Heat-shrinkable Medium and low voltage cable accessories used a lot of product types are mainly heat-shrinkable accessories, prefabricated accessories, cold shrinkable accessories.
They have the following characteristics: The materials used in general are polyethylene, ethylene-acetic acid ethylene (EVA) and ethylene-propylene glycol, such as the composition of a variety of materials, such as blends. This kind of product mainly uses the stress tube to treat the electric stress concentration problem. The parameter control method is adopted to relieve the stress concentration of electric field. The main advantages are light, easy to install, performance is still good, the price is cheap. The stress pipe is a heat shrinkable tube with special electrical parameters (1010-1012ΩCM) with a large dielectric constant (20--25), and the stress of the insulation shielding fracture is forced to be dispersed along the stress pipe by electrical parameters. This technique is commonly used in 35kV and below cable accessories.
Because of high voltage level, the stress tube will heat up and not work reliably.
Prefabricated type The materials used are generally silicone rubber or ethylene-propylene rubbers. This paper mainly uses the geometrical structure method, i.e. stress cone, to deal with stress concentration problem. The main advantage is that the material performance is excellent, the installation is more convenient and quick, without heating can be installed, good elasticity, so that the interface performance is greatly improved. Medium and low voltage and high-voltage cable used in the main form. The problem is that the outer diameter of the insulating layer of the cable is required high, the usual interference volume in the 2~5mm (that is, the cable insulation outside diameter is greater than the diameter of the cable attachment 2~5mm), too little interference, cable accessories will be faulty; too much interference, cable accessories installation is very difficult (high technology requirements). Especially in the middle of the problem is prominent, installation is not convenient, and often become a fault point. In addition, the price is more expensive.
The key technical problems in its use are: The size of the attachment and the size of the cable to be installed to meet the required requirements. Also need to use silicone grease lubrication interface to facilitate installation.
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