Questions about cable classification

一、 What are the five categories of wire and cable products?

1. Bare wires and bare conductor products. The main characteristics of this type of product are: pure conductor metal, without insulation and sheath layer, such as steel core aluminum stranded wire, copper aluminum busbar, electric locomotive wire, etc; The processing process is mainly pressure processing, such as smelting, calendering, drawing, stranding/compression stranding, etc; 2. Power cables. The main characteristics of this type of product are: extruding (winding) an insulating layer around the conductor, such as overhead insulated cables, or twisting several cores (corresponding to the phase, neutral, and ground wires of the power system), such as overhead insulated cables with more than two cores, or adding a protective layer, such as plastic/rubber sheathed wires and cables. The main process technologies include drawing, stranding, insulation extrusion (wrapping), cabling, armor, sheath extrusion, etc. The different process combinations of various products vary. 3. Electric wires and cables for electrical equipment. The main characteristics of this type of product are: a wide variety of specifications, a wide range of applications, and a wide range of operating voltages of 1 kV and below. In the face of special situations, new products are constantly derived, such as fire-resistant cables, flame retardant cables, low smoke zero halogen/low smoke low halogen cables, anti-termite, mouse resistant cables, oil resistant/cold resistant/temperature resistant/wear-resistant cables, medical/agricultural/mining cables, thin-walled wires, and so on. 4. Communication cable and optical fiber (brief introduction). With the rapid development of the communication industry in the past twenty years, products have also experienced an alarming rate of development. From simple telephone and telegraph cables in the past to thousands of pairs of telephone cables, coaxial cables, optical cables, data cables, and even combined communication cables. 5. Electromagnetic wire (winding wire). Mainly used for various motors, instruments, etc.

二、 What inspections should be carried out after the construction of the busbar device?

The following inspections should be carried out: ① The processing, preparation, and welding of metal components should comply with regulations; ② All bolts, washers, cotter pins, and other components should be complete and reliable; ③ The bus configuration and installation frame should meet the requirements, and the electrical distance between phases and ground should meet the requirements; ④ Porcelain, iron, and glued parts should be complete, the oil filled sleeve should be free of oil leakage, and the oil level should be normal; ⑤ The paint is complete, the phase color is correct, and the grounding is good.

三、 There are several methods for improving the electric field distribution at the sheath disconnection point in power cable joints of 35 kv and below (please list five), and briefly describe their methods.

(1) Bulging bell mouth: pry up the edge of the lead package at the cutting point of the lead package to form a horn shape, and its edge should be smooth, round, and symmetrical; (2) Reserved blanket insulation: A section of blanket insulation paper is left between the lead wrap cut and the separation point of the cable core; (3) Cutting off semi conductive paper: Cut off the semi conductive paper below the bell mouth; (4) Wrapping stress cone: Using insulating tape and conductive metal materials to wrap into a cone, artificially expanding the shielding layer to improve the electric field distribution; (5) Equipotential method: For dry wrapped or cross-linked polyethylene cable heads, wrap a section of metal tape on the general insulation surface of each wire core and connect them together; (6) Installation of stress control tube: For 35kV and lower heat shrinkable tube cable heads, first wrap two layers of semiconductor tape from the direction of the end of the copper shield layer of the wire core through the semiconductor tape to the insulation profile of the wire core, and then wrap the corresponding specifications of the stress tube at the end of the copper shield for heat shrinkable forming.

四、 What requirements should the processing of cable supports meet?

(1) The steel should be flat and straight without obvious distortion, the blanking error should be within 5mm, and the cut should be free of curls and burrs; (2) The support shall be firmly welded without obvious deformation, and the vertical clear distance between each cross brace shall not deviate from the design by more than 5mm; (3) The metal support must undergo anti-corrosion treatment. When located in areas with damp heat, salt, fog, and chemical corrosion, special anti-corrosion treatment should be carried out according to the design.

五、 List the cable racks you are familiar with.

Splice welded E-frame, fabricated E-frame, bridge cable frame, cable tray, hook bracket, single cable support, etc.