WO2023037235A1

WO2023037235A1 - Basic formulation for manufacturing insulating compounds or semiconductor compounds, insulating compound composition suitable for use in electrical energy conductors, semiconductor compound composition suitable for use in electrical energy conductors, and cable for distributing electrical energy that prevents unwanted, unauthorised connection to same

Info

Publication number: WO2023037235A1
Application number: PCT/IB2022/058356
Authority: WO
Inventors: José Antonio Di Ciommo; Edgardo Kliewer; Raúl Antonio Medina
Original assignee: Di Ciommo Jose Antonio; Edgardo Kliewer; Medina Raul Antonio
Priority date: 2021-09-07
Filing date: 2022-09-06
Publication date: 2023-03-16
Also published as: AR123444A1

Abstract

The present invention relates to a basic formulation for manufacturing insulating compounds or semiconductor compounds, an insulating component composition and semiconductor component composition comprising same, and a cable for distributing electrical energy that prevents unwanted or unauthorised connection to same for the purpose of electrical power theft. Therefore, this cable is considered an anti-theft cable, and it comprises at least one center conductor (1) concentrically surrounded by an insulating layer (2), concentrically surrounded by a layer of semiconductor material for the electrical current (3), followed by a concentric conductor ring (4) taped with synthetic material (5) and surrounded by an outer sheath (6).

Description

BASIC FORMULATION TO MANUFACTURE INSULATING COMPOUNDS OR

SEMICONDUCTOR COMPOUNDS, COMPOUND COMPOSITION

INSULATION SUITABLE FOR USE IN ELECTRICAL ENERGY CONDUCTORS,

COMPOSITION OF SEMICONDUCTOR COMPOUND SUITABLE FOR USE IN

ELECTRIC POWER CONDUCTORS AND DISTRIBUTION CABLE

OF ELECTRICAL ENERGY THAT PREVENTS UNDESIRABLE CONNECTION

NOT AUTHORIZED TO THE SAME

Object of the invention

The objective of the present invention is to present a cable for electric power distribution that prevents unauthorized access to electric power distribution networks, which through a product and a method of using it, indirectly or passively, intends to block unauthorized access to the electricity distribution network, since this unauthorized access has the effects of theft of electricity in the electricity network in distributors and electricity distribution operators.

The construction method of the cable models is indicated and one of the components is included to obtain the desired use. Specifically, the description of the component, where it is a compound that, according to its formulation and manufacturing method, allows the construction of cable models that are considered preventive of improper access to the electric power network.

As a particular objective, it is intended to show a modeled cable in which an electrical failure occurs in case of intention of unauthorized and improper access to conductive parts. Technical field of the invention

The present invention belongs to the field of electrical energy, more specifically to the cables defined as anti-theft, used in the electrical wiring of an electrical energy distribution network and to the component materials thereof for a specific use.

Background of the invention

Currently, as a preventive method of unwanted or unauthorized connection to the electricity distribution network, a particular type of cable is used for connection in connection to customers of electricity distribution companies. This cable is formed by conductors insulated with plastic material and where the neutral conductor is concentrically wired on the insulation.

Typical fraud model:

The unwanted or unauthorized connection to a Low Voltage (LV) electric power distribution cable is made by accessing its conductive parts. This unwanted connection is made in the drop connection cable or in the electrical power distribution cable; this unwanted connection occurs prior to the electric power meter. This meter accounts for the energy consumed by the user, since this measured energy is what is billed and charged accordingly, the energy consumed and not registered is the result of fraud.

This effect of diversion of electrical energy due to unwanted and improper connection is what is sought to be prevented, for the use of the cable herein.

Publication WO2018065881 refers to an "OVERHEAD CABLE FOR TRANSPORTING LOW AND MEDIUM VOLTAGE ELECTRICAL ENERGY AND DIGITAL SIGNALS, MADE OF CONCENTRIC CONDUCTORS OF ALUMINUM ALLOY CONTAINING A FIBER OPTIC CABLE AND DRAWN WIRE TREATMENT PROCESS", which corresponds to an invention of the present researchers, in which it is disclosed "A way to avoid clandestine connection includes the use of multiconductor cables that contain 2, 3 or 4 insulated conductors in the same cable, also called concentric cables (for their geometric configuration); in these cables, the proximity of the insulated conductors causes clandestine connections to short-circuit the phases, being dangerous for people who steal energy".

Publication US 2018461 A shows a multiconductor cable with sectors of conductors that are insulated within the same cable. Said cable is built starting from three conductor cables with a concentric structure, with alternate layers and then laminated in a sectorial manner, which are twisted in order to produce said multiconductor cable.

Publication US 5732875 A refers to a method for manufacturing cables with sectorized insulated conductors that, like the previous invention, have three sectors; in this, each of the sectors that make up the conductors are inserted into a metal sheath.

Patent US 7696430 B2 refers to a metallic conductor that includes an assembly of wires that have a certain polygonal cross section. A multiconductor cable is formed from the wire assemblies having the cross section.

The present development uses a completely different from the existing ones to avoid improper access to the connection cables and that will be described throughout this.

Summary of the invention

The present refers as a first variant of the invention to a basic formulation to manufacture insulating compounds or semiconductor compounds that comprises the following components in weight/weight concentration according to the following Table A:

Table A

In a second of the invention, the present also refers to an insulating compound composition suitable for use in electrical energy conductors obtained from the basic formulation according to the first variant, which comprises the addition of charges selected from at least one of the following additional components: halogenated or non-halogenated mineral fillers, non-conductive carbon black, colored compounds in a concentration of 0 to 3% w/w according to Table 2:

Table 2

In the previous variant of the invention, the composition of insulating compound suitable for use in electrical energy conductors according to the previous variant, the concentration of non-conductive carbon black is from 2% to 3% weight/weight to provide resistance to UV rays to the composition.

In the second variant of the invention, the insulating compound composition suitable for use in electrical energy conductors, the concentration of colored compounds is from 1% to 3% weight/weight to provide the desired color to the composition.

A third variant of the invention refers to a semiconductor compound composition suitable for use in electrical power conductors obtained from the basic formulation of the first variant of the invention that comprises the addition of conductive carbon black at a concentration of 18 at 35% w/w according to the following Table 1:

Table 1

A fourth variant of the invention corresponds to a cable for electrical power distribution that prevents unwanted connection to it (due to possible destruction of the connection), which comprises a central conductor (1) concentrically surrounded by an insulating layer ( 2) made of a composition of insulating compound suitable for use in electrical energy conductors according to the second variant of the invention and this insulation surrounded in the form concentric by a semiconductive layer (3) made with a semiconductor compound according to the third variant of the invention, suitable for use in cables and electrical energy conductors, followed by a crown of concentric conductor (4), this being taped crown of synthetic material (5) and surrounded by an external casing (6).

In the cable for electrical power distribution that prevents unwanted connection to it, according to the previous variant of the invention, between the central conductor (1) and the semiconductor layer (3) more separate concentric conductor crowns can be contained. by insulating layers (2).

In the electric power distribution cable that prevents unwanted connection to it according to the previous variants, the insulation layer (2) is also made up of a material selected from PE (polyethylene), XLPE (cross-linked polyethylene), EPR ( crosslinked ethylene-propylene rubber), EVA (vinyl acetate), thermoplastic rubber (TPE) and all other insulating polyolefins with flame retardant characteristics and the casing (6) is composed of a material selected from PE (polyethylene), XLPE (cross-linked polyethylene), PVC (polyvinyl chloride), thermoplastic rubber (TPE), LSOH (Low smoke zero halogen).

In the cable for electrical power distribution that prevents unwanted connection to it in accordance with the previous variants, the central conductors (1) are made of copper or its alloys or aluminum or its alloys or bimetallic copper and aluminum or aluminum steel -ACSR - and the concentric conductors (4) are made of copper or its alloys or aluminum or its alloys or bimetallic copper and aluminum, or galvanized steel. In a preferred variant, the cable for electrical power distribution that prevents undesired connection, the central conductor (1) also includes two or more signal cables made up of copper wires each covered with insulation included in an electrostatic screen with a plastic wrap. insulating type.

In the previous variants, the cable for electrical power distribution that prevents undesired connection to it, the outer sheath material is not flame propagating.

Another variant of the invention refers to a cable construction that comprises one or more conductors for electrical energy distribution, this conductor being copper and its alloys and/or aluminum and its alloys, aluminium-steel-ACSR-insulated, where The insulation layer (2) is made with the insulating composition of the second variant of the invention and is also composed of a material selected from PE (polyethylene), XLPE (crosslinked polyethylene), EPR (crosslinked ethylene-propylene rubber), EVA ( vinyl acetate), thermoplastic rubber (TPE) and all other poly-olefin insulators of electrical energy with flame retardant characteristics, with a semiconductor layer on the insulation of each conductor stranded in a helical fashion along with a bare conductor, the conductor being bare copper or its alloys, aluminum and its alloys, aluminum-steel -ACSR-, galvanized steel.

As demonstrated herein, it is clear that the product with the anti-theft function as prevention according to the aforementioned uses and description, is determined by the use of the semiconductor compound in a specific way in a design that determines a cable with constructive characteristics and for private use. Brief description of the figures

For a better understanding of this description, a series of illustrations are attached where the main components are schematized, as well as the spatial arrangement of the cable for electrical power distribution that prevents unwanted connection to it. They are presented by way of example of a particular configuration, but they do not exhaust the possibilities of the fundamental concept of the invention.

FIGURE A: Electrical resistance of the sample as a function of the temperature of the sample of the component material of the semiconductor layer.

FIGURE B: Electrical (volumetric) resistivity as a function of temperature, of the sample of the component material of the semiconductor layer.

FIGURE 1: Single-phase cable with concentric neutral conductor of the prior art

FIGURE 2: Single-phase cable with concentric neutral conductor with semiconductor layer on the insulation

FIGURE 3: Construction of bundled cables for aerial use with a semiconductor layer on their insulated conductors

FIGURE 4: Signal cables covered with concentric conductors with semiconductor coating

FIGURE 5: Cross section of the semiconductor layer sample. FIGURE 6: Construction of cables with 2 insulated phases each with its semiconductor layer, a semiconductor coating, a concentric neutral conductor and outer jacket

Detailed description of the invention

constructive model

The particular objective of the product resulting from the design as described is to obtain an electrical failure that occurs in the cable for use in the electrical power distribution network, under certain circumstances of unwanted or unauthorized connection to it. Faced with this attempt, an insulation failure occurs, which is the desired one, and damage is produced by contact of the conductive parts of different electrical potential, consequently a partial or total destruction of the cable is generated from this failure, so that it is difficult to o Avoid the unauthorized derivation of electrical energy, also being in evidence the attempt of improper connection.

The constructive model proposes a metallic conductor, this being that it is insulated by combustible polyolefinic materials and that the mentioned semiconductor layer is firmly adhered to this insulation. On this, a crown of wires and/or metal strips is then placed and on this crown an external envelope with flame propagating characteristics can be placed. This external insulation can be avoided when the crown is placed at the neutral potential of the electrical power distribution system.

The semiconductor material is suitable for continuous service at the conductor's operating temperature of 90°C, in emergency service of the conductor at the temperature of 130°C for 500 hours, short-circuited at the conductor temperature of 250°C for 5 seconds.

Description of the anti-theft concentric drop cable Previous Art:

This cable model known in the prior art can be seen in Figure 1. The cable as a whole is made up of a central phase conductor, an insulation, a neutral conductor that is arranged on the insulation as a concentric conductor, an external sheath . The "anti-theft" characteristic is defined when the coverage of the concentric conductors (one or more) on the surface of the insulation of each conductor is greater than 95%.

Description of the concentric connection cable with prevention of unwanted connection, single-phase anti-theft model with semiconductor layer.

The following constructive configuration of the single-phase anti-theft concentric cable with a semiconductor layer is presented... as seen in figure 2: central copper conductor, which may be another non-magnetic material that conducts electricity, eg: aluminum and its alloys, bimetallic aluminum -copper (1), an insulating layer of cross-linked polyethylene (XLPE) which may be another flame-propagating polyolefin insulating material (2), a layer of semiconductor cross-linked polyethylene according to table 1 (3), a concentric conductor of wires made of electrically conductive material, for example: copper, aluminum and their alloys, aluminum-copper bimetallic (4), a polyester or paper wrap (5), an external sheath of polyolefin insulating material, whether or not it propagates the flame (6). Operation and protection a. Description of an unwanted or unauthorized bypass connection in a basic "anti-theft" concentric cable on a single-phase cable according to prior art.

An unwanted or improper connection of the bypass can be made at any point of the single-phase anti-theft concentric cable laying. One type of proceeding is as follows: the outer sheath of the cable is cut and removed, this is to expose the concentric conductor. To access the central phase, a possible procedure used by those who try to fraud the connection by illegal access to the electric power cable, bending the cable, can be in a U shape and separate the wires of the concentric conductor. The wires of the concentric conductor will be separated on one side and the isolated phase on the other. The wires of the concentric neutral conductor can also be partially or totally cut, in order to expose more of the insulation surface of the central phase conductor with phase voltage.

To connect to the mentioned central conductor, the insulation that covers it is cut and removed. The electrical connection of the center conductor with an external conductor is made, the connection can be covered with insulating tape or another insulating element. Another external conductor is connected to the previously separated neutral conductor for the neutral connection function. The entire assembly can be covered with electrical tape to hide the connection. b. Description of the prevention of an unwanted or unauthorized branch connection in a "single-phase anti-theft" concentric cable with a semiconductor layer according to the present document.

A model of prevention and attempt to avoid unwanted or unauthorized connection to the electrical network, in a low-voltage cable, be it connection of connection or distribution of electrical energy, the mentioned anti-theft concentric cable with semiconductor layer is used.

The particular condition of this model is that it allows the conduction of electrical energy and/or signals through it and allows the possible generation of an electrical type fault with destructive characteristics in the event of an unauthorized connection attempt to the electrical energy conductors of the cable, or to the signal cables if it has them. This failure causes two simultaneous or alternative effects, the destructive breakage of the cable at that point and/or the failure of its insulation, which makes it possible to identify the unwanted or clandestine connection.

The mechanical process of intrusive intent, which allows improper access to the conductive parts of the cable by destroying the insulating and semiconductor layers, allows the establishment of the circulation of electric current between the phase and neutral conductors via or through the semiconductor layer.

The fault condition (defect) is produced by the destruction of the insulation by -ignition and flame in the semiconductor layer. This is turned on by action resulting from the heat generated in the semiconductor layer by circulation of electric current through it. This flame or ignition is characterized by occurring at a higher temperature than the Rrev occurs and by an electric current circulating through the semiconductor layer, determined by the electrical resistance at that point according to the temperature value reached by the material. This effect also generates the destruction of the insulation layer, because it is it is intimately linked to the semiconductor layer. Once the insulation is destroyed, an electrical short circuit is generated between two phases at different potential or between phase and neutral depending on the electrical power distribution system.

The circulation of current and the consequent generation of heat in the semiconductor layer occur only when on the cable, according to the constructive characteristics presented, an action is carried out that breaks, tears or breaks the insulating layer and the semiconductor layer, allowing it to be put on. contacting the semiconductor layer totally or partially, directly or indirectly with the two conductors at different electrical potential.

The neutral conductor in this case may even be cut with an electrical discontinuity at the undesired connection point and the failure may occur by closing an electrical circuit through the semiconductor layer.

The electrical fault continues to be fed back as long as the power supply to the cable is not interrupted. Before the action of a fuse-type protection or an external thermo-magnetic switch, the circulation of electric current towards the generated fault is prevented. By interrupting the power supply, by any method, the flame tends to stop. If the outer casing has a flame retardant characteristic, the flame is extinguished by the effect of this casing.

The semiconductor compound only acts for the desired effect of lighting up if electric current flows through it. The aforementioned compound does not affect or modify the normal operation of the cable, when it is connected as a supply of electrical energy in the distribution network, be it low or medium voltage and under normal and nominal operating conditions. Single-phase anti-theft concentric cable design with semiconductor layer

drivers

The phase conductor is made up of copper wires and their alloys, aluminum and their alloys, aluminum-steel, bimetallic conductors of copper and aluminum. The formation can be of 1 wire, semi-rigid of 7 wires, or flexible of several wires. The maximum electrical resistance of the conductor is defined by the nominal section, as for example in the IEC 60228 and ICEA S 95-658 standards, among others.

isolation

The insulation materials for the phase conductor are composed of: polyethylene (PE), crosslinked polyethylene (XLPE), crosslinked ethylene-propylene rubber (EPR), ethyl-vinyl-acetate (EVA), thermoplastic rubber (TPE) and all other insulating polyolefin with flame retardant characteristics. The insulation must withstand the dielectric strength test in alternating current or direct current, determined by the end user in the use and product specification, as the case may be: example, applied voltage of 2500V 50/60 Hz or higher, for a minimum of one ( 1) minutes. Always complying with the security requirements of the network where the cable will be installed, other test values are applicable.

semiconductor layer

The semiconductor layer is made of a material composed of cross-linked polyethylene with semiconductor characteristics of electric current. When applied by simple extrusion or simultaneous direct double extrusion, depending on the type of cable to be used and according to the state of the art, the The semiconductor layer must be adjusted to the insulation that covers the metallic conductor(s) with a central arrangement, or on the last insulation of a conductor with phase voltage other than neutral.

From the mechanical and electrical point of view, it must be possible to remove the semiconductor layer on the insulation without damaging it, at least 1 cm to install any type of connection terminal.

The thickness of the semiconductor casing must allow the circulation of electric current and at the same time have mechanical resistance to detach it from the insulation.

This cable with a layer of semiconductor material does not admit connection by means of perforation morsets if the semiconductor layer is not previously removed.

concentric conductor

The concentric conductor that covers the insulated conductor assembly and with a semiconductor layer, is made up of copper wires and their alloys, aluminum and their alloys, bimetallic conductors of copper and aluminum. The cabling must be in the form of a helical spiral, while the cabling pitch is from 50 to 200 mm, but other pitch dimensions are allowed according to the state of the art. The smaller the pitch length, the more difficult is the separation of the concentric layer wires and thus the access and maneuverability for the clandestine bypass connection. The coverage of the surface on the semiconductor layer must be greater than 95% of the circumference of the same.

It is possible to build the concentric conductor by making a braided mesh of metal wires, with coverage greater than 90% of the surface of the semiconductor layer. Another constructive form is a crown as a set of wires wired in a helical shape covered with metal strips in an open or overlapping path, with a minimum coverage of 95% of the surface. A layer of metallic tapes applied helically with a minimum overlap of 10% can also be used as a concentric conductor.

The concentric conductor on all the active phases of the cable can also be made of galvanized steel, in any format with wires and tapes.

A combination of galvanized steel wires, tinned copper wires and/or aluminum wires and their alloys is possible, always taking care not to produce a galvanic couple that leads to corrosion between metals.

outer casing

The materials of the outer sheath of the cable as a whole applied to the concentric conductor and its taping, among others, can be made of a material selected from PE (polyethylene), XLPE (cross-linked polyethylene), PVC (polyvinyl chloride), thermoplastic rubber ( TPE), LSOH (Low smoke zero halogen), polyolefins and any external sheath that protects the cable from water ingress and environmental aggressions.

Insulating outer wraps may have flame retardant characteristics.

In some configurations the concentric conductor does not require an external wrap.

Basic Formulation

In one of the variants of the invention, surprisingly it has been found that starting from a basic formulation (Masterbatch) during the extrusion thereof, it is possible to obtain the insulating compound or the semiconductor compound simply by varying the charge compounds used. This is unprecedented until the date of presentation hereof.

Advantages of using the Basic Formulation:

The main advantage of the basic formulation is that its use does not require extrusion with a catalyst. The basic formulation is placed according to the list of its components in the extruder and the charges that are required can be added, in this way, the extruder is placed directly on the cable.

The formula admits high concentration of fillers, as will be seen later, especially carbon black material that is very difficult to mix and disperse uniformly and therefore solves a long-standing problem found in the prior art.

On the other hand, this advantage of being able to mix it with other products allows compositions with special characteristics to be obtained by only adding selected fillers without adding catalyst.

The inventors found the following basic formulation that allows obtaining both the composition of the insulating compound and the composition of the semiconductor compound, which can be used in the present invention, reproduced in the following Table A:

Table A

the insulating compound.

In another variant of the invention, it refers to a formulation of an insulating compound and a manufacturing method from a basic formulation (Masterbatch) during its extrusion process; it is possible to obtain the insulating compound simply by varying the filler compounds used.

The basic formulation (Masterbatch) (which will also be used in the composition of the semiconductor compound) was used, that is, the following reproduced in Table A:

Table A

But to the previous one, it was used as it is or loads were added up to a quantity of 3% in order to obtain the following insulating composition reproduced in Table 2:

Table 2

It is important to distinguish that the compound obtained by the basic formulation already by itself forms a cross-linked polyethylene compound suitable for insulating low voltage cables. For example, it complies with the standards IEC 60502-1, ICEA S-95-658 type Xl among others.

The previous composition of basic formulation accepts the incorporation of different types of loads in order to meet certain special regulatory requirements.

Using other types of charge, other types of properties of the compound are obtained.

The basic formulation has the characteristic of being thermostable and resistant to attack by mineral oils.

The incorporation of mineral fillers gives it additional properties such as increasing hardness.

For example, non-conductive carbon black can be added to the basic formulation from 2% to 3% by mass, to maintain UV resistance. The type of carbon black recommended for this use has a particle size not greater than 35nm (ASTM D1248 Item 4.1.2.6).

This base compound accepts the incorporation of colors in pigmented form or as masterbatch, in variable concentrations and less than 3%, ensuring a uniform dispersion without lumps, complying with the wide variety of colors established in international tables such as RAL or MUNNSEL Incorporating Masterbatch colored compounds are obtained, they are generally mixed at 1% and comply with color codes, for example MUNSEL (Electronics Industries Association (EIA) specification EIA RS359-A identifies electrical wire color codes for wire and cable insulation), DIN EN 60446 VDE 0198 :2008-02 Basic and safety principles for man-machine interface, marking and identification Identification of conductors by colors or alphanumerics

The incorporation of mineral loads that are hologenated or not, they modify final properties that are fireproof and have low smoke density. By incorporating mineral charges, compounds with other additional properties are obtained. By incorporating halogenated fillers, for example with bromine Br, flame retardant compounds are obtained. These charges can be incorporated as Masterbatch during the final extrusion or non-halogenated with hydrated aluminum. The spectrum of mineral fillers is very broad.

In addition to the application of cross-linked polyethylene for the extrusion of cables, pipes and hoses. The compound is suitable to be processed in extruders/injectors to obtain engineering parts. The compound can be processed in machines of the rubber industry, in presses with molds that operate with pressure and temperature. The compound inside the mold at the right temperature softens, and copies the shape it melts and produces a homogeneous compound. Once cooled inside the mold, the piece is removed. Chemical curing occurs by exposure to ambient or artificial moisture. Crosslinking occurs on exposure to ambient moisture. The parts to be manufactured apart from the cable category are, for example, washers, gaskets, O'rings.

Insulating Compound Manufacturing Considerations

Insufficient addition of reagents results in imperfect cross-linking and excessive feeding of reagents impairs the surface quality of the product.

Production process of the insulating compound

To produce the insulating material composite, 2 process steps are used.

Stage 1: Mixed: the elements of the formula are loaded (see table A) in a closed double Z mixer, the elements of the formula are mixed at a temperature between 80°C and 85°C, the mixing time lasts between 8 to 10 hours. The finished compound is unloaded from the mixer in the markets according to the technique and state of the art. The slices obtained from the already mixed compound can be taken directly to the extruder or left parked to carry out the process at another time.

Using for the same process alternatively, a Bambury-type mixer at a temperature of 80 - 85 °C, with a minimum of one (1) hour. Mixing in an open mill carries the risk of spreading dust into the environment, and at the same time there is the risk of contaminating the mixture with external impurities.

Stage 2: Pellet: To achieve grains of adequate size to feed extruders, the slices from the mixing of stage 1 are cut to the appropriate size to be taken by the extruder screw, to undergo an extrusion and pellet cutting process. , cooled and bagged. The extrusion process is carried out in a conventional type extruder, preferably the screw must have a profile to process polyethylene. The temperature profile for heating the extruder areas is slightly upwards from the hopper to the pellet cutter head, with a maximum temperature of 128°C. The molten compound extracted from the extrusion is cut by blades at the exit of the screen. Then it is cooled by a blow of ventilated air at room temperature and bagged in a double bag with a valve.

Once the bag is filled with pellets, the bag is vacuumed with a double valve to prevent moisture from entering. Storage is in accordance with the state of the art for crosslinkable plastic materials: the compound can be stored for 6 months without any problem following the rules of good art, dry environment, room temperature between 15°C and 40°C.

Extrusion on the cable product with anti-theft function.

The final extrusion process of the insulating compound resulting from stage 2 is carried out on the bare conductor, the insulated phase or the cable.

The temperature distribution for the different areas of the extruder machine is as follows: 90°C in the first access area of the pellet to the hopper. Then, the head temperature is set at 155°C and the temperature is decreased 10°C to 15°C for each zone, from the head to the hopper. The temperature of the melt in the head is 155°C. Nozzles and pressure extrusion method are used for the purpose of achieving adhesion.

Suggested Extrusion Temperature Profile

The crosslinked semiconductor polyethylene used does not require immersion in hot water to carry out the crosslinking process, or parking in a sauna bath supersaturated with steam. The formulation of the compound and its manufacturing process imply that the hydrolysis that produces the crosslinking only depends on the entry of water molecules into the compound. Therefore, the final material resulting from stage 2 must be stored at room temperature and humidity, based on an environment of 5 - 40°C and ambient relative humidity of 10-99%.

Some commercial compounds of the silane type require the migration or addition of catalysts to carry out the crosslinking. The semiconductor compound of the present invention does not require aggregates, catalysts or physicochemical processes subsequent to stage 2 mentioned to achieve crosslinking.

For all processes involved in manufacturing stages of plastic compounds and extrusions, temperature tolerances are +- 3 C.

semiconductor compound.

In another variant of the invention, the present invention refers to a formulation of a semiconductor polyolefin compound and a manufacturing method from a basic formulation (Masterbatch) during its extrusion process. It is possible to obtain the insulating compound or the semiconductor compound simply by varying the charge compounds used and replacing it with conductive carbon black.

Until now, the highly loaded mixture of conductive carbon black to achieve a semiconductor composition for cables required a lot of work to achieve a uniform dispersion and use of compounds with catalysts that, when incorporated into the extruders, had a setting time that was in contrast to each other. with the mixing efficiency; obtaining non-homogeneous products. The inventors circumvented this drawback in the manner described below.

It was used for the basic formulation (Masterbatch) of the conductive compound described above, that is, the one reproduced in the following Table A: Table A

Semiconductor polyolefin is used in low and medium voltage power transmission cables, data cables, fiber optic cables, cathodic protection cables.

The compound is suitable for the manufacture of internal and external homogenization layers of insulated medium voltage cables, also for the internal homogenization layer of semi-insulated medium voltage cables for overhead power lines.

The semiconductor compound is determined by its formation according to Table 1 that will be described below, where the conductive carbon black is added at high load to the basic formulation and the semiconductor compound is achieved by the manufacturing process.

Table 1

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Semiconductor Composite Manufacturing Considerations Insufficient addition of reagents results in imperfect cross-linking and excessive feeding of reagents impairs the surface quality of the product.

Production process of the semiconductor compound

To produce the semiconductor material compound 2 process steps are used.

Stage 1: Mixing: the elements of the formula (see table 1) are loaded into a closed double Z mixer, the elements of the formula are mixed at a temperature between 80°C and 85°C, the mixing time lasts between 8 at 10 hours. The finished compound is unloaded from the mixer in the markets according to the technique and state of the art. The slices obtained from the already mixed compound can be taken directly to the extruder or left parked to carry out the process at another time.

Stage 2: Pellet: To achieve grains of adequate size to feed extruders, the slices from the mixing of stage 1 are cut to the appropriate size to be taken by the extruder screw, to undergo an extrusion and pellet cutting process. , cooled and bagged. The extrusion process is carried out in a conventional type extruder, preferably the screw must have a profile to process polyethylene. The temperature profile for heating the extruder areas rises slightly from the hopper to the pellet cutter head, with a maximum temperature of 128°C. The molten compound extracted from the extrusion is cut by blades at the exit of the screen. Then it is cooled by a blow of ventilated air at room temperature and bagged in a double bag with a valve.

Once the bag is filled with pellets, the bag is vacuumed with a double valve to prevent moisture from entering. Storage is in accordance with the state of the art for crosslinkable plastic materials: the compound can be stored for 6 months without inconvenience following the rules of good art, dry environment, room temperature between 15°C and 40°C.

Extrusion on the cable product with anti-theft function.

The final extrusion process of the semiconductor compound resulting from stage 2 is carried out on the bare conductor, the isolated phase or the cable.

Suggested Extrusion Temperature Profile

The crosslinked semiconductor polyethylene used does not require immersion in hot water to carry out the crosslinking process, or parking in a sauna bath supersaturated with steam. The formulation of the compound and its manufacturing process imply that the hydrolysis that produces the crosslinking only depends on the entry of water molecules into the compound. Therefore the final material resulting from stage 2 should be stored at ambient temperature and humidity, based on an environment of 5 - 40°C and ambient relative humidity of 10-99%.

Crosslinked Semiconductor Material Test

A cross-linked polyethylene casing with semiconductor characteristics was applied by extrusion to a conductor with a circular cross-section of 6 mm2 insulated in XLPE, according to the compound described in Table 1.

The insulated conductor with a diameter of 5.2 mm and the conductive layer on the insulation, a thickness of 0.8 mm.

The manufactured cable has the constructive characteristic of a concentric cable, with the formulation of materials for the semiconductor layer and with the indicated processing and manufacturing conditions. This was stored for crosslinking under ambient conditions. A sample was taken from the semiconductor layer of the mentioned material, to record the following test values.

Table 2

Regardless of the use as a semiconductor layer for anti-theft prevention purposes in concentric cables, these values in table 2 additionally exceed the physical and electrical requirements, for example, of the standards applicable to medium voltage cables ICEA and IEC for semiconductor layers of homogenization of the conductor and insulation.

Electrical properties of the semiconductor compound of the single-phase anti-theft concentric cable_ with a semiconductor coating.

Samples of extruded and crosslinked semiconductor material were taken according to the aforementioned manufacturing conditions, longitudinal cuts were made parallel to the axis of the conductor to remove the semiconductor layer from on the insulation.

This material is based on the compound in Table 1.

All the samples used are of the same material and cross section, they come from the same manufacturing process, varying from each other only in their length.

For determination of electrical characteristics proceeded as follows:

2 electrodes were placed, one at each end of the sample, making firm, frank and direct contact with the face of the external surface of the sample at one end and with the face of the internal surface (opposite to the previous one) at the other. extreme.

A voltage of 216 Vca, 50 Hz was applied, depending on the electrodes connected to the sample.

For the electrical tests, a circuit consisting of a bipolar switch to connect to the electrical power network, a digital multimeter to measure the electrical current, a digital thermometer with type K junction to measure the temperature on the external layer of the sample and a digital voltmeter to record the voltage applied to the sample, the time being measured with a digital stopwatch.

The following variables were measured: t = time (s), from the beginning of the connection of V

I = electric current (A),

V = mains voltage (volt).

L = sample length between electrodes (cm)

S = cross section of the sample cm2; see figure 5

T = sample temperature (°C)

The following magnitudes were calculated using the following electrical engineering equations:

R = electrical resistance (Ohm); calculated R = V/I;

RO = volume resistivity (ohm.cm); RO= R.S/L;

We call it Reversal Resistance. (rev)

Rrev = maximum electrical resistance in which, from successive temperature increases in the sample, no increases in resistance R are generated, and this may resistance take constant values in a temperature range from the point where the temperature reaches Trev. Being,

Trev = minimum sample temperature at which Rrev occurs.

Tamb = room temperature at which the test was performed

ROrev = maximum volumetric resistivity of the sample in which, from successive increases in temperature, no increases in resistivity, RO, are generated, this resistivity being able to take constant values in a temperature interval from the Trev point.

Irev = minimum current flowing through the sample at the Trev temperature for the Rrev. trev = the time elapsed from the start of the test and when Trev, Rrev, ROrev, Irev occur.

The results of the corresponding tests are shown with their characteristic values, according to the previous equations and the variables that were measured in the samples defined by their length. According to indicated figures A and B.

Table 3

The process to determine the values of table 3 is continuous in time, so that the test is started and that after obtaining the value of Rrev, the test process continues until the occurrence of failure by ignition of the layer. semiconductor. Descriptive process of the behavior of the sample of the compound before the circulation of electric current.

First phase: The sample is heated by the accumulation of heat due to the circulation of electrical current, the electrical resistance increases with increasing temperature until the electrical resistance of the sample reaches the maximum value, with PTC, coefficient of increase of the resistance with the temperature, positive this being the point the "reversal resistance" and the "reversal temperature" (Rrev; Trev).

Second phase: The sample is heated by the accumulation of heat due to the circulation of electric current, the temperature increases without variation of the electrical resistance. The value of the maximum electrical resistance (Rrev) is kept constant from the reversal temperature (Trev), (ZTC coefficient of resistance increase with zero temperature).

Third phase: The sample is heated by the accumulation of heat due to the circulation of electric current in it, increasing the temperature, (in all phases it is exceeding the amount of heat dissipated by it). In this phase, as the temperature increases, the electrical resistance decreases from the maximum value already obtained in phase 2 of the reversal resistance (Rrev). That is: the electrical resistance decreases with the increase in temperature due to the accumulation of heat, directing the whole process towards the destruction of the sample by heat, (NTC coefficient of resistance increase with negative temperature).

This dynamic process from the third phase, results in the destruction of the sample by ignition and consequent flame of the semiconductor material. Functional stress test 120 See

On the single-phase concentric cable, made up of a 6 mm2 cross-section copper conductor, insulated with 1 mm cross-linked polyethylene, 0.8 mm semiconductor cross-linked polyethylene layer, 6 mm2 cross-section aluminum concentric conductor, taped polyester and 1.2 mm flame retardant PVC outer wrap, outer wrap removed 10 cm. By manipulating the cable, it was possible to separate the concentric conductor from the insulated central conductor and gain access to it. A network voltage of 120 Vea 50 Hz was applied between the central phase conductor and the concentric neutral conductor that surrounds the insulation with the semiconductor layer. An incision was made in the insulation plus semiconductor layer assembly up to the central conductor with a cutting element, sparks were produced and the cutting element was removed, the current circulation process began with smoke generation and flame development. After 3 minutes of flame the insulator was consumed, there was a short circuit between phase and neutral with destruction of the central conductor. The flame was always kept within the open area and freed from the external envelope. Finally power to the sample was removed and the flame was extinguished.

Behavior of the semiconductor material within the finished cable assembly

It is worth mentioning that if the semiconductor compound is subjected and exposed to heat generated by an external source to the mentioned cable or also heat generated by the current that circulates through the metallic conductors of the cable in normal operation and design, not through the semiconductor layer, will not present the process of described catastrophic destruction because there is no difference in electrical potential on the semiconductor layer that is in contact with a conductor at a certain electrical potential and isolated from another conductor at another electrical potential, therefore there will be no current flow through it. The non-ignition of the semiconductor compound being in a passive state, that is, without being subjected to an electrical potential difference, is verified in the aging tests of the same in a hot air oven at 121°C, the result being the change of properties mechanical but not ignition.

Background

Differences are observed in the present study regarding the values and test methods of other semiconductor materials.

In the present study, an alternating voltage applied at an industrial frequency of 50 Hz during a dynamic process is proposed for the samples, while the values indicated in the literature are measured in direct current and in equilibrium, avoiding the generation of heat.

For example, US 9,607,737 B2: proposes a resistivity (RO) value at 60°C of 990 ohm.cm. Taking this material, constructing a sample of the same geometric dimensions as that of the present study, for a length of 16 cm, and a 0.15 cm2 cross section, a current circulation of 2 mA at 60°C is obtained; while for the sample of the present study a current circulation of 90 mA at 60°C is obtained, it implies a current 45 times greater, producing 2000 times more heat.

This implies a generation of heat in the sample by circulation of electric current, being that the irreversible process of the decrease of the resistance is achieved with the increase in temperature from the maximum value of the electrical resistance (reversal resistance). (See paragraph 60 body 1 of US 3861029).

We recall that the objective of patent US9607737 is to achieve an equipotential surface that does not generate electric field concentrations in the crosslinked polyethylene (XLPE) insulation of medium voltage cables. The objective of the present invention is a product (cable) with an option to an anti-theft function, when the cable is attacked by means of a cutting element, it is intended that the semiconductor layer can lead to the destruction of the cable due to heat accumulation and consequent ignition when current flows through the semiconductor layer between the cut and the concentric conductor.

According to what was proposed by US3861029 and ratified by US4200973, semiconductor compounds for use in self-regulating cables have a maximum electrical resistivity at a certain temperature, they call it (Rp), for temperatures higher than the one that occurs (Rp) the resistivity decreases. constantly with increasing temperature. Then it is declared that at 60°C the resistivity (RO) is 69000 ohm.cm in direct current (table 3 US3861029), while the sample of the present study shows a resistivity (RO) of 34.5 ohm.cm at 60 ° C tested in alternating current of 50Hz. According to the test, the proposed material shows a volumetric resistivity of 8.9 ohm.cm at 25°C measured in direct current.

Construction of cables for use in electrical energy and communications

Cable for electric power distribution system and home connection. 1. Construction of anti-theft concentric conductor cables with a semiconductor layer, single-phase, two-phase, three-phase. (Multiconcetric). Being that the construction of concentric cables implies the use of one or more concentric layers with each other, with insulated conductors and with a semiconductor layer according to designs, which act as active or neutral poles depending on the electrical configuration of the system used for power distribution. electrical.

In these designs the layer of semiconductor material refers to the material described in this specification.

Single-phase cable with one phase plus a concentric neutral conductor with a semiconductor layer: It consists of a central conductor. A layer of insulating material and over it a layer of semiconducting cross-linked polyethylene. A concentric conductor above the semiconductor layer and with coverage greater than 95% of the surface of the semiconductor layer. A taping band and an outer wrap.

Two-phase anti-theft concentric conductor cable with a semiconductor layer: It consists of a central conductor, a layer of insulating material on it and a concentric conductor wired on it. A second layer of insulating material over the concentric conductor and over it a layer of semiconductor cross-linked polyethylene. A second concentric conductor wired over the semiconductor layer with coverage greater than 95% of the surface of the semiconductor layer. A taping band and an outer wrap.

Three-phase anti-theft concentric conductor cable with a semiconductor layer: It consists of a central conductor. A layer of insulating material over it and a concentric conductor wired over it. A second layer of insulating material on the concentric conductor, then a wired concentric conductor is arranged on it. A third layer of insulating material on the concentric conductor and a concentric conductor wired thereon and on it a layer of semiconductor cross-linked polyethylene. A third concentric conductor wired over the semiconductor layer with coverage greater than 95% of the surface of the semiconductor layer. A taping band and an outer wrap.

The conductors can be made of copper and its alloys, aluminum and its alloys, bimetallic copper and aluminum, aluminium/steel -acsr-. The insulation can be made of PE (polyethylene), XLPE (crosslinked polyethylene), EPR (crosslinked ethylene-propylene rubber), EVA (vinyl acetate), thermoplastic rubber (TPE) and any other insulating polyolefin with flame retardant characteristics. The casings can be made of PE (polyethylene), XLPE (cross-linked polyethylene), PVC (polyvinyl chloride), thermoplastic rubber (TPE), LSOH (Low smoke zero halogen). Outer wraps may be flame retardant.

2. Construction of pre-assembled or pre-assembled cables.

Cable for electric power distribution system and home connection of type conductors with pre-assembled or pre-assembled semiconductor layer for aerial or underground use.

The pre-assembled or pre-assembled cables are made up of 1, 2, 3 or more phases wired in a visible spiral on a bare carrier conductor. In the protection scheme proposed in this specification, it is necessary that the carrier is connected to the neutral of the system. electric. Each phase consists of a conductor, an insulation, and a layer of semiconductor material. The conductors can be made of copper and its alloys, aluminum and their alloys, bimetallic copper and aluminum. The insulation materials of the phase conductor are: PE (polyethylene), XLPE (crosslinked polyethylene), EPR (crosslinked ethylene-propylene rubber), EVA (vinyl acetate), thermoplastic rubber (TPE) and all other insulating polyolefins of flame spreading characteristics. A layer of semiconductor cross-linked polyethylene is extruded over the insulation of each conductor, according to the characteristics of Table 1. The supporting conductor must be bare and can be made of copper and its alloys, aluminum and its alloys, aluminum-steel, or galvanized steel. .

3. Construction of cables with isolated phases joined with a semiconductor layer and a concentric neutral conductor.

Each phase consists of a conductor, an insulation and a layer of the semiconductor material according to table 1, on it. Two or three isolated phases and with the semiconductor layer are wired in close contact or arranged in parallel. An extruded coating of semiconductor material, according to table 1, on the set of assembled insulated conductors and each one with a semiconductor layer. On this coating, in a circular or oval format, a concentric conductor with coverage greater than 95% of the surface of the semiconductor layer, a strapping tape and an external wrap are applied (see Figure 6).

The conductors can be copper and its alloys, aluminum and its alloys, bimetallic copper and aluminum, aluminum/steel -AcSR-.

The insulation materials of the phase conductor are: PE (polyethylene), XLPE (crosslinked polyethylene), EPR (crosslinked ethylene-propylene rubber), EVA (vinyl acetate), thermoplastic rubber (TPE) and all other insulating polyolefins of flame spreading characteristics. the wrappers They can be made of PE (polyethylene), XLPE (cross-linked polyethylene), PVC (polyvinyl chloride), thermoplastic rubber (TPE), LSOH (Low smoke zero halogen).

4. Signal cables covered with concentric conductors.

Optical fiber cables covered by concentric conductors for the transmission of electrical energy according to patent US 20200049914 Al and symmetrical shielded pair signal cables of all possible dimensions and configurations with concentric layer cable coverings can be additionally protected extruding the semiconductor layer according to the material of table 1, on the insulation below the outermost concentric conductor (see Figure 4).

Claims

1. A basic formulation to manufacture insulating compounds or semiconductor compounds characterized in that it comprises the following components in weight/weight concentration according to the following Table A:

Table A

2. A composition of insulating compound suitable for use in electrical energy conductors obtained from the basic formulation according to claim 1, characterized in that it comprises the addition of selected charges of at least one of the following additional components: halogenated mineral charges or not, non-conductive carbon black, colored compounds in a concentration of 0 to 3% w/w according to Table 2:

Table 2

3. The insulating compound composition suitable for use in electrical power conductors according to claim 2, characterized in that the concentration of non-conductive carbon black is from 2% to 3% weight/weight to provide resistance to UV rays at the composition.

4. The insulating compound composition suitable for use in electrical energy conductors according to claim 2, characterized in that the concentration of colored compounds is from 1% to 3% weight/weight to provide the desired color to the composition.

5. A semiconductor compound composition suitable for use in electrical energy conductors obtained from the basic formulation according to claim 1, characterized in that it comprises the addition of conductive carbon black in a concentration of 18 to 35% weight/weight according to the following Table 1:

Table 1

6. A cable for electrical power distribution that prevents unwanted connection to it (due to possible destruction of the connection), characterized in that it comprises a central conductor (1) concentrically surrounded by an insulating layer (2) made of a Insulating compound composition suitable for use in electric power conductors according to claim 2 and this insulation concentrically surrounded by a semiconductive layer (3) made with a semiconductor compound according to claim 6, suitable for use in cables and conductors of electrical energy, followed by a concentric conductor crown (4) on it, this crown being ribboned with synthetic material (5) and surrounded by an outer casing

7. The cable for electrical power distribution that prevents unwanted connection to it, according to claim 6, characterized in that between the central conductor (1) and the semiconductor layer (3) it can contain more concentric conductor crowns separated by insulating layers (2).

8. The cable for electrical power distribution that prevents unwanted connection to it according to claim 6 or 7, characterized in that the insulation layer (2) is also made up of a material selected from PE (polyethylene), XLPE (polyethylene crosslinked), EPR (crosslinked ethylene-propylene rubber), EVA (vinyl acetate), thermoplastic rubber (TPE) and all other insulating polyolefins with flame retardant characteristics and the casing (6) is composed of a material selected from PE (polyethylene), XLPE (cross-linked polyethylene), PVC (polyvinyl chloride), thermoplastic rubber (TPE), LSOH (Low smoke zero halogen).

9. The cable for electrical power distribution that prevents unwanted connection to it according to claim 6 or 7, characterized in that the central conductors (1) are made of copper or its alloys or aluminum or its alloys or bimetallic copper and aluminum or aluminum steel -ACSR- and the concentric conductors (4) are made of copper or its alloys or aluminum or its alloys or bimetallic copper and aluminum, or galvanized steel.

10. The cable for electrical power distribution which prevents unwanted connection to it according to claim 6, characterized in that the central conductor (1) also includes two or more signal cables made up of copper wires each covered with insulation included in an electrostatic screen with an insulating type wrap .

11. The cable for electrical power distribution that prevents unwanted connection to it according to any of claims 6 to 10, characterized in that the material of the outer sheath is not flame propagating.

12. A cable construction characterized in that it comprises one or more conductors for electric power distribution, this conductor being copper and its alloys and/or aluminum and its alloys, aluminium-steel-ACSR-insulated, characterized in that the insulation layer ( 2) is made with the insulating composition of claim 2 and also composed of a material selected from PE (polyethylene), XLPE (crosslinked polyethylene), EPR (crosslinked ethylene-propylene rubber), EVA (vinyl acetate), thermoplastic rubber (TPE ) and all other polyolefin insulators of electrical energy with flame propagating characteristics, with a semiconductor layer on the insulation of each conductor stranded in a helical fashion together with a bare conductor, the bare conductor being copper or its alloys, aluminum and its alloys, aluminum-steel -ACSR-, galvanized steel.