Cable attachment metal layer grounding method

The cable preventive test basically stops the running cable once a year according to the plan. The metal layer in the cable accessory installation process is connected according to the traditional grounding method. Therefore, the cable test project mainly includes two items, the main insulation insulation resistance of the cable, and the cable. Main insulation DC withstand voltage test, usually the cable is added according to the test voltage specified in the table, if the cable is wet or damaged, the inner layer insulation may break down the cable, and then find the fault point, repair, pressurization with the same test voltage 5 minutes, after the normal operation, if still breakdown or leakage current is not normal, perform a search for the fault point and repair until the cable is completely normal. There are many unfavorable factors in this kind of process. Firstly, the power failure repair after cable breakdown is very long. For a company, the loss is incalculable. Secondly, preventive testing is often conducted in a concentrated manner. The cable tests are not only labor-intensive but also difficult to analyze each cable carefully. Each time a cable's preventive test is done with a DC voltage withstand test, it will produce a cumulative effect of internal degradation of the insulation, which will accelerate the aging of the cable insulation and shorten the service life of the cable.

The metal layer in the cable attachment installation process needs to change the traditional grounding method. The following method should be used.

When making the handover test, first-hand data should be kept. The data of the subsequent preventive test should be compared with the data of the handover test. When the cable main insulation insulation resistance value, cable sheath insulation resistance value, cable inner liner insulation resistance value, copper shield resistance and conductor resistance ratio value, and the transfer test data are compared and the data change is not great and they are all qualified In the range, DC withstand voltage tests should not be performed. When it is judged that the outer jacket and inner liner of the cable are damaged or water is infiltrated, or a new terminal is manufactured and a new intermediate connector is manufactured, and the copper shield of the cable is processed, the DC withstand voltage test of the cable is required. This will maximize the protection of the cable and extend the life of the cable.

Grounding method of metal layer in cable accessories:

1. Terminal: The armor layer and copper shield of the terminal should be separately grounded with insulated twisted wires. The cross-section of the ground wire of the copper shield shall not be less than 25m; the cross-section of the ground wire of the armor shall not be less than 10m.

2. Intermediate connector: The grounding wire of the copper shield in the middle connector must not be connected with the armor layer. The armored layer on both sides of the connector must be connected with another grounding wire and must be insulated from the copper shield. If there is no inner lining layer in the original structure of the joint, an inner lining layer should be added outside the copper shielding layer, and the lining of the inner lining layer of the cable body must be sealed well, that is, the integrity and continuation of the cable must be ensured. The outer layer of the ground wire connecting the armor must have the outer sheath and the same insulation and sealing performance as the outer sheath of the cable, ie the integrity and continuity of the outer sheath of the cable must be ensured.

Kexun cable tells us that the metal layer grounding method in the cable attachment, we now know it!