As a part of power lines, power cables are widely used because of their low failure probability, safety and reliability, and flexible outlets. However, once a failure occurs, the maintenance is difficult and dangerous, so special attention should be paid to the maintenance and testing.

1. Preparation before work

One type of work ticket should be used for power cable power outage work, and the second type of work ticket should be used for work that does not require power outage. Before working, you should check the relevant path maps, arrangement drawings and drawings of concealed works in detail. You must check the cable name in detail and check whether the nameplate is consistent with the work ticket. Only after the safety measures are correct and reliable can you start work.

2. Matters needing attention in work

When working, the cables to be repaired must be confirmed.

The cables to be repaired can be divided into 2 types:

(1) Cables with terminal head failures and obvious failure points on the surface of the cable body. This type of faulty cable has obvious fault signs and is easy to confirm.

(2) The cable on the cable surface does not expose the fault point. For this type of faulty cable, in addition to checking the data and verifying the cable name, it must also be identified with a cable identifier to distinguish it from other live cables in operation, especially when there are many cables in the same cross section. It is particularly important to distinguish between cables that require maintenance and other live cables. At the same time, it can also effectively prevent the accident of accidentally breaking the live cable due to the wrong cable being hanged and the wrong cable recognized. Sawed cables must have reliable safety protection measures. Before sawing the cable, it must be confirmed that the cable needs to be cut and the cable has no electricity. Then, use a grounded iron with a wooden handle (with an epoxy handle) to nail the cable core to work. People with wooden handles should wear insulating gloves and stand on the insulating pads, and pay special attention to ensure the good grounding of the iron brazing. If you need to move the cable during work, you should be careful, avoid brute force, and prevent damage to other cables in operation. The cable head must be installed according to the process requirements to ensure quality and leave no hidden dangers. After the cable is repaired, the phases at both ends of the cable should be carefully checked, the original phase-color mark should be removed first, and then the correct phase-color mark should be put on to prevent the new and old phase colors from being confused.

3 Precautions during high voltage test

The high-voltage test of the cable should strictly abide by the "Safety Regulations for Electricity Industry". Even in the case of poor on-site working conditions, the safety requirements must not be reduced in any way. The division of labor must be clear, and safety precautions should be arranged in detail. The test site should be equipped with closed shields or fences, hang the sign "Stop, high voltage hazard!", And send someone to guard. In particular, the other end of the cable must also be sent to guard and keep the communication smooth to prevent unexpected events. The test device and wiring shall meet the safety requirements, and the operation must be standardized. Attention should be focused during the test, and the operator should stand on the insulation pad. At the end of the change to the line or the test, the test power supply should be disconnected, discharged, and the high-voltage part of the high-voltage equipment should be short-circuited to ground. During the high-voltage DC test, the cable should be discharged to ground several times and short-circuited to ground at each end or at the end of the test before contacting the cable.

4 Other considerations

When opening the cable well or cable trench cover, measures should be taken to prevent traffic accidents. Fences should be arranged around the well, with obvious warning signs and obstacles to prevent vehicles from entering by mistake. At night, the cable shaft should be illuminated to prevent pedestrians or vehicles from falling into the shaft. Before entering the cable well, the turbid gas in the well should be removed. Workers in the well should wear safety helmets, and take measures to prevent fire, water, and falling objects. The wellhead should be guarded.