The prefabricated and cold shrink cable accessories are made of the material characteristics such as high elasticity, high resistance volume ratio, good hydrophobicity and good aging resistance of silicon image adhesive. The raw materials of the two accessories are basically the same, but the different production and installation process and design principle make the two cable accessories show different characteristics.
First, prefabricated:
Advantages: because of the lack of pre expansion, the production process is relatively simple, the productivity is high, the volume is small, the installation process is simple, and the fire is not used, time saving and labor saving, which greatly reduces the quality accidents caused by improper operation, and the possibility of installation error is low;
Disadvantages: due to the limitation of prefabrication process, the inner diameter of prefabricated terminal is only slightly smaller than the outer diameter of cable insulation layer, so the radial pressure produced by the terminal to the cable is less obvious, the sealing is relatively weak, and the possibility of internal creeping electric shock is greatly increased due to the gap (of course, this is not to say that the prefabricated cable accessories are attached Unsafe, please don't break the rules, but it is a little lower in this respect than the cold shrinkage type). The terminal will not be positioned firmly due to the small radial pressure of the cable, and the breakdown accident will occur because the stress cone deviates from the copper shield section due to dislocation (such as the pole on the supporting cable) during the process of moving the cable.
Cold shrink:
Advantages: it is suitable for wide surface, one specification is suitable for three square cables; after installation, the proper radial pressure on the cable body shall be maintained, so that the internal interface is closely connected and will not be shocked due to the respiratory function of the cable during operation. The installation operation is simple, no fire is needed, time saving and labor saving, which solves the phenomenon that the prefabricated cable accessories are not tight or not installed. The sealing property is good in the environment of high humidity, heat and salt fog.
Disadvantages: due to the production process, there is more expansion process and expansion and contraction characteristics, so that the silica gel used for the cold shrinkable cable accessories is much higher than the prefabricated ones (such as tensile rate and tear resistance), so the production cost is higher than that of prefabricated accessories; the storage period is shorter, generally half a year to two years, because the cold shrinkable cable accessories are pre expanded, The internal brace may be scattered or the silicone material fatigue shrinkage is not in place when the inner brace is stored for a long time. (therefore, the cold shrink cable accessories will generally be produced with high-performance liquid silica gel. At present, there are some cheap cold shrinkable cable accessories with poor performance with solid silica gel, and the aging is easy to crack and shrink tight. The advantages of the cold shrink type accessories produced by solid silica gel will soon disappear. It is suggested that when you choose cold shrink cable accessories, you should not be greedy and cheap. Try to choose the products that make imported liquid silica gel to produce cable accessories. For example, the liquid silica gel of Dow Corning in the United States should be the best at present) compared with the prefabricated type, the installation of cold shrink cable accessories requires higher requirements for installation workers and is more complex.
The pre cast cable accessories are coming out earlier than the cold shrinkage type. The design of the cold shrinkable cable accessories based on the prefabricated attachment foundation benefits from the progress and evolution of silica gel materials (because the performance requirements of the silica gel materials used by the cold shrinkable accessories are very high, the performance of the silica gel materials when the prefabricated accessories appear can not meet the requirements of the present cold shrinkable accessories). The design concept of cold shrink cable accessories should be more advanced, and it has the tendency to replace prefabricated cable accessories.