Cable accessories are not sealed tightly (especially direct burial of middle connector).

Once the moisture or water enters into the cable insulation from the cable end or the cable outer sheath.

It is possible that they vertically penetrate from the gap of cooper wire shield or conductor, imperiling the entire cable system.

Damp cable can lead to 'the water branches' phenomenon under the action of high electric field.

Thus the XLPE insulation performance decline, eventually leading to the cable insulation breakdown.

Therefore, the damp cable must be dried up.

So far, there is no standard operating method of dry processing and also no uniform identification of treatment results.

Dry processing principle is to use compressed gas medium (usually dry) in one end of the cable.

Testing B phase resistance with megger to find a cable earth fault, zero means unidirectional ground fault.

This cable length is 450m.

Due to the low impedance fault, the distance between fault point and test point can be directly calculated by low pressure pulse method mentioned above.

After selecting cable parameters, use the tester to find the cable end breakdown.

From test to finding the fault, it just costs 30min, not only saving the repair time but also reducing losses.

In the reconstruction of city power grid, cables especially PE insulated power cables have been widely used.

However, due to the special nature of cable, special requirements for the installation, operation and maintenance of cables are needed.

Lowered cable insulation resistance caused by cable moisture and water entering is the main reason for the cable lines accident.