1. What kinds of wires and cables are commonly used according to their uses?

A: According to the use can be divided into bare wire, insulated wire, heat-resistant wire, shielded wire, power cable, control cable, communication cable, RF cable and so on.

2. What kinds of insulated wires are there?

A: There are often the following kinds of insulated wires: PVC insulated wires, PVC insulated cords, nitrile PVC mixture insulated cords, rubber insulated wires, agricultural underground directly buried aluminum core plastic insulated wires, rubber insulated cotton yarn textile flexible wires, PVC insulated nylon sheathed wires, power and lighting PVC insulated cords, etc.

3. What are the cable accessories?

A: The commonly used electrical accessories are cable terminal junction box, cable intermediate junction box, connecting pipe and terminal, steel plate wiring slot, cable bridge, etc.

4, what is the cable adapter?

A: The device that connects the cable with the conductor, insulating shielding layer and protective layer of the cable to connect the cable line is called the cable connector.

5. Which aspects should be considered in choosing the section of power cable?

A: The following aspects should be considered:

(1) The working current allowed through the cable for a long time;

(2) Thermal stability once short-circuited;

(3) The voltage drop on the line cannot exceed the allowable working range.

6, when choosing the section of the power cable, what provisions should be followed?

A: The selection of power cables should follow the following principles:

(1) The rated voltage of the cable should be greater than or equal to the rated voltage of the power supply system at the installation point;

(2) The continuous allowable current of the cable should be equal to or greater than the maximum continuous current of the power supply load;

(3) The core section should meet the stability requirements of the power supply system when it is short circuited;

(4) Check whether the voltage drop meets the requirements according to the cable length;

(5) The minimum short-circuit current at the end of the line should enable the reliable operation of the protection device.

7. What are the advantages of cross-linked polyethylene cable and oiled paper cable?

A: (1) Easy to install because it allows a small minimum bending radius and light weight;

(2) not subject to line drop *;

(3) Good thermal performance, high allowable working temperature, large transmission capacity;

(4) The cable accessories are simple and dry structure;

(5) Simple operation and maintenance, no oil leakage problem;

(6) The price is lower;

(7) High reliability, low failure rate;

(8) Fewer manufacturing processes, simple processes, and significant economic benefits.

8, fixed AC single-core cable clamp has what requirements? Why?

A: The fixture should have no iron to form a closed magnetic circuit, this is because when the cable core through the current, the magnetic force line around it, the magnetic force line is proportional to the size of the current through the core, if the use of iron parts and other magnetic materials, according to the electromagnetic induction, will produce eddy currents in the iron parts to make the cable heat, or even burn the cable. Therefore, it is not possible to use iron parts as a fixed fixture for single-core AC cables.

9. What are the biggest characteristics and advantages of the accessories of the heat shrink cable head?

A: The biggest feature of the heat shrink attachment is to replace the traditional stress cone with a stress tube, which not only simplifies the construction process, but also reduces the size of the terminal of the joint, convenient installation, saving time and labor, superior performance, and metal saving. The heat shrink cable accessories are both poured and dry pack, combining the advantages of these two accessories.

10. What inspection work should be carried out before cable laying?

A: (1) The support should be complete, paint complete.

(2) Cable model, voltage, specifications meet the design.

(3) The cable is well insulated, and when there is doubt about the sealing of the oil-paper cable, it should be judged by moisture; Direct buried cables and small bottom cables should pass the DC voltage test; The oil sample of the oil-filled cable should be qualified.

(4) The oil pressure of the oil-filled cable should not be lower than 1.47MPa.

11, When there is doubt about the oil-paper insulated power cable seal, how to use a simpler way to check whether the cable insulation paper is damp?

A: Light the cable insulation paper or put it into the cable oil at about 150 ° C to check that there is no "hissing" sound or white foam, indicating that it is not damp.

12, cable signs should indicate what content? What are the requirements for writing?

A: The sign should indicate the cable line design number, cable model, specification and starting point, and the cable used in parallel should have a serial number. The handwriting should be clear and not easy to fall off.

13. Where should the bearing mark of the directly buried cable be set?

A: At both ends of the cable, the cable connector between 50 and 100m in the straight section of the cable is a bend in the direction of the cable.

14, What is the role of the cable outer protective layer and the inner protective layer?

A: Outer protective layer: protects the interior of the cable from mechanical damage and chemical corrosion to enhance mechanical strength.

Inner protection layer: the insulation layer will not be in contact with water, air or other objects, to prevent the insulation from moisture and the insulation layer from mechanical damage.

15, What are the advantages of cross-linked heat shrink cable accessories?

A: This is a new type of material, which has superior electrical performance, small size, small quality, easy installation, material matching and other advantages compared with other types of accessories, in addition to weather resistance, pollution resistance, flame retardant self-extinguishing ability.

16, power cable insulation material should have what main performance?

Answer; Should have the following main properties:

(1) High breakdown strength;

(2) Low dielectric loss;

(3) quite high insulation resistance;

(4) Excellent discharge resistance;

(5) It has certain softness and mechanical strength;

(6) Long-term stability of insulation performance.

17. What are the regulations on cable protection tubes?

A: (1) When the cable needs to be laid through the protective pipe, the inner diameter of the pipe should not be less than 1.5 times the outer diameter of the cable, and the inner diameter of the concrete pipe, clay pipe, asbestos and cement pipe should not be less than 100mm;

(2) The bending radius of the cable tube shall comply with the bending radius of the cable penetrated;

(3) Each pipe should not exceed three elbows at most, and right Angle bends should not exceed two.

18, how to measure the outer diameter of the cable sheath?

A: At five points uniformly distributed on the circumference of the sheath, measure the outer diameter of the sheath and its average value, whose average outer diameter is the outer diameter of the sheath.

19. How to connect copper core cables of different sections?

A: Copper core cables with different sections can be connected by open weak back copper nozzle and tin welding method, or pure copper rod can be connected into copper nozzle according to different section requirements and connected by crimping method.

20. What are the insulation materials for the cable terminal or intermediate connector?

A: There are insulation adhesive, insulation tape, insulation pipe, insulation gloves, insulation resin and so on.

21, What are the requirements for the fire sealing of the cable holes?

A: For large cable through holes, such as cable through the floor, the use of fireproof plugging material, should be based on the actual situation, first on the cable surface coated with four to six layers of fireproof paint, the length from about 1.5m below the hole, and then refractory materials processing into a certain strength of the plate support fireproof plugging material, to ensure that the sealing is firm and easy to replace the cable disassembly. The sealing is compact and void free to effectively block smoke and fire.

22, commonly used low-voltage power cables according to the insulation and protective layer of different, can be mainly divided into what categories?

A: (1) oil-impregnated paper insulated lead-covered (or aluminum-covered) power cable;

(2) non-dripping oil-impregnated paper insulated power cable;

(3) PVC insulated PVC sheathed power cable;

(4) cross-linked polyvinyl chloride insulated polyethylene sheathed power cable;

(5) Cross-linked PVC insulated PVC sheathed power cable;

(6) Rubber insulated power cable.

23, what are the factors that determine the long-term allowable capacity of the cable?

A: There are three factors:

(1) Long-term allowable working temperature of the cable;

(2) heat dissipation performance of the cable itself;

(3) The cable installation and the heat dissipation conditions of the surrounding environment.

24. What tests and inspections should be carried out before laying power cables?

A: Before laying, check whether the type, specification and length of the cable meet the requirements and whether there is external damage. The low-voltage cable uses a 1000V megohm meter to measure the insulation resistance, and the resistance value is generally not less than 10MΩ. The high-voltage cable uses a 2500V megohm meter to measure the resistance value.

25, cable engineering can be divided into several projects?

A: (1) Site transportation: including the loading and unloading of engineering materials from the warehouse to the construction site, transportation and empty car return trip.

(2) Local engineering: including road excavation, tunnel, trench construction, etc.

(3) Laying engineering: including laying, middle head making, cover lifting, buried pipe, school tide, traction head making, etc.

(4) Both ends of the project: including support, suspension bridge and its foundation production and installation, terminal head production, oil pressure and signal device installation, electrical performance testing.

(5) Plugging project: including the production of oil-filled cable plug head, fuel tank, automatic drainage and signal device installation.

(6) Grounding engineering: including insulation joints, transposition boxes, protectors, grounding box installation, etc.

26, what inspection should be carried out for the acceptance of cable lines?

A: (1) The cable specifications should meet the requirements, the arrangement should be neat, no damage, the label is complete, correct and clear;

(2) The fixed bending radius of the cable, the relevant distance and the wiring of the metal sheath of the single-core power cable should meet the requirements;

(3) The cable terminal and middle head do not leak oil, the installation is firm, the oil pressure of the oil-filled cable and the setting value of the meter should meet the requirements;

(4) Good grounding;

(5) The color of the cable terminal is correct, and the metal parts of the bracket are painted completely;

(6) There should be no debris in the cable trench, tunnel and bridge, and the cover plate should be complete.

27, cable in the transportation and loading process should pay attention to what?

A: (1) In the process of transportation and loading and unloading, the cable and cable tray should not be damaged, it is strictly prohibited to push the cable tray directly from the car, and the cable should not be transported flat, flat storage.

(2) Before transporting or rolling the cable tray, it must be ensured that the cable tray is firm, the oil pipe between the cable wound and the oil-filled cable and the pressure tank should be fixed and not damaged, the pressure tank should be firm, and the pressure indication should meet the requirements.

28, what are the measures of cable fire prevention?

A: (1) flame-retardant cable;

(2) Use fireproof cable bracket;

(3) The use of fireproof paint;

(4) Fire partition wall and fire baffle shall be set up at the cable tunnel and sandwich exit;

(5) Overhead cables should avoid oil pipelines and explosion-proof doors, otherwise local pipes or heat insulation and fire prevention measures should be taken.

29, choose the section of the power cable should be considered from what aspects?

A: The following aspects should be considered:

(1) The working current allowed through the cable for a long time;

(2) Thermal stability once short-circuited;

(3) The voltage drop on the line cannot exceed the allowable working range.

30. What are the advantages of power cables and overhead lines?

A: (1) reliable operation, due to the installation in underground and other hidden places, the external damage is small, the chance of failure is less, the power supply is safe, and will not cause harm to the person;

(2) Maintenance workload is small, do not need frequent inspection;

(3) No need to erect poles and towers;

(4) Help to improve the power factor.