A conductor assembly and a cable assembly

Abstract

The cable 100 comprises at least one electrical conductor 110-1, 110-2, a ground conductor 150, at least one inner sheath 120 surrounding a respective one of the at least one electrical conductors, an

Description

Background

[001] Electrical cables, which comprise one or more conductors, can be used to transmit data and / or power from one point to another. Ideally, this transmission occurs without loss or distortion. Field

[002] The present disclosure relates generally to a conductor and conductor sheath assembly for use, in particular, in a cable assembly. Summary

[003] Aspects of the present disclosure are defined in the accompanying independent claims . Overview of disclosure

[004] A conductor assembly is disclosed.

[005] The conductor assembly comprises: at least one electrical conductor; at least one inner sheath, each surrounding a respective one of the at least one electrical conductors; and an outer sheath surrounding the at least one inner sheath.

[006] Optionally, the conductor assembly comprises a ground conductor (or 'electrical ground conductor').

[007] Optionally, the ground conductor is in contact with the outer sheath.

[008] Optionally, the at least one inner sheath is formed of an electrically dissipative material having at least one of: an electrical volume resistivity of more than 100,000 Ohm-cm; an electrical volume resistivity of more than 200,000 Ohm-cm; an electrical volume resistivity of less than 50,000,000,000 Ohm-cm; an electrical volume resistivity of less than 100,000,000,000 Ohm-cm.

[009] Optionally, the outer sheath is formed of an electrically dissipative material having at least one of: an electrical volume resistivity of more than 100,000 Ohm-cm; an electrical volume resistivity of less than 100,000,000,000 Ohm-cm; or an electrical volume resistivity of less than 50% of the electrical volume resistivity of each of the at least one inner sheaths (in other words, an electrical volume resistivity of less than 50% of the electrical volume resistivity of the one of the at least one inner sheaths having the lowest electrical volume resistivity); or an electrical volume resistivity of more than 200% of the electrical volume resistivity of each of the at least one inner sheaths (in other words, an electrical volume resistivity of more than 200% of the electrical volume resistivity of the one of the at least one inner sheaths having the highest electrical volume resistivity).

[010] Optionally, the combination of the electrical volume resistivity of the at least one inner sheaths 120 and of the outer sheath 130 may be one of: At least one inner sheaths 120 Outer sheath 130 more than 200,000 Ohm-cm and less than 100,000,000,000 Ohm-cm more than 100,000 Ohm-cm and less than 50% of that of each of the at least one inner sheaths more than 100,000 Ohm-cm and less than 50,000,000,000 Ohm-cm more than 200% of that of each of the at least one inner sheaths and less than 100,000,000,000 Ohm-cm [Oil] Optionally, the ground conductor is disposed between the at least one inner sheaths and the outer sheath.

[012] Optionally, the outer sheath is in electrical contact with the ground conductor at least every 20 cm along a length of the outer sheath.

[013] Optionally, the ground conductor is embedded in the outer sheath.

[014] Optionally, the at least one inner sheaths are formed of a plurality of layers each formed from an electrically dissipative material having an electrical volume resistivity as given above, e.g., an electrical volume resistivity of more than 200,000 Ohm-cm and less than 100,000,000,000 Ohm-cm; or an electrical volume resistivity of more than 100,000 Ohm-cm and less than 50,000,000,000 Ohm-cm.

[015] Optionally, the outer sheath is formed of a plurality of layers each formed from an electrically dissipative material having an electrical volume resistivity as given above, e.g.: an electrical volume resistivity of more than 100,000 Ohm-cm and less than 50% of the electrical volume resistivity of each of the at least one inner sheaths or each of the plurality of layers thereof; or an electrical volume resistivity of less than 100,000,000,000 Ohm-cm and more than 200% of the electrical volume resistivity of each of the at least one inner sheaths or each of the plurality of layers thereof.

[016] Optionally, the at least one electrical conductors are each formed of a plurality of strands.

[017] Optionally, the plurality of strands are slack within the respective one of the at least one inner sheaths.

[018] Optionally, each of the plurality of strands has a respective cross-sectional area of less than 0.1 square millimetres.

[019] Optionally, contact, within the respective one of the at least one inner sheaths, between each of the plurality of strands is longitudinally substantially evenly distributed.

[020] Optionally, a respective length of each of the plurality of strands within the respective one of the at least one inner sheaths exceeds a length of the respective one of the at least one inner sheaths by at least 5%. In other words, optionally, each of the plurality of strands has a portion that is within the corresponding inner sheath and that has a respective length, and that length is at least 1.05 times the length of the corresponding inner sheath.

[021] Optionally, a respective length of each of the plurality of strands within the respective one of the at least one inner sheaths exceeds a length of the respective one of the at least one inner sheaths by at least 10%.

[022] Optionally, a respective length of each of the plurality of strands within the respective one of the at least one inner sheaths exceeds a length of the respective one of the at least one inner sheaths by no more than 60%.

[023] Optionally, each of the plurality of strands is arranged within the respective one of the at least one inner sheaths in a serpentine manner.

[024] Optionally, at least one of the plurality of strands is formed of a plurality of entwined sub-strands.

[025] Optionally, at least an inner portion of the outer sheath is made of an electrically dissipative and mechanical vibration damping material.

[026] Optionally, at least an inner portion of the at least one inner sheaths is made of an electrically dissipative and mechanical vibration damping material.

[027] Optionally, at least an inner portion of one (or both) of the outer sheath and the at least one inner sheaths is made of an electrically dissipative and mechanical vibration damping material having at least one of: a Shore 00 hardness of less than 83; or a loss factor (or 'tan delta', or 'tan 5', or 'tan(S)', or 'flexural loss factor', or 'mechanical energy loss factor') greater than 0.2.

[028] Optionally, at least an inner portion of one (or both) of the outer sheath and the at least one inner sheaths is made of an electrically dissipative and mechanical vibration damping material having at least one of: a Shore 00 hardness of less than 70; or a loss factor (or 'tan delta', or 'tan 5', or 'tan(S)', or 'flexural loss factor', or 'mechanical energy loss factor') greater than 0.1.

[029] Optionally, at least an inner portion of one (or both) of the outer sheath and the at least one inner sheaths is made of an electrically dissipative and mechanical vibration damping material having a Shore 00 hardness of less than 50.

[030] Optionally, the electrically dissipative and mechanical vibration damping material is a polyolefin.

[031] Optionally, the electrically dissipative and mechanical vibration damping material is: polypropylene (PP), polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyisobutene, polycarbonate (PC), polyamide (nylon or PA), polybutylene terephthalate (PBT), thermoplastic polyurethane, thermoplastic elastomer (TPE), low durometer silicone rubber compounds, foamed polymers such as polyurethane compounds, or a combination thereof.

[032] Optionally, the plurality of strands are bonded to the electrically dissipative and mechanical vibration damping material.

[033] Optionally, the plurality of strands are not bonded to the electrically dissipative and mechanical vibration damping material.

[034] Optionally, at least an inner portion of the other of the outer sheath and the at least one inner sheath is made of an electrically dissipative and mechanical vibration damping material having a Shore 00 hardness of at least 83.

[035] Optionally, the at least one conductor comprises a plurality of conductors, the at least one inner sheath comprises a plurality of inner sheaths, and at least two of the plurality of inner sheaths are integrally formed with each other.

[036] A cable assembly is disclosed.

[037] The cable assembly comprises at least one of the conductor assemblies disclosed herein, or a plurality of the conductor assemblies disclosed herein.

[038] Optionally, the outer sheaths of each of the plurality of the conductor assemblies are integrally formed with each other.

[039] Optionally, the cable assembly comprises a jacket (or 'overall jacket') surrounding the at least one of the conductor assemblies .

[040] Optionally, the jacket is formed of an electrically dissipative material having at least one of: an electrical volume resistivity of more than 100,000 Ohm-cm; an electrical volume resistivity of more than twice the electrical volume resistivity of the electrically dissipative material of the outer sheath of each of the conductor assemblies (in other words, an electrical volume resistivity of more than twice the electrical volume resistivity of the outer sheath having the highest electrical volume resistivity); an electrical volume resistivity of less than 100,000,000,000 Ohm-cm.

[041] Optionally, the ground conductor is disposed between the outer sheaths of each of the at least one of the conductor assemblies and the jacket.

[042] Optionally, the at least one inner sheath is not bonded to the respective one of the at least one electrical conductors.

[043] Optionally, the at least one inner sheaths are not bonded to the outer sheath.

[044] Optionally, an outer perimeter of each of the at least one inner sheaths is in electrical contact with the ground conductor.

[045] Optionally, the outer sheath is in electrical contact with the ground conductor.

[046] Optionally, each of the at least one conductors and / or the at least one inner sheaths are formed and / or arranged to dampen vibrations of the respective one of the at least one conductors.

[047] Optionally, an average length of each of the plurality of strands within the at least one inner sheath exceeds the length of the at least one inner sheath by a total excess length factor (which is greater than 1). Optionally, in a (or preferably any) portion of the at least one inner sheath having a length of at least 30mm, an average length of each of the plurality of strands within the respective at least one inner sheath exceeds the length of the respective at least one inner sheath by a segment excess length factor (which is greater than 1). Optionally, the segment excess length factor in any of the portions of the at least one inner sheath varies between 50% and 200% or, preferably, 80% and 120%, of the total excess length factor.

[048] Optionally, each of the plurality of strands is arranged within the respective one of the at least one inner sheaths in a serpentine (or 'sinuous', or 'zigzagging', or 'meandering', or 'winding') manner.

[049] Optionally, no more than 70% of a respective length, within the respective one of the at least one inner sheaths, of each one of the plurality of strands is in contact with any others of the plurality of strands.

[050] Optionally, contact, within the at least one inner sheaths, between the one of the plurality of strands and the any others of the plurality of strands is longitudinally evenly distributed.

[051] Optionally, the electrically dissipative material of any of the outer sheath or at least one inner sheaths is formed from an electrically insulative material that is mixed, infused or otherwise compounded with an electrically conductive material.

[052] Optionally, the electrically dissipative material of any of the outer sheath or at least one inner sheaths is formed from an electrically insulative material that is mixed, infused or otherwise compounded with one or a combination of carbon, an allotrope of carbon, carbon fibre, or fibre of a carbon allotrope.

[053] Optionally, the electrically dissipative material of any of the outer sheath or at least one inner sheaths is a solid, fibrous, foam, granular or gel material, or a combination thereof.

[054] Optionally, the electrically dissipative material of any of the outer sheath or at least one inner sheaths is in the form of fibres, films, filaments, sheets, tubes, extrusions, woven, fabric, braids, or twists, or a combination thereof.

[055] Optionally, the electrically dissipative material of any of the outer sheath or at least one inner sheaths is formed of other materials to achieve other desirable properties such as, but not limited to, being low cost, corrosion free, or easier to produce, or for controlling resistivity.

[056] Optionally, the electrically dissipative material of any of the outer sheath or at least one inner sheaths is a conductive plastic that is formed by using conductor material including but not limited to one or a combination of carbon, carbon allotropes or steel that is added to plastic or polyolefin including but not necessarily limited to one or a combination of polyolefins, polypropylene (PP), polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyisobutene, polycarbonate (PC), polyamide (nylon or PA), polybutylene terephthalate (PBT), thermoplastic polyurethane (rubber), thermoplastic elastomer (TPE), low durometer silicone rubber compounds, loose fibrous materials, foamed polymers such as polyurethane compounds, or a combination thereof.

[057] Optionally, each of the at least one inner sheaths comprises an inner layer made of an electrically dissipative, mechanically damping material, and an outer layer made of a second electrically dissipative material. Optionally, the plurality of strands are bonded to the electrically dissipative, mechanically damping material.

[058] Optionally, the outer sheath is made of an electrically dissipative, mechanically damping material.

[059] Optionally, the outer sheath comprises an inner layer made of a mechanically damping material and an outer layer made of a electrically dissipative material.

[060] Optionally, the cable assembly further comprises a first electrical connector and a second electrical connector at respective ends of the cable assembly.

[061] Optionally, the at least one inner sheaths of each of the plurality of the conductor assemblies are integrally formed with each other. Brief description of the drawings

[062] Examples of the present disclosure will now be explained with reference to the accompanying drawings in which: Fig. 1 shows a key for the subsequent figures of the present disclosure. Figs. 2A and 2B show a conductor assembly according to a first implementation. Fig. 3A shows an inner sheath 120 and strands 110-1 and 110-2 in which strands 110-1 and 110-2 are in tension within the inner sheath 120. Fig. 3B shows an inner sheath 120 and strands 110-1 and 110-2 in which the strands 110-1 and 110-2 are slack within the inner sheath 120. Fig. 3C shows an inner sheath 120 and strands 110-1 and 110-2 in which the strands 110-1 and 110-2 are slack within the inner sheath 120 and are mounted within a respective bung 160A and 160B at each end of the inner sheath 120. Fig. 3D shows a side section of a conductor assembly 100 according to a first implementation, where the conductor strands 110-1 and 110-2 are slack within the inner sheath 120. Figs. 4A and 4B shows a cable assembly 200 according to a first implementation, in which the ground conductor 150 is disposed between the outer sheath 130 and the jacket 140. Figs. 5A and 5B show a cable assembly 200 according to a second implementation, in which the ground conductor 150 is embedded within the outer sheath 130, and the outer sheaths 130 of the inner sheaths 120A and 120B have a second cross-sectional shape and are integrally formed with each other. Figs. 6A and 6B show a cable assembly 200 according to a third implementation, in which the ground conductor 150 is disposed between the outer sheath 130 and the jacket 140, and the inner sheaths 120 of conductor 110A and HOB have a second cross-sectional shape and are integrally formed with each other. Figs. 7A and 7B show a cable assembly 200 according to a fourth implementation, in which the respective inner sheaths are formed of two layers where the outer layers of inner sheaths 120B and 120C are integrally formed together as inner sheath 120A, and the outer layers of inner sheaths 120E and 120F are integrally formed together as inner sheath 120D, and the outer sheaths 130 of the inner sheaths 120A and 120D are integrally formed with each other. Fig. 8 shows a cable assembly 200 according to a fifth implementation in which the orientation with which inner sheaths 120A, 120D, 120G and 120K are disposed within the outer sheath 130 are not necessarily aligned with each other.

[063] Throughout the description and the drawings, like reference numerals refer to like parts. Detailed description

[064] In overview, the present disclosure relates to a conductor assembly for use in a cable assembly. The conductor assembly comprises an electrical conductor, an inner sheath surrounding the electrical conductor, an outer sheath surrounding the inner sheath, and a ground conductor that is in contact with the outer sheath. A cable may be formed that comprises at least one of the conductor assemblies and a jacket surrounding the conductor assemblies.

[065] The following features of the conductor assembly allow accuracy of transmission of electrical signals via the conductor assembly to be enhanced: • using an electrically dissipative material (i.e., not an insulator) to form the inner sheath; • using an electrically dissipative material (i.e., not an insulator) to form the outer sheath; • using a conductor which is not bonded to the inner sheath; • forming the inner sheath from particular materials; • forming the outer sheath from particular materials; • using a conductor that is formed of multiple strands; • using a conductor that is formed of strands in which the strands are slack (i.e., not under tension) within the inner sheath, where the strands are longer than the inner sheath; • using strands which are loosely bunched, i.e., avoiding contact between each of the strands and, optionally, mounting the strands in a respective bung at each end of the inner sheath; • using fine strands, i.e., strands with low cross-sectional area; and / or • laying the strands in a cavity.

[066] The following feature of the cable assembly allows accuracy of transmission of electrical signals via the cable assembly to be enhanced: • using an electrically dissipative material (i.e., not an insulator) to form a jacket.

[067] These features each allow transmission to be enhanced when used alone, and allow transmission to be further enhanced when used in combination. Accordingly, the presence of any one of the above features at least partially counteracts the absence of any others of the above features. For example, the conductor strands need not be loosely bunched when they are disposed in an inner sheath. As another example, the strands need not be as long compared to the inner sheath (and therefore need not undulate as much) when they are disposed in an inner sheath having an inner portion formed from a damping material.

[068] As a result, any of the features of the sections titled 'Conductor assembly', 'Slack strands' , 'Loosely bunched strands' , 'Termination', 'Fine strands', 'Strands laid in a cavity', 'Bonding to the inner sheath' , 'Inner sheath', 'Outer sheath', 'Damping material' , 'Ground conductor', 'Cable assembly', 'Further implementations' , 'Performance', and 'Other examples of the disclosure' may be combined unless indicated otherwise. In particular, the features of the sections titled 'Conductor assembly' and 'Cable assembly' may be combined with any or all of the features of the sections titled 'Slack strands' , 'Loosely bunched strands' , 'Termination', 'Fine strands' , 'Strands laid in a cavity', 'Bonding to the inner sheath' , 'Inner sheath', 'Outer sheath', 'Damping material' , 'Ground conductor', 'Further implementations' , 'Performance', and 'Other examples of the disclosure'. Principles of operation

[069] At a high level, the present disclosure relates to a unique structure of an electric cable assembly that is formed to eliminate tribo-electric and static-electric charges in the material with which the cable assembly is made, and to dampen mechanical resonance vibrations occurring in the cable assembly.

[070] In electrical cables of prior art, conductor sheaths and jackets are formed using at least one layer of insulative dielectric materials.

[071] Static charge is present in electrically insulative materials and occurs by induction from close proximity to electrical fields, from vibrations in the material that generate tribo-electric charges, and from mechanical agitation during its manufacture and processing.

[072] The static charges in insulative material around a cable's signal conductor interact with the electrical field of the signal current around the conductor and affect the signal.

[073] When the material of the cable is vibrated, the static charge provides a medium that couples the mechanical vibrations in the cable to the electrical fields around the conductors. This modulates and magnifies the effect that the static charge in the insulative material has on the signal according to the resonance modes and mechanical properties of the cable.

[074] Because static charge in insulating material is polarised according to the material's electrical properties, vibrations in the cable cause asymmetrical modification to the electrical signal charges on the conductors, and so cause the cable to affect the signal it passes in a manner according to an asymmetrical transfer function.

[075] The combination and interaction of the following factors govern the transfer function that describes the effect of the cable on the signal that it passes: • The physical properties of the conductor; its structure, materials, resonance modes and physical characteristics. • The physical properties of the dielectrics, sheath and jacket materials and the resulting resonance characteristics. • The electrical resistivity and static electric dissipating properties of the materials constituting the cable.

[076] Therefore, the overall interference of a cable on electric signals carried by conductors within the cable can be reduced by: • Selecting materials and forming the constituent components of the cable to dampen the individual mechanical resonance modes of each individual component and the overall lumped resonant mode of the cable and to dissipate vibration energy in the cable. • Forming the components that constitute an electrical cable, other than the conductors, from materials that are electrically dissipative, or resistive, or static-dissipative, or semi-conductive materials and not electrically insulative.

[077] It is therefore advantageous, but by no means necessary, to both remove the presence of static and to dampen the mechanical resonance modes in the cable.

[078] The cable assembly of the present disclosure reduces the effect of vibrations acting on charges within the cable and reduces the amount of static charge occurring and stored in the cable.

[079] The generation of triboelectric charges generated by the mechanical excitation of the cable is measured according to ANSI (American National Standards Institute) / AMMI (Association for the Advancement of Medical Instrumentation) EC53:2013 (ECG trunk cable and patient leadwires) part 5.3.2 'Cable and leadwire noise'(available at https: / / webstore. ansi.org / standards / aami / ansiaamiec532013r2020?srsit id=AfmBOorsTo6IMRrhItl799swwAPgGYccOvCCs7w5qszXYH-dMXP9CL35).

[080] The dynamic mechanical analysis tests are conducted according to ASTM E756-05 (2017) testing standard ('Standard Test Method for Measuring Vibration-Damping Properties of Materials' ).

[081] This disclosure therefore describes electrical cable assembly methods that can significantly decrease the amount of charge induced onto electrical conductors in the cable assembly that is caused by mechanical disturbances acting on triboelectric and static electric charges in a cable structure.

[082] The technology of the present disclosure gives significant benefit and describes methods of elimination of insulating materials in cables with the use of electrically dissipative materials and, optionally, the inclusion of a ground conductor to provide a means to discharge and prevent accumulation of static charge in cable constituent components.

[083] The result is a significant improvement in the clarity of transmission of the signal that can be both measured and is discernible to the receiver. For example, when used in audio reproduction systems, the reproduced sound appears much clearer and more natural. As another example, square waves and other waves with abrupt signal changes retain their original form more closely and exhibit less resonance ring. Applications

[084] A number of potential applications of the technology of the present disclosure are now described. These applications are described by way of example only and are not to be taken as limiting the present disclosure.

[085] The technology of the present disclosure may be applied to any one of or any combination of but not limited to the following: signal cables, reference voltage cables, reference ground wires, mains ground conductors, cables in systems where enhanced signal resolution is desired, cables for applications such as but not limited to audio applications, sonar, ultrasound, sensitive signal transmission, radio receivers, high frequency equipment, data transmission.

[086] The technology of the present disclosure may be applied to digital data cables in order to reduce modulation of signal due to static charges in the electric fields around the conductors, and so increase stability and reduce ambiguity of data signal timing of data waveforms and so increase useable bandwidth.

[087] The technology of the present disclosure may be applied to the ground circuit wiring in power distribution systems and power cables within systems where enhanced signal resolution is desired so as to reduce the interactions between the fields around energised power conductors and ground conductors. Measurements and measurement standards

[088] In this disclosure, the term 'conductive material' is defined as a material having the electrical property of volume resistivity less than 100,000 Ohm-cm.

[089] In this disclosure, the term 'dissipative material' is defined as those having an electrical property of volume resistivity equal to or greater than 100,000 Ohm-cm but less than 100,000,000,000 Ohm-cm.

[090] In this disclosure, the term 'insulative material' is defined as those having the electrical property of volume resistivity of at least 100,000,000,000 Ohm-cm.

[091] In this disclosure, the volume resistivity of sheath materials and jacket materials are measured in accordance with the IEC (International Electrotechnical Commission) 62631-3-1 (2023) testing standard ( 'Dielectric and resistive properties of solid insulation materials- Part 3-1: Determination of resistive properties (DC methods) - Volume resistance and volume resistivity -General method', available from https: / / webstore. iec. ch / eri / publication / 62314 ) .

[092] In this disclosure, Shore hardness is measured in accordance with the ASTM (American Society for Testing and Materials) D2240-15el (2021) testing standard ('Standard Test Method for Rubber Property—Durometer Hardness', available from https: / / doi.org / 10.1520%2FD2240-15E01).

[093] In this disclosure, loss factor is measured in accordance with the ASTM E756-05 (2017) testing standard ('Standard Test Method for Measuring Vibration-Damping Properties of Materials' , available from https : / / do1.org / 10.1520 / E0756-05F17).

[094] The preferred Shore hardness, loss factor, resistance, and volume resistivity values set out herein are obtained at temperatures that may depend on the intended application. The preferred Shore hardness, loss factor, resistance, and volume resistivity values set out herein may be obtained at any (or, preferably, all) temperatures between 15 and 85 degrees Celsius (e.g., for internal equipment wiring for electric equipment), or any (or, preferably, all) temperatures between 15 and 28 degrees Celsius (e.g., for domestic audio cables). Yet more preferably, the preferred Shore hardness, loss factor, resistance, and volume resistivity values set out herein are obtained at least at a temperature of 23 degrees Celsius.

[095] The preferred loss factor values set out herein may be obtained using dynamic mechanical analysis at frequencies that may depend on the operating frequencies of the intended application. The preferred loss factor values set out herein may be obtained at any (or, preferably, all) frequencies between 20 Hz and 1 kHz; preferably, the preferred loss factor values set out herein are obtained at least at a frequency of 800 Hz. Conductor assembly

[096] A number of implementations of the conductor assembly and cable assembly of the present disclosure are illustrated in the figures.

[097] The conductor assembly 100 comprises at least one electrical conductor 110 formed of a single strand 110-1 or of multiple strands 110-1, 110-2, ..., 110-N, at least one inner sheath 120 surrounding the at least one electrical conductor 110, an outer sheath 130 surrounding the inner sheath 120, and a ground conductor 150 that is disposed outside the perimeter of the inner sheath 120 and is in contact with the outer sheath 130. The strands 110-1, 110-2, ..., 110-N may be mounted within a respective bung 160 at each end of each of the at least one inner sheath 120.

[098] Fig. 1 shows a key for the figures of the present disclosure. In particular, Fig. 1 shows an electrical conductor 110, an electrically conductive material of the first strand 110-1, an electrically conductive material of the second strand 110-2, an inner sheath material of the inner sheath 120, an outer sheath material of the outer sheath 130, a jacket material 140, a ground conductor 150 of an electrically conductive material and a bung material of the bung 160. Slack strands

[099] In order for the strands 110-1, 110-2, ..., 110-N to act independently of each other to avoid common resonance modes and entrainment and to act independently of the inner sheath 120, the strands 110-1, 110-2, ..., 110-N may be slack within the inner sheath 120. By 'slack', it is meant that the strands 110-1, 110-2, ..., 110-N are not under tension.

[100] Figs. 2A, 2B and 3D show a conductor assembly 100 according to a first implementation in which the strands 110-1, 110-2, ..., 110-N are slack within a cavity of the inner sheath 120. In particular, Figs. 2A, 2B and 3D respectively show an isometric view, a cross-sectional view and a side sectional view of the conductor assembly 100.

[101] Slackness is achieved by making the strands 110-1, 110-2, ..., 110-N longer than the inner sheath 120. In some implementations, a respective length of each of the plurality of strands 110-1, 110-2, ..., 110-N within the inner sheath 120 thus exceeds a length of the inner sheath 120 by at least 5%.

[102] The excess length of the strands 110-1, 110-2 is illustrated in Figs. 3A, 3B and 3C. Fig. 3A shows a side sectional view of an inner sheath 120 and strands 110-1 and 110-2 in which the strands 110-1 and 110-2 are in tension within the inner sheath 120. The inner sheath 120 has a length LI, and the strands 110-1 and 110-2 have a length L2, where L2 is greater than LI. Fig. 3B shows a side sectional view of the inner sheath 120 and strands 110-1 and 110-2 in which the strands 110-1 and 110-2 are now slack within the inner sheath 120. The strands 110-1 and 110-2, which still have length L2, are now contained in the inner sheath 120 of length LI. The strands 110-1 and 110-2 are thus axially compressed. Fig. 3C shows a side sectional view of an inner sheath 120 and strands 110-1 and 110-2 in which the strands 110-1 and 110-2 are slack within the inner sheath 120 and are mounted within a respective bung 160A and 160B at each end of the inner sheath 120.

[103] When the strands 110-1, 110-2, ..., 110-N are slack, each of the plurality of strands 110-1, 110-2, ..., 110-N may be arranged in a serpentine (or 'sinuous', or 'zigzagging', or 'meandering', or 'winding') manner within the inner sheath 120. Loosely bunched strands

[104] When strands 110-1, 110-2, ..., 110-N are bound together, and particularly when they are under tension, they behave like one monolithic mass with a consequently stronger resonance mode. In order to act independently of each other, and not respond as conjoined elements with an associated lumped resonance mode, the strands 110-1, 110-2, ..., 110-N may be loosely bunched. In other words, in some implementations, contact between each of the strands 110-1, 110-2, ..., 110-N is avoided, and the strands 110-1, 110-2, ..., 110-N are not closely bound or twisted together.

[105] In order to ensure that the strands 110-1, 110-2, ..., 110-N are loosely bunched along their full length, contact between each strand and any other strand(s) may be evenly, or substantially evenly, distributed along the length of the conductor 110.

[106] More specifically, in some implementations, an average length of each of the plurality of strands 110-1, 110-2, ..., 110-N within the at least one inner sheath 120 exceeds the length of the at least one inner sheath 120 by a total excess length factor (which is greater than 1, e.g., 1.3). In any portion of the inner sheath 120 having a length of at least 30mm, an average length of each of the plurality of strands 110-1, 110-2, ..., 110-N within the inner sheath 120 exceeds the length of the inner sheath 120 by a segment excess length factor (which is greater than 1, e.g., 1.2). The segment excess length factor (e.g., 1.2) in any of the portions of the inner sheath 120 varies between 50% and 200% or, preferably, 80% and 120% of the total excess length factor. Termination

[107] In order to ensure that, in handling and application, the strands maintain their loose arrangement, a respective bung 160 may be placed at each end of the inner sheath 120, and the strands may be bonded / mounted within the bung 160. Such an arrangement is illustrated in Fig. 3C where bung 160A and 160B are shown at each end of the inner sheath 120. The bung may be made of any soft bonding agent, such as a silicone compound. Fine strands

[108] As the resonant frequency of an elongated object is a function of its diameter and Young's modulus of the material from which it is formed, the electrical conductor(s) 110 may be made of fine strands 110-1, 110-2, ..., 110-N in order to ensure that the resonant frequencies of the strands 110-1, 110-2, ..., 110-N are out of the range of the frequency range of the resonant frequencies of other components comprising the cable in order to reduce vibrational entrainment of the strands by other components comprising the cable.

[109] By 'fine', it is meant that each of the plurality of strands 110-1, 110-2, ..., 110-N has a respective cross-sectional area of less than 0.1 square millimetres. Strands laid in a cavity

[110] In order to dissociate the strands from vibration in the inner sheath and cable body, the strands 110-1, 110-2, ..., 110-N may be laid in a cavity (or 'void'), within the inner sheath 120 as shown, for example, in Figs. 3B, 3C, and 3D. The greater the size of the cavity, the more room there is for the strands to spread out and thus avoid contact with each other. Bonding to the inner sheath

[111] In some implementations, the strands 110-1, 110-2, ..., 110-N are bonded to the inner sheath 120. In other implementations, the strands 110-1, 110-2, ..., 110-N are not bonded to the inner sheath 120. Inner sheath

[112] The inner sheath 120 is formed from an electrically dissipative material so that triboelectric charges generated in the material or charges that are induced in the material are dissipated and concentrations of static charge accumulating in the inner sheath 120 are prevented.

[113] The inner sheath 120 is formed of a material having an electrical volume resistivity less than 100,000,000,000 Ohm-cm because antistatic dissipative materials are generally materials with electrical volume resistivity of less than 100,000,000,000 Ohm-cm. Preferably, but not necessarily, the inner sheath 120 is formed of a material having an electrical volume resistivity less than 50,000,000,000 Ohm-cm.

[114] As the inner sheath 120 is not an insulator, the inner sheath 120 must be formed with a degree of electrical resistivity to provide an electrically resistive barrier between the conductor 110 and the external surface of the inner sheath 120. The electrical volume resistivity of the material with which the inner sheath 120 is formed may be selected to provide at least the minimum desired electrical resistance between the inner surface of the inner sheath 120 and the outer surface of the same inner sheath 120.

[115] The measurement of resistivity of a material and the surface area of the inner surface of the inner sheath 120 and the outer surface area of the outer surface of the same inner sheath 120 can be approximate, and therefore calculations for resistivity and resistance may be used to calculate the minimum desirable resistance between the conductor 110 contained within the inner sheath 120 and the outer surface of the inner sheath 120 as follows.

[116] The approximate electrical resistance, R, measured between the inner surface and the outer surface of the inner sheath 120 along the length L of the inner sheath 120 can be given by the equation R=p t / A Where: R is the resistance in Ohms, 'p' is the electrical volume resistivity of the inner sheath material in Ohm-cm (Ohm-centimetres) 't' is the thickness in centimetres (cm) of the material of the inner sheath 120 measured between its inner surface and outer surface measured across the cross-section that is perpendicular to the inner sheath's longitudinal axis, 'A' is calculated as the length L of the inner sheath 120 multiplied by the average circumference between the circumference of the inner surface Cl of the inner sheath and the outer circumference C2 of the inner sheath where circumferences Cl and C2 are measured in the cross-section perpendicular to the inner sheath's longitudinal axis. This may be expressed mathematically as: A = L x ( (Cl + C2) / 2 )

[117] The resistivity of the electrically dissipative material may be selected according to the rearrangement of the equation R=p t / A as p = (R x A ) / t (R x L x ( (Cl + C2) / 2 ) / t

[118] For example, in one implementation of the conductor assembly 100, where the length L is 300cm, the thickness t is 0.5cm and the inner circumference Cl is 0.2cm and outer circumference C2 is 0.7cm and the desired resistance R is 50,000 Ohms, then a minimum resistivity of 2,635,000 Ohm-cm may be needed.

[119] The inner sheath 120 may be formed from multiple layers of the inner sheath 120 electrically dissipative material.

[120] When there is a plurality of inner sheaths 120, two or more inner sheaths 120 may each have a second layer of material of inner sheaths 120 that may be integrally formed with each other.

[121] Where there is a plurality of conductors 110 and inner sheaths 120, the inner sheaths 120 of a least two of the plurality of conductors may be integrally formed with each other. Outer sheath

[122] The outer sheath 130 is formed from an electrically dissipative material that has an electrical volume resistivity of more than 100,000 Ohm-cm and less than 100,000,000,000 and may be either less than 50% of the electrical volume resistivity of the inner sheath 120 or more than 200% of the electrical volume resistivity of the inner sheath 120.

[123] When the outer sheath 130 is formed from a material with a significantly lower electrical volume resistivity than the electrical volume resistivity of the inner sheath 120, the outer sheath 130 diffuses voltages occurring on the outer surface of the inner sheath 120 and so diffuses static charge that occurs in the inner sheath 120 as well as tribo-electrical charges that occur in the outer sheath 130.

[124] When the outer sheath 130 is formed from a material with significantly higher electrical volume resistivity than the electrical volume resistivity of the inner sheath 120, the outer sheath 130 resists voltages that occur on the outer surface of the inner sheath 120 from transferring to the outer surface of the outer sheath 130, and diffuses tribo-electrical charges that occur in the outer sheath 130.

[125] Where the outer sheath 130 is in contact with more than one inner sheath 120 and the electrical volume resistivity of the outer sheath 130 is less than the electrical volume resistivity of the inner sheath 120, then the outer sheath 130 is formed of material that has an electrical volume resistivity that is lower than 50% of the electrical volume resistivity of the inner sheath 120 with the lowest electrical volume resistivity.

[126] Where the outer sheath 130 is in contact with more than one inner sheath 120 and the electrical volume resistivity of the outer sheath 130 is greater than the electrical volume resistivity of the inner sheath 120, then the outer sheath 130 is formed of material that has an electrical volume resistivity that is greater than 200% of the electrical volume resistivity of the inner sheath 120 with the highest electrical volume resistivity. Damping material

[127] The inner sheath 120 and the outer sheath 130 may be made of a variety of electrically dissipative materials. However, the inventor has arrived at the insight that, if at least an inner portion of the inner sheath 120 and / or at least a portion of the outer sheath 130 is made of an electrically dissipative material that is also a damping material, performance can be significantly improved. In order to work as a damping control system, the damping material is preferably highly compliant, i.e., has a low durometer hardness: high mechanical compliance increases efficient energy absorption from vibration of the strands 110-1, 110-2, ..., 110-N.

[128] The inner sheath 120 or the outer sheath 130, or at least an inner portion thereof, may nevertheless be made of a non-damping material. In some implementations in which at least an inner portion of the inner sheath 120 is made of a non-damping material, the plurality of strands 110 are not bonded to the inner sheath 120. This ensures that, although the inner sheath 120 is made of a nondamping material, resonance due to energy exchanges between elements, for example between conductor strands and inner sheath, is nevertheless reduced.

[129] In tests, the desired level of damping begins to become apparent with damping materials of durometer hardness of 83 Shore (00), and becomes significantly more efficient as this approaches 70 Shore (00).

[130] The damping properties of the damping material can also be characterised by its vibrational energy dissipation, or 'loss factor', of the material. This is referred to as 'tan delta' in dynamic mechanical analysis (DMA). A tan delta of 1 means a 50% loss of energy in tests, which is a high damping level. The higher the tan delta, the more dissipative the material.

[131] In tests, the desired damping begins to become apparent with damping materials of flexural loss factor greater than 0.2, and becomes significantly more apparent as this becomes greater than 0.4 (e.g. foamed, or soft low density polymers).

[132] Accordingly, in some implementations, at least an inner portion of the inner sheath 120 is made of a damping material having one or both of: a Shore 00 hardness of less than 83 or, more preferably, less than 70; or a flexural loss factor (or 'tan delta') greater than 0.2 or, more preferably, greater than 0.4. Alternatively, in some implementations, at least an inner portion of the inner sheath 120 is made of a (non-damping) material having one or both of: a Shore 00 hardness of at least 83, or at least 70; or a flexural loss factor of no more than 0.2 or, more preferably, no more than 0.4.

[133] Accordingly, in some implementations, at least an inner portion of the outer sheath 130 is made of a damping material having one or both of: a Shore 00 hardness of less than 83 or, more preferably, less than 70; or a flexural loss factor (or 'tan delta') greater than 0.2 or, more preferably, greater than 0.4. Alternatively, in some implementations, at least an inner portion of the outer sheath 130 is made of a(non-damping) material having one or both of: a Shore 00 hardness of at least 83, or at least 70; or a flexural loss factor of no more than 0.2 or, more preferably, no more than 0.4.

[134] There is a large range of materials that meet, or can be engineered to meet, at least one of the Shore hardness and loss factor criteria set out above. A person of ordinary skill in the art will have no difficulty in identifying and obtaining such a material. Nevertheless, a selection of some suitable materials is set out below.

[135] The inner sheath 120 and / or the outer sheath 130 and / or the jacket 140 may be formed from an insulative material that is absorbent or porous or fibrous or in foam form; where the said insulative material is modified to be made to be electrically dissipative by doping or mixing or otherwise compounding it with conductive material such as, but not limited to carbon, graphite, liquid graphite, or proprietary electrically dissipating products such as Licron®.

[136] The inner sheath 120, and / or the outer sheath 130 and / or the jacket 140 may be a plastic that is modified to be made an electrically dissipative material by mixing, blending or otherwise compounding a conductive material with an insulative material. Such electrically dissipative materials are commonly known as conductive plastics .

[137] Examples of conductive materials that are commonly added to plastics to form conductive plastics and dissipative materials include, but are not limited to, one or a combination of carbon, carbon allotropes or steel.

[138] Examples of plastics that commonly have conductive materials mixed, blended or otherwise compounded to become electrically dissipative materials and that can yield Shore 00 hardness of less than 83 and / or a damping factor of greater than 0.2 include, but are not necessarily limited to, one or a combination of: polyolefins, polypropylene (PP) , polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyisobutene, polycarbonate (PC), polyamide (nylon or PA), polybutylene terephthalate (PBT), thermoplastic polyurethane (rubber), thermoplastic elastomer (TPE), low durometer silicone rubber compounds, loose fibrous materials, foamed polymers such as polyurethane compounds, or a combination thereof.

[139] In some implementations, the damping material may be a combination of materials that form an electrically dissipative material and meet one of the Shore hardness and loss factor criteria set out above.

[140] In some implementations, the inner sheath 120, the outer sheath 130 and the jacket 140 may be formed with a plurality of layers and / or with graduation of volume electrical resistivity; for example, an inner layer of the inner sheath 120 may be formed of a dissipative foam material with a volume electrical resistivity of 100,000 Ohm-cm and Shore hardness (00) of 83 and an outer layer of the inner sheath may be formed with a foam with a volume electrical resistivity of 200,000 Ohm-cm and Shore hardness (00) of 70. Ground conductor

[141] In some implementations, a ground conductor 150 is arranged to be in electrical contact with the outer sheath 130 along at least a portion of the axial length of the outer sheath 130. The ground conductor 150 ensures an equipotential voltage is maintained along the length of the outer sheath 130.

[142] The ground conductor 150 may be electrically connected, or connectable, to an electrical ground or other electrical reference. Connection of the ground conductor 150 to a ground or other electrical reference prevents charge accumulating in the outer sheath 130.

[143] The ground conductor 150 may be electrically connected, or connectable, to serve as a current return path in an electrical circuit of an appliance, for example but not limited to, to serve as a ground connection wire of a loudspeaker circuit.

[144] The ground conductor 150 may be connected, or connectable, to an electrical ground or other electrical reference voltage via an electrical resistor to reduce electrical current flow in the ground conductor 150.

[145] A ground conductor 150 may be disposed along the axial length of the outer circumference of the outer sheath 130, or embedded in the outer sheath 130, or disposed between the inner sheath 120 and the outer sheath 130.

[146] The ground conductor 150 may be made of a variety of conductive materials or may be made of a mixture of a variety of conductive and semiconductive elements and non-conductive elements, and may be made in a variety of forms and deposited in a variety of ways. For example, but not limited to, the ground conductor 150 may be formed of carbon fibre and polymer braid, or a copper wire spiralled around the inner sheath, or a copper braid, or a conductive foil. Cable assembly

[147] The conductor assembly 100 can be used to form a cable assembly 200. The cable assembly 200 comprises at least one of the conductor assemblies 100 described herein, and a jacket 140 surrounding the at least one of the conductor assemblies 100.

[148] The jacket 140 provides solidity to the conductor assembly 100 and allows multiple conductor assemblies 100 to be kept together.

[149] The jacket 140 may be made of a variety of materials. However, the inventor has arrived at the insight that, if at least a portion of the jacket 140 is made of an electrically dissipative material, performance can be significantly improved.

[150] The cable assembly 200 may further comprise a first electrical connector and a second electrical connector at respective ends of the cable assembly 200. The first and second electrical connectors may bind the jacket 140 to the at least one of the conductor assemblies 100, thus enabling the cable assembly 200 to be handled without upsetting the internal arrangement of the cable assembly 200 (i.e., pulling the strands out). At least until the first and second electrical connectors are placed on the ends of the cable assembly 200, the bungs 160 at each end of the inner sheath(s) 120 (if present) may also provide such protection.

[151] When there are multiple conductor assemblies 100, the cable assembly 200 comprises a plurality of inner sheaths 120 and a plurality of outer sheaths 130. However, the outer sheaths 130 of each of the plurality of the conductor assemblies 100 may be integrally formed with each other.

[152] The jacket 140 is formed from an electrically dissipative material having an electrical volume resistivity of less than 100,000,000,000 Ohm-cm and more than 100,000 Ohm-cm and at least two times more than the electrical volume resistivity of the outer sheath 130.

[153] The jacket 140 having a significantly higher resistivity than the outer sheath 130 provides an electrically resistive barrier between the outer sheath 130 and anything external to the cable assembly 200. This electrically resistive barrier limits incidental electrical contact of the inner sheath 130 with anything external to the cable assembly 200, and limits consequential eddy current in the material of the jacket 140.

[154] Where the jacket 140 is in contact with more than one outer sheath 130, then the resistivity of the jacket material 140 is more than twice that of the outer sheath 130 that is formed with material that has the highest resistivity of the outer sheaths 130.

[155] As the conductor assemblies 100 can be made and sold without a jacket 140, the conductor assemblies 100 are disclosed both separately, and in combination with, the jacket 140. Further implementations

[156] Figs. 4A and 4B show a cable assembly 200 according to the first implementation. In particular, Figs. 4A and 4B respectively show an isometric view and a cross-sectional view of the cable assembly 200. The cable assembly 200 comprises a single conductor assembly 100 surrounded by a jacket 140. The conductor assembly 100 in turn comprises an electrical conductor formed of strands 110-1 and 110-2, surrounded by an inner sheath 120, which in turn is surrounded by an outer sheath 130 where a ground conductor 150 is disposed between the outer sheath 130 and the jacket 140.

[157] Figs. 5A and 5B show a cable assembly 200 according to a second implementation. In particular, Figs. 5A and 5B respectively show an isometric view and a cross-sectional view of the cable assembly 200. The cable assembly 200 comprises two conductor assemblies 100 according to a second implementation surrounded by a jacket 140, in which the respective inner sheaths 120A and 120B have a first, circular cross-sectional shape and the respective outer sheaths 130 have a second cross-sectional shape and are integrally formed with each other, and the ground conductors 150 of the two conductor assemblies 100 are integrally formed with each other and embedded in the outer sheath 130.

[158] Figs. 6A and 6B show a cable assembly 200 according to a third implementation. In particular, Figs. 6A and 6B respectively show an isometric view and a cross-sectional view of the cable assembly 200. The cable assembly 200 comprises two conductor assemblies 100 according to a third implementation surrounded by a jacket 140, in which the respective inner sheaths 120 have a second cross-sectional shape and are integrally formed with each other, and the respective outer sheaths 130 have the second cross-sectional shape and are integrally formed with each other, and the ground conductors 150 of the two conductor assemblies 100 are integrally formed with each other and disposed between the outer sheath 130 and the jacket 140.

[159] Figs. 7A and 7B respectively show an isometric view and a cross-sectional view of a cable assembly 200 according to a fourth implementation. In particular, Fig. 7A shows a cable assembly 200 comprising four conductor assemblies 100, in which the respective inner sheath 120 of the conductor assemblies 100 are formed in two layers, the inner layers 120B, 120C, 120E and 120F have the first, circular cross-sectional shape and the second layers 120A and 120D are formed in the second cross-sectional shape around inner layers 120B and 120C, and 120E and 120F respectively. The conductor assemblies 100 are surrounded by the jacket 140, and the ground conductors 150 of the four conductor assemblies 100 are integrally formed with each other and disposed between the outer sheath 130 and the jacket 140.

[160] Fig. 8A shows a cross-sectional view of a cable assembly 200 according to a fifth implementation. In particular, Fig. 8 shows a cable assembly 200 comprising eight conductor assemblies 100, in which the pairs of inner sheaths 120B and 120C, 120E and 120F, 120H and 120J, 120L and 120M are embedded in four respective second layers of inner sheaths 120A, 120D, 120G and 120K, where the orientation of the positions with which the inner sheaths 120A, 120D, 120G and 120K are disposed within the outer sheath 130 are not necessarily aligned with each other.

[161] Although the technology of the present disclosure has been illustrated primarily by way of electrical conductors 110 comprising two strands 110-1, 110-2, it will be understood that a single strand or many more strands may be used - for example, tens or hundreds of strands may be used. Similarly, although the technology of the present disclosure has been illustrated primarily by way of cable assemblies 200 comprising one or two conductor assemblies 100, it will be understood that many more conductor assemblies 100 may be used.

[162] Although the technology of the present disclosure has been illustrated primarily by way of electrical conductors 110 comprising strands 110-1, 110-2, ..., 110-N of equal length, these strands 110-1, 110-2, ..., 110-N may have different lengths.

[163] Although the technology of the present disclosure has been illustrated primarily by way of cable assemblies 200 in which the jacket 140, conductor assemblies 100, inner sheaths 120 and / or outer sheath 130 have a circular cross-section, it will be understood that the cross-section may have any shape - for example, the crosssection may have an oval shape or a rectangular shape.

[164] Although the technology of the present disclosure has been illustrated primarily by way of conductor assemblies 100 in which the electrical volume resistivity of the outer sheath 130 is less than 50% than electrical volume resistivity of the at least one inner sheaths 120 with the lowest electrical volume resistivity, it will be understood that the electrical volume resistivity of the outer sheath 130 may alternatively be more than 200% of the electrical volume resistivity of the at least one inner sheaths 120 with the highest electrical volume resistivity. Performance

[165] The performance of the conductor assemblies 100 and cable assemblies 200 according to the technology of the present disclosure is now presented.

[166] The measurement of the generation of triboelectric charges generated by the mechanical excitation of the cable is according to ANSI(American National Standards Institute) / AMMI (Association for the Advancement of Medical Instrumentation) EC53:2013 (ECG trunk cable and patient leadwires) part 5.3.2 'Cable and leadwire noise' (available at https: / / webstore. ansi.org / standards / aami / ansiaamiec532013r2020?srslt id=AfmBOorsTo6IMRrhItl7 99swwAPgGYccOvCCs7w5qszXYH-dMXP9CL35)

[167] The measurement of the generation of triboelectric charges generated by the mechanical excitation of a cable assembly 200 in which a plurality of twisted strands 110-1, 110-2, ..., 110-N are surrounded by an inner sheath 120, an outer sheath 130 and a jacket made from electrically insulative materials was significantly greater than the measurement of the generation of triboelectric charges generated by the mechanical excitation of a cable assembly 200 in which a plurality of loose strands 110-1, 110-2, ..., 110-N are surrounded by an inner sheath 120 made of electrically dissipative, damping material, and an outer sheath 130 and jacket 140 made of electrically dissipative material.

[168] This clearly demonstrates improvement in transmission quality of a cable by the reduction of static charge generated from mechanical excitation of the cable being impressed on a signal carried by the cable when the technology of the present disclosure is implemented. Other examples of the disclosure

[169] An electrical signal transmission lead may be formed with a conductor and sheath arrangement where a conductor is formed from electrically conductive strands where each strand has a cross-sectional area that is less than 0.1 square millimetres, where the conductor is surrounded by and contained inside an inner sheath, and an electrical ground is disposed on the outside perimeter of the inner sheath, where the inner sheath and electrical ground are contained within an outer sheath, and where the outer sheath and ground conductor are contained within a jacket. The inner sheath material may be formed from foamed conductive plastic that has a Shore hardness (00) of less than 83 and an electrical volume resistivity that is greater than 200,000 Ohm-cm and less than 100,000,000,000 Ohm-cm. The electrical ground may be an electrically conductive wire that is placed on the outside surface of the inner sheath and is in electrical contact with at least part of the outer perimeter of the inner sheath along the length of the inner sheath. The material that the outer sheath is formed from may be a foamed conductive plastic that has a Shore hardness (00) of less than 70 and an electrical volume resistivity that is greater than 100,000 Ohm-cm and less than 50% of the electrical volume resistivity of the inner sheath. The material that the jacket is formed from may have an electrical volume resistivity that is less than 100,000,000,000 Ohm-cm and greater than two times the volume resistivity of the outer sheath. The ground may be connected to one terminal of an electrical resistor that has a resistance of between 10 Ohms and 100 Ohms, (e.g. 50 Ohms), where the other terminal of the said electrical resistor is connected to an electrical ground.

[170] An electrical signal transmission lead may be formed with a conductor and conductor sheath arrangement where a conductor is formed with electrically conductive strands where the conductor is surrounded by and contained inside an inner sheath, where the inner sheath is contained within an outer sheath, and an electrical ground conductor is disposed on the outside perimeter of the outer sheath, and where the outer sheath and ground conductor are contained within a jacket. The material that the inner sheath is formed from may have a mechanical loss factor of more than 0.4 and an electrical volume resistivity that is greater than 200,000 Ohm-cm and less than 100,000,000,000 Ohm-cm. The material that the outer sheath is formed from may be a foamed conductive plastic that has a mechanical loss factor of more than 0.2 and an electrical volume resistivity that is greater than 100,000 Ohm-cm and less than 50% of the electrical volume resistivity of the inner sheath. The electrical ground may be an electrically conductive wire that is disposed on the outside surface of the outer sheath so the ground conductor is in electrical contact with at least part of the outer circumference of the outer sheath along the length of the outer sheath. The material that the jacket is formed from may have an electrical volume resistivity that is greater than two times the volume resistivity of the outer sheath and less than 100,000,000,000 Ohm-cm.

[171] An electrical signal transmission lead may be formed with a conductor and sheath arrangement where the conductor is formed of strands that are twisted together, where the conductor is surrounded by and contained inside an inner sheath, and an electrical ground is disposed on the outside perimeter of the inner sheath, where the inner sheath and electrical ground are contained within an outer sheath. The material that the inner sheath is formed from may have a Shore hardness (00) of less than 40 and an electrical volume resistivity that is greater than 200,000 Ohm-cm and less than 100,000,000,000 Ohm-cm. The material that the outer sheath is formed from may have a mechanical loss factor of more than 0.2 and an electrical volume resistivity that is greater than 100,000 Ohm-cm and less than 50% of the electrical volume resistivity of the inner sheath. The ground may be connected to one terminal of an electrical resistor that has a resistance of between 100 Ohms and 1,000 Ohms, (e.g. 500 Ohms), where the other terminal of the said electrical resistor is connected to an electrical ground.

[172] An electrical signal transmission lead may be formed with an arrangement of two conductors, an inner sheath, an outer sheath, a ground conductor and a jacket where the inner sheath is formed with two cavities that are separate and parallel along its entire length, so as to form a figure of eight form in cross-section, and one of the two conductors is placed in each respective cavity, where the outer sheath is formed around the inner sheath along the axial length of the inner sheath, where the electrical ground conductor is disposed along the axial length of the outer sheath and is in electrical contact with the outer sheath, where the outer sheath and ground conductor are contained within the jacket along the axial length of the outer sheath. The material that the inner sheath is formed from may be a foamed conductive plastic that has a Shore hardness (00) of less than 83 and an electrical volume resistivity that is greater than 200,000 Ohm-cm and less than 100,000,000,000 Ohm-cm. The material that the outer sheath is formed from may be a foamed conductive plastic that may have a Shore hardness (00) of less than 70 and an electrical volume resistivity that is greater than 100,000 Ohm-cm and less than 50% of the electrical volume resistivity of the inner sheath. The material that the jacket is formed from may be an electrically dissipative material with an electrical volume resistivity that is greater than two times the volume resistivity of the outer sheath and less than 100,000,000,000 Ohm-cm.

[173] An electrical signal transmission lead may be formed with a conductor, an inner sheath, an outer sheath and a ground conductor where the conductor is surrounded and contained within the inner sheath, and the inner sheath is contained within an outer sheath and the ground conductor is embedded in the material of the outer sheath, where the inner sheath is formed from electrically dissipative material that has an electrical volume resistivity that is greater than 100,000 Ohm-cm and less than 50,000,000,000 Ohm-cm and the outer sheath is formed from a material that has an electrical volume resistivity that is at least twice that of the inner sheath and is less than 100,000,000,000 Ohm-cm and the conductor is formed with strands where each strand is laid in parallel to other strands without twisting strands or binding them and each strand remains un-tethered or un-bound to any other strand. Apart from casual contact between neighbouring strands each individual strand is able to move independently from other strands. Apart from casual contact between strands and inner sheath each individual strand is able to move independently from the inner sheath. The path of the longitudinal axis of each strand is concertinaed or otherwise caused to sinuously deviate from the mean axis of the inner sheath when the inner sheath is laid in a straight line to form an irregular mesh along their longitudinal axis. The total deviation from the mean axis of the inner sheath when the inner sheath is laid in a straight line amounts to a reduction in the axial length of each strand as laid in the conductor by a minimum of, e.g., 5 percent of the length of the said conductor strand when laid straight along its longitudinal axis. The distribution of the conductor strand that deviates from the mean axis of the inner sheath when the inner sheath is laid in a straight line is (approximately) evenly distributed along the length of the inner sheath, e.g., to within 25 percent tolerance. Each individual strand diameter has a maximum cross sectional area of 0.1 square mm. The void within the inner sheath that contains the collection of strands has a minimum cross-sectional form that is equal to the outline of the cross-sectional projection of the group of conductor strands when the axis of the strands are sinuously deviated from the mean axis of the inner sheath in said manner. The maximum cross-sectional area of the void is, e.g., 400 square mm. Interpretation

[174] Section titles are provided above to ease understanding of the disclosure, and are not to be construed as limiting the scope of the disclosure.

[175] Those skilled in the art will recognise that the scope of the invention is not limited by the examples described herein, but is instead defined by the appended claims.

Claims

1. A conductor assembly comprising:at least one electrical conductor;a ground conductor;at least one inner sheath, each surrounding a respective one of the at least one electrical conductors; andan outer sheath surrounding the at least one inner sheath, wherein:the at least one inner sheath is formed of an electrically dissipative material having an electrical volume resistivity of more than 200,000 Ohm-cm and less than 100,000,000,000 Ohm-cm and the outer sheath is formed of an electrically dissipative material having an electrical volume resistivity of more than 100,000 Ohm-cm and less than 50% of the electrical volume resistivity of each of the at least one inner sheaths; orthe at least one inner sheath is formed of an electrically dissipative material having an electrical volume resistivity of more than 100,000 Ohm-cm and less than 50,000,000,000 Ohm-cm and the outer sheath is formed of an electrically dissipative material having an electrical volume resistivity of more than 200% of the electrical volume resistivity of each of the at least one inner sheaths and less than 100,000,000,000 Ohm-cm.

2. The conductor assembly of claim 1, wherein the ground conductor is disposed between the at least one inner sheaths and the outer sheath.

3. The conductor assembly of claim 2, wherein the outer sheath isin electrical contact with the ground conductor at least every 20 cm along a length of the outer sheath.The conductor assembly of claim 1wherein the groundconductor is embedded in the outer sheath.

5. The conductor assembly of any preceding claim, wherein at least one of:the at least one inner sheaths are formed of a plurality of layers each formed from an electrically dissipative material having an electrical volume resistivity of more than 200,000 Ohm-cm and less than 100,000,000,000 Ohm-cm;the outer sheath is formed of a plurality of layers each formed from an electrically dissipative material having an electrical volume resistivity of more than 100,000 Ohm-cm and less than 50% of the electrical volume resistivity of each of the at least one inner sheaths or each of the plurality of layers thereof;the at least one inner sheaths are formed of a plurality of layers each formed from an electrically dissipative material having an electrical volume resistivity of more than 100,000 Ohm-cm and less than 50,000,000,000 Ohm-cm; orthe outer sheath is formed of a plurality of layers each formed from an electrically dissipative material having an electrical volume resistivity of more than 200% of the electrical volume resistivity of each of the at least one inner sheaths or each of the plurality of layers thereof and less than 100,000,000,000 Ohm-cm.

6. The conductor assembly of any preceding claim, wherein the at least one electrical conductors are each formed of a plurality of strands .The conductor assembly of claim 6, wherein the plurality ofstrands are slack within the respective one of the at least oneinner sheaths.

8. The conductor assembly of any of claims 6 to 7, wherein each of the plurality of strands has a respective cross-sectional area of less than 0.1 square millimetres.

9. The conductor assembly of any of claims 6 to 8, wherein contact, within the respective one of the at least one inner sheaths, between each of the plurality of strands is longitudinally substantially evenly distributed.

10. The conductor assembly of any of claims 6 to 9, wherein a respective length of each of the plurality of strands within the respective one of the at least one inner sheaths exceeds a length of the respective one of the at least one inner sheaths by at least 5%, optionally at least 10%.

11. The conductor assembly of any of claims 6 to 10, wherein a respective length of each of the plurality of strands within the respective one of the at least one inner sheaths exceeds a length of the respective one of the at least one inner sheaths by no more than 60%.

12. The conductor assembly of any of claims 6 to 11, wherein each of the plurality of strands is arranged within the respective one of the at least one inner sheaths in a serpentine manner.

13. The conductor assembly of any of claims 6 to 12, wherein atleast one of the plurality of strands is formed of a plurality ofentwined sub-strands.

14. The conductor assembly of any preceding claim, wherein at least an inner portion of one of the outer sheath and the at least one inner sheaths is made of an electrically dissipative and mechanical vibration damping material having at least one of:a Shore 00 hardness of less than 83; ora loss factor greater than 0.2.

15. The conductor assembly of claim 14, wherein the electrically dissipative and mechanical vibration damping material is a polyolefin.

16. The conductor assembly of any of claims 14 to 15, wherein the electrically dissipative and mechanical vibration damping material is: polypropylene (PP), polystyrene (PS), acrylonitrile butadiene styrene (ABS), polyisobutene, polycarbonate (PC) , polyamide (nylon or PA), polybutylene terephthalate (PBT), thermoplastic polyurethane, thermoplastic elastomer (TPE) , low durometer silicone rubber compounds, foamed polymers such as polyurethane compounds, or a combination thereof.

17. The conductor assembly of any of claims 14 to 16 when dependent on claim 6, wherein the plurality of strands are bonded to the electrically dissipative and mechanical vibration damping material.

18. The conductor assembly of any of claims 14 to 17, wherein at least an inner portion of the other of the outer sheath and the at least one inner sheath is made of an electrically dissipative and mechanical vibration damping material having a Shore 00 hardness of at least 83.

19. The conductor assembly of any preceding claim, wherein the at least one conductor comprises a plurality of conductors, the at least one inner sheath comprises a plurality of inner sheaths, and at least two of the plurality of inner sheaths are integrally formed with each other.

20. A cable assembly comprising a plurality of the conductor assemblies of any of claims 1 to 19, wherein the outer sheaths of each of the plurality of the conductor assemblies are integrally formed with each other.

21. A cable assembly comprising:at least one of the conductor assemblies of any of claims 1 to 19; anda jacket surrounding the at least one of the conductor assemblies .

22. The cable assembly of claim 21, wherein the jacket is formed of an electrically dissipative material having an electrical volume resistivity of more than twice the electrical volume resistivity of the electrically dissipative material of the outer sheath of each of the conductor assemblies, and less than 100,000,000,000 Ohm-cm.

23. The cable assembly of any of claims 21 to 22, wherein the ground conductor is disposed between the outer sheaths of each of the at least one of the conductor assemblies and the jacket.

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