What are the common types of aluminum alloy cables

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

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

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

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


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


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

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

 

What should we pay attention to when installing cables?

Matters needing attention in Electrical cable installation:

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


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


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

Precautions for testing cross-linked cables

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

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

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

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

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

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

Treatment method of polyethylene insulated power cable damp and water

In urban power grid renovation projects, cables, especially polyethylene insulated power cables, have been widely used. However, due to the particularity of the cable, there are special requirements for the installation, operation and maintenance of the cable. Moisture or water in the cable reduces the insulation resistance of the cable, which is a few important aspects that cause operation accidents in the cable line.


Causes and hazards of cables being damp
(1) When XLPE insulated cable  is shipped from the factory, both ends of the cable are sealed with plastic sealing sleeves. However, after a section of the cable is used according to the actual situation at the construction site, the remaining part is simply wrapped with plastic cloth to wrap the fracture. Placed in the open air and poorly sealed, over time, water vapor will inevitably seep into the cable.
(2) During cable laying, it is necessary to cross roads, bridges and culverts frequently. Due to weather or other reasons, a lot of water often accumulates in the cable trench. During the laying process, it is inevitable that the cable head will be immersed in water. , Because the plastic cloth is not tightly wrapped or damaged, water enters the cable; in addition, the outer sheath or even the steel armor is sometimes scratched when pulling and piercing the pipe. This phenomenon is particularly prominent when using mechanical traction.


(3) After the cable is laid, the cable head cannot be made in time due to the constraints of the site construction conditions, so that the unsealed cable fracture is exposed to the air for a long time, or even immersed in water, causing a large amount of water vapor to enter the cable.
(4) In the process of making cable heads (including terminal heads and intermediate joints), due to the negligence of the construction personnel, the newly processed cable ends sometimes accidentally fall into the stagnant water on site.


(5) In the normal operation of the cable, if breakdowns such as breakdown occur due to some reason, the water in the cable trench will enter the cable along the fault point; in civil construction, especially when large construction machinery is used It is not uncommon for cables to be damaged or broken down due to various human factors on construction sites in China. When such an accident occurs, the cable insulation is severely damaged, and water can enter the cable.
After the cable enters the water, under the action of the electric field, the aging phenomenon will occur, and finally the cable will break down.

The structure and specification of YJV cable

Let me introduce to you what YJV means, yj means cross-linked polyethylene, v means polyvinyl chloride, then YJV is cross-linked polyethylene insulated PVC sheathed cable, and the range of use is for the rated voltage (U0/U) 0.6/1—26/35kv power line transmission and distribution, the rated temperature of the cable conductor is 90 degrees when in use, and the temperature of the cable conductor does not exceed 250 degrees when short-circuited (the duration does not exceed 5S). It has the advantages of light weight and simple structure, so it is widely used in urban power grids.
YJV cable model specification


The cores of YJV cables are single core, 2 cores, 3 cores, 4 cores, 5 cores, 3+1, 3+2, 4+1. 3+1 represents 3 phase wires and 1 ground wire, 3+ 2 represents 3 phase wires and 2 ground wires, 4+1 represents 4 phase wires and 1 ground wire. According to the standard model, the specific size specifications include: 1 square, 1.5 square, 2.5 square, 4 square, 6 square, 10 square, 16 square, 25 square, 35 square, 50 square, 70 square, 95 square, 120 square, 150 Square, 185 square, 240 square, 300 square. For example, the YJV 3*120+2*70 cable is a cable composed of three 120 square phase wires and two 70 ground wires.

The combination between the ground wires is regulated by the standard, so the 70 square behind the YJV 3*120+2*70 cable can be omitted. The main specifications of the YJV cable range from 1 square to 240 square meters (also can be customized separately). It is a cable used for transmission and distribution of electric energy. It is often used in urban underground power grids, lead-out lines of power stations, internal power supply of industrial and mining enterprises, and underwater transmission lines that cross rivers and seas. In power lines, the proportion of cables is gradually increasing. Power cable is a cable product used to transmit and distribute high-power electrical energy in the main line of the power system, including 1-500KV and above various voltage levels, various insulated power cables.

How to protect cables from damage in cold winter

In winter, when laying and installing Aerial Bundle Cable (ABC) XLPE Insulated, many construction personnel will find that the wire and cable products with good quality usually have some problems, such as wire body hardening, insulation sheath falling off and damage. Many construction personnel think that the quality problems of wire and cable products have occurred, and the cable manufacturers insist that the products have been inspected before leaving the factory and are qualified Products often lead to misunderstanding between both sides. In fact, it is not the quality of the product itself, but the cold in winter.

The outer skin of PVC insulated AS / NZS 3560.1 power cable products is mostly ordinary plastic (PVC) or rubber. When they are in the environment below zero, they will become hard, and the whole wire and cable product line body will be hard and brittle, resulting in the skin may fall off and be damaged under slight external force. In winter, especially in the northern region, the outdoor temperature is often below zero, and the surface temperature may be lower. Therefore, if the wire and cable products are placed outdoors or directly on the ground, the product skin may fall off. So, how can we prevent the phenomenon of wire and cable sheath falling off in winter? Take the following measures from each stage.

1. When laying and installing the product: it is better to operate under the condition of relatively warm temperature in the middle and afternoon. If possible, the product can be “warmed up” in advance by using air heater and other equipment before use, so that the product can reach the best performance state. If buried, a protective layer can be laid in the cable trench, such as cloth and foam. If it is through the tube, the inside and outside of the pipe must be smooth in advance, so as not to scratch the wire. Special attention should be paid to the iron pipe. If the quality of the iron pipe is qualified, there may be a large number of sharp convex points in the poor quality iron pipe, which is likely to scratch the wire skin.

2, storage: it is best to store products in the room, and lay a layer of isolation layer on the surface of the storage, such as boards, bedding, foam and so on, to prevent the product from getting cold and damp.

3. When arriving at the destination or construction site, it is better for the product supplier to send personnel to supervise to prevent rough operation during unloading.

4. Ex factory transportation: when the products are loaded on the transport tools, they need to be kept warm and protected. For example, the use of closed means of transport to prevent direct exposure of products; put a soft cushion on the product, such as bedding or other softer foam, etc. when loading, gently handle lightly, do not load rough, at the same time avoid excessive bending of the product.

All in all, in winter, wires and cables will become very fragile, we need to “take care of”.

Causes of fire accidents on overhead cables

Now the use of Aerial Bundle Cable has become more and more extensive, but with its popularity in the national power supply lines, some of its safety problems have gradually attracted people’s attention, especially in recent years, the  cable fire accidents reminds people to pay more attention to when using this kind of cable. So, what are the causes of fire accidents of overhead cables?

1. The nominal conductor cross section of cable core does not meet the requirements. Generally, the specified nominal interface is larger than the actual cable produced, and the cable whose nominal value deviates from the standard will have larger unit current density. In its working process, the cable is easy to cause fire accident because it can not generate heat normally.

2. (ABC)XLPE  Insulated cable production process is poor. Although not every manufacturer is like this, it is inevitable that some businesses in the market will not operate strictly according to the standards in the process of cable production in order to seek personal interests. Even some businesses will use some low-quality products to make rough, resulting in the final production of the cable because the quality is not up to standard, causing fire in the process of use.

3. The material of the cable is impure or unqualified. The core wire of the cable is generally made of some copper or aluminum conductive materials, and many businesses often use unqualified or insufficient purity materials in the production process, which will lead to the reduction of power due to the presence of more impurities. Therefore, the materials used as core wires must be some high-quality electrolyte materials, mainly copper and aluminum.

4.Improper transportation. Most cables are subject to strict quality inspection before leaving the factory, but in the process of transportation, due to the lack of proper protection measures, it is squeezed and collided, resulting in the damage of insulation layer or the breakage of internal core wire

5. The composition of the insulating material does not meet the requirements or the processing is poor. We know that the outside of the cable is generally wrapped with a kind of insulating material. If the quality of the insulating material is unqualified, it will reduce its own withstand voltage performance in the process of use, and will form unqualified resistance value. In addition, long-term use will also shorten its service life, it is easy to have some short-circuit faults and cause fire.

Analysis of XLPE ACWU90 AC90 Cable Waterproof Structure

Cable waterproof structure type:
For XLPE ACWU90 AC90 Cable, there are usually the following waterproof structures:
1. For single-core cables, wrap a semiconducting resistance hose on the insulation shield of the cable, wrap a common water blocking tape outside the metal shield, and then squeeze the outer sheath. The outer sheath material can be ordinary For PVC, HDPE material with radial water blocking function can also be used, depending on other performance requirements of the cable. For three-core cables, in order to ensure the full contact of the metal shield, only the single-conductance resistance hose is wrapped outside the insulating shield, and the water blocking tape is no longer wrapped outside the metal shield. Water blocking filling, inner lining and outer sheath materials are the same as those described in single-core cables.


2. The aluminum-plastic composite tape layer is longitudinally wrapped inside the outer sheath or inner lining layer as a waterproof layer.
3. Squeeze the HDPE outer sheath directly on the outside of the cable.

Cable waterproof structure type:
For XLPE insulated power cables, there are usually the following waterproof structures:
1. For single-core cables, wrap a semiconducting resistance hose on the insulation shield of the cable, wrap a common water blocking tape outside the metal shield, and then squeeze the outer sheath. The outer sheath material can be ordinary For PVC, HDPE material with radial water blocking function can also be used, depending on other performance requirements of the cable. For three-core cables, in order to ensure the full contact of the metal shield, only the single-conductance resistance hose is wrapped outside the insulating shield, and the water blocking tape is no longer wrapped outside the metal shield. Water blocking filling, inner lining and outer sheath materials are the same as those described in single-core cables.


2. The aluminum-plastic composite tape layer is longitudinally wrapped inside the outer sheath or inner lining layer as a waterproof layer.
3. Squeeze the HDPE outer sheath directly on the outside of the cable.
For PVC XLPE Insulated Power Cable, the metal sheath is mainly used to make the cable meet the waterproof requirements. The most important feature of the metal sheath is that it is completely impermeable, so the cable with the metal sheath has very good radial water blocking performance. The main types of metal sheaths are: hot-pressed aluminum sleeve, hot-pressed lead sleeve, welded corrugated aluminum sleeve, welded corrugated steel sleeve, and cold drawn metal sleeve.


Cable waterproof form:
Cable waterproofing methods are generally divided into longitudinal water blocking and radial water resistance. Water blocking yarn, water blocking powder and water blocking tape are commonly used in longitudinal water blocking. Their water blocking mechanism is that these materials contain a material that can swell in contact with water. When water flows from the cable end or from the sheath After entering the defect, this material will quickly expand with water to prevent further diffusion of water along the longitudinal direction of the cable, thus achieving the purpose of longitudinal waterproofing of the cable. Radial water resistance is mainly achieved by extruding HDPE non-metallic sheath or hot pressing, welding, and cold drawing metal sheath.
Cable waterproof test basis:
The cable waterproof test method, the cable longitudinal water resistance performance can be tested and judged by the IEC 60502-1997 ANNEX D (normative) or GB/T 12706.2-2002 Appendix D (standard catalog) water permeability test; and the cable radial water resistance Performance, currently is mainly determined by indirect methods, such as checking whether the HDPE non-metal sheath or non-metal sheath is defective. If these sheaths are determined to be intact, then the cable is considered to have good radial water resistance. performance. However, many users of this method have raised some questions, caused some disputes, and lacked convincing power. Therefore, cable manufacturers and users now urgently need a test method to determine the radial water blocking performance of the cable. This can avoid disputes between manufacturers and users about the cable’s radial water blocking performance due to the lack of a radial water blocking test method.

 

Basic cable performance test

1. Inspection method
Routine test: It is an experiment conducted by the manufacturer on all finished cables. Its purpose is to check whether the quality of the product meets the requirements of the technical conditions in order to find accidental defects in the manufacturing process. It is a non-destructive experiment, such as the DC resistance of the wire and the insulation resistance time. And withstand voltage test, partial discharge detection, etc.
Type test: It is the manufacturer who regularly conducts comprehensive performance inspection of the product, especially for a new product before it is finalized for mass production, or the structure, material and main process of a product have changed, which may affect the performance of the cable Time. Pass type test: It can be tested whether the product can meet the requirements of operation, and can be compared with the old product. Such as thermal aging performance of insulation and sheath, long-term stability test of power cable, etc.
Acceptance test: It is an acceptance test performed on the cable after the cable is installed and laid in order to check the installation quality and find possible damage during the construction. Such as withstand voltage test after installation.

2. Test items
2.1 Measurement of DC resistance of wires
The conductive core of the wire and cable mainly transmits electric energy or electric signal. The resistance of the wire is the main indicator of its electrical performance. When the AC voltage is applied, the core resistance is larger due to the skin effect and the adjacent effect surface than when the DC voltage is applied, but the difference between the two is very small when the electric eye frequency is 50Hz. The current standard stipulates That can only require the detection of whether the DC resistance or resistivity of the core exceeds the value specified in the standard. Through this inspection, certain defects in the production process can be found: such as wire breakage or partial single wire breakage; Meet the standard; the length of the product is incorrect, etc. For aerial bundled cables 1418 standard, you can also check whether it will affect the allowable current carrying capacity of wire and cable products during operation.
There are single-arm DC resistance method and double-arm DC bridge method to measure the DC resistance of conductors. The accuracy of the latter is higher than that of the former. The test procedure is also more complicated than the former.

2.2 Test of insulation resistance
Insulation resistance is an important indicator reflecting the insulation characteristics of wire and cable products. It is closely related to the product’s electrical strength, dielectric loss, and the gradual deterioration of insulating materials under working conditions. For communication cables, low insulation resistance between wires will also increase loop attenuation, crosstalk between loops, and long-distance power supply leakage on conductive cores. Therefore, insulation resistance should be higher than the specified value.
Defects in the process can be found by measuring the insulation resistance, such as the insulation is dry and impermeable or the sheath is damaged and damp; the insulation is contaminated and conductive impurities are mixed in; the insulation layer is cracked due to various reasons. In the operation of aerial bundled cables(abc) sans1418, the insulation resistance and leakage current are often tested as the main basis for continued safe operation.
At present, in addition to the ohmmeter (shaking meter), the current measurement of the insulation resistance of wires and cables is the galvanometer comparison method and the high resistance meter method (voltage-current method).

How to identify poor quality Aerial Bundled Cable

1. Look closely at the label printing, the handwriting is blurred and the address is unknown. It means to look at the printed words on the label and the insulating skin. If there are typos, or the printing is of different shades, or the words are blurred, pay attention to it.
2. Use your fingernails to mark and flick the line , and the line will be cut off. Refers to the use of nails to scratch and pinch the insulating skin. The ones that can be scratched or pinched are generally inferior threads.

3.Twist the insulation skin with your hands, and the color will fade and the characters will be of poor quality. Refers to rubbing the insulating sheath with your fingers. Some inferior insulated wires are easy to fade, especially the red wire. This problem occurs. After rubbing, the color of the thread is left on the finger or the words printed on the thread are wiped off Generally inferior quality Aerial Bundled Cable

4. Repeatedly bend the insulated wire and break (ABC)SANS 1418 Standard three to four times. Refers to repeated bending of insulated wires. Inferior wires are generally of poor quality, and the insulation layer will break after bending 3 to 4 times.

 

5. Use fire to ignite the wire insulation and spontaneously ignite away from the open flame. It refers to the inferior wire that ignites the insulating layer and can ignite spontaneously after leaving the open flame.

6. ​​Aluminum and copper are commonly used for wire cores, and the color becomes darker and lighter. It means to look at the color of the core, the color of inferior thread is gray and without metallic luster.

7, finely measure the inner diameter and outer diameter, and look at the pine when weighing. It means that if it is not determined by the above 6 methods, the outer diameter and core diameter of the insulated wire can also be measured. The allowable error is ±10%. If the measured value exceeds the allowable error, it is basically a low-quality insulated wire.