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.

Frequency Conversion Cable Structure Design

The energy saving effect of frequency conversion device is very obvious, the use of frequency conversion speed regulating motor in high power motor, the whole generator set can save 30% electricity. And after the use of frequency conversion speed regulation, the soft start of the motor is realized, so that the motor works smoothly, the motor bearing wear is reduced, and the service life and maintenance cycle of the motor are extended. Therefore, frequency control technology in petroleum, metallurgy, power generation, railway, mining and other industries have been widely used.

 

1. ACSR Cable design

For 1.8/3KW and below frequency conversion motor special cable, and symmetrical 3+1 core and 4 core cable can only be used for the main power supply input cable, but the best use of symmetrical structure cable. Inverter and frequency conversion motor ask cable all needs to adopt symmetrical cable structure, symmetrical cable structure with three core and 3 + 3 core 2 kinds, 3 + 3 core cable structure is a small four to three core insulation wire core in the fourth core (neutral) is decomposed into three smaller insulation wire core section, the three big three symmetrical string cable core cable, special cable for 6/10 kv frequency conversion motor, the cable structure and 6/10 kv power cable, ordinary ordinary power cable is three insulation wire core adopts copper tape screened cable, special cable is made by copper wire and frequency conversion motor copper tape screened after extruded phase splitting the sheath, and symmetric cabling, The symmetrical cable structure has better electromagnetic compatibility because of the interchangeability of the wires, which plays a certain role in suppressing electromagnetic interference, can offset the odd frequency in the high order harmonic, improve the anti-interference of the special cable for frequency conversion motor, and reduce the electromagnetic radiation in the whole system.

2.Design of shielding structure

The shielding of special cables for frequency conversion motor 1.8/3kV and below generally adopts the total shielding, and the shielding for special cables for frequency conversion motor 6/10kV is composed of phase separation shielding and the total shielding. The phase separation shielding can generally adopt copper tape shielding or copper wire and copper tape combination shielding. The total shielding structure can adopt copper wire and copper tape combined shielding, copper wire braided shielding, copper wire braided shielding, copper wire braided copper tape shielding, etc. The section of shielding layer and the section of main line core are in a certain proportion. The shielded cable with this structure can resist the interference of electromagnetic induction, bad grounding and power line conduction, reduce the inductance and prevent the induction electromotive force from being too large. The shielding layer can not only restrain the emission of electromagnetic wave, but also act as the channel of short-circuit current, which can protect the neutral wire core.6/10kV frequency conversion motor special cable, considering that the cable is often affected by radial external force in the process of use, galvanized steel belt pin mounting layer is added outside the cable shielding layer (isolation sleeve is added between the shielding layer and the steel belt pin mounting layer).The steel belt pin is mainly used as the radial mechanical protective layer of the cable, and it also plays an additional role of total shielding. In particular, the steel belt armor and the copper wire and copper belt shield are two different shielding materials, which play a complementary role in electromagnetic shielding, and the shielding effect will be better.

 

3.Overhead ACSR Cable 336.4 MCM design

1.8/3KV and below frequency conversion motor special cable electrical performance according to GB/ TL2706, 2002 standard design. In addition to meeting the GBT/ L2706.2002 standard, the cable for 6/10kV frequency conversion motor has increased the electrical performance requirements such as capacitance and inductance. According to the actual use of the special cable for frequency conversion motor and the technical conditions of GB/T 12706.2002 and ABB Company for electric power transmission cable, the electrical performance parameters of the cable are determined.

  1. Main manufacturing technology of cables

In the production process of special cable for frequency conversion motor, the extrusion process of insulating wire core and cable forming process are the most critical processes.

Insulation core extrusion process Insulation core quality will directly affect the electrical performance of the cable. In order to improve the quality of cables, we choose insulating materials with high electrical performance for production. For example, 10kV cross-linked insulating materials are used for 1.8/3kV variable frequency motor special cables, and 35kV cross-linked insulating materials are used for 6/10kV variable frequency motor special cables. Imported materials are used for conductor shielding, insulating shielding and insulating materials. In the production process, we pay special attention to the purification of raw materials, shielding and insulation material extrusion close, control insulation eccentricity and insulation diameter uniformity, which can reduce the interface effect, improve the electrical performance of the cable.

Variable frequency cable requires symmetrical structure, and uniform tension of insulating wire core must be ensured during cable construction, so that the length of wire core after cable construction should be kept as consistent as possible, otherwise it will lead to structural changes, resulting in inhomogeneity of capacitance and inductance, and affect the electrical performance of the cable.

Cable Quality Defects and Their Elimination Methods

The crosslinking degree (thermal elongation) is not acceptable

If the crosslinking degree is not up to the standard, the thermal and mechanical properties of the cable are not qualified and can not meet the requirements of the working temperature of 90℃. The reasons for the unqualified crosslinking degree are as follows: first, the formula is unqualified, and the type and proportion of the complex agent is improper, so the formula should be adjusted to solve the problem; Two is the vulcanization process is not appropriate, such as the pressure is too low, the line speed is fast, the cooling water level is high, The solution is to first find out what the reason is, it may be one or several reasons exist at the same time, and eliminate the reasons.

Disqualified structure and appearance

(1) The thinnest point of insulation layer thickness is lower than the minimum value specified in the standard, or the average thickness is lower than the nominal value. The reasons for the unqualified insulation thickness are high linear speed, small amount of extruder, improper selection of mold, etc.

The solution is to reduce the linear speed or extruder speed, adjust the size of the die.

(2) eccentricity

The reason for the eccentricity is that the mold is not adjusted or the suspension control has changed after being collected and adjusted.

The solution is to keep the drape as stable as possible during driving.

The cable outside the bamboo joint is caused by the electrical, mechanical system causes the traction speed is not stable, the second is the die core is too small, or the conductor outside diameter is not uniform.

The elimination method is to check the mechanical, electrical system, troubleshooting. Properly adjust the size of the core, control the outer diameter of suburban counties as uniform as possible, more than the process requirements of the strand can be used.

Surface scratch

(1) the ACSR conductor encounters the upper or lower wall or foreign body in the vulcanized pipe. Therefore, it is required to adjust the suspension degree, try to make the wire core move in the middle of the crosslinked pipe, and clean it up in time when foreign bodies are found.

(2) there is burnt material on the outer edge of die sleeve. The solution is to adjust the temperature of the mold sleeve when starting the car to prevent overheating. Once burnt, it should be stopped immediately, or it will not get better by itself.

impurities

Most of the impurities in insulating material and semi-insulating material are brought into the process of mixing and extruder feeding. During the operation, strict attention should be paid to the cleaning of the material to prevent external impurities from mixing. Another impurity is coke pimp, its existence affects the performance and service life of the cable, so the temperature is strictly controlled when mixing and extrusion, to prevent the occurrence of coke phenomenon.

Air bubbles

There are two possible causes of air bubbles in insulation. One is caused by extrusion. The solution is to choose the right mold. The shielding layer has bubbles, the main reason is that there is water in the material, before extrusion should be dry, two is not sufficient cooling, then there will be as follows, in the isometric circumference of the line core appears a circle of bubbles.

The elimination method is to strengthen cooling, rise the water level and lower the temperature of cooling water.

(1) Cable performance is not up to standard

Disqualification of free discharge and dielectric loss

Free discharge and dielectric loss unqualified causes are very complex, it has to do with external shielding. Whether the insulation contains bubbles and impurities, and the properties of raw materials are closely related. Elimination method is to keep raw materials clean, strictly according to the process of production.

(2) cable insulation breakdown

Cable insulation breakdown is mainly caused by the insulation material mixed with impurities and external damage. Due to the strict avoidance of external damage, impurities should be avoided as far as possible. Semi-finished products should be strictly managed to prevent tripping and bruising.

(3) cushion breakdown

The main reason for the breakdown of the cushion is that the steel has burr, roll edge and puncture the cushion. The method to eliminate the steel strip is not equal to the unqualified quality requirements. The cushion is made of plastic belt with greater hardness, and the thickness of the cushion should be ensured.

Is it better to buy ACSR Cable online or in physical stores?

I don’t know whether to buy ASTM 477 MCM ACSR Cable online or in physical stores. It mainly depends on which part of the demand you need to meet. For users with higher quality requirements, you can buy them in physical stores. After all, you can get in touch with the real thing. , Specifications, voltage, etc. to prevent errors.


Those users who are more price sensitive can order directly online; the advantage of online purchase is that the price is much cheaper than offline, because it can save the cost of site rent increase and other costs, especially the one-stop supply of ACSR Cable online. Manufacturers have special supply channels and direct sales at factory prices, which is very cost-effective.


For users who are unsure about the quality of the wire purchased online, this is actually unnecessary. We can identify the quality of the product through the sample map. Users in the same city can also directly check the production workshop; and the manufacturer has spent so much money to make the website online, it is not necessary For the sake of a single order, the previous efforts have been broken, so it is still very reliable to place an order online, provided that you must look for a more formal wire and cable website.
Yu Zheng is entangled in whether the cable is bought online or bought in a physical store. Jinhaotai suggests that you can first consult the product price online, then go to the physical store to check the quality in the same city, and then decide where to buy. After all, the advantages of online and physical stores have their own advantages.

The main functions and advantages of ACSR

在先进科学技术的现代时代,许多现代工业设施已经出现在我们的世界中并存在于我们的生活中。钢芯铝绞线也是在电力中起重要作用的主要力量。ACSR是由单层或多层铝绞线在镀锌钢芯外部绞合而成的增强钢丝。内部是钢“芯”,外部通过绞合用铝线包裹在钢芯上。; 钢芯主要用于增加强度,铝绞线主要用于传输电能。它在电力和输电线路行业中占有重要地位。对于高压传输线,由于线路的路径有限,因此无法将其安装在一条路径上。对于多行,人们想出了一种使用一条路径,一组铁塔和多根电线的方法,即一条线相当于多条线。对于500KV输电线路,我国大部分地区采用悬挂四根电线的方法。这种接线方法称为同塔并联。这就是为什么某些杆用于“ L J”和“ LGJ”的主要原因。

下面简要介绍一下ACSR的优点和应用。ACSR具有结构简单,安装,维修方便,低线成本,传输容量大,并且有利于特殊地理条件如杂交河流和沟壑铺设。它具有出色的导电性以及令人满意的机械强度和拉伸强度。高强度和可扩展的塔杆间距等功能。因此,广泛用于各种电压等级的架空输配电线路。

钢芯铝绞线的缩写:“ LGJ”是绞合的铝线和钢丝,普通铝绞线“ L J”主要用于架空输电线路。ACSR的内部为钢“芯”,外部通过绞合用铝线包裹在钢芯上。钢芯主要增加强度,而铝绞线主要传输电能。它们都是裸线,用途基本相同,型号规格不同。
普通铝绞线:型号以“ L J”表示,为裸线。目前,中国一般使用铝包钢绞线(LGJ)作为导体。钢芯主要用于增加强度,铝绞线主要用于传输电能。根据电压的不同,导线的截面积也不同。例如,500 kV传输线的电流导体通常使用LGJ-400 / 35导体。其中,L是铝线的缩写,G是钢芯的缩写,J是绞线的缩写,400是铝的400平方毫米,而35是钢的35平方毫米。