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Electric cable cross-linking quality defects and troubleshooting methods



Electric cable is the abbreviation of XLPE insulated electric cable. The cross-linked electric cable is suitable for transmission and distribution lines with a power frequency AC voltage of 500KV or less. At present, most of the high-voltage electric cables are made of XLPE insulation. Cross-linked electric cable usually means that the insulating layer of the electric cable is made of a cross-linked material. The commonly used material is cross-linked polyethylene (XLPE), what is the electric cable cross-linking?



Crosslinking degree (heat extension) failed



If the degree of crosslinking is not up to standard, the thermal-mechanical performance of the electric cable is unqualified and cannot meet the requirements of a working temperature of 90 °C.

electric cable

The reasons for the unqualified cross-linking degree are: the formula is unqualified, the proportion of the compounding agent is improper, and the formula should be adjusted to solve the problem; the second is improper curing process, such as low pressure, fast line speed, high cooling water level, etc.



The solution is to first find out what is the cause, it may be one kind, or it may be that several reasons exist at the same time, and the reasons are excluded.







Unqualified structure and appearance

(1) The thickness of the insulation layer is lower than the standard value, or the average thickness is lower than the nominal value. The reason for the unsatisfactory thickness of the insulation is that the line speed is fast, the amount of glue produced by the extruder is small, and the mold is improperly matched.


electric cable
The solution is to reduce the line speed or extruder speed and adjust the size of the mold.



(2) Eccentricity



The reason for the eccentricity is that the suspension control has changed after the mold has not been adjusted or raised.



The solution is to stabilize the drape control as much as possible during the driving process.



Bamboo shape



The reason why the electric cable is bamboo-like is that the traction speed is unstable due to electrical and mechanical systems. Second, the core is too small, or the outer diameter of the conductor is not uniform.



The troubleshooting method is to check the mechanical and electrical systems and troubleshoot them. Appropriately adjust the size of the core, control the outer diameter of the suburbs as uniform as possible, and the strands that exceed the process specifications can be used.



Surface scratch

electric cable

(1) The electric cable hits the upper and lower walls or foreign objects in the vulcanization tube. Therefore, it is required to adjust the suspension degree, try to make the core move in the middle of the cross-linked tube, and find foreign matter and clean it in time.



(2) There is burnt material on the outer edge of the mold sleeve. The solution is to adjust the temperature of the mold sleeve when starting the car to prevent overheating. Once it is burnt, it should be stopped immediately or it will not get better.



Bubble



There are two possible reasons for the bubbles generated in the insulation, one of which is caused by extrusion. The solution is to choose the right mold. There are bubbles in the shielding layer, the main reason is that there is moisture in the material, it should be dry before extrusion, and the second is insufficient cooling. At this time, the following appears, a circle of bubbles appear on the circumference of the equidistant distance from the core.



The method of elimination is to enhance cooling, raise the water level and lower the temperature of the cooling water.



Electric cable performance is unqualified

(1) Unsatisfactory discharge and dielectric loss



The reasons for the failure of free discharge and dielectric loss are complicated, and it is shielded from the outside. Whether the insulation contains bubbles and impurities, and the properties of the raw materials are closely related. The elimination method is to keep the raw materials clean and strictly according to the process.



(two) electric cable insulation breakdown



The reason for the electric cable insulation breakdown is mainly caused by impurities and external damage caused by the insulation material. Due to strict avoidance and external damage, the impurities are mixed as much as possible, and the semi-finished products are strictly managed to prevent smashing.
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