient temperature occasions, sheathed cables should be used; for special high temperature occasions, heat-resistant cables should be used.

Structural features
1. Conductive core: when used for internal installation of power, lighting and electrical equipment, copper core is preferred. For large cross-section wires, it is better to use compact core; bare conductors for fixed installation generally adopt category 1 or category 2 conductor structure .
2. Insulation: Insulation materials generally use natural styrene-butadiene rubber, polyvinyl chloride (PVC) cable, polyethylene, and nitrile polyvinyl chloride compound; heat-resistant wires use polyvinyl chloride with a temperature resistance of 90°C.
3. Sheath: There are generally five types of sheath materials: polyvinyl chloride, cold-resistant polyvinyl chloride, anti-termite polyvinyl chloride, black polyethylene, and neoprene rubber.


Especially cold-resistant and outdoor overhead laying should use black polyethylene and neoprene sheathed wires.
In environments with external forces, corrosion, humidity, etc., rubber or plastic sheathed wires can be used.

Environmental cables will become the global cable development trend?

In the new century, the importance of the ecological environment has become increasingly prominent, and environmental protection has gradually become the focus of attention and the mainstream of international development. Countries, organizations, companies and individuals all over the world are actively seeking environmental protection methods, and the laws and regulations that are compatible with them are becoming more complete and specific. Wires and cables are special commodities related to people’s life safety and the normal operation of almost all industries. In the face of people’s growing concern about the living environment and living environment, the market prospects of environmentally friendly cables are also increasingly promising, and gradually become the development trend of global power cables .The development potential cannot be underestimated.

Environmentally friendly cables refer to no heavy metals such as lead, cadmium, hexavalent chromium, mercury, etc., and no bromine-based flame retardants. They have been tested by SGS recognized testing organizations for environmental performance, and comply with the European Union Environmental Protection Directive (RoSH) and exceed its index requirements . It does not produce harmful halogen gas, does not produce corrosive gas, generates less fever when burned, and does not pollute the soil.

 

With the formulation of the European Union’s environmental protection directives, Europe, the United States, Japan and other countries have increasingly higher environmental protection requirements for the cables used. They have banned the use or import of non-environmental-friendly cables. The international market’s demand for environmentally-friendly cables is advancing with each passing day. With the maturity of environmentally-friendly cable production technology, the research and development and large-scale adoption of eco-friendly wires and cables has become an international trend.

Although the pace of China’s environmental protection cables lags behind foreign countries, it still conforms to the green trend and is constantly developing and improving the environmental protection cable market. The development and production of domestic environmental protection cables have also attracted attention from all parties. At the annual meeting of the national wire and cable industry, a green environmental protection — sustainable development strategy was formally proposed. It also clearly stipulates that “civil buildings with a height of more than 100 meters must use low-smoke, halogen-free, Class A flame-retardant wires and cables. High-rise buildings with a height of more than 100 meters and civil buildings less than 100 meters, such as a certain scale Hospitals, public entertainment venues, underground shopping malls, libraries, stations, supermarkets, terminal buildings, office buildings…, at least smoke-free, low-halogen and flame-retardant cables should be used.” One of the key projects of Zhejiang Province’s block industry standardization in 2012 ——The successful acceptance of the environmental protection wire and cable alliance standard marks a big step forward in the formulation of environmental protection standards in China.

It can be seen that the ecological environment-friendly cable market has a very broad prospect, which will undoubtedly bring new space and opportunities to the sustainable development of the wire and cable industry.

In many places in key projects, low-smoke and halogen-free wires and cables are used in places such as fire fighting, monitoring, and alarms. People usually call them environmentally friendly cables. In fact, environmentally friendly cables do not refer to low-smoke, halogen-free wires and cables. It is a cable produced in accordance with the Japanese FN cable manufacturing standard.

With the global promotion and spread of the concept of green environmental protection, the concept of environmental protection is gradually permeating all walks of life, and with the gradual use of environmentally friendly products and gaining popularity, the wire and cable industry has also begun to attach importance to the development and promotion of environmentally friendly cables. Our country also attaches great importance to this field, and relevant laws and regulations expressly require that in the construction of major projects, the use of non-environmental protection cables is strictly prohibited.

So what is an environmentally friendly cable, and what are its characteristics?

1. High flame Retardancy: The environmental protection cable can fully guarantee its high building requirements for fire protection. In the event of a fire, the environmental protection cable can not only be difficult to burn, but also prevent the spread of flames and the expansion of disasters after burning.

2. Halogen-free: The use of green environmental protection insulation layer, sheath an special oxygen barrier materials not only make the environmental protection cable have good electrical and physical and mechanical properties, but also ensure that the product is halogen-free and solve the problem of burning “Secondary pollution” avoids carcinogenic “dioxin” substances produced when traditional PVC cables burn.

3.metals harmful to the human body. When the environmental protection cable is used and disposed of, it will not pollute the soil and water sources. And after harsh toxicity experiments, the white rats were safe and sound under the specified experimental conditions.3. Low toxin: The insulation and sheath of cable do not contain lead, cadmium and other heavy

4. No corrosive gas: new special coating materials that do not pollute the environment are used, so that environmentally friendly cables will not produce toxic gases such as HCL during production, use and combustion, and emit very little acid gas, which is harmful to personnel, equipment and instruments. Less damage and more environmentally friendly features.

5. High light transmittance: The smoke produced when the environmental protection cable burns is extremely thin, which is conducive to the evacuation of personnel and the conduct of firefighting. Generally speaking, the light transmittance of environmentally friendly cable products is greater than 40%, which is far higher than the standard of less than 20% for traditional flame-retardant cables and cables.

6. High protection against ultraviolet rays or water: This performance can make the environmental protection cable less likely to be weathered during use, slow down the aging speed of the environmental protection cable to a certain extent, and extend its service life.

In general, environmentally friendly cables are a major trend. In recent years, the sales share of environmentally friendly cable products has increased dramatically. Because environmentally friendly cables have the characteristics of non-toxic and non-polluting to people and the environment, high safety and reliability, and long service life, they are expected to become the mainstream of the future cable market.

Heating reason of power cable in operation

When the power cable passes through a certain load current, it will be heated. With the increase of the load current, the cable surface temperature will be higher. If it is not handled in time, the consequences can be imagined. For example: PVC cable, the core temperature of 70 degrees is considered as the upper limit, and the surface temperature will be 5-10 degrees lower. Therefore, the cable surface temperature below 60 ℃ is basically safe. Considering the power supply maintenance, of course, the lower the temperature, the better.

The heating reasons of power cable in operation are as follows:

1. Cable conductor resistance does not meet the requirements, resulting in cable heating in operation.

2. Improper selection of cable leads to too small conductor cross-section of the cable used and overload phenomenon in operation. After long-term use, the imbalance of heating and heat dissipation of the cable causes heating phenomenon.

3. If it is too close to the cable, it may cause heat dissipation when the cable is too close to the cable.

4. Poor joint manufacturing technology and loose crimping will lead to excessive contact resistance at the joint and also lead to cable heating.

 

5. The insulation performance of cable phase to phase is not good, resulting in low insulation resistance and heating phenomenon during operation.

6. The partial sheath damage of armored cable will cause slow damage to the insulation performance after water inflow, resulting in the gradual decrease of insulation resistance, and also the heating phenomenon during the operation of the cable.

If the cause is not found out and the fault is eliminated in time, the insulation thermal breakdown will occur after the power cable is continuously energized. This will lead to phase to phase short-circuit tripping of cables, which may cause fire in serious cases.

Treatment method of PVC power cable affected by damp

Cables, especially PVC insulated power cables, have been widely used in urban power grid reconstruction projects. However, due to the particularity of the cable, the installation, operation and maintenance of the cable have special requirements. Cable insulation resistance is reduced by damp or water intrusion, which is an important aspect of cable line operation accidents.

Cause and harm of cable damp and water inflow

PVC power cable affected by damp  (1) When the new cable is delivered from the factory, both ends of the cable are sealed with plastic sealing sleeve. However, after a section of cable is used at the construction site according to the actual situation, the remaining part is simply wrapped with plastic cloth. As it is usually placed in the open air and the sealing is not good, water vapor will inevitably seep into the cable after a long time.

(2) During power cable laying, it is necessary to often cross roads, bridges and culverts. Due to weather or other reasons, a lot of water is accumulated in the cable trench. During the laying process, it is inevitable that the cable head will be immersed in the water, and the water will enter the cable due to loose wrapping or damage of plastic cloth. In addition, the outer sheath and even steel armor will sometimes occur during traction and pipe threading Scrape phenomenon, when using mechanical traction, this phenomenon is particularly prominent.

(3) After the completion of cable laying, due to the limitation of site construction conditions, the cable head can not be made in time, so that the cable fracture without sealing treatment is exposed to the air for a long time, even immersed in water, so that a large amount of water vapor enters the cable.

(4) During the manufacturing process of cable head (including terminal head and intermediate joint), due to the negligence of construction personnel, the newly treated cable end sometimes falls into the water on site.

(5) In the normal operation of the cable, if the breakdown and other faults occur for some reason, the water in the cable trench will enter the cable along the fault point; in the civil construction, especially in the construction site using large construction machinery, the cable damage or breakdown accidents caused by various human factors are also common. When this kind of accident occurs, the cable insulation will be seriously damaged, which will also cause cable water intrusion.

 

After the cable enters water, the aging phenomenon will occur under the action of electric field, which will eventually lead to cable breakdown.

Five aspects of high temperature wire and cable exit

At present, many domestic high-temperature wire and cable enterprises have entered the foreign market, but compared with foreign domestic products, the competitiveness of China’s high-temperature wire and cable products needs to be improved, especially some enterprises act rashly without understanding the foreign industry standards, which leads to an embarrassing situation for the development of enterprises. As a well-known brand in the high-temperature wire and cable industry, Chuncao has made certain achievements in the foreign market. Here are five aspects to be noted in the export of high-temperature wire and cable.

1、 Technical standards: advanced standards such as IEC or British standard, American Standard and other advanced standards are generally required for foreign high-temperature wires and cables. Therefore, it is not enough to be familiar with domestic standards, but also familiar with international standards.

2、 Laying conditions: the environmental conditions in West Asia, Southeast Asia and other regions are relatively special, such as the extreme maximum temperature of 50 ℃ and the maximum daily average temperature of 40 ℃. Therefore, the description of technical parameters related to the environment (such as the correction coefficient of current carrying capacity) should be paid attention to in the technical data.

3、 High temperature wire and cable structure: due to the high temperature wire and cable laying environment, the high temperature wire structure should not only meet the standard requirements, but also have some additional requirements. Therefore, enterprises should pay attention to it in the design and manufacturing process of high-temperature wires and cables.

4、 Packaging of high-temperature wire and cable: for export high-temperature wire and cable, the delivery tray generally adopts large plate or steel plate structure, and is fully enclosed with sheet iron or wood. In addition to the length and minimum allowable bending radius of the high temperature line, the size of the container should also be considered. Strictly follow the order requirements. As the packaging of export high-temperature line is more complicated than that in China, it will affect the cost and delivery time of high-temperature line. Therefore, attention should be paid when signing the contract.

5、 Other precautions: before delivery, the main technical parameters, sectional drawings, laying instructions and other data of high-temperature wires and cables shall be provided to users, and the test reports shall also be delivered with the goods. The technical data shall be complete; the manufacturing length of high-temperature wires and cables shall be strictly controlled, and the error of delivery length shall be minimized. All export products must pass the inspection of the State commodity inspection department and issue the commodity inspection certificate.

With the accelerated process of world economic integration, the market competition of domestic high-temperature wire and cable enterprises will not be limited to the domestic market, and the foreign market is the greater stage. It is hoped that domestic enterprises can carefully consider the above five points before entering the foreign market, and make the most suitable development plan according to their own conditions.