With the rapid urbanization in China and the rising living standards of both urban and rural populations, the use of cables in distribution networks—especially in large and medium-sized cities—has been steadily increasing. This has led to a surge in demand for cable accessories, driving innovation and continuous improvement in their design and performance.
**The Role of Power Cable Accessories**
Power cable accessories play a crucial role in ensuring the safe and efficient operation of power systems. At cable terminations and joints, the electric field distribution is more complex compared to the cable body due to the interruption of the metal sheath and shielding layer. This creates axial stress at the termination, making it essential to use proper cable accessories that can maintain continuity, insulation, and sealing. These accessories act as connection devices that meet strict insulation and sealing requirements, ensuring reliable power transmission.
A typical power cable consists of four main layers: conductor, insulation, shielding, and sheathing. The accessories used at terminations and intermediate joints must replicate these layers, with secure conductor connections, reliable insulation, effective sealing, and sufficient mechanical strength. Properly designed and installed cable accessories are vital for maintaining the quality and reliability of the entire power distribution network.
**Classification of Medium Voltage Cable Accessories (35kV and Below)**
Cable accessories for 35kV and below can be broadly categorized based on their insulation molding techniques. Common types include wrapped, heat-shrinkable, cold-shrinkable, and pre-fabricated accessories. There are also cast and detachable types used in specific applications.
**2.1 Wrapped Cable Accessories**
Wrapped accessories are made by wrapping tape around the insulation and shielding. They use stress cones or high-dielectric-constant tapes to control electric fields. Although effective, this method requires advanced technical skills and is increasingly being replaced by more modern solutions.
**2.2 Heat-Shrinkable Cable Accessories**
These accessories utilize the "elastic memory" effect of polymers. Pre-molded components like tubing, branch sleeves, and rain covers are installed on processed cables and shrink when heated. They are cost-effective and easy to install but may suffer from reduced lifespan due to thermal expansion and contraction, affecting long-term reliability.
**2.3 Cold-Shrinkable Cable Accessories**
Made from silicone or EPDM rubber, cold-shrinkable products are pre-expanded on a support core and installed without heat. Once the core is removed, they contract and fit tightly. While offering good performance, they have a limited shelf life and are generally more expensive.
**2.4 Prefabricated Cable Accessories**
Prefabricated accessories are molded in factories using rubber materials and include reinforced insulation and semi-conducting shielding. They are assembled on-site after the cable ends are prepared. These accessories can be factory-tested, improving reliability and reducing on-site installation time. They share similarities with cold-shrinkable types but differ in material properties and manufacturing processes.
**2.5 Cast Cable Accessories**
Made from thermosetting resins, cast accessories are poured into molds and cured on-site. They are ideal for connecting plastic-insulated and paper-insulated cables, offering strong mechanical and electrical properties.
**2.6 Separable Connectors**
These fully insulated connectors allow for easy connection and disconnection of cables and equipment. Used in switchgear, ring main units, and branch boxes, they are considered a new type of cable termination, often using pre-fabricated structures.
From the above classification, it's clear that technologies that simplify on-site installation, such as prefabrication and cold shrinking, are becoming central to the development of cable accessories.
**New Technologies in Cable Accessories**
**3.1 Conductor Connections**
Good conductor connections are essential for reliable power transmission. The contact resistance at the connection point must be low and stable. Modern bolted connection methods reduce the need for specialized tools, simplifying installation while ensuring quality. For aluminum cables, special oxidation removal is no longer required.
**3.2 Insulating Materials**
EPDM and silicone rubber are widely used in prefabricated accessories. In high-voltage applications, European-style silicone-based designs and Japanese-style EPDM-based options are common. Medium-voltage accessories made from improved EPDM offer better mechanical strength and tear resistance than similar silicone products.
**3.3 Field Pre-Expansion**
This technique involves pre-expanding cold-shrinkable accessories on-site before installation. It helps preserve product performance during transport and storage, ensuring consistent radial pressure and long-term reliability. Ideal for spare parts in critical systems.
In conclusion, the future of cable accessory technology lies in prefabrication and simplification. Factory-tested cold-shrinkable pre-fabricated accessories are set to become the standard, enhancing system safety and economic efficiency. By reducing the skill requirements for on-site work, these advancements ensure higher-quality installations and more reliable power supply.
Our aluminium Die Casting capabilities offer several advantages to our customers:Precision and accuracy: With our advanced equipment and skilled workforce, we can achieve tight tolerances and intricate geometries, meeting the most demanding design specifications.Cost-effectiveness: Aluminium die casting allows for high-volume production with minimal material waste, resulting in cost-effective manufacturing solutions for our customers.Versatility: We can produce a wide range of components, from small intricate parts to larger structural components, catering to diverse industry requirements.Rapid prototyping: Our in-house tooling capabilities and flexible manufacturing processes enable rapid prototyping and quick turnaround times, facilitating the development and testing of new designs.
High Pressure Aluminum Die Casting,Aluminium Die Casting Mould,aluminum die castings,casting aluminum,aluminum gravity die casting
Taiyuan Simis Investment Casting Co., Ltd , https://www.precision-casting.biz