EP2148336A1 - Power cable specifically designed for high-speed data transmission - Google Patents

Abstract

The cable (1) has an electromagnetic shield (50), and an exterior sheath (10) defining a cavity in which electricity conducting wires (20, 30, 40) such as phase wire, neutral wire and ground wire, are arranged. The wires are surrounded by corresponding electrically insulating sheaths (21, 31, 41), and maintained in rigorous geometrical position, within the exterior sheath. Each electrically insulating sheath is made of material having a dielectric dissipation factor that is less than or equal to 5.10power-2 over a range of frequencies comprised between 1megaHertz and 100megaHertz.

Description

Field of the invention

The invention relates to a cable or wire, intended to simultaneously carry an electric current, for powering devices consuming several hundred Watts, and data at a rate of more than 1Mbits / s.
The invention may in particular find application for home energy networks or tertiary and industrial energy networks of a housing complex.

Prior art

Current electrical networks are either individual insulated electrical son that are pulled into ducts or chutes and posed in an unorganized way in this sheath or chute, or electrical cables consisting of individual son assembled together and sheathed.

• leurs capacités à transmettre l'énergie électrique ;
• leurs propriétés de protection électrique des biens et des personnes ;
• leur comportement à la flamme et à l'incendie.

These energy wires or cables (electrical) meet a set of standards relating to:

• their ability to transmit electrical energy;
• their electrical protection properties of goods and persons;
• their behavior in the flame and fire.

For several years, we have been looking for solutions so that energy wires or cables can also transmit information.

• la transmission d'informations à bas ou moyens débits sur ces fils ou câbles d'énergie permettant d'assurer un pilotage d'appareils dans l'habitat, comme, par exemple, la télécommande d'appareils domestiques par réseau d'énergie ; ou encore
• la transmission de données informatiques pour relier des ordinateurs entres eux ou assurer la transmission de services aussi divers que les sons ou les images.

We thus find as application:

• the transmission of information at low or medium rates on these energy wires or cables making it possible to control appliances in the home, such as, for example, the remote control of household appliances by energy network; or
• the transmission of computer data to connect computers between them or to provide the transmission of services as diverse as sounds or images.

For this, it has been implemented the technique called "Current Carrier Online" (CPL).

The CPL technique is based on the frequency multiplexing of carriers carrying the data. These carriers are typically spread over a frequency spectrum from 2 to 30 MHz ensuring data transmissions at a rate of the order of 200 Mbps. It is also expected that products under development can reach a data transmission rate of the order of 1 Gbit / s, based on optimized encoding methods, and using a carrier frequency spectrum ranging from 2 to 100MHz.

Solutions are therefore currently used based on information multiplexing techniques conveyed in cables or wires whose structure has been adapted only and designed for the transport of electrical energy.

Indeed, in the case of energy son, due to an anarchic positioning son in the chute, the characteristic impedance is extremely variable and unpredictable. In addition, the attenuation of these wires on the information transmission power tends to strongly increase beyond a frequency of 40 MHz (This behavior is illustrated by the curve 3 of the figure 2 ).

In the case of power cables, due to a more rigorous positioning of the conductive wires, the characteristic impedance is predictable and relatively smooth, but the linear attenuation of these cables is very high (see curve 2 of FIG. figure 2 ).

An example of such an energy cable is illustrated in the patent FR 2,848,718 .

Moreover, these energy wires or cables are not designed to protect themselves from surrounding electromagnetic disturbances which has a detrimental influence on the signal-to-noise ratio and therefore on the quality of the data transmission. Moreover, these energy wires or cables are not designed to protect the environment from the electromagnetic disturbances they generate, and these disturbances increase as soon as they are used as a data transmission medium.

Therefore, there are no energy wires or cables designed to make the most of current or future PLC solutions in terms of transmission rate, signal attenuation, and also electromagnetic protection. compared to the environment.

Summary of the invention

An object of the invention is therefore to provide a power transmission wire or cable, whose data transmission characteristics are improved.

An object of the invention is to provide a power transmission wire or cable, offering both a relatively constant characteristic impedance over a wide frequency range and a relatively low power attenuation of the information signal, on this same frequency range.

Another object of the invention is to propose a power transmission wire or cable, having the technical characteristics mentioned above, as well as an improvement of the electromagnetic protection with respect to the environment, namely a reduction of sensitivity to surrounding electromagnetic disturbances, and a decrease in electromagnetic disturbances generated on the environment.

At least one of these objectives is achieved by means of a cable comprising an outer sheath defining a cavity in which one or more electrically conductive wires are arranged, the or each conductive wire being surrounded by an electrically insulating sheath. , said cable being further intended to simultaneously convey an electric current for powering devices consuming several hundred Watts and data at a rate of more than 1Mbits / s, characterized in that the or each conductive wire, maintained in a rigorous geometric position within the outer sheath, comprises an electrically insulating sheath of a material having a dielectric dissipation factor of less than or equal to 5.10 ^-2 over a frequency range f between 1 MHz and 100 MHz.

• la gaine isolante est faite en un matériau présentant une permittivité diélectrique ε_r quasi-constante sur la gamme de fréquences allant de 1MHz à 100MHz, c'est-à-dire présentant une variation maximum de 10%, et préférentiellement de 5%, de sa valeur nominale mesurée à 1MHz ;
• la gaine isolante est faite en un matériau présentant une permittivité diélectrique inférieure à 3,2 sur la gamme de fréquences allant de 1MHz à 100MHz ;
• la gaine isolante électriquement est faite en polyéthylène chargé ou non, ou encore en polypropylène chargé ou non, le polyéthylène ou le polypropylène pouvant être réticulé ou non ;
• la gaine isolante électriquement est faite en polysiloxane réticulé ou non ou en polyéthylène téréphtalate réticulé ou non ;
• les fils conducteurs sont maintenus avec un ruban entourant lesdits fils conducteurs, par exemple en polyester ;
• le ou les fils conducteurs sont maintenus en position rigoureuse les uns par rapport aux autres à l'aide d'un matériau de bourrage ;
• le ou les fils conducteurs sont maintenus en position rigoureuse les uns par rapport aux autres à l'aide d'une gaine en matériau polymère ;
• les fils conducteurs sont torsadés ensemble ;
• le pas de torsadage est compris entre 100mm et 300mm, de préférence de l'ordre de 200mm ;
• il est prévu un ou plusieurs écran(s) électromagnétique(s), le ou chaque écran est disposé de manière géométriquement rigoureuse au sein du câble, à savoir à distance constante des autres éléments électriques constituant le câble ;
• le ou l'un au moins des écran(s) électromagnétique(s) comprend un ruban constitué d'au moins une couche d'aluminium et d'une couche de polyester ;
• le ou l'un au moins des écrans est disposé sur la périphérie intérieure de la cavité formée par la gaine extérieure dudit câble ;
• le câble prévoit, entre la périphérie intérieure de la cavité formée par la gaine extérieure dudit câble et le ou l'un des écran(s), une nappe de continuité en un matériau conducteur de l'électricité, par exemple en cuivre étamé, en contact électrique avec une face métallique de l'écran et permettant un raccordement à la terre aux extrémités du câble installé.

The cable according to the invention may also comprise at least one of the following technical characteristics, taken in itself, or in combination:

• the insulating sheath is made of a material having a quasi-constant dielectric permittivity ε _r over the frequency range from 1 MHz to 100 MHz, that is to say having a maximum variation of 10%, and preferably 5%, of its nominal value measured at 1 MHz;
• the insulating sheath is made of a material having a dielectric permittivity of less than 3.2 over the frequency range from 1MHz to 100MHz;
• the electrically insulating sheath is made of filled polyethylene or not, or polypropylene loaded or not, the polyethylene or polypropylene may be crosslinked or not;
• the electrically insulating sheath is made of cross-linked or non-crosslinked polysiloxane or crosslinked polyethylene terephthalate or not;
• the conductive son are held with a ribbon surrounding said conductive son, for example polyester;
• the one or more conducting wires are held in a rigorous position relative to one another by means of a stuffing material;
• the conductor son or son are maintained in a rigorous position relative to each other by means of a sheath made of polymeric material;
• the conductive wires are twisted together;
• the pitch of twisting is between 100mm and 300mm, preferably of the order of 200mm;
• one or more electromagnetic screen (s) is provided, the or each screen is arranged in a geometrically rigorous manner within the cable, namely at a constant distance from the other electrical elements constituting the cable;
• the at least one electromagnetic screen (s) comprises a ribbon consisting of at least one layer of aluminum and a layer of polyester;
• the at least one screen is disposed on the inner periphery of the cavity formed by the outer sheath of said cable;
• the cable provides, between the inner periphery of the cavity formed by the outer sheath of said cable and the or one of the screen (s), a continuity ply made of an electrically conductive material, for example tinned copper, in electrical contact with a metal face of the screen and allowing a ground connection to the ends of the installed cable.

Other features, objects and advantages of the present invention will appear on reading the detailed description which follows.

Brief description of the drawings

• the figure 1-a represents a sectional diagram of a cable according to the invention;
• the figure 1-b represents a sectional diagram of another embodiment of a cable according to the invention
• the figure 2 represents test results providing the attenuation of a signal transmitting data on several types of power cable for the transmission of electricity, as a function of the frequency of said signal.

Detailed description of the invention

The figure 1-a illustrates a cable 1 according to the invention for simultaneously carrying an electric current to power devices consuming several hundred Watts and data at a rate of over 1Mbits / s.

The cable 1 comprises an outer sheath 10 defining a cavity in which one or more conductive wires are arranged.

In the example shown on the figure 1-a three electrically conductive yarns 20, 30, 40 of said phase, neutral and earth respectively are shown. The cable thus illustrated also comprises one or more electromagnetic screens 50, but a cable according to the invention could possibly comprise no electromagnetic screen of this type.

On the figure 1-a , the conductive son 20, 30, 40 and the electromagnetic screen (s) are maintained in a strict geometric position within the outer sheath 10 of the cable.

By way of non-limiting example, it should be understood that the or each conductive wire, and the or each screen is disposed at a constant distance from the other electrical elements constituting the cable.

More particularly, when several son drivers are provided, it should also be understood that they can be arranged parallel (at a constant distance from one another) relative to each other over their entire length.

Alternatively, it can be expected that the (three in the example shown on the figure 1-a ) Conductors are tight or twisted together.

To maintain several son son 20, 30, 40 in rigorous geometric position relative to each other (they are parallel or twisted together), we can provide a ribbon 60 enveloping them, for example made of polyester. It is also possible, additionally or alternatively, to use a polymer material 801 deposited by extrusion (so-called stuffing technique of plugging the holes to make the section of the cylindrical cable) to hold the wires inside the cable in a geometric position. predetermined.

In the case where the conductive son 20, 30, 40 are twisted together, the twist pitch may be between 100mm and 300mm, preferably of the order of 200mm. Such a step, in particular when it is of the order of 200 mm, makes it possible to give the cable a certain flexibility, thus improving its implementation and facilitating its coiling on the drum.

The figure 1-b represents an alternative embodiment of the cable according to the invention.

In this example, in the cable 2, the conductors 20, 30, 40 are maintained in a rigorous geometric position thanks to a sheath 802 of polymer material, and possibly, additionally, a ribbon 60, for example polyester; the other technical characteristics of the cable remaining similar.

In the case of Figures 1-a or 1-b the three conductive wires 20, 30, 40 are moreover electrically insulated from each other because each conductor wire is surrounded by an electrically insulating sheath 21, 31, 41.

By way of nonlimiting examples, the electrically insulating sheath 21, 31, 41 may be made of polyethylene (high density or low density), polypropylene, and more especially for applications requiring compliance with fire standards, polyethylene or filled polypropylene. (more generally called "zero halogen"); or alternatively polysiloxane, or polyethylene terephthalate; or all the polymeric materials mentioned above, crosslinked to have a better thermal and mechanical resistance.

However, it has been found that such a cable makes it possible to obtain extremely low attenuation levels, and almost constant over a very wide frequency range, typically between 1 MHz and 100 MHz.

Such an effect can in particular be visualized on the curve 4 of the figure 2 , for which the sheath is made of polyethylene.

On this curve 4, the attenuation level is indeed very low, whatever the frequency (eg less than or of the order of 10 dB over a distance of 100m up to 70 MHz, and less than 20 dB on a distance of 100m at a frequency of 100MHz).

This is quite surprising insofar as the current energy cables having a rigorous geometrical arrangement of the conducting wires are known (as recalled in the "prior art" part of the present application) as cables having a very high attenuation, which, moreover, only increases with the increase of the frequency of the transmitted signal.

In particular, we can refer to curve 2 of the figure 2 which compares a cable of the prior art, where the attenuation is already of the order of 20 dB over 100m for a frequency of 20MHz, and reaches about 50 dB over a distance of 100m at a frequency of 100MHz.

In order to better characterize the cables likely to meet the requirements for improving existing cables, the Applicant has tested many cables, and was able to note that the cables having a controlled geometric arrangement, rigorous or electrically conductive son and the possible screens or screens, combined with the fact that the or each insulating sheath 21, 31, 41 of the wire conductor has a dielectric loss angle δ adapted, improved transmissions of PLC signals.

More specifically, the insulating materials are characterized in particular by the dielectric dissipation factor (often noted tg (δ) - tangent of the angle δ) which characterizes the electrical charge losses because the material is not a perfect dielectric.

It has thus been possible to show that the cables developed in the context of the invention are characterized by a dielectric dissipation factor tg (δ) less than or equal to 5.10 ^-2 over a frequency range f between 1 MHz and 100 MHz.

The cable according to the invention also has other relatively interesting features.

It is known that the characteristic impedance Zc of the cable can be written in the form: $$Z_{\mathrm{VS}}\mathrm{\square }\frac{K}{{\mathit{\square }}_r{V}_r}\ln \left(\frac{D}{d}\right)$$

• K est une constante ;
• V_r est la vitesse relative du signal transmis dans le fil conducteur par rapport à la célérité de la lumière dans le vide ;
• d est le diamètre du fil conducteur ;
• D est la distance séparant le centre de ces fils conducteurs ;
• ε _r est la permittivité diélectrique de la gaine isolante entourant le fil conducteur.

Or

• K is a constant;
• V _r is the relative speed of the signal transmitted in the conductor wire with respect to the speed of light in the vacuum;
• d is the diameter of the conductive wire;
• D is the distance separating the center of these conductive wires;
• ε _r is the dielectric permittivity of the insulating sheath surrounding the conductor wire.

It is more precisely understood by this relation (1) that a geometrically rigorous construction of the wires assembled in the cable stabilizes the characteristic impedance (the distance D is controlled and relatively constant).

So there is the difference between for example a cable with three copper conductors of 2.5mm ² pulled in chute (D varies along the chute), and a cable with three 2.5mm copper conductor wires ² rigorously assembled (D constant).

However, as can be seen through relation (1), the characteristic impedance Z _C also depends on the permittivity dielectric insulation 21, 31, 41 surrounding each lead wire 20, 30, 40.

Conventionally, the conductive wires (whether they are arranged in a trough or assembled in a geometrically rigorous manner, for example by a tight fitting) are surrounded by an insulating sheath made of polyvinyl chloride (PVC), chosen for its ability to meet electrical safety standards.

However, it has been noted that PVC has a dielectric permittivity which varies very significantly as a function of frequency, which is detrimental to the transmission of data, the characteristic impedance Z _c then being continuously variable with the frequency.

However, the materials (non-limiting polyethylene loaded or not, polypropylene loaded or not, polysiloxane, polyethylene terephthalate, these polymers being crosslinked or not) used for the insulating sheath 21, 31, 41 or the conductive son of the The electricity of the cable according to the invention also has a quasi-constant electrical permittivity over a wide range of frequencies, ranging from 1 MHz to 100 MHz.

Again, to better characterize the cables having this characteristic, the Applicant has found that it was necessary to understand by quasi-constant that the permittivity varies at most by ± 10%, preferably ± 5%, around its nominal value. measured at 1 MHz and this over the entire frequency band that is sought to be used for PLC applications (namely from 1MHz to 100MHz).

Thus, having a cable with a rigorous geometric construction of the conductive wires on the one hand and an insulating sheath of the conductive wire or wires in a specific material on the other hand makes it possible to further improve the stabilization of the impedance feature over existing cables, and allows better control of the quality of data transmission in a cabling using the cables according to the invention.

An improvement in the quality of the communication makes it possible to lower the constraints imposed on the CPL couplers arranged at the ends of the cable and thus make the PLC data transmission system more efficient while simplifying and reducing the costs of the couplers.

Preferably, but not exclusively, the insulating sheath 21, 31, 41 will also be made of a material having a dielectric permittivity less than or equal to 3 over the frequency range from 1 MHz to 100 MHz, which is particularly the case with the materials presented in a non-limiting manner for the sheath (filled or unloaded polyethylene, filled polypropylene or not, polysiloxane, polyethylene terephthalate).

This advantageously makes it possible to prevent any influence of the dielectric permittivity on the attenuation level for the low frequencies, namely of the order of 1 MHz or less than a few MHz.

To reduce the sensitivity to external electromagnetic disturbances, but also to reduce the electromagnetic radiation generated by the cable on its environment, one or more electromagnetic screens may be provided, for example disposed on the inner periphery of the cavity formed by the outer sheath of said cable.

The screen 50, or if there are several, at least one of the electromagnetic screens (s) is for example made by a complex ribbon combining an aluminum layer and a polyester layer.

In the case of data transmissions, in particular by PLC, the maximum permissible throughput of the network (ie the maximum power that can be injected into the network) is limited for pollution (radiation) issues of the network. environment. Indeed, the higher the injected power, the more the cable radiates.

Thus, the less the cabling system radiates, especially because of the use of one or more screen (s) 50 in the cable according to the invention, the higher the power potentially injectable by the transmitters, the higher the transmittable rate is high, and better is the data communication.

In this way, the invention also has the advantage of meeting the standards in force, particularly with regard to Decree 2006-1278 of 18 October 2006 (France) on electromagnetic compatibility, which states the responsibility of the installer on damage related to electromagnetic fields.

The presence of one or more screens also allows the simple realization of functional equipotential bonds (used to improve data transmission and reduce EMC pollution). These embodiments are associated with energy cabling systems in accordance with the recommendations of standardizations NFC 15 100 chapter 545 "provisions for earthing and functional equipotential bonding" and of the guide UTE C 15 900 chapter 6.9.

The screened cable of the invention also has the advantage of improving the compatibility between the LC and VDSL2 technologies, technologies which, using the same frequency spectrum and the same process of data multiplexing are prone to cross-disturbance when they use supports placed in parallel.

Moreover, the presence of one or more screens 50 contributes to improving other characteristics such as fire resistance and the non-release of halogenated substances from the wires or cables in case of fire.

Finally, it is also possible to provide, between the inner periphery of the cavity formed by the outer sheath of said cable and the one or one of the screen (s), a layer 70 of continuity in an electrically conductive material, for example made of tinned copper, in electrical contact with the metal face of the complex ribbon and allowing a connection of this screen to the ground at both ends of the cable.

Claims (15)

Cable (1) comprising an outer sheath (10) defining a cavity in which are arranged one or more conductive wires (20, 30, 40) of electricity, the or each conductive wire being surrounded by an electrically insulating sheath (21 , 31, 41), said cable being further intended to simultaneously convey an electric current for powering devices consuming several hundred Watts and data at a rate of more than 1Mbits / s, characterized in that , the or each wire conductor, maintained in a strict geometrical position within the outer sheath (10), comprises an electrically insulating sheath made of a material having a dielectric dissipation factor less than or equal to 5.10 ^-2 over a frequency range f between 1MHz and 100MHz . Cable according to claim 1, wherein the insulating sheath (21, 31, 41) is made of a material having a quasi-constant dielectric permittivity ε _r over the frequency range from 1 MHz to 100 MHz, that is to say with a maximum variation of 10%, and preferably 5%, of its nominal value measured at 1 MHz. Cable according to one of the preceding claims, wherein the insulating sheath (21, 31, 41) is made of a material having a dielectric permittivity of less than 3.2 over the frequency range of 1MHz to 100MHz. Cable according to one of the preceding claims, wherein the electrically insulating sheath (21, 31, 41) is made of filled polyethylene or not, or polypropylene loaded or not, the polyethylene or polypropylene may be crosslinked or not. Cable according to the preceding claims, wherein the electrically insulating sheath (21, 31, 41) is made of crosslinked polysiloxane or not, or crosslinked polyethylene terephthalate or not. Cable according to the preceding claims, wherein the conductive son are held with a ribbon (60) surrounding said conductive son, for example polyester. Cable according to one of the preceding claims, wherein the one or more conducting wires are held in a rigorous position relative to each other by means of a stuffing material (801). Cable according to one of claims 1 to 6, wherein the or the conductive son are held in a rigorous position relative to each other with a sheath (802) of polymeric material. Cable according to one of the preceding claims, wherein the conductive son are twisted together. Cable according to the preceding claim, wherein the twist pitch is between 100mm and 300mm, preferably of the order of 200mm. Cable according to one of the preceding claims, wherein there is provided one or more screens (50) electromagnetic (s), the or each screen is disposed geometrically rigorous within the cable, namely at a constant distance from other electrical elements constituting the cable. Cable according to the preceding claim, wherein the at least one electromagnetic screen (s) comprises a ribbon consisting of at least one layer of aluminum and a polyester layer. Cable according to one of claims 11 or 12, wherein the or at least one of the screens (50) is disposed on the inner periphery of the cavity formed by the outer sheath (10) of said cable. Cable according to one of the preceding claims, wherein there is provided, between the inner periphery of the cavity formed by the outer sheath (10) of said cable and the or one of the screen (s), a layer (70) of continuity in an electrically conductive material, for example tinned copper, in electrical contact with a metal face of the screen and allowing connection to the earth at the ends of the installed cable. Use of a cable according to one of the preceding claims, for the supply of domestic, tertiary or industrial electrical energy of a building complex.

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