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Stress Control Method for Cold Shrinkable Cable Accessories

2022-10-22
Cold shrinkable cable accessories are components of various cable accessories made of elastomer materials (silicone rubber and ethylene propylene rubber are commonly used) injected and vulcanized in the factory, then expanded diameter and lined with plastic spiral supports.

When installing Cold shrinkable cable accessories on site, put these pre-expansion pieces on the end or joint of the treated cable, pull out the plastic spiral strip (support) of internal support, and press the cable accessories formed by cable insulation. Because cold contraction cable accessories rely on elastic retraction force at room temperature, rather than heat contraction cable accessories to use fire heating shrinkage, so it is commonly known as cold contraction cable accessories.

Common stress control methods of cold shrinkable cable accessories are as follows:

1. Electrical stress control method:

The essence of electric stress control is to control the size and distribution of electric field intensity in cable accessories. Effective measures such as structural design are taken to evacuate the concentrated electric field inside the cable accessories, to achieve the purpose of equalizing the electric field, reduce the probability of local breakdown, so as to improve the reliability and service life of the cable accessories.

2. Stress cone dispersion method:

The stress cone dispersing method is to reasonably extend the fracture of the outer shielding layer of the cable, form a stress cone with arc shape, make its zero potential form a horn shape of external tension, increase the radian of the power line, so as to evacuate the concentrated electric field intensity and improve the distribution of electric field. From the electrical point of view, the stress cone dispersion method is the safest and most reliable method. However, the insulation layer size of cable accessories is extremely strict, and the installation of cable joints is complex, and lubricating oil should be introduced to avoid the formation of new tips.

3. Electrical stress layer control method:

Electric stress layer control method, that is, a composite dielectric layer with high dielectric constant (electric stress layer) is introduced into the fracture of the semi-conductive shielding layer of cable. The electrical parameters of the dielectric of the electric stress layer are adjusted to regulate the potential distribution of the insulating surface at the fracture of the shielding layer and improve the electric field distribution. Usually, the high dielectric constant electrical stress control material is a composite material with polyethylene or ethylene propylene rubber as the matrix, and the dielectric constant is greater than 20.


Cold Shrinkable Cable Accessories


The Cold Shrinkable Cable Accessories of HUAYI CABLE ACCESSORIES Co.,Ltd. mainly uses the stress cone dispersion method.

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