How to identify true and false cross-linked cables

In the process of partial discharge and high voltage test of medium-voltage cable finished products using the series resonance test system, the phenomenon of false breakdown may suddenly occur during the test due to the respective reasons. How to correctly identify whether the cable itself has a true breakdown or other The reason for the false breakdown of the cable is of great significance for improving the efficiency of the cable factory test.

The partial discharge and high voltage test of medium-voltage cross-linked power cables are carried out in a shielded room one by one. At this time, re-examination of the insulated cores may be considered. If the core is replaced after the voltage test is passed, it should be determined that the cable is true. The breakdown occurred. Alternatively, if the breakdown voltage is gradually reduced, it can be determined that a true breakdown of the cable has occurred. If the breakdown voltage of the cable is the same value, consider whether the end of the cable has occurred. Breakdown, at this time, can be partially placed in the shielded room door to the door interlock switch, artificially closed, will open the shield door, boost pressure, observe the breakdown phenomenon, will be able to quickly determine the end of the breakdown position. If there is no breakdown of the cable ends after the investigation, replace the insulated cores and cables, and even retest the once-qualified cable retest live. The breakdown voltage always maintains the same value, and the cable should be confirmed The phenomenon of spurious breakdown was examined and the equipment was inspected and tested after troubleshooting. However, for some large-scale single-core medium-voltage cross-linked cables that have been crossed, it is also necessary to check whether they have exceeded the allowable load of the test equipment. In this case, the detuning tripping phenomenon will occur during the test and do not arbitrarily determine the occurrence of the cable. Breakdown.

There is a special case that needs to be explained here. A short circuit occurs inside the predominant cable insulation. The series resonance test system may not be resonantly boosted, which is also a special type of cable breakdown phenomenon. If you encounter this phenomenon, you can confirm it by replacing the insulated wire core with good insulation.

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