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9 Measures To Prevent Cable From Entering Water
Oct 07, 2018

1.The cable head should be sealed.
  Sawed off the end of the cable, whether stacked or laid, should be sealed with plastic (using a special cable sealing jacket), to prevent moisture infiltration.
2.Making cable head in time
  After cable laying, cable head must be made in time.
3.When buying cable

  Manufacturers with high quality must be chosen. Because the impurities and pores in insulation are the starting point of water tree, the quality of cable is very important to prevent the aging of water tree.
4.Strengthening the management of cable head manufacturing process
 Once the cable water, the earliest breakdown phenomenon is often the cable head, so the wire head made well, can extend the overall life of the cable. For example, when a cable peels off a semiconductor layer, we scratch a few lines vertically on the semiconductor layer, and then peel off the semiconductor like cane peeling. But when the knife is drawn, if it is too deep, it will damage the insulation layer and bring opportunities to the generation of water trees. In addition, when soldering tin, because can not find the power source, will directly melt solder with a spray lamp, at this time, the flame will damage the copper shield layer and insulation layer, so to eliminate this phenomenon, the correct way to configure UPS, because soldering tin takes only 10 minutes, power is not more than 500 W.
5.Cold shrink cable head
 The cold shrink silicone rubber cable accessories are simple and convenient to manufacture. And the silicone rubber cable accessories are elastic, tightly attached to the cable, to overcome the shortcomings of thermal shrinkable materials (thermal shrinkable materials are not elastic, in the process of thermal expansion and cold shrinkage of the cable, there will be gaps between the cable body, which provides convenience for the development of water trees)
6.Cable branch box for long cable
  If several long cables, each length of about 3 km, for such cables, in addition to making intermediate connectors, can also be used one or two cable branch box, once one of the cable into the water, will not spread to other sections of the cable, and in the cable fault is also easy to find section by section.
7.PVC plastic double wall bellows
  The pipe has good corrosion resistance, smooth inner wall, strength and toughness, so it can greatly reduce the damage of cable sheath when laying cable directly.
8.Design of cable trench (pipe) and cable well
  Due to the limitation of the conditions, our cable laying are in the form of direct buried or cable trench, and more directly buried, our area belongs to the coastal rainy area, cable trench or cable well in the long-term water. Because the depth of the cable trench or cable well will exceed the depth of the sewer, drainage is difficult, so in planning, should be coordinated to facilitate the drainage of cable trench (well). If the cable well can not be accumulated, the intermediate joint of the cable well should be braced.
9.After the completion of the test cable head of the cable
  Before the commissioning of a high-voltage DC leakage test, after the substation, we only do pre-test cable, other cables do not do the test. Because, once the substation cable fault, short-circuit current will cause a great impact on the substation equipment, and therefore found that there are wire problems, it is necessary to strengthen the operation management and timely replacement. In our opinion, the post-processing of cable faults is as troublesome as the cable faults found after cable tests: finding fault points or even changing cables. The disadvantage of the former is: unplanned blackouts, short-circuit current impact advantages are: do not do the test can extend the life of the cable (some cable test made unsatisfactory, but still can run for a long time, and DC test will increase the possibility of cable breakdown), the fault point is more obvious, easy to find. The latter's advantages and disadvantages are just opposite to the former. Therefore, for the cable users who do not do the test, we focus on the reliability of their power supply. For example, the 10kV switching stations which supply power to the users all adopt double power supply to realize the dispatching automation. Once one incoming cable fails, they switch to another cable to supply power immediately. In fact, the new "Preventive Test Rules for Electric Power Equipment" no longer stipulates that cross-linked cables should be tested at regular intervals for DC withstand voltage, only measuring insulation resistance, thus simplifying the preventive test of cables.