How to solve these problems in PVC

1、 Troubleshooting of common faults in injection molding of ACSR Cables
Under note
Fault analysis and Troubleshooting:
(1) The temperature of the melt is too low. The forming temperature should be increased properly.
(2) Forming cycle is too short. It should be extended appropriately.
(3) Insufficient injection pressure. It should be improved appropriately.
(4) The injection rate is too slow. It should be accelerated appropriately.
(5) Insufficient supply. The supply shall be increased.
(6) The temperature of the die is too low, so it should be properly raised. In particular, the cooling circuit of the mold should be set reasonably to keep the temperature of the mold uniform.


(7) The shape and structure of plastic parts are not designed reasonably or the wall is too thin. Adjustments should be made in the event of possible changes.
(8) The structure size of the pouring system is small. Gate and runner sections shall be enlarged appropriately.
(9) The exhaust of the mold is poor. The exhaust hole should be added to improve the exhaust performance of the AAAC Cables.
(10) The strength of the die is not enough. The rigidity should be improved as much as possible.
· shrinkage marks
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. The barrel temperature shall be properly reduced.
(2) Insufficient injection pressure. It should be improved appropriately.
(3) The holding time is too short. It should be extended appropriately.
(4) The cooling time is too short. The cooling efficiency shall be improved or the cooling time shall be prolonged.
(5) Insufficient supply. The supply shall be increased.
(6) The temperature of the die is not uniform. The cooling system of the mould should be adjusted and the cooling circuit should be set reasonably.
(7) The shape structure design of plastic parts is unreasonable or the wall of plastic parts is too thick. Adjustments should be made where possible.
(8) Gate cross section is too small. It should be increased appropriately.
· weld marks
Fault analysis and Troubleshooting:
(1) The temperature of the melt is too low. The forming temperature should be increased properly.
(2) Insufficient injection pressure. It should be improved appropriately.
(3) The injection rate is too slow. It should be accelerated appropriately.
(4) The temperature of the die is too low, so it should be properly raised.
(5) The gate section is too small. It should be increased appropriately.
(6) Poor exhaust of mould. The exhaust hole should be added to improve the exhaust performance of the die.
(7) The structure size of cold material hole is too small or the position is not correct. It should be adjusted reasonably.
(8) Impurities are mixed in the raw materials. Foreign matters and impurities shall be removed thoroughly or new materials shall be used.
(9) The dosage of release agent is too much. The amount of the product should be minimized.
(10) The insert is not set up reasonably. It should be adjusted appropriately.
(11) The raw material is not uniformly colored. The colorant with good dispersibility and the mixing time should be prolonged to make the raw material coloring even.
Flow marks
Fault analysis and Troubleshooting:
(1) The temperature of the melt is too low. The forming temperature should be increased properly.
(2) Insufficient injection pressure. It should be improved appropriately.
(3) The holding time is too short. It should be extended appropriately.
(4) The temperature of the die is too low, so it should be properly raised.
(5) The temperature of the die is not uniform. The cooling system of the mould should be adjusted and the cooling circuit should be set reasonably.
(6) Gate cross section is too small. It should be increased appropriately.
(7) The structure size of cold material hole is too small or the position is not correct. It should be adjusted reasonably.
(8) The raw material is not uniformly colored. The color additive with good dispersibility should be selected, and the mixing time should be prolonged.


Poor gloss
Fault analysis and Troubleshooting:
(1) The temperature of the melt is too low. The forming temperature should be increased properly.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) Screw back pressure is too low. It should be improved appropriately.
(4) The temperature of the die is too low, so it should be properly raised.
(5) The structure size of the pouring system is small. Gate and runner sections shall be enlarged appropriately.
(6) Poor exhaust of mould. The exhaust hole should be added to improve the exhaust performance of the die.
(7) Impurities are mixed in the raw materials. Foreign matters and impurities shall be removed thoroughly or new materials shall be used.
(8) The dosage of release agent is too much. The amount of the product should be minimized.
(9) Raw materials are not fully dried. The drying temperature and time should be increased appropriately.
· bubbles
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. The barrel temperature shall be properly reduced.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) Insufficient injection pressure. It should be improved appropriately.
(4) The injection speed is too fast. It should be slowed down appropriately.
(5) The holding time is too short. It should be extended appropriately.
(6) The temperature of the die is not uniform. The cooling system of the mould should be adjusted and the cooling circuit should be set reasonably.
(7) The shape structure design of plastic parts is unreasonable or the wall of plastic parts is too thick. Adjustments should be made where possible.
(8) Gate cross section is too small. It should be increased appropriately.
(9) The exhaust of the mold is poor. The exhaust hole should be added to improve the exhaust performance of the die.
(10) Raw materials are not fully dried. The drying temperature and time should be increased appropriately.
? uneven color
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. The barrel temperature shall be properly reduced.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) The raw material is not uniformly colored. The color additive with good dispersibility should be selected, and the mixing time should be prolonged.
Burnt and black
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. The barrel temperature shall be properly reduced.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) The injection pressure is too high. It should be reduced appropriately.
(4) The injection rate is too fast. It should be slowed down appropriately.
(5) Screw back pressure is too high. It should be reduced appropriately.
(6) Gate cross section is too small. It should be increased appropriately.
(7) The exhaust of the mold is poor. The exhaust hole should be added to improve the exhaust performance of the die.
(8) The dosage of release agent is too much. The amount of the product should be minimized.
(9) Raw materials are not fully dried. The drying temperature and time should be increased appropriately.
· overfill edge


Fault analysis and Troubleshooting:
(1) The temperature of the melt is too high. The temperature of the barrel and the nozzle shall be properly reduced.
(2) The injection pressure is too high. It should be reduced appropriately.
(3) The injection rate is too fast. It should be slowed down appropriately.
(4) The holding time is too long. It should be shortened appropriately.
(5) There is too much supply. It should be reduced appropriately.
(6) The closing force is insufficient. It should be improved appropriately.
(7) The mold temperature is too high. It should be reduced appropriately.
(8) The shape structure design of plastic parts is unreasonable, and should be adjusted appropriately in case of possible changes.
(9) The strength of the die is not enough. We should try to increase its rigidity.
(10) The insert is not set up reasonably. According to the shape of plastic parts and the structure of the mold, proper adjustment shall be made.
Warping and deformation
Fault analysis and Troubleshooting:
(1) The barrel temperature is too low. It should be improved appropriately.
(2) Forming cycle is too short. It should be extended appropriately.
(3) The injection pressure is too high. It should be reduced appropriately.
(4) The injection speed is too fast. It should be slowed down appropriately.
(5) The holding time is too long. It should be shortened appropriately.
(6) The mold temperature is too high. It should be reduced appropriately.
(7) The cooling system of the mould is not reasonable, and the cooling circuit should be set reasonably according to the cooling requirements of the plastic structure.
(8) Gate cross section is too small. It should be increased appropriately.
(9) The setting of ejector is unreasonable. The area of jacking out and the point of jacking shall be increased as much as possible.
(10) The strength of the die is not enough. We should try to increase its rigidity.
· delamination
Fault analysis and Troubleshooting:
(1) If the melt temperature is too low, the temperature of the barrel and nozzle should be increased properly.
(2) The injection rate is too fast. It should be slowed down appropriately.
(3) The mold temperature is too low. It should be improved appropriately.
(4) Impurities are mixed in the raw materials. Foreign matters and impurities shall be removed thoroughly or new materials shall be used.
? discoloration of the surface
Fault analysis and Troubleshooting:
(1) The barrel temperature is too high. It should be reduced appropriately.
(2) The molding cycle is too long. It should be shortened appropriately.
(3) The injection rate is too fast. It should be slowed down appropriately.
(4) Screw back pressure is too high. It should be reduced appropriately.
(5) The gate section is too small. It should be increased appropriately.
(6) Poor exhaust of mould. The exhaust hole should be added to improve the exhaust performance of the die.
(7) Impurities are mixed in the raw materials. Foreign matters and impurities shall be removed thoroughly or new materials shall be used.
2、 Troubleshooting of common faults in injection molding of soft PVC
Poor gloss on the surface of the product
Fault analysis and Troubleshooting:
(1) The processing temperature is too low, and the material is not plasticized. The processing temperature should be improved properly to improve the plasticizing effect.
(2) The mold temperature is too low. The mold temperature should be increased appropriately.
(3) The material fluidity is too bad, the raw material should be replaced or the raw material formula should be adjusted.
(4) The surface finish of mold cavity is too poor. The surface finish of mold cavity should be improved properly.
(5) During the forming process, the auxiliary agent precipitates, and forms scaling on the surface of the mold. The mold surface scale should be removed in time. If it is serious, the formula should be adjusted.
(6) Too much recycled material. The amount of recycled material shall be reduced appropriately.
(7) The material temperature is too high, and the resin is decomposed. The injection temperature should be reduced and the thermal stability system should be improved.
? shrinkage deformation
Fault analysis and Troubleshooting:
(1) The holding time is too short. The time of pressure preservation should be prolonged, especially when shrinkage occurs near the gate, the method of prolonging the pressure holding time can be used to solve.
(2) The pressure holding pressure is too low. The pressure holding time should be improved properly.
(3) Injection pressure is too low. Injection time should be improved appropriately.
(4) The molding temperature is too high. The forming temperature shall be reduced appropriately.
(5) The amount of feed is insufficient. The amount of feed shall be increased appropriately.
(6) The mold temperature is too high or the heating is uneven. The cooling efficiency of the mould should be improved.
(7) The mold is opened too early and the product cooling is insufficient. The cooling time of the product in the mold shall be extended.
(8) The thickness difference of the products is too big, and the parts of the thickness of the products in process are prone to sag shrinkage due to the insufficient pressure. The design of the product shall be modified.
(9) Gate cross section is too small. It should be increased appropriately.
Under injection, lack of material
Fault analysis and Troubleshooting:
(1) Injection pressure or pressure retaining pressure is too low. Injection pressure or pressure retaining pressure should be increased appropriately.
(2) The holding time is too short. The holding time shall be extended appropriately.
(3) The processing temperature is too low. The processing temperature should be raised appropriately.
(4) The injection rate is too slow. The injection speed should be increased appropriately.
(5) The temperature of the mold or nozzle is too low. The temperature of the mold or nozzle shall be increased appropriately.
(6) Impurities or decomposition are blocked at the nozzle. The injection molding machine nozzles shall be cleaned.
(7) The gate section is too small. It should be increased appropriately.
(8) The exhaust hole of the mold is blocked. The plug in the die vent should be removed.
(9) Injection rate of injection molding machine is too small. The injection volume should be increased appropriately.
Coking decomposition
Fault analysis and Troubleshooting:
(1) The injection temperature is too high, the material is coking and decomposed, and the focus of the product is formed with the injection mold of the molten material. The injection temperature should be properly reduced to remove foreign matters from the dead angle of the barrel and the runner.
(2) Injection speed is too high. The injection rate should be reduced properly.
(3) Impurities or decomposition are blocked at the nozzle. The injection nozzle shall be cleaned.
(4) The thermal stability of raw materials is too poor. The material should be replaced or the formula adjusted to improve the thermal stability system.
(5) The lubricant is not used enough. The lubricant dosage should be increased appropriately.
(6) Poor exhaust of mould. The die exhaust system should be improved.
(7) The gate section of the mold is too small. The gate section of the mold shall be expanded appropriately.

What is the difference in the temperature resistance of cables?

UL standard

In UL standard, the common temperature resistance grades are 60 ℃, 70 ℃, 80 ℃, 90 ℃, 105 ℃, 125 ℃ and 150 ℃. How do these temperature ratings come? Is it the long-term operating temperature of the conductor? In fact, these so-called temperature ratings are called rating temperature in UL standards. It is not the long-term operating temperature of the conductor.
▍ rated operating temperature
If the reverse push method is adopted in UL standard system, it can be concluded that: a material aged for 300 days at a temperature a ℃ and its elongation rate is no more than 50%. Then the temperature a is subtracted by 5.463, and then divided by 1.02 to obtain the temperature B ℃, and the rated temperature of temperature B ℃ can be determined. This rated temperature is by no means the maximum long-term working temperature of the conductor allowed by the insulating layer. Because the “long term” in the long-term maximum working temperature should be the service life of the cable at this working temperature, which should be calculated at least in years. For example, in the photovoltaic AAC Cable standard en50618, the service life of the cable is designed to be 25 years, and the rated temperature in UL standard is generally higher than the long-term maximum working temperature of the conductor.


▍ short term aging temperature
The short-term aging temperature of materials, that is, the most common 7 days and 10 days in the standard, such as 105 ℃ materials, aging conditions are 136 ℃ × Seven days. So what is the relationship between this and the rated temperature? In UL standard, the temperature of short-term aging is obtained by the long-term experience of materials, but some methods are also summarized to confirm. The short-term aging temperature of a material is determined as described in ul2556-2007, chapter 4.3.5.6 and appendix D. First, select a rated temperature, aging temperature and aging time according to Table 1-1. If the elongation change rate of the material tested according to the above conditions is greater than 50%, it is recognized that the aging temperature can be determined according to this condition. If the elongation change rate is more than 50%, the rated temperature and short-term aging temperature of the material shall be reduced by one grade.

En/iec standards

In en/iec standards, rated temperature is rarely seen as UL standard, instead of conductor long-term operating temperature or temperature index. So what is the difference between the two temperatures?
In fact, in the en/iec standard system, the evaluation of the temperature resistance of AAAC Cables is mainly conducted according to en 60216 or IEC 60216. This standard is mainly used to evaluate the thermal life of insulating materials. The evaluation method is to test the aging of the material at different temperatures, and take the change rate of elongation at break as the end point of aging, and get the aging days of the materials at different temperatures. Then, the aging days and aging temperature are treated by linear regression, and a linear relationship curve is obtained. Then, the maximum operating temperature is determined according to the life of the cable, or the service life of the cable is determined according to the long-term working temperature. The temperature index refers to the temperature corresponding to the change rate of elongation at break when the change rate of insulation material is 50% after the heat aging of 20000h. Taking the PV cable standard EN 50618:2014 as an example, the design life of the cable is 25 years, the long-term working temperature is 90 ℃, and the temperature index is 120 ℃. The short-term aging temperature of insulating materials is also derived from the linear relationship. Therefore, the aging temperature of insulation materials in en 50618:2014 is 150 ℃. This aging temperature is very close to the aging temperature of materials rated 125 ℃ in UL standard series at 158 ℃.


It is not difficult to see that the long-term working temperature of the same conductor is different due to the different design life of the cable, and the aging temperature may be different. Under the same long-term working temperature, the shorter the design life of cable, the lower the short-term aging temperature of insulation materials can be required. For example, the long-term maximum working temperature of XLPE insulation required in IEC 60502-1:2004 is 90 ℃, while the aging temperature of this material is 135 ℃. The 135 ℃ here is very close to the aging temperature of 136 ℃ rated at 105 ℃ in UL standard, but it is much different from the aging temperature of insulation in en 50618:2014, which is also the longest-term maximum working temperature of 90 ℃. Although the design life of the cable was not found in 60502-1:2004, the design life of the two cables must be different.

National and industrial standards

In the process of compiling national and industrial standards, many contents refer to UL standard or en/iec standard. But because it is a multi-party reference, some of the statements I think are inaccurate. For example, in gb/t 32129-2015, jb/t 10436-2004 and jb/t 10491.1-2004, the temperature resistance grades of both materials and wires are 90 ℃, 105 ℃, 125 ℃ and 150 ℃, which is obviously used for reference to UL standard system. However, the expression of heat resistance is the maximum allowable conductor operating temperature for a long time. The expression of heat resistance is also clearly referred to the IEC standard system. In IEC standard system, the long-term maximum working temperature of conductor should be related to the design life of cable. However, there is no expression of cable life in these national standards and line standards. Therefore, the expression of “the maximum allowable operating temperature of the applicable cable conductor in a long term is 90 ℃, 105 ℃, 125 ℃ and 150 ℃” remains to be discussed.
Can XLPE of silane crosslink reach the temperature resistance level of 125 ℃? The more rigorous answer should be that the silane crosslinked XLPE can reach the rated temperature of 125 ℃ specified in UL standard, because in the general provisions of insulation and sheath materials in ul1581 chapter 40, it is clearly proposed that no provisions on the chemical composition of the materials are made. Whether the XLPE conductor can work at 125 ℃ for a long time is related to the design life and the use situation of the cable. At present, no relevant data system has been found to evaluate the life of the material. It is estimated that if the design life of cable is 25 years, the maximum temperature of conductor allowed in long term can be more than 90 ℃. In IEC standard, the maximum working temperature of traditional power cable, building line and solar cable design conductor will not exceed 90 ℃, but it does not mean that the maximum allowable temperature of long-term maximum working temperature of materials used for such cables cannot be greater than 90 ℃. It is also impossible to say that the irradiation crosslinking material can reach the temperature resistance level of 125 ℃, while the silane crosslinking material can not reach the temperature resistance level of 125 ℃, which is unreasonable.
In short, whether a material can reach a certain temperature level cannot be simply answered, or not, but should be considered in combination with the evaluation method of material temperature resistance grade or the design life of cable, and it is not allowed to mix several standard systems with random use.

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What is the difference between copper conductor and copper alloy cable?

Copper bar is the main raw material of AAC Cable industry. There are two main production methods: continuous casting, continuous rolling and continuous casting. Due to different processes, the oxygen content and appearance of copper rods are also different. When the oxygen content is lower than 10ppm, it is called oxygen free copper rod; When the oxygen content is less than 10ppm, it is called oxygen free copper rod.


Low oxygen copper rod
Disadvantages of process D:
The electrolytic copper melts when it is added. There is no complete reduction condition for copper water. The whole smelting process and copper water process are inseparable from oxygen, so the oxygen content is very high. The fuel for molten copper is usually gas. In the process of gas combustion, it will directly affect the chemical composition of liquid copper. Sulfur and hydrogen are the most important factors.
Process advantages:
(1) High yield. Generally, the output of small units can reach 10-14 tons per hour.
(2) The layout of copper bar adopts plum blossom type, which is convenient for wire drawing machine.
(3) Bearing capacity, generally not more than 4 tons per plate.
Grade and characteristics of low oxygen copper rod: low oxygen copper rod
It is divided into three levels: T1, T2 and T3. The low oxygen copper bar is hot rolled, so it is a soft bar, code R.
(1) T1: production of low oxygen copper rod with high purity electrolytic copper as raw material (copper content greater than 99.9975%).
(2)T2:1 × The low oxygen copper rod (copper content above 99.95%) is made of electrolytic copper.
(3)T3:2 × The low oxygen copper rod (copper content above 99.90%) is made of electrolytic copper. Due to high purity electrolytic copper and 2 × Electrolytic copper is very few, generally 1 × Electrolytic copper is used as raw material, so the grade of low oxygen copper rod is T2R.


Oxygen free copper rod
Oxygen free copper rod is pure copper without oxygen or any deoxidizer residue. But in fact, it still contains a very small amount of oxygen and some impurities. According to the standard, the oxygen content is not more than 0.02%, the total impurity content is not more than 0.05%, and the copper purity is more than 99.95%.
It is generally produced by electrolytic copper, and its resistivity is lower than that of low oxygen copper rod. Therefore, oxygen free copper rod is more economical in the production of products with strict resistance requirements; High quality raw materials are needed to make oxygen free copper rods;
According to the oxygen content and impurity content, the oxygen free copper rod can be divided into TU1 and TU2 copper rods. The purity of TU1 oxygen free copper rod is 99.99%, and the oxygen content is not more than 0.001%; The purity of TU2 oxygen free copper is 99.95%, and the oxygen content is not more than 0.002%.


The difference between the two
Due to different manufacturing methods, low oxygen copper rod and oxygen free copper rod have their own characteristics.
1、 On the removal of oxygen and its existing state
Oxygen content of low oxygen copper rod is generally 200 (175) – 400 (450) ppm, so oxygen is inhaled into liquid copper. On the contrary, the oxygen in the oxygen free copper rod is reduced and removed after a certain period of time. Generally, the oxygen content of bar is below 10-50ppm, and the lowest is 1-2ppm. Oxygen content in oxygen free copper is very low, so the structure of copper is uniform and single-phase, which is conducive to toughness.
2. Difference between impurity content and existing hot rolling defects
The tensile properties of oxygen free copper bar are better than that of oxygen free copper bar in all wire diameters. In addition to the above microstructure reasons, the oxygen content of oxygen free copper bar is less and stable, there is no possible defect in hot rolling, the oxygen monitoring is not strict, and the oxygen content is unstable, which will directly affect the performance of copper bar. If the oxide on the surface of the bar can be made up in the continuous cleaning of the subsequent process, the problem is that there are quite a lot of oxide under the skin, which has a more direct impact on the broken wire.
3. The toughness of low oxygen copper rod is different from that of oxygen free copper rod
Both can be pulled to 0.015 mm, but the distance between low temperature grade oxygen free copper wires is only 0.001 mm.
4. Low oxygen copper rod
The wire making process of copper rod is different from that of oxygen free copper rod. The wire making process of low oxygen copper bar should be the same as that of oxygen free copper bar, at least the annealing process of the two should be different. Because the softness of wire rod is greatly affected by material composition, bar manufacturing, wire manufacturing and annealing process, it can not be simply said that low oxygen copper or oxygen free copper is soft or hard.

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Discussion of the cable production process: conductor stranding

Discussion on the cable production process: conductor twisting and twisting
: the process of twisting many small diameter monofilaments into a large cross-section conductive core according to certain rules.
1. There are two types of twisted wires: normal twisted wires and irregular twisted AAC Cables.
Ordinary strands can be divided into ordinary concentric single stranded strands and ordinary concentric single stranded strands
(1) Ordinary stranded wire: single wires of the same diameter are twisted layer by layer according to concentric circles, and the direction of each layer is opposite.
(2) Combined stranded wire: made of a single wire of the same diameter, different materials or different diameters and different materials (representative products (such as overhead conductors))
Ordinary concentric stranded wire: a multi-stranded ordinary stranded wire or bundle Stranded wire concentrically stranded.
Irregular stranding (strand): strands formed by multiple single strands in the same direction, which does not comply with the law of twisting. The positions of the single strands are not fixed to each other, and the shape of the strands is difficult to maintain Round.

2. The biggest difference between the bundle wire and the ordinary stranded wire is that each single wire of the ordinary stranded wire has a fixed position and is regularly twisted layer by layer. There is no fixed position between the single wires of the bundle According to the law of twisting, the position will not be twisted together.
3. The characteristics of irregular twisting (bundling) : Since each single wire in the bundle is twisted in one direction, there is a residual amount of sliding between each single wire during bending. The amount is large and the bending resistance is small, so the bending performance of the bundle is particularly good. For wire and cable products that need to be flexible and frequently moved, the wire bundle is used as the conductor core.
4. The characteristics of the stranded core:
(1) Flexibility Good; by using a core composed of several single wires with smaller diameters, the bending resistance of the cable can be improved, and the processing, manufacturing, installation and laying of the wires and cables are convenient.
(2) Good stability; the core is It is composed of multiple single wires twisted according to a certain direction and twisting rules, because each single stranded wire is located in the stretched area above the twisted wire in the twisted wire, and is located in the lower compressed area When the stranded wire is bent in sequence, the stranded wire will not be deformed.
(3) Good reliability; due to material inhomogeneity or defects in twisting, using a single wire as the cable and the conductor of the cable easily affects the reliability of the conductor core. The defects of the conductor core formed by multiple single wires are scattered and will not be concentrated on a certain point of the conductor, so the reliability of the conductor core is much stronger.
(4) High strength; the strength of the single-stranded core is higher than that of the single-stranded core.

5. Explanation of terms:
(1) Pitch: the distance that a single filament advances one circle along the axis.
(2) Pitch diameter ratio: the ratio of the pitch length to the strand diameter.
(3) The relationship between the pitch and the flexibility of the strands: the smaller the pitch, the better the flexibility of the strands; on the contrary, the larger the spacing, the worse the flexibility of the strands.
(4) Stranding factor: the ratio of the actual length of a single wire to the pitch length in the pitch of the twisted wire.
(5) Twisting direction of the stranded wire: right direction (z direction) left direction (s direction)
(6) Compact conductor: common compact conductors are compact round, sector and compact tile-shaped (five-core cables) Semi-circular (two-core cable)
6. Compression purpose:
(1) Compact sector conductor: reduce the outer diameter of the cable, save product costs, and reduce the weight of the cable.
(2) Compact circular conductor: Improve the surface quality of the stranded conductor, reduce the diameter of the conductor, and increase the filling factor of the conductor. The compacted conductor surface is smooth without burrs, and the electric field on the conductor surface is uniform. Save materials and reduce costs (to learn more about cable technology, please click here. A lot of dry goods are waiting for your visit.)
7. Conductor classification:
According to GB/t3956 “Cable Conductor”, there are four types of conductors, namely the first One, the second, the fifth and the sixth. The first is a solid conductor, and the second is a stranded conductor, both of which are suitable for fixed laying of cables. The fifth and sixth types are stranded conductors, which are used for flexible cables and cords. The sixth is softer than the fifth.
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Tips for ACSR cable fault location

The occurrence of ACSR Cable 336.4 MCM  faults is accompanied by the laying and use of cables. The location of cable faults varies with cable laying methods, and the difficulty in locating is gradually increasing. Among them, the positioning and searching of bridges, tunnels, and trenches are relatively simple, while the direct-buried method is the most difficult to locate. When the nature of the fault is simple, a dedicated cable fault location device can be used to locate the fault within tens of minutes. When the fault is special, it often takes 4-5 days or even longer to locate the fault.
When using the echo method to locate cable faults, sometimes through the transfer of faulty phases and wiring methods, complex faults are often transformed into simple faults, and the fault location can be quickly determined to gain time for on-site line repairs. This is important for power supply departments. Significant.


Low-voltage power cables are generally multi-core cables. After a fault occurs in continuous use after laying, they generally show two-core and multi-core phase-to-phase or relative-to-ground short-circuit faults. Sometimes when it is detected that the fault waveform collected by a certain core is not ideal, consider switching the wiring to other faulty cores for fault waveform detection. Unexpected effects will often occur, and the collected and detected waveforms will become More typical and regular, so you can quickly determine the specific location of the cable fault point.
In the long-term on-site measurement process of cable customers, it is found that after the failure of small cross-section copper core direct-buried power cables (35mm2 and below) and aluminum core cables, there may be short-circuit and disconnection faults at the same time. During on-site detection, according to the nature of the failure of each faulty core The difference between the short-circuit fault and the disconnection fault measurement will often get twice the result with half the effort.


For low-voltage cable and  direct-buried power cables with extruded armored inner lining, most of the faults are caused by external mechanical damage. When the insulated core fails, the inner lining may have been damaged. When encountering a special cable insulation fault, it is difficult to use a professional cable fault meter to collect waveforms. Consider using the acoustic measurement method to directly apply high-voltage pulses between the steel strip and the copper shielding layer of the cable, which will often quickly fix the point.
During the on-site measurement process, we also found that when the low-voltage cable fault point is determined by the acoustic measurement method, when the high-voltage wire and the ground wire are connected between the bad phase and the metal shield or armor, the insulation resistance of the two shows a low-resistance metallic connection. State, the sound is very small, the probe cannot be used to listen to the fixed point, and the effect is not ideal. Through the actual listening side many times, it was found that the distance between the discharge ball gaps was appropriately increased, and the high voltage and grounding wires were reconnected between the two phases where the fault occurred. Often the discharge sound will become louder, and the fault point will be quickly determined. .

Overhead lines need “nine checks”

The inspection of overheadcable is one of the basic contents of the operation and maintenance of overhead lines. Defects can be found in time through inspections so that preventive measures can be taken to ensure the safe operation of the line. Usually, line inspectors should do “nine inspections” when inspecting overhead lines.
Check the pole tower. Check whether the tower is collapsed, tilted, deformed, decayed, damaged, whether the foundation is cracked, and whether the iron components are bent, loose, skewed or rusted. Check whether the wire length of the iron bolts or iron screw caps of the tower is insufficient, the screws are loose, the binding wires are broken and loose. Check whether there are bird nests and other objects on the tower.
Second, check the crossarm and fittings. Check whether the cross arm and fittings are displaced, whether they are firmly fixed, whether the weld seam is cracked, whether the nut is missing, etc.
Three check the situation along the line. Check whether flammable, explosive or strongly corrosive substances are piled on the ground along the line, whether there are illegal structures near the line, whether there are buildings and other facilities that may harm the line during thunderstorms or strong winds; check the poles and towers Whether to erect other power lines, communication lines, broadcast lines, and install broadcast speakers, etc.; check whether the lines are connected to electrical equipment without authorization.

Four check the route. Check the wires and lightning protection wires for broken strands, back flowers, corrosion, damage from external forces, etc.; check whether the distance between the wires, the ground and adjacent buildings or adjacent trees, sag, etc. meet the requirements, and whether the sag of the three-phase wire is unbalanced Phenomenon: Check whether the wire connector is in good condition, whether there are signs of overheating, severe oxidation, and corrosion.
Five check insulators. Check the insulator for cracks, dirt, burns and flashover marks; check the deflection of the insulator string and the damage to the iron parts of the insulator.
Six check lightning protection devices. Check whether the size of the protection gap is qualified and whether the auxiliary gap is intact. Check whether the external gap of the tubular arrester changes and whether the grounding wire is intact. Check whether the porcelain sleeve of the valve-type arrester is cracked, dirty, burned, or flashover marks, and the sealing is good. Check whether the down conductor of the arrester is intact, whether the grounding body is exposed by water washing, and whether the connection between the grounding down conductor and the grounding body is firm.

Seven check pull lines. Check the power cable for rust, slack, broken strands and uneven force on each strand. Whether there is any decay or damage to the cable pile and protection pile Whether the cable anchors are loose, lack of soil and sinking of soil irrigation. Whether the wire rod, wedge-shaped wire clamp, UT-shaped wire clamp, and wire-holding hoop are corroded, whether the nut of the UT-shaped wire clamp is missing, and whether the stop device of the turnbuckle is in good condition. Whether the pull cord is pulled into the wood pole at the binding place.
Switch equipment on eight check poles. Check whether the switchgear is installed firmly, whether there is any deformation, damage or discharge traces, whether the operating mechanism is intact, and whether the distance between the leads and the ground meets the regulations.
Nine check crossing points. Check whether there are new crossing points, whether the crossing distance meets safety requirements, and whether the original crossing points endanger the safe operation of the line. Whether the protective measures are perfect.

Main Types of Overhead Cable & Wire

Overhead power lines mainly refer to overhead electrical wires, erected on the ground, and are transmission lines that use insulators to fix transmission wires on poles standing upright on the ground to transmit electrical energy.

What type of wire is used for overhead?
The wires used in low-voltage overhead lines are divided into bare wires and insulated wires. According to the structure of the conductor, it can be divided into single-strand conductor, multi-strand conductor and hollow conductor; its common types are AAC/AAAC/ACSR/ACAR.
The bare wire is the main body of the overhead line and is responsible for transmitting electrical energy. Since the wires are erected on the poles, they must often bear the effects of self-weight, wind, rain, ice, snow, harmful gas erosion, and air temperature changes. Therefore, the wire is required not only to have good electrical conductivity, but also to have sufficient mechanical strength and good corrosion resistance.

(1). All Aluminum Conductor (AAC): This bare concentric-lay stranded conductor is constructed with a straight round central wire surrounded by one or more layers of helically layed wires. These wires are of aluminum 1350 and can be provided in different classes of stranding and tempers.

(2). All Aluminum Alloy Conductor (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 was designed to attend the needs of an economic conductor for the applications on aerial circuit that require a larger mechanical resistance than the one of an All Aluminum Conductor (AAC), and a better corrosion resistance than the one produced by the aluminum conductor steel reinforced(ACSR). The conductors of Aluminum Alloy 6201-T81 are harder and have a better resistance to the abrasion than the conductors of aluminum 1350.

(3).Aluminum Conductor Steel Reinforced Conductor (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.Used as bare overhead transmission cable and as primary and secondary distribution cable. ACSR offers optimal strength for line design. Variable steel core stranding enables desired strengthto be achieved without sacrificing ampacity.

(4).Aluminum Conductor Alloy Reinforced Conductor (ACAR)This bare concentric-lay-stranded conductor is made from round aluminum 1350-H19 (extra hard) wires and round aluminum alloy 6201-T81 core wires for use as overhead electrical conductors.It presents a higher mechanical resistance.

Overhead insulated cable is an overhead wire equipped with an insulating layer and a protective sheath. It is a special cable manufactured by a production process similar to that of a cross-linked cable. It is a new transmission method between overhead wires and underground cables.

Aerial bundled cables (also aerial bundled conductors or simply ABC) are overhead power lines using several insulated phase conductors bundled tightly together, usually with a bare neutral conductor. The conductor can be all aluminum, aluminum alloy or aluminum with a steel core, used for overhead power distribution as an alternative to bare conductor.

 

Construction:
ABC cable used for low voltage overhead line transfer, structured by stranded aluminum conductor or aluminum conductor with steel core , both single core and multi-cores ,insulated by UV resistant XLPE.

Overhead ABC Cable Advantage:
ABC cable provide better level of safety and reliability ,lower power losses, easier to install ,less maintenance and operative cost.

  1. High reliability of power supply
    The use of overhead cables can greatly reduce various short-circuit faults (especially the common flashover faults of overhead bare wires). Compared with overhead bare wires, the failure rate is 4-6 times lower.
  2. Good power supply safety
    The use of overhead cables greatly reduces personal injury and death accidents due to electric shock.
  3. Convenient installation and maintenance
    Overhead cables can be erected on any kind of poles and towers, or along walls. Under special circumstances, they can also run through the bushes and be directly fixed on tree poles with hardware. It can be erected on a single circuit or multiple circuits on the same pole without requiring a wide “electrical corridor”.
  4. Reasonable economy
    Although the use of overhead cables is more expensive than the use of overhead bare wires, it is cheaper than ordinary underground cables. Therefore, although the one-time investment is slightly higher for the use of overhead cables, the operating cost will be significantly lower than that of overhead bare conductors based on other factors.

Laying method of overhead ABC cable 
A single conventional laying method. This erection method is to use the current conventional cement poles, iron accessories and ceramic insulator accessories with bare conductors, and erect according to the bare conductor erection method, which is more suitable for the area where the old line is reconstructed and the corridor is sufficient.
A special insulating bracket is used to suspend the wires for single laying. This method can increase the number of circuits erected, save the line corridors, and reduce the cost of the line unit.

How to Ensure Outdoor Cable Performance ?

Many users and installations are faced with the problem of cheap and efficient data transmission between buildings in the park environment. The choice of routing, transmission distance and application environment will all affect the choice of cable medium. Incorrect or inappropriate choice will result in a shortened period of wiring investment, and reinstallation will also cause the network system to stop running.
If it is an outdoor application, the fiber optic system is usually the choice for campus network connection. The real cost of optical fiber lies in the termination of optical fiber cabling system and optoelectronic equipment. When users only need to transmit 10Mbps or 100Mbps within a distance of 50 meters between buildings, optical fibers are generally not used.

Buying conventional Category 5 copper cables underground or laying overhead may cause transmission failure of a certain network along the wiring line. Therefore, choosing the existing outdoor direct-buried enhanced type cable will bring a cheap link. Before deciding to choose these outdoor LAN cables, you should fully understand their design.

Anti-moisture protection nets have been used in communication cables for many years. These aluminum polymer materials have overlapping seals as protection to reduce the penetration path of water vapor to prevent water from entering. However, an unprotected dry cable will need to suffer as long as six months to a year of liquefaction due to infiltration, and a dry cable with a moisture-proof protective net will be completely protected. The cable designed in this way is approximately similar to a foil-screened LAN cable, and it is easy to connect and use.

Therefore, the wiring system designer must consider the application environment, which includes the following environment and parameters that affect the cable:
1. Whether the cable is placed under the eaves; as long as the cable is not directly exposed to sunlight or ultra-high temperature, the standard LAN cable can be used. It is recommended to use pipes:
2. External walls; avoid direct sunlight on the walls and man-made damage;
3. In the pipe (plastic or metal); if in the pipe, pay attention to the damage of the plastic pipe and the heat conduction of the metal pipe;
4. For suspended applications/overhead cables, the sag and pressure of the cable should be considered. Which bundling method you intend to use. Whether the cable is directly irradiated by sunlight; laying directly in the underground cable trench, this environment is the smallest control range. The installation of the cable trench should be checked regularly for dryness or humidity;
5. Underground pipeline. In order to facilitate future upgrades, cable replacement, and isolation from surface pressure and the surrounding environment, laying pipes is a better method. But don’t expect that the pipe will always remain dry, which will affect the choice of cable types.

Factors affecting cable performance include:
1. Ultraviolet (UV)-Do not use cables without UV protection in direct sunlight. You should choose cables with black polyethylene or PVC sheaths, such as Brand-Rex’s 4 pairs of reinforced type 5 MegaOutdoor outdoor cable, with metal mesh moisture-proof protective layer and black polyethylene sheath, is suitable for most inter-building connections, whether it is overhead laying, ground installation or pipeline construction, it can be used:

2. Heat-the temperature of the cable in the metal pipe or trunking is very high. Many polymer materials will reduce the service life at this temperature. Black polyethylene or PVC sheathed power cable should be selected;

3. Water-Water is the real killer of LAN cables. The moisture in the twisted-pair cable of the local area network will increase the capacitance of the cable, thereby reducing the impedance and causing near-end crosstalk problems. If it is extremely effective to prevent moisture and water vapor, a protective layer of metal shielding net is required;

4. Mechanical damage (repair costs)-the repair of optical cables is very expensive, and at least two terminations are required at each discontinuity;

 

Grounding-if the shielding layer of the cable needs to be grounded, the corresponding standards must be followed;

The total length of the route (not only between the buildings)-Use outdoor-grade LAN twisted-pair cables between the buildings, and the total length should be limited to 90 meters.
For a network of 100Mbps or 1000Mbps, the laying distance cannot exceed this limit. If the laying distance is between 100 meters and 300 meters, optical cable should be selected.
The following simple experiments can be used to self-test whether the wiring investment is safe: use a 20-meter enhanced category 5 UTP cable to terminate at both ends; carefully remove the cable sheath at the midpoint of the cable to expose a small section of copper cable (1 cm ); Test the cable according to AN/NZSD standard; soak the cut part of the cable in water for 1-2 minutes, and then retest.