Burning test for ACSR Conductor production

There are two key links in the wire and cable manufacturing industry, namely theAluminum conductors steel-reinforced production link and the wire and cable testing link, especially the wire and cable testing link. This is the last stop for quality control and a comprehensive assessment of the performance of wires and cables.
The burning test of the cable is an extremely important one of its many tests. The national cable performance classification has special grade requirements for it, such as the number GB/T31248-2014. This standard divides the burning of the cable into 4 grades, A Class (non-flammable cable or optical cable, equivalent to metal sheathed cable or optical cable), Class B1 (flame-retardant B1 cable or optical cable, equivalent to halogen-free low-smoke flame-retardant cable or optical cable), Class B2 (flame-retardant B2 cable or Optical cable, equivalent to low-halogen, low-smoke flame-retardant cable or optical cable) and Class B3 (ordinary cable or optical cable).

Especially for fire-resistant and flame-retardant special cables, the burning test is a very important test for their professional performance. These fire-resistant and flame-retardant cables are required to have certain flame-retardant properties, and they must also have a certain flame-retardant performance. The characteristics of normal operation for a certain period of time, so the burning test is also a test of the performance of this type of cable.
In addition, there are a number of data for various combustion conditions. The values ​​need to be tested. For example, the heat release rate of the cable is the heat energy released by the combustion of the cable within a certain period of time under the specified conditions. This value is the normal combustion of the cable. Detect the data, and the value of the data will be affected by many factors, such as the combustion state, and the amount of non-metallic materials.

There is also an average heat release rate, which refers to the average heat release rate within 30 seconds. The average heat release rate during the combustion process is also a value that changes with the continuation of the combustion time. The peak heat release rate is the maximum value of the average heat release rate during the entire combustion period. The standard stipulates that the combustion time is 1200 seconds, which is the maximum value among the 40 average heat release rates. This value is related to the combustion state of Aerial Bundled Cable during combustion. If the flame is particularly large in a certain period of time within 1200 seconds, the peak heat release rate may not meet the requirements. The total amount of heat release refers to the integral value of the heat release rate within a specified time.
The various test data of the cable in the flame combustion can reflect the performance and influence of the cable in the flame, and can fully reflect whether the cable is qualified and up to the standard, and whether the fire performance of the fire-resistant cable meets the requirements, these are extremely important Therefore, the burning test is also one of the routine tests of wire and cable manufacturers.

Factors Affecting Cable Performance and Placement in Wiring

Factors affecting Aerial Bundled Cable (ABC) SANS 1418 Standard and placement in the wiring six factors affecting cable performance:

  • Ultraviolet (UV)– Do not use cables without UV protection in direct sunlight.
  • Heat — The temperature of the cable in the metal tube or groove is very high, and many polymeric materials will degrade their service life at this temperature.
  • Water — moisture in a twisted-pair cable on a LAN can increase the capacitance of the cable, thereby reducing the impedance and causing near-end crosstalk problems.
  • Mechanical damage (repair cost)– Cable repair is very expensive and requires at least two terminations at each break point.
  • Grounding — If the shielding of the cable needs to be grounded, the appropriate standards must be complied with.
  • Total length of routing (not just between buildings)– Outdoor LAN twisted pair cables are used between buildings and the total length is limited to 90 meters. For 100Mbps or 1000Mbps networks, the paved distance cannot exceed this limit. If the laying distance is between 100 meters and 300 meters, optical cable should be chosen.

Is the cable placed in:

1.Under the eaves. 4/0 Aluminum Cable can only be used when they are not directly exposed to sunlight or ultra-high temperatures. Standard LAN cables are recommended.

  1. Exterior wall. Avoid direct sunlight exposure to the wall and man-made damage.
  2. In pipes (plastic or metal).If in pipes, pay attention to the damage of plastic pipes and the heat conduction of metal pipes.
  3. Hanging applications/overhead cables. Consider cable sag and pressure. What kind of binding do you plan to use? Whether the cable is exposed to direct sunlight.

  1. It is directly laid in the underground cable trench, which is the least controlled environment. The installation of cable trench should be checked regularly for dryness or humidity.
  2. Underground pipes. In order to facilitate future upgrades, cable replacement and isolation from surface pressure and surrounding environment, auxiliary pipe isolation, auxiliary pipe is a better method. But don’t expect the pipes to stay dry forever, which will affect the type of cable you choose.

Plastic Extrusion and Traction Speed of Cable Technology

The rate of plastic extrusion

According to the flow rate analysis of the viscous fluid in the material conveying and homogenizing section of the ABC conductor,  the flow rate of the plastic (that is, the extrusion speed) is proportional to the screw speed, and the screw speed is an important operating variable to characterize the extrusion speed in the extrusion process because of the convenience of adjustment. Therefore, in general, increasing the screw speed is an important means to improve the production capacity of modern plastic extruder and realize high-speed extrusion. But the analysis of the plastic melting length shows that the increase of the screw speed, on the one hand, increases the viscous dissipation heat due to the enhanced shear effect; On the other hand, in the absence of head pressure control, the screw speed increases, the flow rate increases, and the material stays in the machine time is shortened. Moreover, the influence of the latter is more than that of the former, and the normal extrusion process will be destroyed due to the extension of the melt length to the homogenizing section. Therefore, it is necessary to increase the screw speed to improve the extrusion speed, but also to increase the heating temperature or use the control of the head pressure to achieve the purpose.

Plastic extrusion speed or the quality of plasticizing is related to the use of plastic material and temperature control, the plasticizing temperature of various plastics is different. If you want to quickly extrude plastic, only the material is good, the temperature is appropriate, to achieve. In addition, the extrusion speed is closely related to the extrusion thickness. In the normal extrusion process, the amount of glue is large and the extrusion speed is slow. On the contrary, the extrusion speed is fast, on the premise of ensuring the quality, the extrusion speed can be appropriately improved.

Traction speed

Extruded products are dragged through the machine head by traction device, in order to ensure the quality of products, the traction speed is required to be uniform and stable, in coordination with the screw speed, to ensure the uniformity of extrusion thickness and outer diameter of products. If the traction speed is not stable, the extrusion layer is easy to form bamboo joints, and the extrusion thickness is large when the traction speed is too slow, and the phenomenon of glue stacking or empty pipe occurs. When the traction speed is too fast, it is easy to cause extruding and thinning, or even the phenomenon of degumming and leakage. Therefore, in the normal extrusion process, we must control the traction speed.

Cable Knowledge: Classification, Use and Function of Armoured Cables

ABC cable is made of conductors of different materials mounted in insulated metal bushing, which is processed into a flexible and solid assembly.Armoured cable is generally fixed power cable, generally speaking, is fixed in a place and basically do not move, power line transmission of electric energy.The armoured cable includes armoured thermocouple, armoured thermal resistor, armoured heater and armoured lead, which are mainly used for temperature measurement, signal transmission and special heating in chemical industry, metallurgy, machinery manufacturing, power generation and scientific experiments. The largest amount of armoured thermocouple is used.

Classification of Armoured Cables

Armoring is classified into steel tape armoring (22,23), fine steel wire armoring (32,33) and coarse steel wire armoring (42,43).

Steel tape armoured cable models are VV22, VVP22, ZRVV22, NH-VV2;

Control cable steel tape armoured cable, models are KVV22, KVVP2, KVVP22, ZR-KVV22

Steel wire armoured power cable, model VV32, YJV32, ZR-VV32

Steel wire armoured control cable Cable model KVV32 KVVP32

Armored communication cable models: HYA53, HYAT53, HYA23, HYV22, HYA22(rat proof, buried)


 Model Meaning of Armoured Cable

In order to enable the cable to withstand the radial pressure, double steel tape and gap wrapping technology is adopted, which is called steel tape armoured cable.After the cable is finished, the steel strip is wrapped around the cable core and the plastic sheath is extruded. This type of cable is expressed as control cable KVV22, plastic cable VV22, communication cable SYV22, etc.The two Arabic numerals in the subscript of the cable type, the first one: “2” means double steel tape armoured;The second: “2” represents the PVC sheath, such as the use of polyethylene sheath to change the “2” to “3”. This type of cable is generally used in the bearing pressure is relatively large occasions.For example: through the highway, square and vibration of the highway, railway side, etc., suitable for buried, tunnel and pipeline laying. In order to make the cable able to bear large axial tension, the cable is wrapped with several low carbon steel wires, which is called steel wire armored cable.After the cable is finished, the steel wire is wrapped on the core wire according to the necessary pitch and then the sheath is extruded. The representation method of this cable type is such as control cable KVV32, plastic cable VV32, coaxial cable HOL33, etc. Two Arabic numerals in the model, the first one: “3” represents fine steel wire armor;Second: “2” for PVC sheath, “3” for polyethylene sheath.This type of cable is generally used in large span, laying the occasion of large drop.

Application of Armored Cable

Armour cable mechanical protection layer can be added to any structure of the cable, to increase the mechanical strength of the cable, improve the ability of corrosion resistance, is designed for the vulnerable to mechanical damage and erosion of the area.It can be laid in any way, and it is more suitable for direct buried laying in rock areas. Armoured cable is generally fixed power cable, generally speaking, is fixed in a place and basically do not move, power line transmission of electric energy. In addition to the above purposes, the cable with armoured layer can also enhance the tensile strength, compressive strength and other mechanical protection to extend the service life. Armour has a certain resistance to external force, but also can be wary of rat bite, not through the armor caused by power transmission problems, the bending radius of the armor should be large, the armor layer can be grounded, protect the cable. Foreign armoured cable production is mainly concentrated in several more developed countries, such as the United States, Britain, Japan, Germany, Russia, Southeast Asia has no manufacturers, but as long as there are chemical, metallurgy, machinery manufacturing, power generation and other industries where there is temperature measurement, the need for armoured cable.

The Role of Armoured Cable

Armoured cable refers to the cable with metal armored protective layer. The purpose of the cable with armored layer is not only to enhance the tensile strength, compressive strength and other mechanical protection to extend the service life, but also to improve the anti-interference performance of the cable through shielding protection. The commonly used armoring materials include steel strip, steel wire, aluminum strip and aluminum tube, among which the steel strip and steel wire armoring layer has high magnetic permeability and good magnetic shielding effect, and can be used to resist low frequency interference, and can make the armored cable buried directly without penetrating the pipe, and is cheap and fine, so it is widely used in practice.

What should I pay attention to when buying Aerial Bundled Cable?

As the main carrier of power transmission,Aerial Bundled Cable  HD 626 S1 Standard is widely used in electrical equipment, lighting circuits, household appliances, etc. Its quality directly affects the quality of the project and the safety of consumers’ lives and properties. There are many types of wires in the market, and you must use the appropriate wires according to your own electricity load.
Some of the wires sold in the market are cheaper and some are more expensive, and some people tend to be cheaper first. However, cheap wires often have a lot of performance that does not meet the performance described by him, and they may bring themselves Many security risks. The production technology of the wire is not too high, and the raw materials are not too different. If it is too cheap, either it is cutting corners or the quantity is not enough. How to identify it. Let me tell you several methods that are easier to identify:

  • Take a look at the packaging. National standard wires are often made better, neat, and have a sense of quality when held in hand.
  • Open the package and take a look at the wires inside. The wire thickness (insulation thickness) of the national standard wire of 1.5-6 square meters is 0.7mm. If it is too thick, it is non-standard, and its inner core is definitely not enough. , You can pull the thread hard, the ones that are not easy to tear are generally the national standard.
  • Burn it with fire, the ones that are extinguished within 5s after leaving, and those with certain flame-retardant function are (ABC) ASTM B230 Standard .Look at the inner core, the higher the brightness of the inner core material (copper), the better the copper, and the brightness is uniform, shiny, and without layering. The national standard requires oxygen-free copper to be used in the core. Non-standard, such as black rod copper, may have potential accidents.
  • The thickness of the acsr core has certain national requirements, but it is not very strict. But you can’t go wrong a lot, it’s just a small error, which is generally invisible to the eye.
    The length, the country does not mandate that the rice must be beaten, but many manufacturers have also beaten the rice, and the rice that is beaten is not necessarily the national standard, but the general national standard generally does not. Non-standard rice harvesting is just a means.
  • The country stipulates that there must be a certain mark on the wire, and the maximum size will not exceed 500mm, and the next same mark will be printed. Generally, there are product trademarks, manufacturer names, and implementation standards.

cable common sense question

1. What are the requirements for fire blocking of cable holes?

Answer: For larger cable penetration holes, such as the cable penetration floor, when using fireproof blocking materials to block, according to the actual situation, first apply four to six layers of fireproof paint on the cable surface, the length is about 1.5m below the hole, and then Refractory materials are processed into a board-supporting fire-proof blocking material with a certain strength to ensure that the blocking is firm and easy to disassemble when the aerial bundled cable 7870 standard  is replaced. The blocking is dense and non-porous to effectively block the smoke and the fire.


2. What checks should be paid attention to before the torch is ignited?

Answer: The following inspections should be carried out:

(1) Whether the pump is leaking or leaking, whether the oil barrel and nozzle are leaking or leaking;

(2) Whether the amount of oil in the oil drum exceeds ¾ of the capacity of the oil drum, and whether the screw plug for refueling is tightened.

3. What should be paid attention to when using blowtorch?

Answer: (1) The maximum fuel injection volume of the blowtorch is ¾ of the volume of the fuel tank;

(2) The pressure should not be too high at the beginning, the flame can be used after being ignited from yellow to blue;

(3) There should be no combustibles around, and the air should circulate;

(4) Turn off the adjustment switch when it is out of service. After the fire is extinguished, slowly loosen the oil hole cover to release air. After the air is exhausted, loosen the adjustment switch, and then loosen the hole cover after it is completely cooled;

(5) Kerosene blowtorch and gasoline blowtorch should be used separately.

4. What is the purpose of manual hydraulic pliers? How to do it?

Answer: The connection of two wires is usually by inserting the two wire ends into a crimping tube made of the same material, squeezing several pits with crimping pliers to connect the wires together. When crimping, when the handle is lifted up, The plunger moves outwards, a vacuum is generated in the lower cavity of the oil inlet valve, and the oil in the oil tank enters the plunger cavity. When the handle is pressed down, the plunger moves inward. After the oil is pressurized, the oil inlet valve is closed and the oil outlet valve is opened, so that the oil pressure enters the hydraulic cylinder, pushing the piston and the male mold, and there is a crimping pipe between the male and female molds. When the depth of the crimped pit reaches a certain value, the oil return valve is opened and the piston automatically returns. After pressing one pit, move the pressing tongs and press the next one.

5. According to the difference of insulation and protective layer, what are the main types of commonly used low-voltage power cables?

Answer: (1) Oil-impregnated paper insulated lead-clad (or aluminum-clad) power cable;

(2) Non-drip oil-impregnated paper insulated power cable;

(3) PVC insulated and sheathed power cables;

(4) Cross-linked PVC insulated and PE sheathed power cable;

(5) Cross-linked PVC insulated and sheathed power cable;

(6) Rubber insulated power cables.

The first 525 kV DC cable pre-qualification test is officially launched

On February 26, the first domestic pre-qualification test of 525 kV DC cables was officially launched. The test mainly detects the long-term performance of domestic 525 kV DC cables, and provides important technical support for Chinese cable companies to take the initiative in international competition.
It is understood that the Dutch government plans to develop a 6.1 gigawatt wind farm by 2030. In the face of the connection of large-capacity, long-distance offshore power grids and onshore power grids, 525 kV DC cables will be the most economical transmission method. The State Power Supplier invited 8 cable manufacturers from around the world to participate in the research and development of 525 kV DC sea and land cable systems. Entrusted by domestic cable companies, Zhejiang Zhoushan Power Supply Company Marine Transmission Engineering Technology Laboratory officially launched the pre-qualification test of 525 kV DC cables.

According to the test schedule, the laboratory has completed mechanical pretreatment tests, full-scale space charge detection, and DC withstand voltage test and other test items, and will carry out a long-term voltage test of 8760 hours and a DC superimposed impulse voltage test in the future.
This test carried out tests on both the submarine cable system and the Aerial Bundled Cable (ABC) BS 7870 Standard system samples, and fully applied the scientific research results of the national key research and development plan project “±500 kV DC cable system test and operation and maintenance technology”. The space charge measurement and evaluation technology under the simulated operating conditions of the high-voltage DC cable, the leakage current under the pre-qualification test of the DC cable and the distributed optical fiber temperature monitoring technology are integrated into the test system to ensure the scientific accuracy of the test.

The smooth advancement of the 525 kV DC cable system pre-qualification test will significantly enhance the international influence of the State Grid Corporation of Compete and win a broader overseas market.

Misunderstandings in the process of wire installation meeting (2)

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

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

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

Home circuit safety

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

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

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

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


Cable maintenance tips

Everyone knows that everything will deteriorate after being used for a long time, and the same goes for wires. WhenAerial Bundled Cable (ABC) HD 626 S1 Standard is aging for household or commercial use, it is easy to cause danger if it continues to be used, and timely inspection can eliminate potential safety hazards. But how to detect wire aging in time requires some tricks.
The wire is mainly insulated by the outer layer of sheath. After a long time, it will be corroded by corrosive gas, and the insulation performance will gradually decrease. It will gradually age and become hard, become brittle or fall off, and then it will not be insulated. In fact, the direct cause of the aging failure of the wire and cable is the breakdown of the insulation due to the degradation.
1. “Check the appearance along the wire, darkening and hard cracks are seen. Bending the wire with both hands for insulation, stiff and cracked skin.” It means to observe the insulation layer along the wire. If the color of the insulation layer is found to be tarnished, darkened, or changed Hard, cracked, and partially peeled off.

When the insulated conductor is bent with both hands, the wire is stiff, even the insulation layer is cracked, the insulation layer falls off, etc., which shows that the wire has experienced different degrees of aging and severe aging.
2. “Accurate method to measure insulation, megohm is not low. The humidity value in rainy days can be small, and the value can be less than half.” It means that the insulation resistance meter can be used to measure the insulation of electrical circuits to determine the insulation status of the circuit more accurately.

3. If the wires cannot be replaced in time, you can also choose to use good internal materials to reduce hidden dangers. Once the insulation of the sheath of the wire casing is damaged, the possibility of fire will increase. The length of time for causing a disaster has a lot to do with the quality of the oxygen barrier. The newly produced diamond mud ceramic silica gel with silicone rubber as the base material by Shanghai Tengruina Chemical Technology Co., Ltd. has good high temperature resistance, fire resistance and fire resistance. The effective prevention and control of fire sources is to prevent fires to a certain extent. avoid lost. If there is a fire around the line, the shell of diamond mud ceramic silicon rubber can also ensure that it will not melt or drip in the flame, which effectively protects the normal use of the line and avoids explosions.
Finally, the editor still has a small reminder: the wire is aging, and the wire needs to be replaced in time. Don’t have a fluke mentality. The diamond mud oxygen barrier can only reduce the possibility of fire. Once a fire occurs, it will affect manpower, material resources and financial resources. The losses should not be underestimated!