China Zhenglan Cable Technology Co., Ltd Company News

With the deepening of research and understanding of insulation water absorption and water tree, people are more and more aware of the importance of waterproof performance for medium and high voltage power cables. In areas where the groundwater level is high or rainy all the year round (such as the area south of the Yangtze River in China). More and more users have put forward waterproof requirements for cables. Most of the power cables are directly buried, so the cables are very likely to suffer from soil pressure and external force damage due to human factors. From the perspective of laying forms, most foreign countries use metal protective sheaths for mechanical protection and waterproofing, or use cables covered with thin metal tapes and other waterproof layers. However, once this kind of cable is damaged, water will invade the inside of the cable from the damage, and then penetrate into the gap inside the cable (between conductor strands, extruded semi-conductive layer, shielding layer or metal sheath, etc.). Extend longitudinally along the cable, making long cables unusable. When the directly buried cable fails, a new cable is usually replaced at the point of the accident to restore the line. Therefore, once water penetrates into the cable, the water seepage distance should be as short as possible. In order to prevent water seepage after immersion, generally The gap part is used to wrap the water-absorbing swelling material, once it is immersed in water, the gap can be easily blocked. Generally, the sheath material used in cables is polyvinyl chloride, and polyvinyl chloride molecules are polar. Polar water molecules can easily penetrate into the cable through the polyvinyl chloride layer. At present, it is necessary to realize the longitudinal water-blocking technology of the cable. There is no problem with the above, as long as a layer of water-blocking material made of water-tight material is added to the jacket. The currently commonly used method is to squeeze a layer of medium-high density PVC inner jacket in the PVC outer jacket or longitudinally wrap a layer of aluminum-plastic composite tape as the longitudinal water-blocking isolation jacket. Polyethylene is easy to absorb water under an alternating electric field, which does not mean that the water tightness of the polyethylene material is not good. The water tightness of polyethylene material is hundreds of times higher than that of polyvinyl chloride. The extruded polyethylene water blocking layer and a layer of moisture-absorbing cushion (such as water blocking tape) can meet the longitudinal resistance of cables laid in general humid environments. Water and moisture-proof requirements. The use of polyethylene material in the water-blocking isolation sleeve is relatively simple in process, and it can be realized without adding any production equipment. Because the polyethylene layer is only used as a water-blocking layer without considering its mechanical strength and other factors, a good effect can be achieved when its thickness is 1.0~1.5mm during process design due to cost and process considerations. Water blocking tape (yarn) can quickly swell in contact with water and reach a certain swelling height and can form a high-strength gel. It is an ideal active water blocking material, using water blocking tape, water blocking rope, and water blocking As a water-blocking material, yarn has simple process and convenient construction and high production efficiency. Therefore, this structure is generally welcomed by users and manufacturers. Because the contact surface between the single-core cable insulation and the sheath is relatively flat, as long as it is between the outer sheath and the core Wrap a layer of water blocking tape to achieve a good longitudinal water blocking effect. If there is a metal shield, you need to wrap the semi-conductive resistance hose on the inner side of the metal shield. Multi-core cables also need to be effectively filled with water-blocking ropes and water-blocking yarns in the gaps between the cable cores, and then wound with water-blocking tapes. For cables with armored layers, it is also necessary to use two layers inside and outside the armoring layer. A layer of water blocking tape is wrapped around each side. Zhenglan Cable Technology can meet your special requirements in cable's water prevention. Welcome your inquiry.

PVC cable plastic can be divided into insulation grade cable material and protective cable material according to its different use in wire and cable.   Types and characteristics of PVC plastics for insulation General insulation grade: has certain electrical insulation performance, good softness, atmospheric resistance and low cost Heat resistant insulation grade: it has better heat-resistant aging and deformation resistance, and has better electrical insulation performance High electrical performance insulation grade: better electrical insulation performance, high insulation resistance, good dielectric performance, and certain heat resistance Oil resistant and solvent insulation grade: it has good oil resistance, solvent resistance and softness, and good electrical insulation performance Flame retardant insulation grade: good electrical insulation performance, high flame resistance and softness   Types and characteristics of PVC plastics for sheath PVC plastic coating has good corrosion resistance, sufficient mechanical properties, certain atmospheric resistance, soft, vibration resistance, light weight, easy processing and laying. General protection level: sufficient mechanical strength, heat resistance, light aging and cold resistance are good. Good heat resistance: Cold protection level: high cold resistance, low soft Soft protection level: it has high softness and good cold resistance Heat resistant protection level: good heat resistance Oil resistant protection level: good oil resistance and chemical resistance Easy to tear protection level: low tear resistance, easy to lay and low price Mould, termite and rodent protection levels: good biological resistance, termite and mildew resistance Fire retardant protection level: good combustion resistance   Zhenglan Cable Technology Co., Ltd can do PVC insulated and PVC sheathed cable and wire. Welcome your inquiry.

Dear Customer, Thanks for visiting our website. Here comes the traditional Qingming Festival, we will be on holiday from April 3rd to 5th (Saturday to Monday). From Tuesday we will resume work. For any of your inquiries during holiday, we will handle as soon as we can when we come back. Thanks for you kind understanding. Upon the coming weekend, hope you have a nice weekend day off. Sincerely yours Zhenglan Cable Technology Co., Ltd April 2nd, 2021

I. Basic introduction of wires and cables Wire and Cable: it is usually twisted by several or several groups of wires [at least two in each group], similar to ropes. Each group of wires is insulated from each other and often twisted around a center. The whole outside is covered with a highly insulated covering layer. It is mostly used to transmit, distribute electric energy or transmit electrical signals. Wires and Cables are mainly composed of the following four parts 1. Conductive wire core: made of high conductivity material (copper or aluminum). According to the requirements of laying conditions for cable softness, each core may be stranded by a single wire or multiple wires. 2. Insulation layer: insulation material used as cable should have high insulation resistance. Insulation material commonly used in cables include oil-immersed paper, polyvinyl chloride, polyethylene, cross-linked polyethylene, rubber, etc. 3. Sealed jacket: protect the insulated wire core from mechanical, moisture, moisture, chemicals, light, etc. For insulation that is prone to moisture, lead or aluminum is generally used to squeeze sealed jacket. 4. Protective Cover: used to protect sealed jacket from mechanical damage. Galvanized steel strip, steel wire, copper strips wire, copper wire, etc. are generally used as armor to wrap around the sheath (called armored cable), and the armored layer can shield the electric field and prevent the interference of external electromagnetic waves at the same time. In order to avoid the corrosion of steel strips and steel wires by the surrounding medium, they are usually coated with asphalt or wrapped with impregnated jute layer or extruded polyethylene and polyvinyl chloride sleeve. II. Wire and Cable Specifications Wire and Cable specifications are the meaning of the representation of the number of cores and cross-sectional dimensions of wires and cables. The complete naming of wires and cables is usually more complicated, so people sometimes use a simple name (usually a category name) combined with model specifications to replace the complete name, for example, "Low Voltage Cable" represents all plastic insulated power cables of 0.6/1kV level. The type spectrum of the cable is relatively perfect. It can be said that as long as the standard model specifications of the wire and cable are written, the specific products can be clearly defined. III. Application classification of wires and cables (1) classified by insulation material, such as oil-immersed paper insulated cables, polyvinyl chloride cables, XLPE cables, etc. (Ii) classified by purpose, divided into power cable, communication cable and control cable, etc. It is applied to power system, information transmission system, mechanical equipment and instrument system respectively. 1. Power system Wire and cable products used in power system mainly include overhead bare wire, busbar (bus), power cable (plastic cable, oil paper power cable (basically replaced by plastic power cable), rubber-sleeve cable, overhead insulated cable), branch cables (replacing some bus bars), electromagnetic wire, electrical equipment wires and cables for power equipment, etc. 2. Information transmission system The wires and cables used in information transmission system mainly include local cable, TV cables, electronic cables, radio frequency cables, optical fiber cables, data cables, electromagnetic wire, power communication or other composite cables. 3. Mechanical equipment, instrumentation system Almost all products except overhead bare wires in this part have applications, but they are mainly power cables, electromagnetic wire cables, data cables, instrument cables, etc. (3) according to product classification, it is divided into five categories 1. Bare wire and bare conductor products The main features of this product are: pure conductor metal, no insulation and sheath layer, such as steel core aluminum stranded wire, copper aluminum busbar, electric locomotive wire, etc.; The processing technology is mainly pressure processing, such as smelting, calendering, drawing, stranding/compact stranding, etc.; Products are mainly used in suburbs, rural areas, user main lines, switch cabinets, etc. 2. Power cable The main features of this kind of products are: Squeezing (winding) insulation layer outside the conductor, such as overhead insulated cable, or several core stranded (corresponding to the phase line, zero line and ground line of the power system), for example, more than two-core overhead insulated cables, or add a sheath layer, such as plastic/rubber cover wire and cable. The main technologies include drawing, stranding, insulation extrusion (wrapping), cable forming, armour, sheath extrusion, etc. Different process combinations of various products have certain differences. The products are mainly used in the transmission of strong electric energy in the transmission, distribution, transmission, transformation and power supply lines, with large current (tens of to thousands of) and high voltage (220V to 500kV and above). 3. Wires and cables for electrical equipment The main features of this kind of products are: there are a wide range of variety and specifications, wide range of application coverage, and the operating voltage is more than 1kV. In the face of special occasions, new products are constantly derived, such as fire-resistant cables, Flame Retardant Cables, low smoke halogen-free/low smoke halogen-free cables, termite-proof, mouse-proof cables, oil-resistant/cold-resistant/temperature-resistant/wear-resistant cables, medical/agricultural/mining cables, thin-walled wires, etc. 4. Communication cable and optical fiber From the simple telephone and telegraph cables in the past to thousands of pairs, coaxial cables, optical cables, data cables, and even combined communication cables. The structure and size of this kind of products are usually small and uniform, and the manufacturing precision is required to be high. 5. Electromagnetic wire (winding wire) It is mainly used for various motors, instruments and meters, etc. 4. What is the difference between wire and cable? In fact, there is no strict boundary between "wire" and "cable. Generally, products with small core number, small product diameter and simple structure are called wires, those without insulation are called bare wires, and others are called cables; Those with large conductor cross-sectional area (greater than 6 mm²) are called large wires, smaller (less than or equal to 6 mm²) is called small cord, and insulated electric conductor is also called covered wire. However, with the expansion of the scope of use, many varieties of "cable with Cable" and "cable with Cable". Therefore, there is no need to strictly distinguish. In daily habits, people call household covered wire and power cable for short. The wire is composed of one or several soft wires, and the outer bread has a light and soft protective layer; The cable is composed of one or several insulated covered wires, the outside is wrapped with a tough outer layer made of metal or rubber. Cables and wires are generally composed of core wire, insulation foreskin and protective sheath.

1. What is the main electrical connection? Answer: the main electrical connection is the connection mode of main electrical equipment and bus in power plant and substation, including the connection mode of main bus and auxiliary power system according to certain functional requirements 2. What regulations should be followed when selecting the section of power cable? A: 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 continuous allowable current of cable shall be equal to or greater than the maximum continuous current of power supply load; (3) The cross section of the core should meet the stability requirements of the power supply system in case of short circuit; (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 shall enable the protection device to operate reliably. 3. What inspection work should be carried out before cable laying? Answer: (1) the bracket should be complete and the paint should be complete. (2) The cable model, voltage and specification meet the design requirements. (3) The cable insulation is good. When the sealing of oil paper cable is in doubt, it should be judged to be affected with damp; the directly buried cable and small bottom cable should pass the DC withstand voltage test; the oil sample of oil filled cable should pass the test. (4) The oil pressure of oil filled cable should not be lower than 1.47mpa. 4. Where should the orientation mark of directly buried cable be set? Answer: at both ends of the cable, at the 50 ~ 100m straight section of the cable, the cable joint is at the bend angle where the direction of the cable changes. 5. What is the function of cable inner sheath? A: the insulation layer will not contact with water, air or other objects to prevent the insulation from moisture and mechanical damage. 6. What are the main properties of the insulation materials of power cables? A: it should have the following main functions: (1) High breakdown strength; (2) Low dielectric loss; (3) High insulation resistance; (4) Excellent discharge resistance; (5) It has certain softness and mechanical strength; (6) The insulation performance is stable for a long time.

Low smoke halogen-free cable refers to the environment-friendly cable which is made of glue without halogen (F, Cl, Br, I, at), lead, cadmium, chromium, mercury and other environmental substances, and will not emit toxic smoke when burning. Low smoke and halogen-free cable, with superior flame retardant performance, little smoke when burning and no corrosive gas escaping, is widely used in nuclear power stations, subway stations, telephone exchanges and computer control centers, high-rise buildings, hotels, radio and television stations, important military facilities, petroleum platforms, etc., as well as places with concentrated personnel and low air density. Characteristics of low smoke halogen free wire: (1) The tensile strength of general PVC wires is greater than 1.05kgf/mm2, while that of low smoke halogen-free wires is greater than 1.2kgf/mm2; (2) It has good weather resistance (- 30 ℃ ~ 105 ℃); (3) It has good softness (hardness 80-90); (4) It has non mobility (because there is no need to add plasticizer in this product formula, so it will not have mobility); (5) There will be no toxic black smoke (a small amount of white smoke) during combustion; (6) The volume resistivity of PVC wire is 1012 ~ 1015 Ω / cm3, and that of LSZH wire is more than 1016 Ω / cm3; (7) It has good high-voltage resistance characteristics: PVC wires are generally resistant to more than 10kV, while low smoke halogen-free wires are up to more than 15kV; (8) It has good elasticity and viscosity. Flame retardant cable refers to the cable that the sample is burned under the specified test conditions, the flame spread is only within a limited range after removing the test fire source, and the residual flame or residual ignition can be extinguished within a limited time. The basic characteristic is: in case of fire, it may be burnt out and cannot operate, but it can prevent the spread of fire. Generally speaking, in case of wire fire, the combustion can be limited in a local scope, without spreading, and other equipment can be kept to avoid greater losses. The general method of flame retardant wire and cable is to add halides and metal oxides containing halogen in the sheath material. From the perspective of flame retardant, this is an excellent method. However, because these materials contain halides, a large amount of smoke and hydrogen halide gas are released during combustion, so the visibility in case of fire is low, which brings great challenges to the safe evacuation and fire fighting of personnel People are more likely to suffocate to death by toxic gases. Now, low smoke halogen-free cable is being promoted to replace the general flame retardant cable. Generally, the price of flame retardant cable is about 8500 yuan per ton, while the price of low smoke halogen-free cable is more expensive.