The operation of the cable route is one of the key steps in the production and manufacturing of power engineering. Whether the safety of the operation of the cable route is related to the safety of the company's production and the personal safety of the people, today it is simple to introduce the relevant problems in the operation and maintenance of the wire and cable in detail.

First, the characteristics of cable lines

The cable route refers to the route of transporting electromagnetic energy by cable, which is composed of the cable itself, the middle connector of the cable line, the end of the electric route, and the corresponding civil engineering equipment, such as cable ditch, pipe trough, shaft, tunnel construction, etc. Generally built in the ground, but also empty frame or water laying.

Cable routes have the following key advantages over transmission lines:

① will not be affected by natural meteorological elements (such as lightning, wind and rain, smoke, pollution, etc.)

② will not be harmed by the growth and development of flowers and trees along the way;

(3) It is beneficial to clean up the natural environment in big cities;

(4) Do not occupy the road corridor, the same underground tunnel can accommodate multiple routes;

⑤ beneficial to avoid electric shock accidents and electricity safety;

⑥ Small maintenance fee. But there are also the following defects;

⑦ The same cable diameter, the transportation current is smaller than the overhead cable:

⑧ The capital construction cost of the project investment is doubled and expanded with the increase of working voltage;

⑨ Common faults take a long time to repair.

At present, the route of high-voltage distribution equipment should be selected under the following conditions:

① According to the overall planning of the big city, lively areas, key areas, key roads, multi-storey building areas and those with unique requirements for the appearance of the city;

② The transmission line aisle can not be solved;

③ High stability of the power supply system or critical load customers;

④ Key scenic spots;

(5) Critical power supply areas in key metropolitan areas where coastal cities are vulnerable to severe tropical storms;

The need for safety in the construction or operation of the power network;

⑦ Metropolitan areas with high load relative density.

Second, the experiment and engineering acceptance of wire and cable put into use

In addition to the work handover experiment and protective experiment, the insulation layer experiment should also be carried out in the whole process of engineering construction to identify and check the cable quality and processing technology quality at each stage of engineering construction. Experiment is carried out on the cable tray before laying to distinguish the advantages and disadvantages of the cable. Carry out experiments after laying and before laying to identify whether the cable is damaged during laying; Experiments are carried out after the construction of cable joints to identify the quality of cable joints. Conduct experiments before and after cable maintenance to identify maintenance quality. The specific contents of the inspection are as follows:

(1) The cable should be sorted neatly, the fixed and bending radius of the cable should meet the design drawing and related requirements, the cable should be free from mechanical equipment damage, and the sign plate should be placed fully, appropriately and clearly. Oil-impregnated paper insulated wire and oil-type cable terminal equipment, the middle of the connection head should not leak oil;

(2) There should be no dirt in the construction of the cable ditch and tunnel, the back cover of the cable ditch should be complete, and the lighting fixtures, natural ventilation, drainage pipes and other equipment in the tunnel construction should meet the requirements of the design scheme;

(3) The mark pile of the directly buried cable should be consistent with the specific way, and the interval should meet the requirements. Labels should be clear, strong and durable; (4) The markings and night lighting equipment on both sides of the Strait and in the no-anchor area of the underwater cable route shall comply with the provisions of the design scheme.

Third, the common problems of line operation

(1) It is not necessary to over-load operation or over-temperature for a long time. Therefore, it is not necessary to ignore the detection of cable load current, external temperature and connector temperature;

(2) Cable line route Coaxial cable maintenance can not be invested in reclosing. The common faults of the cable line are always common faults. If the re-closing position is used, it will certainly expand the safety accident and threaten the smooth operation of the power network.

(3) After the coaxial cable of the cable line is switched on, it is not necessary to ignore the inspection of the cable line. The key to check whether the cable path is excavated or whether the cable line is damaged, if necessary, further check and distinguish according to the experiment;

(4) When inspecting the operation of directly buried cables, it is necessary to pay attention to: the road surface around the cable path can not be excavated at will; Lifting objects, corrosive chemicals and temporary buildings are not allowed on the pavement around the cable route. Cable route marking pile and maintenance equipment can not be moved at will, disassembly;

(5) The cable line must be tested again before it can be delivered for use when it is repaired and operated after being stopped. If the power is off for more than a week but not satisfied with the cable for a month, the grounding resistance should be measured before the money is put into operation again, and the comparison with the previous experimental record cannot be reduced by 30%, otherwise the AC voltage withstand test should be done; If the power failure exceeds one month but is not satisfactory for one year, it is necessary to do AC voltage test, and the experimental working voltage can be half of the protective experimental working voltage; If the power failure time exceeds the experimental cycle time, the protective experiment must be done.

4. Operation and maintenance of cable lines

The key to the operation and maintenance of cable lines is to do a good job in load monitoring, cable metal material sheath erosion monitoring and insulation layer supervision at three levels, to maintain cable equipment in good condition from beginning to end and to avoid cable safety accidents. Key new projects include: creating cable route technical documents, carrying out cable line inspection, cable protection experiments, avoiding cable damage by external force, and analyzing cable fault testing reasons. Cable routes need to add unique content, such as spray killing termites, human river sample analysis, water tree technology slice inspection and power accurate measurement and monitoring of insulation layer.

1. Load monitoring. General cable routes require large currents according to the section of the electrical conductor of the cable and the type of insulation layer. Various instrument panels are used to accurately measure the load current of the cable route or the skin temperature of the cable line as a key load monitoring countermeasure to avoid the cable insulation layer exceeding the allowable high temperature and reducing the service life of the cable line.

2. Temperature monitoring. Accurate measurement of the temperature of the cable should be carried out in summer or when the cable is heavily loaded. When measuring the temperature of the buried cable accurately, the ground temperature without other pyrogen in the same area should be accurately measured. When the cable is laid cross-over or close to the underground heating pipe, the ground temperature around the cable shall not exceed 10℃ above the ground temperature of the same depth as that in other areas of the local section under all conditions. To check the temperature of the cable, the cable should be selected where the sorting is dense or where the heat is destroyed or where there is an external pyrogen hazard.

3. Corrosion monitoring. The special instrument panel is used to accurately measure the surrounding soil layer of the adjacent cable line. If it belongs to the anodic oxidation zone, effective measures should be taken to avoid electrolysis erosion of the metal material jacket of the cable line. The wet soil layer around the cable route or the soil layer filled with domestic waste treatment, the metal material of the cable often produces chemical corrosion and microbial species etching. According to the measured working voltage in the anodic oxidation zone, the appropriate pipeline cathodic protection countermeasures or drainage equipment should be selected.

4. Insulation layer supervision. According to the necessity of each cable route, the protective experiment scheme is designed to deal with the weak points in the cable route in time, and the shortcomings that are likely to produce cable safety accidents are removed. The cable route provided by the insulating layer of the metal material sheath to the ground is generally open to the outside world after the protective test, and the outer protective layer is separately tested for AC voltage to detect and remove the shortcomings of the outer protective layer.

5. Side search of cable fault test

After the cable has a common fault, the general side search process is as follows:

(1) Identify common fault characteristics. According to the occurrence of common faults and some simple experiments, analyze and judge the characteristics of common faults, and determine whether the common fault resistor is high resistance or low resistance, is a short circuit fault or a closed common fault, is a short circuit fault of the grounding device, disconnection, or their mixture, is a single phase, two phase or three phase common fault. For example, when the cable in operation has a common fault, there is only a grounding device data signal, which may be a common single-phase grounding fault; If the relay protection device is over-current tripping, it is possible to produce a two-phase or three-phase short-circuit fault, or a short-circuit fault and a common fault mixed with the grounding device. According to the analysis, the characteristics of common faults can not be determined completely, so it is necessary to accurately measure the grounding resistance and carry out the on-off experiment.

(2) Burning through common fault points. That is, the common faults of high resistance or short circuit fault are changed into common faults of low resistance according to the burn through, which is easy to carry out rough measurement;

(3) Rough measurement. On one side of the cable line, the instrument is used to measure the common fault spacing, and the common fault point is calculated by the technical document of the cable line.

(4) Path search. For engineering drawings with incomplete materials or unknown cable path, the laying path and submerged depth of common faulty cable lines can be found according to audio magnetic induction detection method and monopulse electromagnetic field method, so as to facilitate designated precision measurement. The audio magnetic induction detection method is to express the analog signal current flow into the cable line, and determine the way according to the analog signal received by the receiver in the receiving electromagnetic coil;

(5) Precision measurement points of common fault points. The precise location of common fault points is defined according to the methods of shock charge and discharge acoustic measurement, acoustic magnetic induction method and acoustic magnetic synchronous measurement method. The acoustic measurement method is only applicable to the national standard cable fault test of low resistance grounding device, and the actual effect is not good for the common faults of metallic grounding device. The magnetic induction method is applicable to the common faults of the metallic grounding device and the common faults of the two-color short-circuit fault.

The above five processes are general search processes, and some of the processes can be omitted according to the details of the specific side search. For example, the cable laying path is very accurate without side search, for high resistance common faults, without burning through and immediately apply the short-circuit fault method, for some short-circuit fault common faults, do not specify, you can view the material according to the spacing data information obtained by the side search, you can immediately check and distinguish the middle connector. For cable fault testing in cable trench or tunnel construction, impact charge and discharge can be carried out to identify common fault points.

Qingdao Tianxing Cable Co., Ltd. focuses on the production of customized wire and cable manufacturers, main: fire wire and cable, power cable, control cable and other products, exported to more than 40 countries and regions around the world, the annual production capacity of 1 billion yuan. 6000 square meters of storage, standing hundreds of millions of inventory, order demand for rapid distribution and delivery, large prices more favorable. Hotline: 16678668098