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The principle and construction technology of Cold Shrinkable Straight Through Joint of XLPE Cable

The Features of Cold Shrinkable technology

Cold shrinkage technology is also known as pre-expansion technology, that is, the silicone rubber with elastic characteristics is stretched out in advance within the elastic range by mechanical means, and the plastic core is inserted to be fixed. The cold shrinkable body has a persistent radial pressure on the cable body, which can avoid bubbles in the insulation layer when the heat shrinkable material expands and shrinks. When the wire core is removed during installation, the elastomer rapidly shrinks in turn on the cable body, and the air can be completely discharged by the contraction in turn.

Stress control mechanism of Cold Shrinkable Straight Through Joint

In order to uniform electric field distribution and eliminate local field concentration, a semi-conductive shielding layer is set between the main insulation and conductor of the Cold Shrinkable Straight Through Joint. In addition, the cold shrinkage main body has a strong shrinkage ability and elastic deformation ability, which can not only fully eliminate the electric field concentration at the prominent spot, but also eliminate the potential difference in the gap, so that the power frequency voltage resistance of the joint main body is greatly improved. For multistage series media, attention should be paid to the coordination of the normal field strength component perpendicular to the medium layer and the tangential field strength component parallel to the medium layer

1. The position with the highest probability of partial discharge is the gap between the layers of media, and the burr part of the copper strip of the wire core pressure pipe. It should be strictly polished to eliminate the strong electric field at the tip, and the distribution structure of the smooth electric field of the semi-conductive covering layer should be wrapped at the specified position according to the regulations.

2. The cut length of the main insulation of the cable and the depth of the semi-conductive outer layer of the cable into the main body should be controlled to ensure the reliability of insulation.

3. Handle well the work of wrapping the belt and installing the net, especially the winding of waterproof belt and armor belt, to ensure the sealing performance of the joint and eliminate the influence of external factors on the operation of the joint.
Cold Shrinkable Straight Through Joint
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