Application of Continuous Expansion Technology in Heat-Shrinkable Cable Accessories
In the medium and high voltage cable terminals and connectors, the structural transition between the cable insulation layer, the semi-conductive shielding layer and the connection part is directly related to the electric field distribution and the reliability of the insulation system. After the cable shielding layer is cut off, the local electric field may be concentrated. If the accessory structure, material properties or installation status cannot meet the design requirements, it may increase the risk of partial discharge and insulation aging.
IEC 60502-4 issued by the International Electrotechnical Commission puts forward requirements for the type test of medium voltage cable accessories within the scope of application. Relevant tests are used to verify the performance of cable accessories under specified conditions, rather than judging the reliability of the whole accessory system by a single material parameter. For purchasers, when choosing heat shrinkable tubes, in addition to paying attention to the insulation, semi-conductive or stress control material itself, they also need to understand the product structure, size specifications, heat recovery status and its matching with the target cable accessories.
For thick-walled heat shrinkable tubes and multi-layer composite tubes, these requirements are further extended to the manufacturing process. The size, wall thickness and structural state after expansion need to meet the requirements of product design, so as to provide a suitable specification basis for subsequent installation and thermal recovery.
Based on this demand, CCMT applies the continuous expansion process to the manufacture of heat-shrinkable terminal insulation tubes, heat-shrinkable stress control tubes, heat-shrinkable semi-conductive tubes and heat-shrinkable semi-conductive insulation composite tubes, and focuses on improving the continuous expansion capacity of semi-conductive insulation sleeves. According to the corresponding product specifications, the manufacturing capacity of up to 6.0 mm thickness can be realized, which provides more choices for the development of thick-walled composite pipes.
Continuous Expansion : From Manufacturing Process to Product Structure Control.
The difference between continuous expansion and intermittent expansion is first reflected in the organization of the production process.
· Continuous expansion focuses on the expansion and size control of materials in the continuous production process ;
· Intermittent expansion is processed in sections or batches according to specific equipment and process arrangements.
The actual effect of the two processes depends on the material system, equipment design, temperature control, expansion conditions and subsequent setting process, and the product performance cannot be judged only by the process name.
For heat shrinkable cable accessories, buyers should pay more attention to whether the process can meet the technical requirements of the final product, including the dimensional relationship before and after expansion, the wall thickness after recovery, dimensional tolerances and the integrity of the product structure.
Continuous Expansion and Application Requirements of Four Types of Heat Shrinkable Products.
1. Heat shrink termination sleeve.
It is mainly used for insulation protection of cable terminal and connection parts. The continuous expansion process helps to meet the dimensional manufacturing requirements of products of different specifications. The purchaser should focus on checking the inner diameter, wall thickness and product coverage after recovery to ensure that it matches the target cable structure.
2. Stress control sleeves.
It is used for electric field stress control of cable terminals and other parts. When purchasing, in addition to paying attention to the size and recovery state after expansion, the electrical performance of the material and the applicable voltage level of the product should also be confirmed. The continuous expansion process needs to be combined with the size requirements and quality control of specific products.
3. Heat shrink semi-conductive tube.
The semi-conductive functional structure used in cable accessories, its selection involves size adaptation, material electrical properties and structural state after thermal recovery. The continuous expansion capability can be used to meet the manufacturing requirements of different specifications, and the actual product quality still needs to be verified by the corresponding size detection and performance test.
4. Semiconductive insulation sleeves.
It is composed of a semi-conductive layer and an insulating layer, and has clear requirements for the overall size and composite structure. We have a thickness manufacturing capability of up to 6.0 mm. For the purchaser, in addition to confirming the thickness, it is also necessary to check the test data of each layer structure, recovered size and corresponding model to evaluate whether the product meets the requirements of the target cable accessories.
From Product Parameters to Quality Verification : What Should Be Paid Attention to When Purchasing?
Continuous expansion is a manufacturing process and cannot replace product performance verification. For heat-shrinkable terminal insulated pipe, stress control pipe, semi-conductive pipe and semi-conductive insulated composite pipe, buyers should check the following data according to product functions and application scenarios :
· Size and wall thickness : check the product model, inner diameter before expansion, inner diameter after recovery, wall thickness after recovery and corresponding tolerances.
· Material properties : check the tensile strength, elongation at break, water absorption, dielectric properties or semi-conductive related indicators.
· Structure and recovery state : The thickness of each layer, structural integrity and recovery state of the composite pipe are mainly checked.
· Test basis : check IEC, UL or other applicable test standards, and confirm that the test items correspond to the product model.
· Adaptability of accessories : Confirm specifications in combination with cable structure, target voltage level, terminal or joint design and installation conditions.
Manufacturing Experience and Project Practice : From Production Capacity to Quality Documents.
CCMT has been engaged in the R & D and manufacturing of cable accessories since 1986, with more than 10,000 square meters of production base and more than 40 sets of production equipment. Our heat-shrinkable pipe related production system includes extrusion, expansion and other processes, and the monthly production capacity of heat-shrinkable pipe can reach 5 million meters.
In terms of customer cooperation, we have provided nearly one million meters of low-pressure heat shrinkable tubes for ABB and participated in projects such as Fangjiashan Nuclear Power Plant, Hainan Nuclear Power Plant and Taishan Nuclear Power Plant. These cooperation experiences reflect our supply and project experience in the field of cable accessories and related products.
In terms of quality management, we have passed the ISO9001 quality management system certification, and have CE-related certification materials and test reports issued by third-party international certified independent laboratories. For different products, the purchaser can obtain the corresponding technical parameter table, test report and quality file according to the specific model, and check the consistency of product performance and project requirements.
Conclusion :
The significance of continuous expansion technology is not only to change the production mode of heat shrinkable tubes, but also to provide manufacturing support for different product structures and specifications. For heat-shrinkable terminal insulated pipe, heat-shrinkable stress control pipe, heat-shrinkable semi-conductive pipe and semi-conductive insulated composite pipe, the process capability needs to correspond to the product function, size requirements and test basis.
In the manufacture of semi conductive insulation sleeves, the continuous expansion ability of CCMT and the thickness manufacturing ability of up to 6.0 mm provide a new choice for the development of thick wall specifications. For buyers with customized requirements, it is recommended to provide cable structure, required inner diameter, wall thickness and application requirements, so as to further confirm the applicable specifications and related technical documents.
