High voltage cable terminal making installation a principle and process, power cable accessories basics 1. What is cable accessories? Cable Accessories are collectively the cable lines in a variety of cable connectors and terminal head. 2. What is the cable connector? Cable connector means the device interconnecting cables and cable plays the circuit flow. Phase or phase to ensure that the insulation, sealing and mechanical protection. 3. What is the Cable Terminal? Cable Terminal refers to the end of the assembly to cable lines, to ensure that the connection to the electrical grid or other electrical equipment, and to provide a device as a cable conductive core insulated leads. 4, the first intermediate connector cable types: A, plug connector only; B, through connector; C, branch connector; D, adapter; E, transition joints. 5. What is the outdoor cable terminal head? Outdoor Cable Terminal refers to cable terminal lead-out portion of the conductor insulation can withstand the atmospheric effects of outdoor cable terminal devices, ie outdoor cable termination head can under various atmospheric conditions (including dates sun, rain, contamination, temperature change) To normal operation. 6. What is the indoor cable terminal head? Cable Terminal Compared with outdoor cable terminal head, not required to withstand atmospheric effects, the operating environment is superior end outdoor cable indoors. 7, the type of cable accessories: A, mainly rubber adhesive tape or plastic tape wrapped around the package molded cable accessories; B, the use of an elastic material (such as ethylene-propylene rubber, silicone rubber, etc.) to cable joints and terminations Head of insulation and external shielding layer, injection molded in a factory or a whole site suit in the treated cable ends or joints, this cable accessory called prefabricated cable accessories; C, application of a polymer material having " elastic memory "of the characteristics of the various components of cable accessories, are made in a factory pipe, gloves, rain cover and so on, and then crosslinked expanding, heat-shrunk molding on-site installation, which is called the heat-shrinkable cable accessories type cable accessories; D, out of the liner elastic material (usually EPR ethylene propylene rubber, silicone rubber, etc.) cable accessories insulation and stress control layer molded and cured in the factory, and then expanding to underlay, on-site installation time , while pressing the cable end through the cable attachment or joint forming process called cold shrink cable accessories; 8, a complete evaluation of cable accessories should be issued several considerations: 1), electrical insulation properties include: Insulation material used in insulation resistance, dielectric loss (intake pressure above) dielectric constant, breakdown strength, and maximum operating field determined by the material and structure of strong, head for the terminal should also consider structural factors external insulation, flash distance as dry, wet flash distance. The organic material is used as external insulation also need to consider anti-leakage trace and electric anti-corrosion properties. 2) Thermal resistance: insulation material in addition to aging as well as electric heat aging, have a direct impact on the safe operation of cable accessories and service life, cable accessories in addition to the conductor of heat resistance, as well as the conductor connecting the contact resistance, and insulation material dielectric loss itself. Factors affecting heat cable accessories in addition to fever heat, as well as insulating materials and accessories for thermal coefficient of heat dissipation. 3), the structure of rationality: In addition to these factors, cable accessories also need to consider sealing reliability, easy sufficient mechanical strength (to resist external and short-circuit the damaging effects of the electromagnetic force) install and operate, compact and lightweight, easy maintenance and other issues . 4) sources of material and costs: a good cables other members should also consider the material source of the problem, as far as possible based on the domestic. At the same time the price of materials and processing costs can not be ignored, because of the low voltage cable accessory is a large wide area of ??products, not expensive, spared no expense. 9, the stress tubes: each phase high-voltage cable insulated outer core has a grounded metal shield, so that the electric field radially evenly distributed in the cable metallic shield cutting head at the cable core to ground (shield) The electric field (because there is no shield at all to the fracture) will concentrate the electric field strength is greater than many other places, the cable shield fracture most likely breakdown, so making the cable head metal shield the fracture should remain 20mm semiconductor layer, and then the semiconductor stress control tube (inside to trap the metal shield 30 mm) over the fracture, because the volume resistivity of the semiconductor material stress tube 8 ohm power 10 / cm, 10 to 12 ohm power / cm, the cable wire shield the electric field stress in the metal layer at a stress fracture of the dispersion tube, increase the pressure capacity of the cable. 10, the role of grease cream: Using grease lubricated interface for easy installation; at the same time the gap filling interface, eliminating the corona and isolate dust, avoid the dust into the cause a short circuit. 11. Why do the fracture semiconductor layer chamfer? Because of the length of the cone is much larger than the length of the right-angle side, it is cut along the cone is far less than the strong field squaring edge to field strength, the possibility of breakdown along the tapered surface is greatly reduced, improving the safety performance of the joint. Second, the power cable 12, power cable structure: cable outer sheath to expand, steel, inner liner, the metal shield, outer semiconducting layer, an insulating layer, the semiconductor layer, a conductive core 3, an outer semiconductor layer effects: the elimination of the metal shield and cable insulation in direct contact with the possible air gap, because the metal shield is typically grounded, so the gap between the high voltage and is in the ground, that is to say in the electric field under the running It may lead to the case of partial discharge, thereby affecting the safe operation and life of the cable. 14, the role of the outer semiconducting layer: high-voltage cable is a stranded conductor is generally formed by a plurality of wires, high voltage cable conductor gap and the insulating layer may have a gap, because the electric field is concentrated, so the surface of the conductor is not smooth. Surface of the conductor is to add a layer of semiconductor material of the shield, the shield conductor with the rank potential and good contact with the insulating layer has, so to avoid partial discharge phenomenon occurs between the conductor and the insulating layer, which shielded within shield high voltage cables. 15, the role of the metal shield: the cable is in normal operation via capacitive current, when the system is short-circuited, the metal shield as a short-circuit current of the channel, play a role in shielding the electric field. 16, high-voltage power cable copper shield and steel armor generally require grounding, grounding end grounded at both ends and what is the difference? The production of cable terminal head, steel armor and copper shield can weld a piece? 35KV high voltage cable more single-core cable, single core cables with the power running, the shield will form an inductive voltage. If the shield at both ends at the same ground, between the shield and the earth form a loop, will be induced currents, so the cable shield may have a fever, loss of a lot of power, affecting the normal operation of the line. To avoid this phenomenon, usually at one end grounded manner; when the line is long, you can use the mid-point ground and cross the Internet and other means. 35kV and below the voltage level of the grounding cable are used at both ends. This is because most of these cables is a three-core cables, in normal operation, the sum of currents flowing through the three core zero outside the aluminum package or a metal shield substantially flux, so that the aluminum bag or both ends of the metal shield is basically no induced voltage, so there is no induction current flows through the aluminum package or after the metal shield grounded at both ends. In the production of cable head, the steel armor and welded copper shield separate grounding, in order to facilitate detection of the quality within the sheath. Upon detecting the sheath, between steel and copper shield armor with voltage, if it can withstand a certain voltage proof inner protective layer is intact. Without this requirement, no need to detect within the cable sheath may be steel armor shield together with copper ground (we advocate separate leads grounded). Third, the cable head 17 making process, the advantages of heat-shrinkable type attachment: is the desired size small, small, relatively easy construction, fast. 18, shortcomings Shrink-on: 1) because of the need to use fire construction, so avoid fire place NA, with miniaturization, indoor use switchgear will also be a limited; 2) Applicable less cable types. Heat Shrink is ideal for non-draining cable directly connected to the grid and large switchgear and other limited space situations, using the sticky-impregnated paper cable, anti-leakage problem not easy to solve, real run for 2 to 3 years was found leaking situation. 3) Shrink-on seal tight mainly by hot melt and systolic stress to achieve. Heat shrinkage at the scene when the temperature exceeds the heat-shrinkable material is crystalline melting point of the object being pressed is an elastic pressing force, after the flame is removed, as the temperature dropped to the crystallization point, again crystallized into a stable structure, temperature and then continued to decline, by cooling the compacted body also will shrink (expansion and contraction), due to thermal element after crystallization has been stable structure, it loses its elasticity clamping force, a hot melt adhesive sealing thanks If the quality is not reliable or uneven hot melt adhesive coating, the reliability of the seal would be difficult to achieve, which indicates if the heat-shrinkable by piece alone without additional sealing material or other sealing structure can not achieve the objective. 4) The structure is layered, overlapping kinds of pipe fittings, during which the gap is inevitable, so the intermediate (10 ~ 35KV) crowded pack type cable with shrink-ons especially in the middle connector (thermal conductive members in direct contact with a high electric field lines core), its local discharge performance is difficult to secure. 5) Since the thermal material after heat shrinkage, next to the room temperature is not flexible, so after shrinking cable accessories, when in place, because the cable is bent Roudong cause disengagement between the thermal components, so that the actual operation The poor performance of partial discharge cable accessories. http://mayu1991619.jdzj.com/ http://mayu1991619.b2b.youboy.com/ http://m1991619.cn.china.cn/ http://mayu1991619.955101.com/ http: // mayu1991619. cn.gongchang.com/ http://www.datoumao.com/gongsi/mayu1991619/ http://www.kejiqi.org/corp/mayu1991619/ http://mayu1991619.8j8.cc/ http: // mayu1991619. cn.b2b168.com// http://www.sooshong.com http://www.cntrades.com/b2b/mayu19911619/