Precautions during overhead cable maintenance tests

Overhead cable as part of the power line, its probability of failure is low, safe and reliable, flexible and widely used outlet. But once the failure and maintenance are more difficult, the risk is also large, and therefore the maintenance, and testing should pay special attention.

1. Pre-work preparation

overhead cable outage work should be filled with the first worksheet, and work without power should be filled with a second job ticket. Check out the front work should be a detailed road map, drawings and hidden works of Pareto chart, check the cable must detail the name, the nameplate is consistent with the job ticket is written, before starting work in the correct and reliable security measures.

2. Operating Notes

You must confirm the need to overhaul the cable work. The cable required maintenance can be divided into two kinds:

2.1 And cable terminal head fault surface have cable clear the fault. Such faulty cable, the more obvious signs of trouble, are easily confirmed.

2.2 Cable surface is not exposed to cable fault points. When the cables for such failure, in addition, to checking data, verify the name of the cable, it must also be identified with the cable identification device, so that the difference between total and charging cable running off the other, especially those with numerous cable in the same section, strict distinguish between required maintenance of cables and another live electric cable is particularly important. 

This will also effectively prevent the cable hanging signs and admit the wrong cable, leading to the wrong diagnosis of energized cables accident. Sawing cable must have reliable security measures. Before sawing cable, it must prove to be a need to cut the cable and the cable is no electricity, and then, with the ground with wooden handle (preferably with an epoxy resin handle) of the soldering iron core driving cable only after work. 

The rotary wooden handle should wear insulated gloves and insulated mat to stand, and should pay special attention to ensure good soldering iron ground. Work To move the cable, you should be careful, should not be foolhardy, to prevent damage to other running cables. The cable heads must be installed according to process requirements to ensure quality, leaving no accidents. After the power cable repair should carefully check the phase ends of the cable, first remove the original mark with color, then put the correct phase color labels to confuse old and new phase colors.

3. When high voltage test

Cable high voltage tests should strictly abide by the "electrical safety work order." Even in the case of poor working conditions in the field safety requirements can not have the slightest decrease. Division of labor must be clear, safety precautions should be carefully arranged. The test site shall be provided with closed masking or fence, hanging out, "stop, dangerous high voltage!" Signs, and sent to guard. 

Especially the other end of the cable must also be sent to guard and keep communication open, to prevent the occurrence of unexpected events. Test equipment and wiring should meet the safety requirements, the operation must be standardized. Attention should be focused on during the test, the operator should stand on the insulating mat. Changes by the end of the line or test, you should first test the power off, discharge, and the high-pressure part shorted to ground high-voltage equipment. 

When the high voltage direct current test, each shall come to an end or the end of the test cable discharge to ground and shorted to the ground several times, only after contact with the cable.

4. Other Considerations

When you open the cable well or cable trench cover, measures should be prepared to prevent traffic accidents. Wells should be arranged around a good fence, do the obvious warning signs, barriers and set the vehicle strayed into the barrier. In the evening, the cable should be well illuminated, preventing pedestrians or vehicles fall into the well. 

Before entering the cable wells, wells should be excluded from the aggregate. Wells staff should wear a helmet, and make fire, water, and anti-altitude falling objects and other measures should be manned wellhead.