Cable accessories refer to the intermediate connections and terminal connections of various cables in the cable line, which together with the cables form a power transmission network. With the continuous development of cable manufacturing technology, cable accessories have gone through several stages, such as cast cable accessories, wrapped cable accessories, heat shrinkable cable accessories, prefabricated cable accessories and cold shrinkable cable accessories. At present, the most widely used are heat shrinkable cable accessories, prefabricated cable accessories and cold shrinkable cable accessories. Next, let’s take a look at it in detail.
Cable Joint Accessories
- Wrapping Type: Cable joint accessories made on-site with rubber strips (self-adhesive) are called wrapping type cable accessories, which are easy to loosen, have poor fire resistance and short life.
- Pouring Type: It is poured on-site with thermosetting resin as the main material. The selected materials are epoxy resin, polyurethane, acrylic, etc. The fatal disadvantage of this type of accessory is that it is easy to produce bubbles during curing.
- Molded Type: It is mainly used for the middle connection of the cable, and the heating is carried out on the spot to be integrated with the cable. The production process of this accessory is complicated and takes a long time, and it is not suitable for termination and joints.
- Cold Shrinkage Type: Use silicone rubber, EPDM and other elastomers to be pre-expanded in the factory and added with plastic support strips to form. During on-site construction, pull out the support bar to shrink the pipe on the cable under the inherent elastic effect of rubber to form a cable accessory. This accessory is most suitable for construction sites that cannot be heated by open flames, such as mines, petrochemicals, etc.
- Heat-Shrinkable Type: An accessory made by making rubber-plastic alloy into different component products with shape memory effect, and heating and shrinking it on the cable on site. The accessory has the characteristics of light weight, simple and convenient construction, reliable operation and low price.
- Prefabricated Type: Accessories made by injecting silicone rubber into different components, vulcanizing them in one go, retaining only the contact interface, and inserting the cables during field construction. This construction process reduces the unpredictable disadvantages in the environment to a minimum. Therefore this accessory has great potential use value and is the development direction of cross-linked cable accessory. However, the manufacturing technology is difficult and involves a variety of disciplines and industries. Prefabricated accessories still use heat-shrinkable materials for installation below the trigeminal and shield ports of the cable. Therefore it is actually a combination of prefabricated and heat-shrinkable type.
Now generally the most commonly used and the most convenient to install and use are: heat shrinkable joint accessories and cold shrinkable joint accessories:
Heat-shrinkable cable accessories, as the name suggests, are cable accessories that only shrink when heated at high temperatures. Generally, they are applicable to places that can be heated by fire. There are certain safety risks, so the scope of use is limited. The advantage is that the price is cheaper compared to cold shrinkage.
Cold-shrinkable cable accessories are generally made of elastic silicone rubber and ethylene-propylene rubber. This material is used for injection vulcanization, and then expanded and lined with plastic spiral supports. It has the advantages of small size, convenient operation, rapidness, no special tools, and wide application range. Compared with heat-shrinkable cable accessories, it does not need to be heated by fire, and moving or bending after installation will not cause the danger of disconnection between the inner layers of the accessory like heat-shrinkable cable accessories.