Phone:0510-87209299
TEL:13901533069
TEL:13901533069
Address: Industrial C District, Guanlin Town, Yixing City
Contact person: Shi Zhiliang
Tel: 0510-87209299
Fax: 0510-87209299
Zip code: 214200
Website: www.wxxadz.com
E-mail: shishu_2007@126.com
1. What kinds of wires and cables are commonly used according to their uses?
Answer: According to its use, it can be divided into bare conductors, insulated wires, heat-resistant wires, shielded wires, power cables, control cables, communication cables, radio frequency cables, etc.
2. What kinds of insulated wires are there?
Answer: There are several kinds of common insulated wires: PVC insulated wires, PVC insulated flexible wires, NBR-PVC mixed insulated flexible wires, rubber insulated wires, plastic insulated wires directly embedded in agricultural land, rubber insulated cotton yarn textile flexible wires, PVC insulated nylon sheathed wires, PVC insulated flexible wires for power and lighting, etc.
3. Where is the cable bridge suitable for?
Answer: Cable bridge is suitable for laying power cables and control cables indoors and outdoors in general industrial and mining enterprises. It can also be used for indoor and outdoor installation of telecommunications, radio and television departments.
4. What are the cable accessories?
Answer: Commonly used electrical accessories are cable terminal junction box, cable intermediate junction box, connecting pipe and terminal, steel plate junction slot, cable bridge, etc.
5. What is cable intermediate joint?
Answer: The device that connects the cable to the conductor, insulating shielding layer and protective layer of the cable so as to connect the cable line is called the cable intermediate joint.
6. What is the main electrical connection?
Answer: Electrical main wiring is the connection mode of main electrical equipment and buses in power plants and substations, including the connection mode of main buses and auxiliary power systems according to certain functional requirements.
7. What regulations should be followed in selecting the section of power cable?
Answer: The selection of power cables should follow the following principles:
(1) The rated voltage of the cable shall be greater than or equal to the rated voltage of the power supply system at the installation point;
(2) The permissible current of the cable shall be equal to or greater than the maximum permissible current of the power supply load.
(3) Core section should satisfy the stability requirement of power supply system in short circuit.
(4) Check whether the voltage drop meets the requirements according to the length of the cable;
(5) The minimum short-circuit current at the end of the line should enable the protection device to operate reliably.
8. What are the advantages of XLPE cable compared with oil-paper cable?
Answer: (1) Easy to install, because it allows the minimum bending radius to be small and the weight to be light;
(2) Not limited by line drop;
(3) Good thermal performance, high allowable operating temperature and large transmission capacity;
(4) The cable accessories are simple and dry.
(5) Simple operation and maintenance, no oil leakage;
(6) Low prices;
(7) High reliability and low failure rate;
(8) There are few manufacturing processes, simple processes and remarkable economic benefits.
9. What are the requirements of fixtures for fixing AC single-core cables? Why?
Answer: Fixture should have no iron parts to form a closed magnetic circuit. This is because when the cable core passes through the current, it generates magnetic lines around it. The magnetic lines are proportional to the current passing through the core. If using magnetic conductive materials such as iron parts, according to electromagnetic induction, eddy current will be generated in the iron parts to heat the cable or even burn the cable. Therefore, iron can not be used as a fixture for single-core AC cable.
10. What are the greatest features and advantages of the accessories below the thermal shrinkable cable head?
Answer: The most important feature of heat shrinkable accessories is to replace the traditional stress cone with stress tube. It not only simplifies the construction process, but also reduces the size of the terminal of the joint. It is convenient to install, time-saving and labor-saving, with superior performance and metal saving. Thermal shrinkable cable accessories are composed of perfusion type and dry package type, which combine the advantages of these two accessories.
11. What inspection work should be done before cable laying?
Answer: (1) The support should be complete and the paint should be complete.
(2) The cable type, voltage and specifications conform to the design.
(3) Cables are well insulated. When doubting the sealing of oil-paper cables, they should be judged to be damp. Direct buried cables and small bottom cables should pass DC withstand voltage test. Oil samples of oil-filled cables should pass the test.
(4) The oil pressure of oil-filled cable should not be less than 1.47 MPa.
12. When doubting the sealing of oil-paper insulated power cables, how to use a simpler method to check whether the cable insulating paper is damp?
Answer: check the cable insulation paper or put it in cable oil at about 150 degrees. No "hissing" or white foam appears, indicating that it is not damp.
13. What should the cable sign indicate? What are the requirements for compilation?
Answer: The design number, cable type, specification and starting point of the cable line should be indicated on the sign. The cables used in parallel should have sequence number. Require clear handwriting, not easy to fall off.
14. Where should the orientation sign of the buried cable be located?
Answer: At both ends of the cable, the bend of several cable joints at 50-100m of the straight line segment of the cable changes direction.
15. How to dehumidify the yellow wax ribbon, black glass lacquer ribbon and alkali-free glass ribbon before construction?
Answer: (1) Constant temperature drying method: the insulating tape is rolled into small coils with diameter of 25-30mm and baked in a constant temperature drying oven at 110-120 C for 4-5h. The insulating tape is cooled and dried out and put into a sealed drum for drying.
(2) oil immersion method: put the insulating tape into the cable oil at constant temperature of 120~130 degrees, keep the 30mm distance from the bottom of the pot. After a certain period of time, the oil surface will no longer produce foam and remove it into the tank with cable oil. The oil level should be more than all the loaded objects and sealed.
16. What is the function of cable outer sheath?
Answer: Protect the inner protective layer from mechanical damage and chemical corrosion, and enhance the mechanical strength.
17. What requirements should outdoor cable trench meet?
Answer: The upper part of cable trench should be slightly higher than the ground. Cover with concrete cover plate. The cable should be laid flat on the bracket with good drainage pipe.
18. What is the function of cable inner cladding?
Answer: Make the insulating layer not contact with water, air or other objects to prevent dampness and mechanical damage to the insulating layer.
19. What should we pay attention to when using wire pliers?
Answer: Before using, we must check whether the insulation of the insulating handle is intact and intact. When using, we must not use wire pliers to cut metal wires beyond the allowable specifications, and prohibit using wire pliers instead of hammer knocking tools to avoid damage.
20. What is insulation strength?
Answer: Insulating material in electric field, when the electric field strength increases to a certain limit, it will be broken down. The electric field strength that leads to insulation breakdown is called insulation strength.
21. What are the advantages of XLP cable accessories?
Answer: This is a new type of material. Compared with other types of accessories, it has the advantages of superior electrical performance, small size, small quality, easy installation, matching materials, and other capabilities, such as weather resistance, pollution resistance, flame retardant and self-extinguishing.
22. What are the requirements for the mechanical strength of cable conductor connections?
Answer: The mechanical strength of the connecting point is generally lower than the tensile strength of the conductor itself. For fixed laying power cables, the tensile strength of the connecting point is not less than 60% of the tensile strength of the conductor itself.
23. What are the main properties of insulation materials for power cables?
Answer: Should have the following main performance:
(1) High breakdown strength;
(2) Low dielectric loss;
(3) fairly high insulation resistance;
(4) Excellent discharge resistance;
(5) It has certain softness and mechanical strength.
(6) Insulation performance is stable for a long time.
24. When laying cables mechanically, what are the requirements for traction strength?
Answer: For copper-core cables, the allowable traction strength is 70N/cm when the traction head is used; for aluminum-core cables, the allowable traction strength is 40N/cm when the traction head is used; if the wire mesh sheath is used for traction, the allowable strength of lead-sheathed cables is 10N/cm; and the allowable strength of lead-sheathed cables is 40N/cm.
25. What are the regulations for cable protection tubes?
Answer: (1) When the cable needs to be laid through 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 concrete pipe, clay pipe, asbestos pipe and cement pipe should not be less than 100 mm.
(2) The bending radius of the cable tube shall conform to the requirements of the bending radius of the cable penetrated.
(3) No more than three elbows per pipe and no more than two right-angled elbows.
26. How to measure the outer diameter of cable sheath?
Answer: At five points evenly distributed around the sheath circumference, the outer diameter of the sheath and its average value are measured. The average outer diameter of the sheath is the outer diameter of the sheath.
27. How to connect copper-cored cables with different sections?
Answer: Copper core cable with different cross sections can be connected by open weak back copper nozzle, tin soldering method, or copper nozzle with pure copper rod according to different cross section requirements, which can be connected by pressing method.
28. Briefly describe the process of making indoor terminal head of 10KV cross-linked cable by thermal shrinkage?
Answer: (1) Preparatory stage: check whether the heat shrinkable cable accessories are complete, whether the models match, check and confirm whether the cable has moisture, check the cable.
(2) Remove the redundant cables and determine the length of the cables according to the site conditions.
(3) Peel off the protective layer.
(4) Weld the grounding wire, and weld the grounding wire on the steel strip.
(5) Filling Trident and winding sealant.
(6) Install the three-core branching sheath, and insert the sheath into the root. The sheath begins to shrink from the middle, first to the root, then to the finger.
(7) Strip the copper strip and the outer semi-conductive layer, and cut the copper strip with three-core branching sleeve more than 20 mm. It is strictly forbidden to damage the main insulation and clean the semi-conductive layer.
(8) Installation of stress pipe, heat shrinkage after butt joint of branch sleeve at the end of pipe.
(9) Install terminal.
(10) Installation of insulating pipes.
(11) Install sealing pipe.
(12) Install the chromophore tube after phase checking.
29. What are the installation steps of indoor and outdoor prefabricated terminals?
Answer: (1) Put the cable in place, fix and clean the surface according to the predetermined position, peel out the outer sheath according to the instruction. If there is special need, the length of the outer sheath peeling can be adjusted. Two groups of ground wires are drawn out by copper belt and outer sheath armor respectively.
(2) Measure the required size upward from the outer sheath opening, remove the redundant cables, insert the heat shrinkable three-finger sheath into the root of the trigeminal opening, heat shrink from the middle, and measure the specified size upward from the upper finger sheath opening (35kv 350-380mm). Remove excess copper tape (retain 20mm), then reserve the predetermined position of semiconductor, press and seal the outlet terminal.
30. The application of wires and cables can be divided into three main categories:
(1) The main wire and cable products used in power system include overhead bare wires, bus bars, power cables (plastic cables, oil-paper cables (basically replaced by plastic power cables), rubber sleeve cables, overhead insulated cables, branch cables (replacing part of buses), electromagnetic cables and electrical equipment cables for power equipment. (2) The main wires and cables used in the information transmission system are telephone cables, television cables, electronic cables, radio frequency cables, fiber optic cables, data cables, electromagnetic cables, power communications or other composite cables. (3) Machinery and equipment, instrument and instrumentation system, this part has almost all other products except overhead bare wires, but mainly power cables, electromagnetic cables, data cables, instrument and instrumentation cables and so on.