Method for uninterrupted manufacture of electric cables
FIELD: electric cable manufacture.
SUBSTANCE: proposed method includes following procedures: (a) conductor feeding at predetermined feed rate; (b) extrusion of thermoplastic insulating layer in position radially external with respect to conductor; (c) cooling down of foamed insulating layer; (d) production of circumferentially closed metal shield about mentioned extruded insulating layer. Novelty is that procedures are conducted uninterruptedly, that is, time passed from end of cooling procedure to initiation of shield formation is inversely proportional to conductor feed rate.
EFFECT: reduced manufacturing time, enhanced mechanical strength of cable.
19 cl, 5 dwg, 2 tbl, 1 ex
The present invention relates to a method of manufacturing electric cables, in particular electrical cables for the transmission or distribution of electricity at medium or high voltage.
In the present description the term "medium voltage" is used to define a voltage typically in the range from about 1 kV to 60 kV, and the term "high voltage" refers to voltages above 60 kV (the term "high voltage" is also sometimes used in the art to determine the stresses over from about 150 kV or 220 kV up to 560 kV or more).
Such cables can be used for transmission or distribution of electricity as direct current (DC)and alternating current (AC).
Cables for the transmission or distribution of electricity at medium or high voltage typically have a metallic conductor which is covered by the first inner semiconductor layer, insulating layer and outer semi-conducting layer. Below in this description referred to the group of elements will be determined by the concept of "lived cable".
In position, the outer (radial direction) relative to that of the cable core, the cable has a metal shield (or screen), usually made from aluminum or copper.
The metal shield may consist of a number of meta is symbolic of wires or tapes, helically wound around the cable core, or from continuous around the circumference of the pipe, such as a metal tape, which given the shape of corresponding tubular form and welded or sealed to ensure tightness.
Metal shield performs an electrical function by creating inside the cable, resulting in direct contact between the metal shield and the outer semi-conducting layer of the cable conductor, a uniform electric field the radial type, at the same time suppressing the external electric field of the cable. Another feature is the counter-currents of short circuit.
Being made in the form of a continuous around the circumference of the pipe, a metal shield also provides a seal against water penetration in the radial direction.
Example metal shields are described in the document U.S. Re36307.
In the configuration of the unipolar type, the said cable further includes a polymeric outer shell in position, the outer (radial direction) relative to the metal shield mentioned above.
In addition, the cables for transmission and distribution of electricity is usually provided with one or several layers to protect the mentioned cables from accidental bumps that may occur on their outer surface.
Random attacks on the cable can is to take place, for example, during transportation or during the operation of the cable when backfilling trenches in the ground. Mentioned random shocks can cause some structural damage to the cable, including the deformation of the insulating layer and the separation insulating layer on the semiconductor layers, i.e. damage that can cause changes in electrical voltage stress of the insulating layer, followed by a decline insulating mentioned layer.
Cables with cross-linked insulation-known, and their method of manufacture are described, for example, in EP 1288218, EP 426073, US 2002/0143114 and US 4469539.
Stitching cable insulation can be executed or using so-called silane crosslinking, or by using peroxides.
In the first case lived cable, including extruded insulation covering the conductor is retained for a relatively long time (hours or days) in the environment containing water ( either in liquid form or in the form of steam, as, for example, wet environment), so that the water can diffuse through the insulation to cause crosslinking. This requires winding on the reel core of the cable of fixed length, and this fact inevitably prevents continuous manufacturing method.
In the second case, the crosslinking caused by the decomposition of peroxide in comparison to the sustained fashion high temperature and pressure. The chemical reactions that take place, to form gaseous by-products, which must be able to diffuse through the insulation layer, not only during curing, but also after curing. So must be provided by the degassing operation, during which she lived cable shall be kept for a period of time sufficient to eliminate such gaseous by-products, before the core of the cable will be imposed with additional layers (in particular, if such layers are gas-tight or substantially gas-tight, as in the case of applying the metal layer, folded in the longitudinal direction).
As practice shows, the applicant, in the absence of stage degassing before applying additional layers under certain environmental conditions (for example, when visible solar radiation conductor cable) mentioned by-products expand, thus causing harmful deformation of the metal shield and/or the polymer of the outer shell.
In addition, in the absence of operation of the degassing gaseous by-products (e.g., methane, acetophenone, semenovii alcohol) remain trapped inside the core of the cable due to the presence of additional layers, superimposed on it, and they can leave the cable only by its ends It is especially dangerous, because some of the side products are flammable (e.g., methane) and, thus, there is a possibility of explosions, for example, during the construction or splicing mentioned cables when backfilling trenches in the ground.
Moreover, in the absence of stage degassing before applying additional layers there is a probability that the detected porosity in isolation, which can degrade the electrical insulation properties.
A method of manufacturing a cable with thermoplastic insulation, described in international application WO 02/47092 on the name of the present applicant, which describes the manufacture of the cable by extrusion and passing through the static mixer thermoplastic material comprising a thermoplastic polymer, mixed with a dielectric liquid, and such a thermoplastic material is applied around the conductor through the extrusion head. After the operation, cooling and drying the core of the cable is kept on the drum and then put the metal shield by blending in a spiral line of thin strips of copper or copper wires on the core of the cable. The imposition of the polymer of the outer shell completes the manufacturing process of the cable.
The continuous supply cable conductor with extruded insulation for the unit to superimpose the shield was not provided. Actually the automatic shield was of this type, which is only suitable for intermittent way overlay, as it required the use of drums mounted on a rotating device, as will be explained below.
The applicant has found that the presence of the rest phase (i.e. exposure without treatment) during manufacture of the cable, e.g., curing or degassing, is undesirable because it limits the length of each segment of the cable (requires keeping on cable drums), it requires space and problems of logistics at the plant, it lengthens the time of manufacture of the cable, and, finally, it increases the cost of manufacture of the cable.
According to one object of the present invention the applicant has found that the cable can be manufactured in a very convenient manner by a continuous way, i.e. in the absence of intermediate phases of rest or keeping by using a thermoplastic insulating material in combination with a rolled in the longitudinal direction, in solid circle with a metal shield.
The first object of the present invention is a method of continuous manufacture of an electric cable, comprising phase supply with a predetermined feeding speed of the conductor, extruding thermoplastic insulating layer,which is the outside in the radial direction relative to the conductor, cooling the extruded insulating layer, forming a closed circumference of the metal shield around the aforementioned extruded insulating layer, characterized in that the time elapsed between the end of the cooling phase and the beginning of a phase of formation of the shield, is inversely proportional to the feeding speed of the conductor.
In particular, closed around the circumference of the metal shield around the aforementioned extruded insulating layer is formed by clotting in the longitudinal direction of the metal sheet having overlapping edges, or United at the junction of the edges.
The phase formation of metal shield according to the method of the present invention preferably includes an operation of overlapping the edges of sheet metal. Alternatively, the forming phase includes a join operation butt edges mentioned metal sheet.
The method preferably includes phase supply conductor in the form of a metal rod.
Furthermore, the method of the present invention preferably includes a phase blending element impact protection around the metal shield. The above mentioned element impact protection impose preferably by extrusion. The above mentioned element impact protection preferably includes dense (newpenny) polymer layer and spenny the (porous) polymer layer. Foamed polymer layer preferably placed radially outside a relatively thick polymer layer. Dense polymer layer and the foamed polymer layer is preferably imposed by co-extrusion (or coextrusion).
The method of the invention further includes a phase blending of the outer shell around the metal shield. The outer shell preferably impose extrusion.
An element of protection from shock impose preferably between closed metal shield and the outer shell.
Thermoplastic polymer material of the insulating layer preferably includes a predetermined number of dielectric liquid.
The applicant has found, moreover, that the cable is obtained according to the continuous method of the present invention unexpectedly has a high mechanical resistance to accidental impacts which can occur on the cable.
In particular, the applicant has found that high impact protection preferably attached to the cable through a combination of closed circumference of the metal shield to protect from impact, comprising at least one foamed polymer layer, the latter is placed on the outside in the radial direction relative to the metal shield.
In addition, the applicant has noticed that in the case of deformation detais for the corresponding impact on cable the presence of a closed circumference of the metal shield is particularly effective, because the shield is deformed continuously and smoothly, thereby avoiding any local jumps of the electric field in the insulating layer.
In addition, the applicant has found that the cable supplied with thermoplastic insulation, closed around the circumference of the metal shield and protection from impact, comprising at least one foamed polymer layer, may be preferably obtained by a continuous production process.
In addition, the applicant has found that mechanical resistance to random shocks can be effectively increased if the cable to give additional foamed polymer layer in position, the inner (radial direction) relative to the metal shield.
Will be preferred, if the foamed polymer layer is blocking the water layer.
The second object of the present invention is an electric cable comprising a conductor, thermoplastic insulation layer located radially outside relative to the conductor, at least one foamed polymer layer around the mentioned insulating layer, closed around the circumference of the metal shield around the mentioned insulating layer and the element of protection against shock in the outer position (in radial direction) relative to the metal soup is a, moreover, the above-mentioned item impact protection includes at least one dense polymer layer around the mentioned metal shield and at least one foamed polymer layer in the outer position (in radial direction) relatively dense polymer layer.
Other details will be illustrated in the following detailed description with reference to the accompanying drawings, in which
Figure 1 is a perspective view of an electrical cable according to the first embodiment of the present invention,
Figure 2 is a perspective view of an electrical cable according to the second embodiment of the present invention,
Figure 3-schematic representation of a plant for the manufacture of cables according to the method of the present invention,
4 is a schematic representation of an alternative installation for the manufacture of cables according to the method of the present invention,
5 is a view in cross section of the electrical cable is manufactured according to the method of the present invention,
6 is a view in cross section of a traditional electric cable, fitted with a shield made of wires, damaged by a blow.
1, 2 show a perspective view, partially in cross section, of the electrical cable 1, typically designed for use in middle or high e.g. the supply, which is made according to the method of the present invention.
The cable 1 comprises a conductor 2, the inner semi-conducting layer 3, an insulating layer 4, the outer semi-conducting layer 5, a metal shield 6 and the protective element 20.
The conductor 2 is preferably a metal rod. The conductor is preferably made of copper or aluminum.
Alternatively, the conductor 2 includes at least two metal wires, preferably made of copper or aluminum, which are twisted together according to conventional techniques.
The cross-sectional area of the conductor 2 is determined depending on the electric power transmitted at the selected voltage. The preferred cross-sectional area for cables according to the present invention are in the range from 16 mm2up to 1600 mm2.
In the present description, the term "insulating material" is used to specify a material having a dielectric strength of at least 5 kV/mm, preferably more than 10 kV/mm For cable transmission medium high voltage (i.e. a voltage of more than about 1 kV) insulation material preferably has a dielectric strength of more than 40 kV/mm
Usually the insulation layer of the cable transmission has a dielectric constant (K) > 2.
Internal floor is routashi layer 3 and the outer semi-conducting layer 5 is usually produced by extrusion.
The main polymeric materials of the semiconductor layers 3, 5, in which case choose from materials listed below in the present description with reference to the foamed polymer layer, add conductive carbon black, such as conductive chimney soot or acetylene soot, so as to give a semi-conducting properties of the polymer material. In particular, the surface area of the carbon black in the total is more than 20 m2/g, and typically from 40 to 500 m2/, Can be used preferably highly conductive carbon black having a surface area of at least 900 m2/g, such as, for example, furnace carbon black, industrial manufactured under the brand name Ketjenblack®EC (firm Akzo Chemie NV). The amount of carbon soot, which must be added to the polymeric matrix may vary depending on the type of polymer used carbon black, degree of expansion, which is assumed to be provided, extenders, etc. Thus, the amount of carbon black should be such as to give a foamed material sufficient conductive properties, in particular, to obtain the value of volume resistivity for the foam material at room temperature is less than 500 Ohms·m, preferably less than 20 Ohms·m the usual amount of carbon black can be changed in the range of 1-50 wt.%, preferably in the range of 3-30 wt.% the weight of the polymer.
In the preferred embodiment of the present invention the inner and outer semi-conductive layers 3, 5 include seamless polymeric material and more preferably a polypropylene material.
The insulating layer 4 is preferably made of thermoplastic material comprising a thermoplastic polymeric material which contains a predetermined amount of dielectric fluid.
Thermoplastic polymeric material is preferably selected from polyolefins, copolymers of different olefins, copolymers of olefins with ethylene-unsaturated complex ester, polyesters, polyacetates, cellulose polymers, polycarbonates, polysulfones, phenolic resins, urea resins, polyketones, polyacrylates, polyamides, polyamines and their mixtures. Examples of suitable polymers are polyethylene (PE), in particular PE low density (LDPE), RE medium density (MDPE), D high density (HDPE), linear PE low density (LLDPE), D ultra low density (ULDPE), polypropylene (PP), copolymers of ethylene/vinyl ester, for example a copolymer of ethylene/vinyl acetate (EVA), copolymers of ethylene/acrylate, in particular ethylene/methyl acrylate (EMA), ethylene/ethyl acrylate (EEA), and ethylene/butyl acrylate (EVA), thermoplastic copolymers of ethylene is/α -olefin, polystyrene, Acrylonitrile/butadiene/styrene (ABS) resins, halogenated polymers, in particular polyvinyl chloride (PVC), polyurethane (PUR), polyamides, aromatic polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (RHT), and their copolymers or mechanical mixture.
The dielectric fluid may be preferably selected from mineral oils, such as, for example, naphthenic oils, aromatic oils, paraffinic oils, aromatic oils, and mentioned mineral oils optionally contain at least one heteroatom selected from oxygen, nitrogen or sulfur, liquid paraffin, vegetable oils, such as soybean oil, linseed oil, castor oil, oligomeric aromatic polyolefin, paraffin waxes, such as, for example, polyethylene waxes, polypropylene waxes, synthetic oils such as silicone oils, alkyl benzenes (such as, for example, dibenzyltoluene, dodecylphenol, di(activesel)toluene), aliphatic esters (such as, for example, therefire of PENTAERYTHRITE, esters sabatinovka acid, phthalic esters), olefin oligomers (such as, for example, optionally hydrogenated polybutene or polyisobutene) or mixtures thereof. Aromatic, paraffinic and naphthenic oils are special is on the preferred.
In preferred embodiments of the invention shown in figures 1 and 2, a metal shield 6 is made of a continuous sheet metal, preferably of aluminum or copper, which is formed in the form of a pipe.
Sheet metal forming the metal shield 6, is rolled in the longitudinal direction around the outer semi-conducting layer 5 with overlapping edges.
In a proper case between the overlapping edges is a sealing and bonding material so as to make a metal shield waterproof. Alternatively, the edges of the sheet metal can be welded.
As shown in figures 1 and 2, a metal shield 6 is covered by an outer shell 23, preferably made of seamless polymeric material such as polyvinyl chloride (PVC) or polyethylene (PE), the thickness of this outer shell can be chosen to give the cable a certain degree of resistance to mechanical stress and shock, but without excessive increase of the diameter of the cable and its strength. This solution is useful, for example, for cables intended for use in protected areas that are expected to be limited strike, or provides protection otherwise.
According to a preferred embodiment of the invention shown in figure 1, which is particularly useful when you need additional protection is from the blow, cable 1 supply protection element 20 placed in position radially outside relative to that of the metal shield 6. According to the above embodiment, the protection element 20 includes a dense polymer layer 21 (in the inner position in the radial direction) and the foamed polymer layer 22 (in the outer position in the radial direction). According to the embodiment of figure 1 dense polymer layer 21 is in contact with the metal shield 6, and the foamed polymer layer 22 lies between the dense polymer layer 21 and a polymeric outer sheath 23.
The thickness of the dense polymer layer 21 is in the range of 0.5-5 mm
The thickness of the foamed polymer layer 22 is in the range of 0.5-6 mm
The thickness of the foamed polymer layer 22 in 1-2 times the thickness of the dense polymer layer 21.
The protection element 20 has the function of providing additional protection of the cable against external blows by at least partial absorption of the impact energy.
Expanded onto a polymer material, which is suitable for use in foamed polymer layer 22 may be selected from the group comprising polyolefins, copolymers of different olefins, copolymers of olefins with ethylene-unsaturated complex ester, polyesters, polycarbonates, polysulfones, phenolic resins, urea resins, and mixtures thereof. Por what measures suitable polymers are polyethylene (PE), in particular PE low density (LDPE), RE medium density (MDPE), D high density (HDPE), linear PE low density (LLDPE), D ultra low density (ULDPE), polypropylene (PP)elastomeric copolymers of ethylene/propylene (EPR) or ternary copolymers of ethylene/propylene/diene (EPDM), natural rubber, butyl rubber, copolymers of ethylene/vinyl ester, such as ethylene/vinyl acetate (EVA), copolymers of ethylene/acrylate, in particular ethylene/methyl acrylate (EMA), ethylene/ethyl acrylate (EEA), and ethylene/butyl acrylate (EVA), thermoplastic copolymers of ethylene/α-olefin, polystyrene, Acrylonitrile/butadiene/styrene (ABS) resins, halogenated polymers, in particular polyvinyl chloride (PVC), polyurethane (PUR), polyamides, aromatic polyesters such as polyethylene terephthalate (PET) or polybutylene terephthalate (RHT), and their copolymers or mechanical mixture.
The polymer material forming foamed polymeric layer 22, preferably is a polyolefin polymer or copolymer based on ethylene and/or propylene, and he selected, in particular, of the following copolymers:
(a) copolymers of ethylene with an ethylene-unsaturated complex ester such as vinyl acetate or butyl acetate, in which the amount of unsaturated complex ester in the range of from 5 to 80 wt.%, preferably from 10 to 50 wt.%,
b) elastomeric copolymers of ethylene, at least one3-C12α-olefin, and, optionally, a diene, preferably copolymers of ethylene/propylene (EPR) or ethylene/propylene/diene (EPDM)having the following composition: 35-90 mol.% ethylene, 10-65 mol.% α-olefin, 0-10 mol.% the diene (for example, 1,4-hexadiene or 5-ethylidene-2-norbornene),
(C) copolymers of ethylene, at least one With4-C12α-olefin, preferably 1-hexene, 1-octene and similar compounds, and, optionally, a diene, generally having a density of from 0.86to 0.90 g/cm3and the following composition: 75-97 mol.% ethylene, 3-25 mol.% α-olefin, 0-5 mol.% diene,
(d) copolymers modified with propylene, copolymers of ethylene/3-C12α-olefin, in which the weight ratio between copolymer of polypropylene and ethylene/3-C12α-olefin is from 90/10 to 10/90, preferably from 80/20 to 20/80.
For example, industrial manufactured products Elvax®(DuPont company), Levapren®(Bayer) and Lotryl®(company Elf Atochem) are in the class (es)products Dutral®(firm Enichem) or Nordel®(Dow-DuPont) are in the class (b), the products belonging to class (b)are Engage®(Dow-DuPont) or Exact®(Exxon company), whereas the copolymers modified with propylene, copolymers of ethylene/3-C α-olefin of the class (g) industrial available under the brand names of Mophen®or Hifax®(company Basell) or Fina-Pro®(firm Fina), and the like.
In class (g) is especially preferred are thermoplastic elastomers comprising a continuous matrix of thermoplastic polymer, for example polypropylene, and small particles (generally having a diameter of about 1-10 μm) of the cured elastomeric polymer such as crosslinked EPR or EPDM dispersed in thermoplastic matrix.
The elastomeric polymer may be embedded in thermoplastic matrix in the uncured state and then dynamically crosslinked during processing by adding the appropriate amount of cross-linking agent.
Alternatively, the elastomeric polymer can be overiden separately and then dispersed in thermoplastic matrix in the form of small particles.
Thermoplastic elastomers of this type are described, for example, in U.S. patent No. 4104210 or in European patent application EP 324430. These thermoplastic elastomers are preferred because they are particularly effective when the elastic absorption of radial forces during thermal cycles of the cable throughout the range of operating temperatures.
The term "foamed polymer" means in the present description, the polymer structuraldamage the percentage of "voids" (i.e. space, employed not by the polymer and the gas or air) is usually more than 10% of the total volume of the above-mentioned polymer.
In General, the percentage of free space in the foamed polymer is expressed in the values of the degree of extension (G). In the present description the term "degree of expansion of the polymer" refers to the extension of the polymer, defined as follows:
G (expansion ratio) = (do/de-1),
where dospecifies the density of the dense polymer (i.e. a polymer with a structure that is essentially free of the volume of voids), and deindicates the apparent density measured for the polymer foam.
The degree of expansion of the foamed polymer layer is preferably selected in the range from 0.35 to 0.7 and more preferably from 0.4 to 0.6.
Dense polymer layer 21 and the outer casing is preferably made of polyolefin materials, usually made of polyvinyl chloride or polyethylene.
As shown in figures 1 and 2, the cable is further provided with a water blocking layer 8 placed between the outer semi-conducting layer 5 and the metal shield 6.
Blocking the water layer 8 preferably is expanded onto, swelling from water semi-conducting layer.
Example expanded onto, swelling from water semi-conducting layer is described in the international patent application WO 01/46965 on the name of the tune is asego of the applicant.
Expanded onto the polymer water blocking layer 8 is preferably selected from polymeric materials mentioned above for use in the foamed layer 22.
The thickness of the water blocking layer 8 is preferably in the range from 0.2 mm to 1.5 mm
Mentioned water blocking layer 8 is designed to create an effective barrier that prevents water penetration into the cable along its length (in the longitudinal direction).
Mentioned swelling from water material in the General case presented in powdered form, in particular in powder form. Particles, forming a swelling from water powder, preferably have a diameter of not more than 250 μm and the average diameter of from 10 μm to 100 μm. More preferably, the number of particles having a diameter of from 10 μm to 50 μm is at least 50% by weight relative to the total weight of the powder.
Swelling from water material in the General case consists of homopolymer or copolymer having hydrophilic groups along the polymer chain, for example crosslinked and at least partially forming a salt of polyacrylic acid (for example, products Cabloc®company C. F. Stockhausen GmbH or Waterlock®company Grain Processing Co.), starch or its derivatives, mixed with the copolymers between acrylamide and sodium acrylate (for example, products SGP Absorbent Polymer®company Henkel AG), carboxymethyl is cellulose sodium (for example, products Blanose®company Hercules Inc.).
The amount of swelling from water material, which must be included in the foam polymer layer is usually from 5 frequent. wt. 100 frequent. wt. up to 120 frequent. wt. 100 frequent. wt., preferably from 15 to frequent. wt. 100 frequent. wt. up to 80 frequent. wt. 100 frequent. wt. (frequent. wt. 100 frequent. wt. = parts by mass relative to 100 parts by weight of the basic polymer).
In addition, foamed polymeric material water blocking layer 8 to modify semi-conducting material by adding the corresponding conductive carbon black, as mentioned above with reference to the semiconductor layers 3, 5.
In addition, due to the supply of cable according to figure 1 of foamed polymeric material having semi-conducting properties and including swelling from water material (i.e. semi-conductive swelling from the water layer 8), form a layer, which is capable of elastically and uniformly absorb radial forces expansion due to thermal cycles, which is subjected to the cable during operation, while providing the necessary electrical integrity between the cable and the metal shield.
In addition, the presence of swelling from water material dispersed in the foamed layer, can effectively block moisture and/or water, and thus avoid the use of Naboo the surrounding water from tapes or free swelling powders.
In addition, due to the supply cable of figure 1 semi-conductive water blocking layer 8 can effectively reduce the thickness of the outer semi-conducting layer 5, since the electrical properties of the outer semi-conducting layer 5 partially implemented the mentioned blocking water semi-conducting layer. Therefore, the aspect of successfully contributes to reduction in the thickness of the outer semi-conducting layer and, thus, the overall weight of the cable.
The manufacturing process and installation
As shown in figure 3, the apparatus for manufacturing a cable according to the invention includes unit 201 for feeding conductor, the first section 202 extrusion to obtain the insulating layer 4 and the semiconductor layers 3 and 5, section 203 of the cooling section 204 for applying the metal shield, the second section 214 of the extrusion to overlay element 20 protection, section 205 of the extrusion of the outer shell section 206 additional cooling and the receiving section 207.
Unit 201 for supplying conductor includes a convenient case of a device for rolling metal rod to the desired diameter of the conductor cable (providing the desired surface finish).
When you need to connect segments of a metal rod to provide a continuous end section of the cable, as it requires the use of (or according to other requirements of the customer is (a), unit 201 for supplying conductor includes respectively a device for welding and heat treatment of the conductor, as well as accumulating units, intended to provide sufficient time for the welding operation without affecting continuous flow with a constant velocity of the conductor.
The first section 202 of the extrusion includes a first extruder 110 that is designed for the extrusion of the insulating layer 4 on the conductor 2, supplied by the unit 201 of the feed conductor, the first extruder 110 is preceded by a second extruder 210, when viewed along the direction of movement of the conductor 2, which is designed for the extrusion of the inner semi-conductive layer 3 on the outer surface of conductor 2 (and below the insulating layer 4), and is followed by a third extruder 310, which is designed for the extrusion of the outer semi-conducting layer 5 on the insulating layer 4 to get the core 2A of the cable.
First, second and third extruders can be installed in series, each with its own head, or preferably they are all connected to a common triple extrusion head 150 to get a joint extrusion of three layers.
An example of a design suitable for extruder 110, described in document WO 02/47092 on the name of the present applicant.
The second and third extruders in a convenient case have analogion the th design, the first extruder 110 (unless you want different devices, due to the use of specific materials).
Section 203 cooling, through which are passed vein 2A of the cable may consist of an elongated open tube, along which the force flow cooling the fluid. Water is a preferred example of such a cooling medium. The length of this cooling sections, as well as the nature, temperature and flow rate of the cooling fluid are determined to ensure the final temperature suitable for subsequent operations.
Dryer 208 in a convenient embodiment, entered before entering the next section, and said dryer is effective for removal of cooling fluid, such as humidity or water droplets, especially when these residues impair the overall operating characteristics of the cable.
Section 204 for applying the metal shield includes a device 209 delivery sheet metal, which is intended for feeding the metal sheet 60 to the unit 210 overlay.
In the preferred embodiment of the invention, the Assembly 210 overlay includes a driver (not shown)through which the metal sheet 60 is coiled in the longitudinal direction in a tubular shape so as to cover the core 2A of the cable, along which it and to form a closed circumference of the metal shield 6.
Appropriate sealing and bonding agent may be applied to the area of the overlapping edges of the sheet 60 so as to form closed at the periphery of the metal sheet 6.
Alternatively, suitable sealing and bonding agent may be applied to the edge of the sheet 60 so as to form a closed circumference of the metal shield 6.
Use folded in the longitudinal direction of the metal shield is particularly useful because it offers the possibility of producing cable in a continuous way without having to use complex machines for rotation of the drum, which, otherwise, would be required in the case of multi-wire (or tape) coiled metal sheet.
If it is convenient for the specific cable design, install additional extruder 211, equipped extrusion head 212, and set up the flow unit 210 overlay, along with the cooler 213 to impose foamed semi-conducting layer 8 around the conductors 2A cable downstream metal shield 6.
The cooler 213 is preferably a cooler with forced air supply.
If you do not want extra protection from impact, the cable receives final treatment is when it passes through a section 205 of the extrusion of the outer shell, which includes an extruder 220 of the outer shell and its extrusion head 221.
After section 206 final cooling installation includes a receiving section 207, through which the finished cable is wound on the drum 222.
Reception section 207 preferably includes a storage section 223, which allows you to replace the filled cable reel to the empty reel without interrupting the production process of the cable.
If you want increased protection from shock, downstream relative unit 210 overlay placed additional section of the extrusion process.
In the embodiment of the invention shown in figure 3, section 214 extrusion includes three extruder 215, 216, 217, have a shared triple extrusion head 218.
More specifically, section 214 extrusion is suitable for application of the protection element 20 that includes a foamed polymer layer 22 and a dense polymer layer 21. Dense polymer layer 21 is imposed by the extruder 216, whereas the foamed polymer layer 22 is imposed by the extruder 217.
In addition, section 214 of the extrusion includes an additional extruder 215, which is designed to overlay a layer of primer suitable for improving the connection between the metal shield 6 and the protection element 20 (i.e. a dense polymer layer 21).
Section 219 of the cooling formed by the respectively downstream relative to section 214 additional extrusion process.
Figure 4 shows the installation is similar to installing on figure 3, according to which the extruders 215, 216, 217 are separated from each other, and it contains three separate and independent of the extrusion head a, a, 217.
Separate cooling channels or pipes 219a and 219b are placed respectively for extruders 215 and 216, while the cooling channel 219 is placed behind the extruder 217.
According to an additional embodiment of the invention (not shown) of the primer layer and the dense polymer layer 21 are imposed together by co-extrusion, and subsequently held the extrusion of foamed polymer layer 22.
According to an additional embodiment of the invention (not shown) of the primer layer and the dense polymer layer 21 are imposed together by means of extrusion, and subsequently imposed together foamed polymer layer 22 and the outer casing 23 by means of co-extrusion. Alternatively, the primer layer and the dense polymer layer 21 are imposed separately by using two separate extrusion heads a, a, whereas the foamed polymer layer 22 and the outer casing 23 are imposed together by co-extrusion.
Figure 3 and 4 shows a diagram of the production installation, which is U-shaped in order to reduce the longitudinal dimensions of the plant. On these figures it is shown that the promotion of the cable roar is ciruits at the end of section 203 cooling through corresponding known devices in the art, for example by means of rollers.
Alternatively, the schema of the production installation develops in the longitudinal direction, and does not occur any reversal in the direction of the feeding cable.
Continuous production process
On the above installation cable can be produced according to a continuous method.
In the present description the term "continuous method" means the method in which the time required for the manufacture of a given segment of the cable is inversely proportional to the feeding speed of the cable line, so that eliminated the intermediate phase of peace between the feed cable and the acceptance of the finished cable.
According to the present invention, the conductor is continuously fed from unit 201 submission.
Unit 201 submission is intended for the continuous feed of the conductor.
The conductor is an element made respectively in the form of a single metal rod (usually aluminum or copper). In this case, the continuous supply conductor is provided with connection available to cut metal conductor (usually loaded on the drum or similar tool) with the additional length of metal rod.
Such a connection can be made, for example, by welding the ends of metal of the conductor.
According to the continuous JV is the property of the present invention, the maximum length is made of a cable is determined by the requirements of the customer or the installer, such as length prolagaeva line (between two intermediate stations), the maximum size of the transport drum, which is used (with appropriate restrictions transportation), the maximum installed length and similar restrictions, not available raw or long raw, or power equipment. Thus, it is possible to install an electric line with a minimum number of connections between segments of the cable to increase the reliability of the line, since it is known that the cable connections are the points of breakage, causing problems in the operation of the line.
Where appropriate, use twisted wires are required of the rotating machine for twisting, and the conductor is made Autonomous accordingly to desired length, and the splicing operation is time-consuming. In this case, the length of the manufactured cables is determined by the available length of stranded conductor (which may be pre-set based on customer requirements) and/or the capacity of the picking drums, while in other respects the method is continuous from the feed conductor to the end of the process.
Extrusion of the insulating layer 4, the semiconductor layers 3 and 5, the outer casing 23, item 20 of the protection (if equipped) and blocking water sloa (if available) can be performed continuously, since different materials and connections subjected to extrusion, serves to respective inputs of the extruder continuously.
Because it does not require the operation of the stitching due to the use of thermoplastic, unstitched materials, in particular, for the insulating layer, it is not required interrupt method.
In fact, the ordinary methods of manufacture cables with crosslinked insulation include a phase of "peace", in which the insulated wire is kept offline for a certain period of time (hours or even days)to a) have passed the crosslinking reaction in the case of silane crosslinking, or (b) occurred emissions as a result of reactions of the crosslinking by-products in the case of peroxide crosslinking.
The resting phase of the case (a) can be carried out through the introduction of cable wound on the supporting drum) in a furnace or by immersing it in water at a temperature of about 80°so as to increase the response speed of the stitching.
The resting phase in case b), i.e. the phase degassing can be accomplished by the introduction of cable wound on the drum) into the furnace so as to reduce the degassing time.
The phase of "peace" is usually carried out by cooling palettechange item on the reels at the end of the extrusion of the respective layers. After that stitched paletteentry element serves on the other, the independence of imuu line, where complete the processing of the cable.
According to the method of the present invention the metal shield 6 is formed from the folded in the longitudinal direction of the metal sheet, which is conveniently wound from the drum mounted on a stationary device, when it rotates freely around its swivel axis, so that the sheet can be wound from the drum. Thus, in the method of the present invention, the metal sheet can be enjoyed without interruption of the process, since the rear end of the sheet used drum can be simply connected (e.g. welded) to the front end of the sheet loaded on the new drum. In the General case is additionally used the corresponding accumulating sheet device.
This would be impossible in the case of using the shield a scroll type (formed is wound in a spiral wires or ribbons), as in this case, the reel carrying wire or tape must be loaded in the rotating device rotating around the cable, and replace the empty reels new drums will require interruption of cable.
However, it is possible to provide the cable with a metal shield made of wires or tapes, while maintaining the continuity of the production process, while using the device, according to which mentioned about the ode/tape served to the cable under the operations of S - and Z-twisting, conducted alternately. In this case, the drums, bearing the above-mentioned wire/tape, will not be required to take a turn around the cable.
However, the use of a metal sheet, folded in the longitudinal direction, turned out to be particularly useful in combination with thermoplastic insulation and semi-conducting layers.
In fact, as mentioned above, in the case of cross-linked material is necessary to provide a certain period of time after completion of the crosslinking reaction, to enable the emission of gaseous by-products. In the standard case, this is achieved by providing palettename product (i.e. conductor cable) to remain dormant for a certain period of time after completion of the crosslinking reaction. In the case of non-continuous around the circumference of the metal shield (as in the case of wires or tapes helically wound around the cable core can cause the emission of gas by diffusion through the metal shield (e.g., via wires or overlapping zones of tapes) and extruded through layers placed radially inside relative to the metal shield.
However, in the case of using a metal sheet, folded in the longitudinal direction, it is distributed by district the tee around the entire perimeter of the cable conductor, thereby forming an essentially impermeable casing, which essentially prevents further removal of gaseous by-products. Therefore, when using a metal shield, rolled in the longitudinal direction, in combination with the crosslinked insulating layers, the degassing of the material must be completed, essentially, before applying the metal shield.
On the contrary, the use of cable insulation layer of thermoplastic unstitched materials that do not emit gaseous cross-linking by-products (and, therefore, does not require any phase degassing) in combination with a metal sheet rolled in the longitudinal direction and is used as a metal shield, enables the production process in a continuous mode, because it does not require phase "peace" in standalone mode.
For further description of the invention given below to illustrate the example.
The example below describes in detail the main operations of the method of continuous manufacture of cable at 20 kV with a cross-section 150 mm2according to figure 1. Linear speed is set to 60 m/min
a) extrusion of the cable core
The insulation layer of the cable is obtained by feeding directly into the hopper of the extruder 110 heterophase copolymer prop is Lena, having a melting point of 165°C, the enthalpy of fusion of 30 j/g, a melt index (MFI) of 0.8 DG/min and a modulus of elasticity in bending of 150 MPa ( Adflex®Q 200 F - industrial manufactured product company Basell).
After that, the dielectric oil Jarylec®Exp3 (industrial manufactured product company Elf Atochem - dibenzyltoluene), pre-mixed with antioxidants, Inuktitut under high pressure in the extruder.
The extruder 110 has a diameter of 80 mm and a ratio L/D (length/diameter) of 25.
Injection of dielectric oils perform during extrusion at a distance of about 20D from the beginning of the screw of the extruder 110 through three points of injection of the same cross-section, separated from each other by 120°. Dielectric oil Inuktitut at a temperature of 70°and pressure of 250 bar.
The respective extruders are used for inner and outer semiconducting layers.
Rod-aluminum conductor 2 (a cross-section of 150 mm2served through the triple extrusion head 150.
Vein 2A cable coming out of the extrusion head 150, is cooled by passing through a channel type section 203 cooling, through which flows cold water.
The resulting lived 2A cable has an inner semi-conducting layer with a thickness of about 0.5 mm, an insulating layer thickness of about 45 mm and an outer semi-conducting layer of a thickness of about 0.5 mm.
b) blocking the water of semi-conductive foamed layer
Blocking water semi-conductive foamed layer 8 having a thickness of about 0.7 mm and expansion ratio of 0.6, put on a vein 2A cable extruder 211, which has a diameter of 60 mm and L/D ratio equal to 20.
The material for the above-mentioned foamed layer 8 below in table 1. The material is chemically expanded by adding about 2% extender Hydrocerol®CF 70 (carboxylic acid + sodium bicarbonate) into the hopper of the extruder.
|Connection||Number (frequent. wt. 100 frequent. wt.)|
In this table,
- Elvax®470 is a copolymer of ethylene/vinyl acetate (EVA) (industrial manufactured product of DuPont),
- Ketjenblack®EU 300 is highly conductive furnace carbon black (industrial manufactured product of Akzo Chemie),
- Irganox®1010 - product pentaerythrol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (industrial is but made product company Ciba Specialty Chemicals),
- Waterloock®J 550 - crushed crosslinked polyacrylic acid (partially in salt form) (industrial manufactured product company Grain Processing),
-Hydrocerol®CF 70 - extender - carboxylic acid/sodium bicarbonate (industrial manufactured product company Boeheringer Ingelheim).
After extrusion head 212 of the extruder 211 provided by the cooling by the cooler 213 forced air supply.
C) applying a metal shield cable
Vein 2A cable supplied with foamed semi-conductive layer 8, and then is covered by unit 210 blend rolled in the longitudinal direction, lacquered aluminium sheet with a thickness of about 0.3 mm, using an adhesive to communicate its overlapped edges. The adhesive is applied by means of the extruder 215.
g) the imposition of element cable protection
After that, the inner polymer layer 21, made of polyethylene, with a thickness of about 1.5 mm is applied by extruder 216 having a diameter of 120 mm and an L/D ratio of 25, on the aluminum shield.
According to the production installation according to figure 3 of foamed polymer layer 22 having a thickness of about 2 mm and expansion ratio of 0.55, subjected to co-extrusion with a dense inner polymer layer 21. Foamed polymer layer 22 is covered by the extruder 217, which has a diameter of 120 mm and the rate of L/D of 25.
The material for the foamed polymer layer 22 below in table 2.
|Connection||Number (frequent. wt. 100 frequent. wt.)|
In this table,
- Hifax®SD 817 - propylene-modified copolymer of ethylene/propylene, industrial manufactured by the company Basell),
- Hydrocerol®BiH40 - extender - carboxylic acid + sodium bicarbonate, industrial manufactured by the company Boeheringer Ingelheim.
The polymeric material undergoes a chemical expansion by adding extender (Hydrocerol®BiH40) into the hopper of the extruder.
At a distance of about 500 mm from the extrusion head 218 section 219 cooling in the form of a pipe or channel through which flows cold water stops the expansion and cools the extruded material prior to extrusion of the outer dense polymer layer 23.
d) extrusion of the outer cable jacket
After that, the outer casing 23, is made of polyethylene, with a thickness of about 1.5 mm is extruded using the extruder 220 having a diameter of 120 mm and an L/D ratio of 25.
The cable coming out of the extrusion g is clever 221, subjected to a final cooling section 206 cooling, through which flows cold water.
The cooling of the finished cable can be made using a multi-pass cooling channel, which effectively reduces the longitudinal dimensions of the cooling section.
The impact resistance and load
In the presence of mechanical stress attached to the cable, such as a blow applied to the outer surface of the cable, or significant local load, can cause deformation of the cable, it was observed that even in the case where the deformation also affects the insulation, for example, due to the fact that the impact energy exceeds the allowable value, which is able to withstand anti-shock layer, or when the protection element selected relatively small thickness, the profile deformation of the metal shield should be continuous, smooth line, thereby avoiding a local increase of the electric field.
In General, the materials used for the insulating layer and the outer sheath of the cable is elastically restore only part of their original size and shape after impact, so that after the impact, even if it happened before it was filed, the voltage on the cable is reduced, the thickness of the insulating layer that can withstand the electrical voltage is.
However, the applicant has noticed that when using the metal shield on the outside layer, insulating cable, the material of such a shield is irreversibly deformed by the impact, further constraining the elastic recovery of deformation, so that the insulating layer has limitations for elastic recovery of its original shape and size.
Therefore, deformation due to impact, or, at least, part of it remains after impact, even when it was removed the cause of the blow.
Mentioned deformation leads to the fact that the thickness of the insulating layer is changed from the initial value of t0to "invalid" values of td(see figure 5).
Therefore, when the cable was energized with voltage, respectively, the real thickness of the insulating layer, which can withstand the load (F) electrical voltage in the impact zone, is not t0and td.
In addition, when the blow dealt to the cable having a metallic shield "intermittent" type, for example made of helically wound wires or tapes, or in the absence of anti-shock layer (as shown in figure 5), or even when protected from shock layer (compacted or foam type), uneven resistance design metal shield, consisting of wires, causes considerable on the formation of the wire, posted closer to the impact zone, and the transfer of such deformation of the underlying layers, as "local" strain, with minimal impact on the neighbouring area.
In the insulating layer, this leads to the effect of "release", which causes deformation of the ring equipotential lines of the electric field in the impact zone, as shown in figure 5, where the initial ring equipotential lines shown in phantom lines, and distorted equipotential lines solid lines.
Deformation of the equipotential lines of the electric field causes them to get thicker in the impact zone, which means a substantial increase in the gradient of the electric field in this area. This local increase of the gradient of the electric field is likely to cause electric discharges, determine cable damage (affected by the shock) when tested by definition partial electrical discharges even if the shocks have a relatively low energy.
However, when a metal shield made of folded in the longitudinal direction of the metal sheet, especially when it is combined with foamed element of protection, the applicant has found that it significantly reduced the local deformation of the shield or the underlying insulating layer.
Actually foam protection element, continuously supported by the second lower metal shield, made with the ability to distribute the impact energy over a relatively large area around the position of the shock, as shown in Fig.6.
Consequently, reduces the deformation of the equipotential lines of the electric field (also associated with greater area), so they are less compacted than in the case of the above-mentioned helically wound wires, if there is a strike with the same energy.
The result minimizes the growth of the local gradient of the electric field caused by the impact, and increases the cable's ability to withstand tests on determination of partial discharges.
1. A method of manufacturing an electric cable (1)comprising phase: feed (201) of the conductor (2) with a predetermined feed speed, extrusion (202) thermoplastic insulation layer (4), which is the outside in the radial direction relative to the conductor (2), cooling (203) extruded insulating layer (4), (210) closed around the circumference of the metal shield (6) around the aforementioned extruded insulating layer (4), characterized in that the time elapsed between the end of the cooling phase (203) and the beginning of phase formation (210) shield is inversely proportional to the feeding speed of the conductor (2).
2. The method according to claim 1, characterized in that the forming phase (210) includes an operation clotting meta is symbolic of the sheet (60) in the longitudinal direction around the aforementioned extruded insulating layer (4).
3. The method according to claim 2, characterized in that the forming phase (210) includes an operation of overlapping edges mentioned metal plate (60) to form a metal shield (6).
4. The method according to claim 2, characterized in that the forming phase (210) includes an operation of joining edges mentioned metal plate (60) to form a metal shield (6).
5. The method according to claim 1, characterized in that it further includes phase supply conductor (2) in the form of a metal rod.
6. The method according to claim 1, characterized in that it further includes a phase overlay layer of primer around the metal shield (6).
7. The method according to claim 6, characterized in that the phase of the overlay layer of primer performed by extrusion.
8. The method according to claim 1, characterized in that it further includes a phase blending element (20) impact protection around the mentioned closed around the circumference of the metal shield (6).
9. The method according to claim 8, characterized in that the phase of the overlay element (20) impact protection includes a phase blending dense polymer layer (21) around the mentioned metal shield (6).
10. The method according to claim 8, characterized in that the phase of the overlay element (20) impact protection includes a phase blending foamed polymer layer (22).
11. The method according to PP and 10, characterized in that the foamed polymer layer (22) impose tight around on karnego layer (21).
12. The method according to claim 1, further comprising a phase blending of the outer casing (23) around the metal shield (6).
13. The method according to PP and 12, characterized in that the outer casing (23) impose around the foamed polymer layer (22).
14. The method according to claim 1, characterized in that the cooling phase (203) extruded insulating layer (4) is performed by feeding in the longitudinal direction of the conductor (2) with thermoplastic insulation layer (4) through an elongated cooling device.
15. The method according to claim 1, characterized in that thermoplastic polymer material of the insulating layer (4) is selected from polyolefins, copolymers of different olefins, copolymers of olefins with ethylene-unsaturated complex ester, polyesters, polyacetates, cellulose polymers, polycarbonates, polysulfones, phenolic resins, urea resins, polyketones, polyacrylates, polyamides, polyamines and mixtures thereof.
16. The method according to item 15, characterized in that the said thermoplastic polymeric material is selected from polyethylene (PE), polypropylene (PP), ethylene/vinyl acetate (EVA), ethylene/methyl acrylate (EMA), ethylene/ethyl acrylate (EEA), ethylene/butyl acrylate (EVA), thermoplastic copolymers of ethylene/α-olefin, polystyrene, Acrylonitrile/butadiene/styrene (ABS) resins, polyvinyl chloride (PVC), polyurethane, polyamides, politycentered the lats (PET), polybutylene terephthalate (RHT) and their copolymers or mechanical mixtures.
17. The method according to claim 1, characterized in that thermoplastic polymer material of the insulating layer (4) includes a predetermined number of dielectric liquid.
18. Electric cable comprising a conductor (2), thermoplastic insulation layer (4)located outside in the radial direction relative to the guide (2)at least one foamed polymer layer (8) around the mentioned insulating layer (4), closed around the circumference of the metal shield (6) around the mentioned insulating layer (4) and the element (20) protection from shock in the outer position in the radial direction relative to the metal shield (6)and the said element (20) protection from impact includes at least one dense polymer layer (21) around the mentioned metal shield (6) and at least one foamed polymer layer (22) in the outer position in the radial direction relatively thick polymer layer (21).
19. Electric cable (1) p, characterized in that the thickness of the foamed polymer layer (22) at 1-2 times the thickness of the dense polymer layer (21).
FIELD: electric cable manufacture.
SUBSTANCE: proposed method includes following steps: (a) feeding conductor at predetermined feed rate; (b) extruding thermoplastic insulating layer in radial direction on external side of conductor; (c) cooling down insulating layer obtained by extrusion to temperature not over 70 °C; (d) forming metal screen closed on circumference around mentioned insulating layer obtained by extrusion. Procedures are run continuously, that is, period between cooling-down step and initiation of screen formation is inversely proportional to conductor feed rate.
EFFECT: facilitated procedure.
19 cl, 10 dwg
FIELD: superconducting wire manufacture.
SUBSTANCE: proposed method for producing superconducting wire includes production of wire material in the form of source powdered metal-covered and oxide-coated superconducting material and heat treatment of wire material obtained in the process in high-pressure environment with total pressure maintained at 1 MPa or higher and below 50 MPa in the course of heat treatment; pressure rise is started with temperature at which 0.2% conventional yield point of metal becomes lower than total pressure in the course of heat treatment. Such procedure makes it possible to eliminate voids between oxide-coated superconducting material crystals and bulging of oxide-coated superconducting wire material, as well as to easily control oxygen partial pressure during heat treatment.
EFFECT: enhanced critical current density in wire material obtained.
22 cl, 27 dwg, 3 tbl
FIELD: cable engineering.
SUBSTANCE: proposed coaxial cable is provided with specially prepared layer of pre-coating which facilitates its removal when cable end is stripped to receive connector. Cable has internal conductor, foamed polyolefin insulating layer, external conductor covering mentioned insulating layer, and pre-coating disposed between internal conductor and insulating layer. Pre-coating layer forms first internal-conductor bonding interface and second insulating-layer bonding interface; ratio of adhesive force on axial shift of first bond A to adhesive force on second axial shift of second bond B is below 1; ratio of adhesive force on axial shift of bond A formed by pre-coating layer between internal conductor and insulating layer to adhesive force on rotational shift of this bond is 5 or higher.
EFFECT: improved electrical characteristics of cable, enhanced reliability of line using this cable.
13 cl, 5 dwg, 1 tbl
FIELD: electrical engineering including cable engineering; midget control cables for wire communication lines of small-size missiles and their manufacturing process.
SUBSTANCE: proposed midget control cable has two electrically insulated enameled copper conductors (current-carrying conductors), one strengthening complex thread of cross securing lea winding of three polyamide threads forming thread assembly, as well as seven strengthening complex threads placed on top of cross securing winding in parallel with copper conductors, and secondary securing winding of one complex strengthening thread; thread assembly is impregnated with water-repelling liquid. Proposed method for manufacturing midget control cable includes manufacture of thread assembly followed by finishing midget control cable for which purpose seven strengthening complex threads are arranged in parallel with thread assembly whereupon finished midget control wire is wound on take-in reel.
EFFECT: improved electrical and mechanical characteristics, ability of using cable immersed in water including sea water.
2 cl, 2 dwg
FIELD: electrical engineering including cable engineering; midget control cables for wire communication lines of small-size missiles and their manufacturing process.
SUBSTANCE: proposed midget control cable has two electrically insulated enameled copper conductors (current-carrying conductors), one strengthening complex thread of cross lea securing winding of three polyamide threads forming thread assembly, as well as four strengthening complex threads placed on top of cross securing winding in parallel with copper conductors, two-layer lea winding of two polyamide threads wound in opposite directions, and one complex thread. Proposed method for manufacturing midget control cable includes manufacture of thread assembly followed by finishing midget control cable for which purpose four strengthening complex threads are arranged in parallel with thread assembly and two-layer winding is placed overall.
EFFECT: improved electrical and mechanical characteristics, ability of using cable immersed in water including sea water.
2 cl, 3 dwg
FIELD: electrical engineering.
SUBSTANCE: proposed superconducting device has superconducting oxide wire made of superconducting oxide material whose post-sintering density is 93% and more, best 95% and more, or most preferably 99% or more, which is attained by heat treatment of wire in enhanced pressure environment of at least 1 MPa and below 50 MPa. Heat treatment of wire at enhanced pressure prevents formation of gaps and bubbles. Stable superconducting oxide phase of Bi2223 is formed in the process.
EFFECT: enhanced critical current density of superconducting device and superconducting cable.
6 cl, 27 dwg, 4 tbl, 6 ex
FIELD: electrical engineering; using silanol cross-linked polyethylene covered wires or cables.
SUBSTANCE: proposed method includes covering of cable or wire conductor with silanol cross-linked polyethylene insulation followed by cooling down wires or cables and placing them in horizontal branches into water-filled basket. After that either current is passed through cable or wire thereby heating it to temperature not over maximal admissible value ensuring insulation resistance to thermal deformation and exposing it to this temperature for period required for silanol cross-linking of polyethylene, or basket is placed in heated tank filled with water, steam, or steam-water mixture, and held in this tank at mentioned temperature for time required for polyethylene cross-linking, or water is drained from basket and then the latter is placed in heated tank filled with water, steam, or steam-water mixture and held in this tank at mentioned temperature for time required to ensure silanol cross-linking of polyethylene.
EFFECT: enhanced quality of insulation, reduced cost, time, and heat energy requirement.
FIELD: electrical and power engineering; sealed entries for passing conductors into pressurized premises or locations.
SUBSTANCE: proposed sealed cable entry designed to pass Lead-in cables into pressurized premises or locations has cylindrical metal body with flanges attached to its butt-ends by way of electric-arc welding for passing through them mineral material covered and insulator-terminated cables; insulators are made of oxide ceramics with titanium evaporated on them at solder points for better wettability of AgCu and ceramic surface. Proposed manufacturing process is characterized in that insulators are joined to metal sheath of mineral insulation covered cables by way of active soldering with AgCuTi system in vacuum furnace.
EFFECT: enhanced quality of soldered joints, simplified design of sealed modules, reduced number of process operations.
2 cl, 1 dwg
SUBSTANCE: proposed method involves filling of cylindrical bag with auxiliary parts which are then removed from bag and replaced by bar assemblies placed in definite sequence affording maximal filling density; sectional area of each auxiliary member differs from that of its substituting bar; central regular-hexagon shaped auxiliary member has face width A1 found from expression where a is hexagonal bar width, M is number of bars in diametric direction; second row around central member is alternately filled with auxiliary members of which three ones are regular-hexagon shaped members having face width A2 found from expression and three other hexagon-shaped auxiliary members have face width found from set of expressions all next rows are alternately filled with auxiliary hexagon-shaped members whose face width is found from set of expressions and remaining free space between hexagon-shaped auxiliary members, as well as cylindrical bags are filled with additional auxiliary members whose cross-sectional area provides for maximal filling of bags.
EFFECT: facilitated procedure, ability of filling billet with thousands of bars during its single assembly process.
3 cl, 7 dwg
FIELD: motor- and ship-building industries, mechanical and construction engineering, oil extraction, and oil-refining industry.
SUBSTANCE: proposed electric wire or cable has multicore copper conductor with core sectional area of 1.0 to 50 mm2 and rubber sheath, 0.4 to 7.0 mm thick, made of composite material based on rubber mixture incorporating mixture of high-molecular polymethylvinylsiloxane rubber and low-molecular polymethylvinylsiloxane rubber as polymeric matrix with molar mass of 20 000 to 70 000 in combination with probably stearic acid, fire-protective filler, dehydrating agent, silica powder, quartz crystal, anti-structuring agent (α, ω-dihydroxydimethylsiloxane), organic peroxide, and water repellant (silicone liquid). Composite material is applied by extrusion at a rate of 0.2-2 m/s and cured in radiation-chemistry curing mode under action of either vapor at pressure of 12-18 at or cobalt gun using gamma-ray source at dose rate of 2.5-20 Mrad, and/or by thermal curing. Electric cable or wire covered with such sheath is characterized in ability of self-quenching fire and can be used at temperatures ranging between -60 and +300 °C.
EFFECT: enhanced crack, oil, and gasoline resistance, flexibility, and electrophysical characteristics of cable or wire.
3 cl 1 tbl
FIELD: electrical engineering; automobile and ship building, mechanical engineering, construction , oil extraction, and oil refining industries.
SUBSTANCE: proposed electric drive has stranded copper conductor with strand sectional area of 1.0 - 50 mm3 and rubber sheath , 0.4 - 7.0 mm thick, made of rubber mixture whose matrix is polymeric mixture of high-molecular polymethyl vinyl-siloxane and low-molecular polymethyl vinyl-siloxane rubber of mole mass of 20 -70 thousands in combination with silica powder, quartz, anti-texturing agent in the form of αω-dihydroxide methylsiloxane and organic peroxide. Rubber mixture is applied by extrusion at speed of 0.2 - 2 m/s and cured under radiation-chemical curing conditions with aid of cobalt gun incorporating γ-radiation source at dose rate of 2.5 - 20 megarad. and/or by thermal curing. Electrical conductor produced in the process is capable of fire self-suppression and is suited to operate at -60 to +300 °C.
EFFECT: enhanced fire, crack, oil, and gasoline resistance, improved electrical and physical characteristics.
3 cl, 1 tbl
FIELD: cable engineering; plastic-covered sector cables.
SUBSTANCE: proposed extrusion head that provides for regulating insulation thickness over perimeter of sector cable cores has body, mandrel holder, mandrel with cylindrical part, die, mandrel evacuation device, and device for positioning conducting core in mandrel; two cuts symmetrical relative to vertical axis of mandrel are made on external surface of its cylindrical part; these cuts are disposed so that fixed radiant position of sector in mandrel is ensured and its rays originate from geometric center of mandrel and cross points limiting left- and right-hand rounding of sector; angle between symmetry axes of cuts is not over 180 deg.; angle of cuts to generating lines of cylinder is minimum 1 deg.
EFFECT: reduced material input of cable.
1 cl, 3 dwg, 1 tbl
FIELD: electrical engineering; drying cable insulation in servicing communication lines.
SUBSTANCE: proposed electroosmotic method for drying paper insulation of cable involves setting-up of electric field; in the process cable conductors are connected to positive pole of current supply, metal electrodes whose quantity depends on that of cable conductors are inserted in paper insulation at open end of cable and connected to negative pole of power supply; damp cable section is cut off. Used as metal electrodes are aluminum or copper strips deepened through 2 m. Voltage of 500 - 2500 V is applied for 6 - 8 h.
EFFECT: enhanced cable saving due to reduced size of cut-off ends.
FIELD: electrical engineering.
SUBSTANCE: invention relates to manufacture of electroconductive materials by way of applying electroconductive coating, impregnated-paper insulation, and electroconductive threads of power cables onto paper base. In particular, material consists of natural paper base and electroconductive layer, whose thickness constitutes 0.03-0.14 that of insulation layer placed on paper and composed of aqueous suspension of carbon black (6-10%) and polyvinyl alcohol (1.0-4.0%) together with additives of acrylic acid ester/methacrylic acid ester copolymer (7-12%) and oxyethylated (with at least 7 ethylene oxide groups) alkylphenol or sodium polyacrylate (0.1-0.5%).
EFFECT: improved workability, electrical conductivity, strength, elasticity, heat resistance, moisture resistance, and resistance to splitting within cable.
FIELD: electrical engineering; electric cables for signaling, control, and data transfer and processing systems.
SUBSTANCE: cable has at least one pair of insulated and stranded current-carrying conductors and cable sheath. Insulating material is either halogen-containing polymer (polyvinyl chloride), or halogen-free polyolefin base material (polyethylene), or its copolymer. Insulation thickness is chosen from equation strand pitch is found from equation h = 25(2Δ + d), where d is conductor diameter; εr is relative dielectric constant of insulating material. With diameter of cable current-carrying conductors being enlarged, capacitance of cable pair was reduced (other characteristics being retained at desired level.
EFFECT: enhanced capacitance of working load on cable pair.
1 cl, 4 dwg, 1 tbl
FIELD: electrical engineering; producing long conductors around superconducting compounds.
SUBSTANCE: proposed method includes formation of single-core billet by filling silver sheath with bismuth ceramic powder; deformation of this single-core billet to desired size by no-heating drawing at deformation degree per pass of 0.5 - 20%; cutting of deformed billet into measured parts; assembly of single-core billet by disposing desired quantity of measured parts of deformed single-core billet in silver sheath of multicore billet; extrusion of multicore billet at temperature ranging between 100 and 200 °C and at drawing coefficient of 4 to 30; air rolling without heating at deformation degree per pass of 1 - 50%; thermomechanical treatment including several heat-treatment stages at temperature of 830 - 860 °C for time sufficient to obtain phase of desired composition and structure in ceramic core with intermediate deformations between heat-treatment stages at deformation degree per pass of 5 - 30 %.
EFFECT: enhanced critical current density due to sequential packing of ceramic core; facilitated manufacture.
1 cl, 1 ex
FIELD: controlling electric cable sheath capacitive reactance.
SUBSTANCE: proposed method for controlling capacitive reactance of tubular sheath formed by means of extrusion of insulating compound on electric cable in extrusion head includes introduction of foaming agent in insulating compound so as to enhance capacitive reactance of tubular insulating sheath; prior to do so, definite amount of foaming agent is used so as to obtain predetermined capacitive reactance for tubular insulating sheath and in order to ensure precision control of capacitive reactance of tubular insulating sheath, gas pressure is applied to at least external surface area of insulating compound extruded by extrusion head, gas pressure being varied so as to control capacitive reactance value of tubular insulating sheath.
EFFECT: enhanced precision of controlling capacitive reactance of electric-cable sheath.
9 cl, 3 dwg
FIELD: electrical engineering; cable filler compositions.
SUBSTANCE: proposed PVC base composition designed for filling conductor-to-conductor space of electric cables by extrusion has following ingredients, parts by weight: divinyl-styrene thermal elastomer, 100; high-pressure polyethylene, 40 - 60; mineral oil, 80 - 95; chalk or kaolin, or aluminum hydroxide, 100 - 50.
EFFECT: enhanced fluidity index and frost resistance; ability of retaining cable flexibility at sub-zero temperatures.
FIELD: multiple twin cables for communications in local network.
SUBSTANCE: proposed multiple twin cable designed to prevent vapor transfer when immersed in petroleum oil has internal and external sheaths that cover insulated signal-transferring conductors and are made in the form of helical structure. Core filler fills up core and spaces between signal transferring conductors. Core filler and internal sheath are made of vapor-tight material and fixed to insulated conductors so that they fill up all grooves and slots around signal transferring conductors. External gas-tight sheath can be provided to make it possible to immerse cable in petroleum oil for long time intervals without impairing its functional capabilities.
EFFECT: ability of preventing vapor transfer lengthwise of cable.
26 cl, 4 dwg
FIELD: cable line engineering; solving problem of cable line immunity to external electromagnetic noise.
SUBSTANCE: proposed method for noise suppression in cable lines includes electrical interconnection of two cable conductors on one end directly or through resistors , addition of signals from their other ends, and at least partial disposition, principally symmetrical, of figures formed by one pair of conductors including conductors proper and space between them in space between other pair of conductors. Circuits of interconnected conductors are balanced, for instance, with respect to their resistance. Cable has two pairs of conductors, each pair is directly or mediately parallel-connected and figure formed by one pair of conductors that includes conductors proper and space between them is at least partially disposed in space between other pair of conductors, principally symmetrically. Cable manufacturing process includes insulation of conductors and their relative fastening in space; each pair of four conductors is directly or mediately parallel-connected and disposed in space so that figure formed by one pair of conductors incorporating conductors proper and space between them is at least partially disposed in space between other pair of conductors, principally symmetrically.
EFFECT: reduced fraction of electromagnetic noise in signal transferred over cable lines.
6 cl, 9 dwg