Quality Control Of Power Cable Laying

Power cable is the communication medium between power transmission equipment and power receiving equipment. The quality of cable and the reliability of cable connection directly affect the safety of power transmission and distribution equipment. Therefore, in the construction process, the quality control of power cable laying is also the focus of supervision.

1. The quality control of cable support and bridge channel is to ensure the connection between cable support and bridge

For the reliability of quality, the supervising engineer shall focus on the following two points:

1. Specification, model, bearing capacity, material and resistance of corroded cable support, bridge and accessories meet the design requirements;

2. The surface of cable support, bridge support device and bridge is smooth without burr, firm and durable, and the appearance is smooth without rust.

2、 Quality control during cable support and bridge installation

1. The maximum allowable distance between two cable supports shall meet the design requirements.

2. The cable support shall be installed firmly horizontally and vertically; The fixing method of supports and hangers shall be carried out according to the design requirements. The cross beam on the same floor of each support shall be on the same horizontal plane, and the height deviation shall be less than 5mm. The deviation of supports and hangers along the rack direction shall not be greater than 10mm. Cable supports installed in sloping cable trenches or buildings shall have the same slope as that of cable trenches or buildings. The distance from the top and bottom of the cable support to the top of the trench, the ground or the bottom of the trench to the ground shall meet the design requirements.

3. The vertical deviation of assembled steel structure shall be less than 2 / 1000 of the length; The horizontal error of supporting cross brace shall be less than 2 / 1000 of its width; The diagonal deviation shall be less than 5 / of its diagonal length 1000.

4. The ladder (tray) shall be firmly fixed on each support and hanger; The bolts of ladder (tray) connecting plate shall be tightened, and the nuts shall be located outside the ladder (tray). When the aluminum alloy ladder is fixed on the steel support and hanger, measures shall be taken to prevent electrochemical corrosion.

5. The turning radius at the turning of the cable tray shall be greater than the maximum of the minimum allowable bending radius of the cable on the tray.

6. After the cable support is installed, ensure good grounding, and test whether the grounding resistance is less than the requirements of national standards and specifications.

3、 Incoming power cable

The quality control supervisor shall first carry out quality control over the cable procurement process to ensure that the specifications and models of power cables used in the project, design drawings and appearance cables shall be free of damage and well insulated. When there is any doubt about the tightness of the cable, the moisture shall be judged and the "three certificates" shall be completed.

4、 Quality control of power cable laying

1. The cable channel is unblocked and well drained. The anti-corrosion coating of the metal part is completed.

2. The pay off frame shall be placed firmly, and the strength and length of the steel shaft shall match the weight and width of the cable reel.

3. Before laying, calculate the length of each cable according to the design and actual distance, and reasonably arrange each row of cable joints.

4. Reliable safety measures shall be taken for cable laying in live area.

5. Quality control of cable connection production

(1) The whole connection process shall be carried out in strict accordance with the requirements.

(2) Spare length is reserved near the intermediate joint to facilitate maintenance in case of failure. 1m shall be reserved at both ends of the intermediate joint

Both ends of the horizontal section shall be fixed firmly.

(3) Steel armor is installed at both ends of the intermediate joint, which is connected with soft copper wire and bound to the steel armor with copper wire with a diameter of 2 ~ 3mm

And firmly welded.

(4) The reserved length of the intermediate joint shall be naturally bent and not less than the bending degree of the cable. Figure 5-3-2 tunnel interior

Curvature radius, and the bending part shall be fixed with no less than 2 cards.

6. Quality control of cable joint layout:

(1) For cables laid in parallel, their joints shall be staggered. Cable trench and machine room

(2) The cable joint on the support shall be fixed with insulating support plate, which shall extend out

7. Lay the cable on the corresponding support layer in strict accordance with the design requirements. Cables shall be led out from the upper end of the tray and shall not be dragged on the support or ground. Mechanical damage not eliminated, such as cable twisting and cracking of protective layer;

8. The speed of mechanical cable laying shall not exceed 15m / min.

9. When cables enter cable trenches, tunnels, shafts, buildings, panels (cabinets) and pipes, they leave. 10. When the cable is parallel to the heat pipe and thermal equipment, the net distance shall not be less than 1., Insulation protection measures shall be taken.

11. When cables enter buildings, tunnels, floors, external walls and other places that may be damaged by machinery, protective pipes or covers with certain mechanical strength shall be installed.

12. There shall be no ponding and sundries blocking in the pipeline. The protective layer shall not be damaged during threading, and non corrosive lubricant (powder) can be used; Before laying cables, clear the cable trough and remove sundries; The section of the cable inserted into the pipe shall meet the design requirements. 13. The bending radius must meet the relevant requirements at the bending position.

14. After cable laying, sundries shall be removed in time and the cover shall be covered. If necessary, seal the cap gap.

15. Quality control of cable fixing point position:

(1) For cables with a vertical or inclined angle of more than 45 °, the spacing between supports or bridges shall be less than 2m;

(2) For horizontally laid cables, supports or bridges shall be set at the head and end, turns and both ends of the cable joint;

(3) Cables laid along the tunnel roof shall be firmly fixed with rigid clamps, and the spacing shall not be greater than 1m.

5、 Power cable test

After the power cable is laid, in order to ensure the safety of power transmission, the construction unit must carry out insulation resistance measurement, DC withstand voltage test and leakage current measurement, and check the phase and connection of the cable line. Meet the requirements of national and industrial standards and regulations. The supervising engineer shall supervise the whole test process and approve the test results on site.