How Do Cold Shrinkable Termination and Heat Shrinkable Termination Provide Insulation and Sealing Protection?
The cable terminal not only undertakes the connection task between the cable and the electrical equipment, but also needs to deal with the problem of electric field concentration at the fracture of the insulation shielding layer, and prevent external factors such as moisture and dust from affecting the insulation structure. Cold-shrinkable cable terminals and heat-shrinkable cable terminals use different shrinkage technologies, but they all need to achieve cable end protection through insulation materials, stress control and sealing structures.
Why Do Cable Terminals Need Insulation and Sealing Protection?
In the process of cable terminal fabrication, some outer sheaths and semi-conductive shielding layers need to be peeled off in order to complete the conductor connection. This will change the original electric field distribution of the cable, especially in the fracture position of the semi-conductive shielding layer, which is prone to local electric field concentration.
If there is no effective stress control and insulation protection, it may cause partial discharge, insulation aging and other problems. In addition, outdoor cable terminals also need to cope with changes in rain, moisture, ultraviolet and temperature. Therefore, the cable terminal needs to focus on three functions:
· Electrical Insulation : Provide insulation protection for conductors and connection areas
· Electric field stress control : improving the electric field distribution at the fracture of the shielding layer
· Environmental sealing : reduce water, dust and pollutants into the terminal internal
Cold Shrinkable Termination How to Achieve Insulation and Sealing?
The cold-shrinkable cable terminal adopts a pre-expanded structure, usually using silicone rubber as the main insulating material. The product is pre-expanded in the factory and maintained by the internal support core.
During installation, the terminal is positioned at the specified position of the cable, and the support core is gradually pulled out. The silicone rubber relies on its own elasticity to recover and generate radial pressure on the cable surface to form a tightly bonded insulation and sealing interface.
The Main Characteristics of Cold Shrinkage Technology:
· Pre-expansion structure: Pre-expansion is completed before leaving the factory, without on-site heating.
· Silicone rubber insulation: Using the elasticity and electrical insulation properties of silicone rubber to provide protection.
· Radial shrinkage pressure: After shrinkage, it is closely attached to the cable surface to reduce the interface gap.
· Convenient installation: No open fire or special heat shrink heating equipment is needed, which is suitable for scenes with limited construction space.
CCMT 's cold shrinkable termination is suitable for 1-36kV power system. It adopts pre-expanded silicone rubber structure and can be used in distribution lines, substations, industrial equipment and new energy projects.
How Does Heat Shrinkable Termination Achieve Insulation and Sealing?
The heat-shrinkable cable terminal activates the shrinkage material through an external heat source to coat the cable surface. The construction personnel heats up according to the specified installation sequence, and the material gradually shrinks and forms an insulation and sealing structure.
Different from the cold shrinkable structure, the installation quality of the heat shrinkable terminal is closely related to the heating process. Heating uniformity, operating distance and shrinkage order will affect the final effect.
The Main Structure and Function of Heat Shrinkable Termination:
· Insulation pipe: covering the connection area and providing electrical insulation.
· Stress control tube: improve the electric field distribution at the fracture of the semi-conductive shielding layer.
· Hot melt adhesive layer: Some products use hot melt adhesive to form interface seal.
· External protection tube: Provide additional external protection.
Some outdoor heat shrinkable terminals are also equipped with umbrella skirt structure to increase the creepage distance and adapt to humid and polluted environments. The specific structure, material and performance parameters of different products need to be confirmed according to the manufacturer 's product specifications and test reports.
Key Parameters and Detection Items That Affect the Performance of Cable Terminals.
The insulation and sealing performance of cable terminals can not only be judged by appearance, but also need to be verified by electrical test and thermal cycle test. The following are the main differences in the technical implementation of the two types of products.
| Performance Items | Cold Shrinkable Termination | Heat Shrinkable Termination |
| Main Materials | Typically made of silicone rubber | Uses heat-shrinkable polymers and other materials according to product design |
| Installation Method | Remove the support core to allow natural shrinkage | Requires external heating for shrinkage |
| Insulation Protection | Relies on insulating materials and termination structures | Relies on insulation tubes and related structures |
| Stress Control | Improves electric field distribution through stress control design | Uses stress control tubes or corresponding materials to improve electric field distribution |
| Sealing Method | Elastic recovery generates radial pressure and works with the sealing structure | Sealed by heat-shrinkable wrapping; some products use hot-melt adhesive sealing |
| Installation Equipment | No external heating equipment required | Requires suitable heating tools |
Cold shrinkable termination detection data of CCMT:
| Test Item | Test Conditions | Test Results |
| AC Withstand Voltage Test | 39 kV, 5 minutes | Passed, no breakdown or flashover |
| Wet AC Withstand Voltage Test | 35 kV, 1 minute | Passed, no breakdown or flashover |
| Partial Discharge Test | 15 kV, ambient temperature | Less than 0.6 pC |
| Impulse Voltage Test | ±95 kV, 10 impulses for each polarity | Passed |
| Thermal Cycling Test | 22 kV, 95–100°C | 60 cycles completed, passed |
| High-Temperature Partial Discharge Test | 15 kV, 95–100°C | Less than 0.6 pC |
These test results can help buyers understand the performance of products under electrical stress and temperature changes.
Installation Conditions and Long-Term Operation Performance.
The long-term operation performance of cable terminals depends not only on the material itself, but also on the installation quality. Purchasers and engineering contractors need to focus on product applications:
· Cable pretreatment: Whether the cable stripping size meets the installation requirements
· Surface cleaning: Whether the insulation surface is clean, no residual impurities
· Stress control positioning: Whether the stress control components are accurately installed
· Sealing interface: Whether the contact position between the cable and the terminal is sealed completely
· Installation operation: Whether according to the product description to complete the contraction and installation
For the cold shrinkable terminal, attention should be paid to the extraction sequence of the support core and the terminal positioning to avoid offset during the shrinkage process. For the thermal shrinkage terminal, it is necessary to control the heating process to avoid local overheating or insufficient shrinkage.
In the product procurement stage, it is recommended to examine the manufacturer 's material control, production equipment, quality management system and third-party testing capabilities at the same time, rather than focusing on product appearance and quotation.
CCMT: Cable Accessories Production and Supply Capacity.
Our company was founded in 1986, with more than 40 years of cable accessories industry experience. Our production base area of more than 10,000 square meters, with more than 200 employees and more than 40 production equipment. With a monthly supply capacity of approximately 20,000 units for cold shrinkable cable terminals, we can support mass production and OEM / ODM customization requirements for products of different specifications.
In addition to cold-shrinkable cable terminals, we also provide products such as heat-shrinkable cable terminals, cold-shrinkable cable joints, and heat-shrinkable cable joints, and support customized production services. Relying on the ISO 9001 : 2015 quality management system and the corresponding product testing capabilities, we provide product supply and technical support for overseas power engineering contractors, electrical equipment manufacturers and cable accessories dealers.
If you are looking for cable termination products for distribution engineering or industrial power projects, please contact CCMT for product specifications, test data and customized product solutions.
