Cross linked cable usually refers to the insulation layer of the cable using cross-linked materials. The commonly used material for Z is cross-linked polyethylene (XLPE). The cross-linking process is to process a linear molecular structure polyethylene (PE) material into a cross-linked polyethylene with a network like branching structure through specific processing methods. By increasing the long-term allowable working temperature from 70 ℃ to 90 ℃ (or higher) and the short-circuit allowable temperature from 140 ℃ to 250 ℃ (or higher), the actual performance has been greatly improved while maintaining its original excellent electrical performance.

Next, the servo cable manufacturer's editor will explain to you - "Insulation shrinkage" of cross-linked cables? How to eliminate it?   

(1) Insulation shrinkage:

During the production process of cross-linked cables, there is thermal stress inside. When a considerable length of the cable is cut, the thermal stress inside the insulation is released, causing axial displacement of the cable insulation relative to the conductor at the end of the cable. This phenomenon, known as "insulation shrinkage", is widely present.

(2) Hazards of "insulation shrinkage":

After running for a period of time, if insulation shrinkage occurs, it will cause air gaps at the terminals and joints, leading to partial discharge and insulation breakdown. If the phenomenon of "insulation shrinkage" in the cable is severe, it indicates that there is significant internal stress in the cable body, which can easily cause dendritic discharge.   

(3) The main reasons for "insulation shrinkage" are:

The main reason is the thermal stress during the cross-linking production process. During the production process of cables, the temperature of cross-linked cables exceeds the crystallization melting temperature, resulting in a significant decrease in the compressive elastic modulus of the cables. However, the cooling process of the cable production line is relatively rapid, which prevents the release of thermal stress and ultimately forms thermal stress in the cable body. The thermal expansion coefficients of cross-linked cable insulation and conductor are different, with a difference of 10-30 times. Cross linked polyethylene is more prone to shrinkage compared to metal conductors.

(4) Measures to eliminate "insulation shrinkage":

The thermal stress inside the cable must be released. Thermal stress must be released during the attachment installation process.

Heat and straighten. Stress relief and straightening. Fixed design. Fixed device is a cable fixing device specially designed for terminals or joints to prevent cable insulation from retracting. After cutting off the cable, leave some time for the cable insulation to slowly retract. The general waiting time is 24 hours. This method is relatively negative.