How do you determine if the XLPE cable is actually pierced?

2023-05-23 123

When a breakdown occurs during the test, the insulating core should be replaced for inspection.


After replacing the insulating core, check the voltage again, and the voltage testing results represent different situations.


In the first case, the voltage test is normal, and it should be confirmed that the cable is faulty.


In the second case, the breakdown voltage gradually decreases, which means that there is a breakdown phenomenon inside the cable.


In the third case, the breakdown voltage is the same every time, which means that the breakdown may occur at the end of the cable.


So how to confirm that the breakdown inside the xlpe cable is a false breakdown?


After the second test, we can control the partial discharge of the shielded indoor cable and increase the voltage level to observe the breakdown phenomenon, so that the breakdown location can be determined.


If the breakdown position is not the end of the cable, the cable should be replaced, and sometimes even the qualified cable or no-load cable should be checked. After checking and replacing, the breakdown voltage value should be the same as before. When the cable breakdown phenomenon is a false breakdown that can be confirmed .


Some of the cross-connect cables sent for inspection may exceed the maximum load of the experimental equipment due to their excessive length. Therefore, it is necessary to determine whether the load is large enough before testing. Otherwise, a trip will occur during the test.


It should also be noted that if the test system cannot boost the voltage, this may be caused by an internal short circuit in the cable insulation, which can only be confirmed by replacing the insulation core.