PL236650B1 - Power cable with a composite core - Google Patents

Description

Description of the invention

The subject of the invention is a power cable with a composite core, used in high voltage transmission lines.

It is known from the description of the invention No. PL208011 a transmission and distribution electric cable with a composite core and a method for producing a composite core element. The invention relates to a composite-core reinforced aluminum cable (ACCC) surrounded by at least one layer of aluminum conductor. The composite core is constructed of at least one type of longitudinally oriented substantially continuous reinforcing fibers in a matrix of thermosetting resin having an acceptable operating temperature range of about 90 to about 230 ° C, with at least 50% fiber volume, tensile strength ranging from about 160 to about 240 Ksi, a modulus of elasticity ranging from about 7 to about 30 Msi, and a coefficient of thermal expansion ranging from about 0 to about 6x10 ^-6 m / m / C. A composite core for a transmission and distribution electric cable, reinforced with resin embedded fibers according to this invention, comprises an improved composite material inner core made of at least one type of substantially continuous reinforcing fiber in a thermosetting resin, and an outer core of a low modulus composite material made of a composite material. at least one type of substantially continuous reinforcing fiber in a thermosetting resin, the composite core having a core tensile strength of at least about 1103 MPa. The types of reinforcing fibers of the composite core are selected from the group consisting of carbon fiber, kevlar, basalt, glass, aramid, boron, liquid crystal fibers, high strength polyethylene and carbon nanofibers. The composite core is made of a thermosetting resin that has a fracture toughness of at least about 0.96 MPa-ml / 2, and at least one type of reinforcing fiber in the inner core has a modulus of elasticity ranging from about 151 GPa to about 255 GPa in when set to a thermal expansion coefficient ranging from about -0.7 to about 0 m / m / ° C and a tensile strength of at least 2413 MPa, and at least one type of reinforcing fiber in the outer core (304) exhibits a tensile strength of at least about 1,241 MPa against a coefficient of thermal expansion ranging from about 5 x 10 ^-6 to about 10 x 10 ^-6 m / m / ° C. The number and type of fibers in the core are selected to achieve the physical properties of the finished composite core, including a tensile strength of at least 1103 MPa, a modulus of elasticity ranging from at least about 48 GPa to about 206 GPa, and an operating temperature ranging from about 90 to about 230 ° C, and a thermal expansion coefficient in the range of at least 0 to about 6 x 10 ^-6 m / m / ° C. In contrast, the fiber / resin volume ratio in the core is at least 50% and the fiber / resin ratio in the core is at least 62%. The inner core and the outer core form a coaxial hybrid core. The core comprises a coaxial hybrid core having an inner layer of carbon fiber / thermosetting resin and an outer layer of glass fiber / thermosetting resin. Also known from this specification is a composite core for an industrial and distribution electric cable, reinforced with resin-embedded fibers, which is characterized in that it comprises one or more types of substantially continuous reinforcing fibers in a thermosetting resin matrix, the core having a tensile strength of at least about 1103 MPa and a Modulus of Flexibility ranging from about 48 GPa to about 207 GPa. The types of reinforcing fibers of the composite core are selected from the group consisting of carbon fiber, kevlar, basalt, glass, aramid, boron, liquid crystal fibers, high strength polyethylene and carbon nanofibers. The core is made of a thermosetting resin which has a fracture toughness of at least about 0.96 MPa-ml / 2.

From the patent description CN104517673A, a solution of a cable with a composite carbon fiber core and a method of its production is also known. The cable includes an internal composite core and aluminum alloy conductors. The aluminum alloy conductors are positioned around an inner composite core, which consists of a plurality of strands of carbon-reinforced composite cores and at least one layer of glass tape protecting the shell, which is diagonally twisted and connected together. Each composite core is reinforced with carbon fiber, which consists of epoxy resin, hardener, accelerator and carbon fibers in the ratio 100: 120: 2: 80, and the carbon fibers are made of polyacrylonitrile.

From the patent application WO2005040017A2, there is known a power cable with a composite core surrounded by wires, which is characterized by, among others, in that it comprises armor fibers of at least one type of material with a tensile strength of at least 1200 MPa

(Carbon fibers) firmly bonded to a thermally cured epoxy resin, the core being surrounded by at least one layer of aluminum wires with a trapezoidal cross-section.

From the description of the invention RU2519598C1 a shielded wire solution is known which can be used as a winding wire or a core of a multi-core cable, comprising an elongated conductor, an insulating layer and a shielding layer surrounding the elongated conductor, wherein the shielding layer comprises a ferromagnetic powder and an insulating material binder.

The mechanical and thermal properties of prior art cables have been thoroughly tested. Nevertheless, the only currently proposed method for checking the integrity of a conduit after its installation is to momentarily stress it. This method is based on the fact that after the conductor is assembled in the place of its use, it is subjected to a tensile force, which reveals the places of core damage.

The disadvantage of this method is that it is a destructive method, potentially dangerous to handling, requiring large changes in the equipment used. This method has never been used in cable assembly procedures.

The technical problem that needs to be solved is to reduce the disadvantages and inconveniences of known solutions and to extend the methods of testing cables.

The aim of the invention is to enable testing of the continuity of power cables, after their installation on power poles, with new non-destructive methods.

The goal was achieved by developing a new power cable with a composite core, enabling the control of the mechanical continuity of transmission lines with magnetic methods.

The essence of a power cable with a composite core containing reinforcing fibers of at least one type of material with a tensile strength of at least 1200 MPa, permanently bonded to a thermally hardened epoxy resin, in which the core is surrounded by at least one layer of wires is that the reinforcing fibers constitute from 50 % to 90% of the volume of the finished core, epoxy resin is from 10% to 50% of the volume of the finished core, and it is filled with ferromagnetic or magnetic powder in the amount of 1 cm ³ to 10 cm ³ , preferably 7 cm ³ in each, over the entire volume. meter of the finished core, and the wires surrounding the core are aluminum and / or annealed aluminum wires, preferably circular and most preferably trapezoidal.

Preferably the reinforcing fibers in the core are carbon fibers and / or carbon nanofibers and / or glass fibers and / or basalt fibers and / or aramid fibers and / or polyethylene fibers.

Preferably, the wire comprises a core which has an outer layer containing reinforcing fibers with a modulus of elasticity below 100 GPa and an inner layer containing fibers with a modulus of elasticity above 100 GPa, the outer layer and the inner layer being coaxial and permanently connected to each other.

Preferably, the ferromagnetic powder in the core is iron, nickel, cobalt or their alloys, or other metal with ferromagnetic properties.

Preferably, the ferromagnetic powder in the core is a powder with a granulation of 0.063 mm.

Preferably, the magnetic powder in the core is neodymium powder or another metal with permanent magnet properties.

Preferably, the magnetic powder in the core is a powder with a granulation of 0.063 mm.

The advantageous effect of the invention is to reduce the drawbacks and inconveniences of known solutions, as well as to increase the research capabilities of transmission lines. This was achieved by modifying power cables with plastic cores in order to enable the use of magnetic methods of diagnosing the condition of cable damage. The introduction of a functional material to the construction of composite cores, consisting of a thermally hardened epoxy resin filled with a ferromagnetic or magnetic powder, made it possible to use magnetic methods of wire rope diagnostics for testing power cables with composite cores. Thanks to the invention, they can be successfully used for detecting damage to the power cable at the site of use.

The subject of the invention has been presented in the examples of embodiments and the drawing, in which the individual figures show:

Fig. 1 - cross-section of the power cable core,

Fig. 2 - cross-section of the power cable core with a layered system,

Fig. 3 - cross-section of a power cable with a core,

Fig. 4 - cross-section of a power cable with a core with a layered system,

PL 236 650 Β1

Fig. 5 - arrangement of devices in the technological line,

Fig. 6 - arrangement of devices in the technological line.

Example I

The power cable has a composite core 1 (Fig. 1 and Fig. 2) made of longitudinally arranged (example II and Fig. 5) or intertwined (example III and Fig. 6) reinforcing fibers 1a of at least one type of material, such as fiber carbon and / or nanofiber carbon and / or glass fiber and / or basalt fiber and / or aramid fiber and / or polyethylene fiber, constituting from 50% to 90% of the volume of the finished core 1, covered with a thermosetting epoxy resin 1b with fracture toughness of at least 0 , 90 MPa * ml / 2, tensile strength of at least 60 MPa and viscosity below 1000 mPa * s at 20 ° C intended for pultrusion processes, constituting from 10% to 50% of the volume of the finished core 1, filled throughout the entire volume with ferromagnetic 1c powder e.g. from iron, nickel, cobalt or their alloys or with magnetic powder 1c e.g. neodymium powder.

Due to the bending resistance of the core 1, in cores 1 that are not monomaterial (Fig. 2), it is particularly advantageous to use an arrangement of low-modulus fibers 1a (with a modulus of elasticity below 100 GPa) in the outer layer I of core elasticity greater than 100 GPa) in the inner layer II of core 1. Exemplary, most advantageous material compositions of the reinforcing fibers along with their volume percentages in core 1 are listed in Table 1.

Table 1

Internal layer II of the core 1 Core layer I outer 1 carbon fibers 40% E type glass fibers 60% carbon fibers 40% polyethylene fibers 60% 30% carbon nanofibers glass fibers type E 70% aramid fibers 50% glass fibers type E 50% basalt fibers 100% S type glass fibers 100%

1c powder is ferromagnetic or magnetic preferably with a grain size of 0.063 mm. The amount of powder 1c is selected so that it is in the volume of at least 1 cm ³ to 10 cm ³ , and preferably 7 cm ³ per running meter of the finished core 1. Higher contents of powder 1c result in greater accuracy of the magnetic method of detecting damage to the core 1.

Core 1 is characterized by the following technical parameters:

- mechanical properties: tensile strength of at least 1200 MPa, modulus of elasticity in the range of 48 GPa to 200 GPa,

- operating temperature from 90 ° C to 230 ° C,

- thermal expansion coefficient from 0 χ 10 ^-6 m / m / ° C to 6 χ 10 ^-6 m / m / ° C.

The final properties of the obtained composite core 1 depend on the type of reinforcing fibers 1a used, their proportions in the case of using more than one type of fibers 1a, the type of weaving used or the way the fibers 1a are arranged in parallel. The arrangement of the fibers 1a in the composite can most simply be controlled by using suitable bushing and shaping plates during manufacture.

Aluminum conductors are used for the overhead transmission lines of the invention. The final diameter of the core 1 depends on the design of the conductor to which it will be applied and is selected so as to provide sufficient load bearing strength for the outer layers of aluminum alloys or pure annealed aluminum.

The finished core 1 according to the invention is surrounded by known methods with one or more layers of wires made of aluminum alloys or pure annealed aluminum.

The composite core 1 according to example 1 may for example be surrounded by two layers of trapezoidal wires 2 (Fig. 3) or four layers of round wires 3 (Fig. 4). More favorable

Trapezoidal wires 2 are used because of the better filling of the cross-section of such a conductor and thus better transmission properties.

In Examples 2 and 3, methods for producing the composite core 1 for power cables according to the invention are described depending on the orientation of the reinforcement fibers 1a.

P r z x l a d II

Example 2 describes the manufacturing method of the core 1 of Example 1 with the reinforcement fibers 1a arranged longitudinally.

At the beginning of the technological line (Fig. 5) there is a device 4 with a system of spools equipped with tension brakes, from which the reinforcing fibers 1a used for a given composite are unwound in the form of carbon fibers and / or carbon nanofibers and / or glass fibers and / or basalt fibers and / or aramid fibers and / or polyethylene fibers.

The introduction of tension facilitates the parallel guiding of the reinforcing fibers 1a and their efficient pulling through the forming plates.

The reinforcing fibers 1a then pass through a guide 5 which guides them into parallel paths of travel and prevents tangling.

The reinforcement fibers 1a then pass through a preheating oven 6 with air circulation at 70 ° C, which serves to remove any moisture from the reinforcement fibers 1a.

The next stage is the passage of the reinforcing fibers 1a through the supersaturation tank 7, in which there is a thermosetting epoxy resin 1b Sicomin SR 1331 with the addition of SH 166 hardener, SX AC1 MI bonding accelerator, and a filler in the form of 1c ferromagnetic Fe-Si 15 powder, granulation 0.063 mm or magnetic powder 1c, which allow to shorten the gel time of resin 1b (initial hardening and obtaining stickiness) to a few minutes. The material is prepared in the vacuum resin mixer 1b and supplied to the supersaturation tank 7 as it is used.

The resin-encased reinforcement fibers exiting the reservoir pass through a scraper system 8 to remove excess resin from them, which can be returned directly to the supersaturation reservoir 7 for reuse.

Then, the reinforcing fibers 1a are directed to the pre-hardening furnace 9 at 80 ° C in order to bring the resin 1b into a sticky state that allows the formation of the final shape of the product - core 1 to begin. In the furnace 9 there are plates with through holes that lay the resin webs 1b with concentrically reinforcing fibers 1a and gradually compact the fibers 1a to the assumed diameter of the core 1, creating a composite. The formed core 1 is introduced into the main curing oven 10 at a temperature ranging from 140 ° C to 210 ° C where the resin 1b crosslinks and the core 1 hardens.

The last step in the basic core 1 manufacturing process is cooling in an oven 11 at a temperature of 20 ° C to 40 ° C.

Additionally, the core 1 may be subjected to a reheating process at a temperature of 20 ° C to 160 ° C and re-cooling at a temperature of 40 ° C to 80 ° C in order to improve the mechanical properties of the resin 1b.

The finished composite core 1 is directed to a winding wheel 12 or directly to a known wire-wrapping process in case of integration with a power cable production line.

P r x l a d III

Example III describes the manufacturing process of the core 1 described in Example I with intertwined reinforcing fibers 1a.

At the beginning of the technological line (Fig. 6) there is a device 13 with a spool equipped with tension brakes, from which the fiber weave 1a used for a given composite is unwound, consisting of carbon fibers and / or carbon nanofibers and / or glass fibers and / or fibers basalt and / or aramid fibers and / or polyethylene fibers.

The introduction of a tension facilitates efficient drawing of the fiber weave 1a through the forming plates.

The weave of the reinforcing fibers 1a then passes through the guide 14, which guides it into the appropriate path and prevents tangling.

The strand of the reinforcement fibers 1a then passes through a preheating oven 15 with air circulation at 70 ° C, which serves to remove any moisture from the reinforcement fibers 1a.

PL 236 650 B1

The next stage is the passage of the weave of reinforcing fibers 1a through the supersaturation tank 16, in which there is a thermosetting epoxy resin 1b Sicomin SR 1331 with the addition of SH 166 hardener, SX AC1MI bonding accelerator, and a filler in the form of 1c ferromagnetic Fe-Si 15 powder, granulation 0.063 mm or magnetic powder 1c, which allow to shorten the gel time of the resin 1b (initial hardening and becoming sticky) to a few minutes. The material is prepared in the vacuum resin mixer 1b and supplied to the supersaturation tank 16 as it is used.

The resin-encased reinforcement strand exits the reservoir and passes through a scraper system 17 that draws excess resin from the reinforcement strand, which can be returned immediately to the supersaturation reservoir 7 for reuse.

Then it is directed to the pre-hardening furnace 18 at a temperature of 80 ° C in order to bring the resin 1c into a sticky state that allows it to start forming the final shape of the product - core 1. In the furnace 18 there are plates with through holes that compress the supersaturated weave, compress it and they gradually thicken the weave to the assumed diameter of the core 1, creating a composite. The formed core 1 is introduced into the main curing oven 19 at a temperature ranging from 140 ° C to 210 ° C where the resin 1b crosslinks and the core 1 hardens.

The final step in the basic core 1 manufacturing process is cooling in an oven 20 at a temperature of 20 ° C to 40 ° C.

Additionally, the core 1 may undergo a reheating process at a temperature of 60 ° C to 160 ° C and re-cooling at a temperature of 40 ° C to 80 ° C in order to improve the mechanical properties of the resin 1b.

The finished composite core 1 is directed to a winding wheel 21 or directly to a known wire wrapping process in case of integration with a power cable production line.

Claims (7)

Patent claims 1. Power cable with a composite core containing armor fibers of at least one type of material with a tensile strength of at least 1200 MPa, permanently bonded to a thermally hardened epoxy resin, in which the core is surrounded by at least one layer of wires, characterized in that the fibers (1a) reinforcing materials constitute from 50% to 90% of the volume of the finished core (1), epoxy resin (1b) is from 10% to 50% of the volume of the finished core (1) and it is filled with ferromagnetic powder (1c) or powder (1c) throughout the entire volume magnetic, in the amount of 1 cm ³ to 10 cm ³ , preferably 7 cm ³ in each meter of the finished core (1), and the wires surrounding the core (1) are aluminum and / or annealed aluminum wires, preferably with a circular cross section and most preferably trapezoidal in section. 2. Cable acc. claim The method of claim 1, characterized in that the reinforcing fibers (1a) in the core (1) are carbon fibers and / or carbon nanofibers and / or glass fibers and / or basalt fibers and / or aramid fibers and / or polyethylene fibers. 3. Cable acc. claim The core of claim 1 or 2, characterized in that the core has an outer layer (I) containing reinforcing fibers (1a) with a modulus of elasticity below 100 GPa and an inner layer (II) containing fibers with a modulus of elasticity above 100 GPa, the outer layer (I) and the inner layer (II) is arranged coaxially and permanently connected to each other. 4. Cable acc. To claim The method of claim 1, characterized in that the ferromagnetic powder (1c) in the core (1) is iron powder, nickel, cobalt or their alloys, or other metal with ferromagnetic properties. 5. Cable acc. claim The method of claim 1 or 4, characterized in that the ferromagnetic powder (1c) in the core (1) is a powder with a granulation of 0.063 mm. 6. Cable acc. To claim The method of claim 1, characterized in that the magnetic powder (1c) in the core (1) is neodymium or other metal powder with permanent magnet properties. 7. Cable acc. claim 6. A method according to claim 1 or 6, characterized in that the magnetic powder (1c) in the core (1) is a powder with a granulation of 0.063 mm.