Insulator for cable termination assembly, termination assembly for cable comprising such insulator, and cable termination system

Abstract

An insulator for a cable termination assembly, a termination assembly for a cable including such an insulator, and a cable termination system. An insulator (10) for a cable termination assembly comprises:-a body (11) of insulating material extending along a longitudinal direction X and having a cylindrical symmetric shape with a first longitudinal end (12) and a second longitudinal end (13) opposite one another, said body (11) being adapted to fit on a cable; -a ring electrode (20) made of a mesh of electrically conductive material integrated in the body (11) at a predetermined distance from the first end (12), said ring electrode (20) being configured to be connected to an external voltage detector.

Description

Technical Field

[0001] The present disclosure relates to an insulator for a cable termination assembly, in particular for a GIS (Gas Insulated Substation) terminal (eg a metal enclosed cable terminal) or an outdoor terminal.

[0002] The present disclosure also relates to a terminal assembly for a cable and a cable terminal system comprising the above insulator. The present disclosure also relates to a method for monitoring a cable terminal assembly. Background Art

[0003] For the purposes of this description, an electrical cable comprises at least one cable core, typically formed of an electrically conductive metal conductor, covered by an insulation system, which is typically covered by an outer protective sheath as the outermost layer of the cable. The insulation system may be formed, in sequence, of an inner semiconducting layer, an intermediate insulating layer, and an outer semiconducting layer. The cable may also comprise a metal shield between the outer protective sheath and the insulation system configured to ground the cable.

[0004] For the purposes of this disclosure, by a terminal assembly for an electric cable is intended a device suitable for connecting a cable to a bare conductor (i.e. an electrical conductor on which, in contrast to an electric cable, no solid insulation system is applied). The terminal assembly comprises electrical connection means between the cable conductor and the bare conductor and electrical separation means between the outer surface of the cable and a component connected to said outer surface (usually at ground potential), and an element under tension (such as the bare conductor).

[0005] Terminal components generally include:

[0006] - electric field control elements, often called "stress members", which are intended to be fitted to the cables;

[0007] - an insulator intended to be fitted to the cable and connected to the electric field control element in such a way as to at least partially surround the electric field control element;

[0008] (For metal-enclosed terminals in GIS, the insulator also serves as a barrier to pressurized insulating gases such as SF6, synthetic air, fluoroketones (such as C5-FK), fluoronitrile (such as C4-FN), etc. A metal insert is embedded in the insulator to establish a connection between the cable conductor and the switchgear conductor.)

[0009] A GIS terminal generally comprises a terminal assembly and a tubular housing adapted to be fixed to and house an insulator. The tubular housing may be a metal tubular housing, for example a steel tubular housing set at ground potential during operation.

[0010] At the beginning of the assembly operation between the terminal assembly and the cable, the end of the cable is subjected to a cutting and stripping procedure so as to present a first length of exposed electrical conductors abutting each other, a second length of exposed insulation, and then the cable with the completed insulation system.

[0011] After the preparation of the cable has been performed, the electric field control element is interference fit on the cable at the boundary between the exposed outer semiconductive layer and the exposed insulating layer; in particular, the electric field control element can be assembled on the prepared cable by sliding on the prepared cable or by pre-expanding on a removable carrier tube.

[0012] The cable, to which the electric field control element is applied, is then interference fit into an insulator. Such insulators are typically made of epoxy resin and include metal inserts configured to be electrically connected to the electrical conductors of the cable.

[0013] In common GIS assembly operations, the insulator is installed into the tubular housing before the cable including the electric field control element is inserted into the insulator. However, in some applications, the assembly operation may require first installing the insulator onto the cable to which the electric field control element is applied, and then inserting the insulator into the tubular housing.

[0014] The metal insert is connected to the exposed electrical conductor of the cable on one side and to the bare conductor on the other side. The bare conductor is configured to be connected to electrical equipment outside the GIS terminal, such as a power transformer, an overhead medium of a high voltage line, etc.

[0015] The space between the tubular housing and the cable with the stress member and the insulation may be filled with an insulating gas, such as sulphur hexafluoride or SF6 gas.

[0016] The insulating gas ensures electrical insulation between the bare conductor and the electrical ground connected to the tubular housing. However, there is still a requirement for the opportunity to monitor the GIS terminals over time in order to avoid possible dangerous discharges.

[0017] However, depending on the application (eg, GIS, outdoor terminal, etc.), the insulator and terminal assembly of the present disclosure may be manufactured in a different shape and assembled in a different method than previously described.

[0018] WO 2014 / 209739 A1 describes a terminal connection device comprising a continuum arranged on an inner conductor. The inner conductor comprises a first end and a second end that can be matched with a cable connector. The body comprises a multilayer structure having an inner conductive layer or a semiconductive layer, an insulating layer and an outer conductive layer or a semiconductive layer arranged on at least a portion of the cable connector. The body surrounds the first end of the inner conductor and extends toward the second end of the inner conductor. The body may also include an electrically isolated portion of a conductive or semiconductive material. The terminal connection device may be a fully integrated structure with a pre-installed connection interface, or the terminal connection device may be constructed as an adapter that can be installed to the connection interface on site. Summary of the invention

[0019] The technical problem faced by the applicant is how to monitor the presence of voltage over time. During maintenance periods, for example, it is required to ensure that cables and electrical equipment are not undervoltage. Therefore, voltage detection and indication systems are required to comply with, for example, IEC62271-213.

[0020] In addition, GIS terminals may be subject to partial discharges and consequent degradation, which may lead to failures. Therefore, partial discharge monitoring is required.

[0021] The Applicant considered implementing this monitoring by equipping the insulator with electrodes connected to a voltage detector, said electrodes being made of a solid metal part buried in the body of the insulator. However, the Applicant observed that this solution would mechanically weaken the insulator, since there could be differences in the rates of thermal expansion of the metal of the capacitive sensor and the insulating material of the insulator, and therefore separation could occur with thermal cycles.

[0022] This separation can serve as an initiation point for cracks that propagate through the insulation material, resulting in the formation of voids that can create entrapped air, which when voltage stress exceeds the dielectric strength of air, leads to the formation of partial discharges that damage the insulator body and cause premature failure of the terminal assembly.

[0023] Therefore, the applicant considered making the electrode into a ring-shaped body of a mesh of conductive material and integrating it into the body of the insulator during the formation of the insulator. In this way, the insulating material of the insulator, such as resin, passes through the free space of the mesh, achieving a deep connection between the electrode and the insulator, avoiding any mechanical discontinuity between them. The electrode is more effectively integrated in the resin in the form of a mesh than in the case of a solid metal ring.

[0024] Therefore, the electrode ring can be placed in an area with a significant electric field and a good connection with the high voltage conductor can be achieved without modifying the shape of the insulator.

[0025] Thus, according to a first aspect, the present disclosure relates to an insulator for a cable termination assembly, the insulator comprising:

[0026] - a body of insulating material extending along a longitudinal direction X and having a cylindrically symmetrical shape with a first longitudinal end and a second longitudinal end opposite one another, said body being suitable for being fitted on a cable;

[0027] - an annular electrode made of a mesh of conductive material integrated in said body at a predetermined distance from said first end, said annular electrode being configured to be connected to an external voltage detector.

[0028] In one embodiment, the annular electrode is provided with at least one protrusion, which is made of a conductive material and extends in a radial direction until it reaches a side surface of the body.

[0029] In one embodiment, the annular electrode comprises an annular metal mesh plate.

[0030] In one embodiment, the ring electrode has a folded edge proximally relative to the first end.

[0031] In this way, it is avoided that the terminal edge is positioned at the first end of the insulator proximal to the exposed cable conductor, which could involve a rise in charge accumulated on the terminal, possibly leading to dangerous discharges through the insulator body.

[0032] In one embodiment, the at least one projection has a threaded bushing made of an electrically conductive material at its free end.

[0033] Thus, during the manufacturing process, the coupling of the electrode to the insulator can be made more stable by using a screw mounted in at least one threaded bushing. If the screw is made of a conductive material, it facilitates the coupling of the detector to the electrode by simply connecting such a voltage detector directly to the screw.

[0034] It is emphasized that if the insulator comprises a plurality of projections with bushings, only one of the projections is intended to be connected to the voltage detector. The remaining projections will only be used for the mechanical coupling of the electrode to the insulator during the molding process, i.e. manufacturing the insulator with the electrode, while using corresponding screws made of insulating material or made of conductive material and surrounded by an insulating sleeve. In particular, screws made of insulating material are used to electrically insulate the metal insert and avoid accidental contact with people or other conductive objects.

[0035] In one embodiment, the coverage factor of the web of conductive material is between 0.2 and 0.5.

[0036] For the purposes of this disclosure, by a material mesh, it is intended an element having a substantially flat shape (i.e., a dimension relatively small compared to the other two dimensions) comprising a series of repeating holes distributed throughout or at least a majority of the element surface. An example of a material mesh is expanded metal, which is a sheet of metal that has been cut and stretched to form a regular pattern (usually diamond-shaped).

[0037] For the purposes of this disclosure, the coverage factor refers to the extent to which the area of ​​the mesh is covered by the solid material. In particular, the coverage factor is the ratio between the surface area of ​​the electrode covered by the solid material and the entire surface area of ​​the electrode.

[0038] In one embodiment, the body is made of epoxy resin.

[0039] In one embodiment, the insulator includes a metal insert configured to be electrically connected to an electrical conductor of the cable on one side and to be electrically connected to a bare conductor on the other side.

[0040] In a second aspect, the present disclosure relates to a terminal assembly for a cable, comprising:

[0041] - an electric field control element, intended to be fitted to said cable;

[0042] - An insulator according to the present disclosure, wherein the insulator is intended to be coupled to the electric field controlling element in such a way as to at least partially surround the electric field controlling element.

[0043] In a third aspect, the present disclosure relates to a gas insulated substation terminal, comprising:

[0044] - a terminal assembly according to the above;

[0045] - a tubular housing adapted to be fixed to said insulator and to house said insulator;

[0046] - a bare conductor configured to be mounted within the tubular housing and electrically connected to an electrical conductor of the cable.

[0047] In another aspect, the present disclosure relates to a cable termination system comprising:

[0048] -cable;

[0049] - an electric field control element mounted to said cable;

[0050] - The insulator according to the present disclosure, wherein the insulator is coupled to the electric field controlling element in such a way as to at least partially surround the electric field controlling element.

[0051] In one embodiment, the cable termination system further includes a tubular housing fixed to the insulator so as to surround the insulator and define a closed space filled with an insulating gas.

[0052] In one embodiment, the ring electrode and the cable electrical conductor are electrically insulated from each other, thereby realizing a first capacitor, wherein a voltage detector is electrically connected to the ring electrode, the voltage detector comprising a second capacitor connected in series with the first capacitor.

[0053] Alternatively, the ring electrode and the cable electrical conductor are electrically insulated from each other, thereby realizing a first capacitor, the insulator comprises a second capacitor connected in series to the first capacitor, and wherein the voltage detector is electrically connected to the second capacitor.

[0054] In one embodiment, the voltage detector is configured to detect the presence of electrical pulses and / or the presence of partial discharges on the cable or cable termination system.

[0055] For the purposes of this specification and the appended claims, unless otherwise indicated, all numbers expressing amounts, quantities, percentages, etc., are to be understood as being modified in all instances by the word "about". In addition, all ranges include any combination of the maximum and minimum points disclosed, and include any intermediate ranges therein, which may or may not be specifically enumerated herein.

[0056] In addition, the term "a" or "an" is used to describe elements and components of the present disclosure. This is done only for convenience and to give a general sense of the present disclosure. The description should be understood to include one or at least one, and unless it is obvious that there is another meaning, the singular also includes the plural.

[0057] As "insulating material", it means that the electrical conductivity is less than 10 -12 Material of S / m.

[0058] As a "semi-conductive material", it means that the conductivity is between 10 -2 Materials between S / m and 100S / m. BRIEF DESCRIPTION OF THE DRAWINGS

[0059] Other features will become apparent from the detailed description given hereinafter with reference to the accompanying drawings, in which:

[0060] - Figure 1 is a schematic perspective view of an insulator according to the present disclosure;

[0061] - Figure 2 yes Figure 1 A schematic cross section of an insulator;

[0062] - Figure 3 yes Figure 2 Detailed picture of

[0063] - Figure 4 yes Figure 1 , Figure 2 A schematic perspective view of an electrode included in an insulator;

[0064] - Figure 5 is a schematic partial perspective view of a cable termination system according to the present disclosure;

[0065] - Figure 6 is a schematic partial cross-sectional view of a cable termination system according to an embodiment of the present disclosure;

[0066] - Figure 7 is a schematic partial cross-sectional view of an alternative embodiment of the present disclosure;

[0067] - Figure 8 is a schematic partial cross-sectional view of another alternative embodiment of the present disclosure. DETAILED DESCRIPTION

[0068] Referring to the drawings, an insulator 10 for a cable termination assembly according to the present disclosure is schematically shown.

[0069] In particular, the insulator 10 is intended for use in a terminal assembly, in particular for a Gas Insulated Substation (GIS) terminal.

[0070] According to the present disclosure, the cable 30 and the GIS terminal applied to such a cable form part of a cable termination system 100 .

[0071] The cable 30 comprises at least one electrical conductor 31 and a cable insulation system 32 surrounding the at least one electrical conductor 31. The cable insulation system 32 may comprise: an inner cable semiconducting layer (not shown) surrounding and contacting the electrical conductor 31, a cable insulation layer (not shown) surrounding and contacting the corresponding inner conductor layer, and an outer cable semiconducting layer (not shown) surrounding and contacting the corresponding insulation layer. Around the outer semiconducting layer, an outer protective sheath 33 is provided, which is considered the outermost layer of the cable. In many applications, the cable comprises a metal shield 34 between the outer protective sheath 33 and the insulation system 32 configured to ground the cable.

[0072] The insulator 10 comprises a body 11 of insulating material extending along a longitudinal direction X and having a cylindrically symmetrical shape, wherein a first longitudinal end 12 and a second longitudinal end 13 are opposite to each other. The body 11 is suitable for being fitted on a cable 30 .

[0073] For example, the body 11 may be made of resin.

[0074] In the illustrated embodiment, the first end 12 and the second end 13 have a circular cross-section, wherein the diameter of the cross-section of the first end 12 is smaller than the diameter of the second end.

[0075] The insulator 10 further comprises an annular electrode 20 made of a mesh of conductive material integrated in the body 11 at a predetermined distance from the first end 12. In particular, the annular electrode 20 is configured to be connected to an external voltage detector 40.

[0076] The web of conductive material may have a cover factor between 0.2 and 0.5.

[0077] In particular, the ring electrode 20 may provide at least one protrusion 21 made of an electrically conductive material.

[0078] In various embodiments, at least one protrusion 21 made of a conductive material extends from the ring electrode 20 to the outer surface of the body 11 .

[0079] exist Figure 6 In the embodiment, at least one protrusion 21 extends in the radial direction until reaching the side surface of the main body 11.

[0080] exist Figure 7 and Figure 8 In the embodiment, at least one protrusion 21 extends along the longitudinal direction X until reaching the second end 13 of the body 11 .

[0081] The ring electrode 20 and the cable electrical conductor are electrically insulated from each other, thereby realizing a first capacitor, the capacity of which can be estimated by a computer-implemented simulator or by experimental measurements.

[0082] The external voltage detector 40 may include a second capacitor connected in series with the first capacitor.

[0083] In an alternative embodiment, the insulator 10 comprises a second capacitor connected in series to the first capacitor, the first capacitor being connected to the ring electrode 20. In this case, the external voltage detector 40 is connected to the second capacitor.

[0084] In any case, the voltage detector 40 is configured to read the voltage across the second capacitor; therefore, by knowing the voltage read by the voltage detector 40 and the estimated capacity of the first capacitor, the voltage detector 40 is able to check whether voltage is present on the cable conductor and estimate the voltage value for safety and operating procedures. Several different voltage detectors can be configured for use with the cable termination assembly of the present disclosure, such as the capacitive voltage detection system Capdis-S2+R4.5 manufactured by Kries-Energietechnik GmbH or the integrated voltage detection system Wega 1.2C manufactured by Dipl.-Ing.H.Horstmann GmbH.

[0085] In some embodiments, the voltage detector 40 may include electronic components that enable the voltage detector 40 to detect the presence of an electrical pulse.

[0086] In this embodiment, the voltage detector 40 is further configured to detect the presence of partial discharge on the cable or cable termination system. This is to perform condition-based maintenance.

[0087] For example, the capacitive voltage detection system CAPDIS-S2_55 (R5) with partial discharge detection manufactured by Kries-Energietechnik GmbH can be adopted as a voltage detector. Other examples of voltage detectors capable of detecting partial discharges are the partial discharge acquisition and monitoring system PryCam Grids manufactured by the applicant or the universal partial discharge measurement and analysis system MPD 800 manufactured by Omicron, but both will be used with a connection quadrupole to separate low-frequency signals from high-frequency signals.

[0088] The ring electrode 20 may be made of metal, such as copper, aluminum, stainless steel, etc.

[0089] In this case, the annular electrode 20 comprises an annular metal mesh 22. The form of the mesh 22 ensures more surface for coupling with the body 11, since the insulating material of the body 11 penetrates and fills the holes of the electrode mesh 22 during the injection molding of the body.

[0090] For example, the plate may have a width between 0.25 mm and 0.6 mm.

[0091] The metal mesh sheet of the ring electrode 20 has a folded edge 23 proximally relative to the first end.

[0092] Thus, the portion of the metal mesh facing the cable conductor is rounded, thereby avoiding the accumulation of electric charges on the terminal portion.

[0093] The at least one projection may have a threaded bushing 24 made of an electrically conductive material at its free end.

[0094] The terminal assembly according to the present disclosure includes an electric field control element 50 (even referred to as a stress element) intended to be mounted on a cable and an insulator 10 intended to be coupled to the electric field control element in a manner of at least partially surrounding the electric field control element. In particular, the electric field control element 50 includes a deflector 52 made of a semiconductor material and an insulator 53 at least partially surrounding the deflector 52.

[0095] In the assembled configuration, the electric field control element 50 is consequently compressed between the cable 30 and the body 11 of the insulating body 10. This compression may be obtained by means of a spring element 51 wound around the electric field control element 50.

[0096] Such a terminal component may form part of a GIS terminal, for example Figure 6 The terminal shown, the GIS terminal also includes a tubular housing 60 adapted to be fixed to and accommodate the insulator 10 and a bare conductor 70 configured to be installed in the tubular housing 60 and electrically connected to the electrical conductor 31 of the cable. The tubular housing can be a metal tubular housing, for example, a steel tubular housing set at ground potential during operation.

[0097] In particular, the tubular housing 60 may be fixed to a flange 61 provided at the second longitudinal end 13 of the insulator by means of screws 62 or other fixing means.

[0098] The space between the tubular housing 60 and the insulator 10 may be filled with an insulating gas, such as sulfur hexafluoride or SF6 gas.

[0099] Furthermore, the bare conductor 70 is intended to be electrically connected to the electrical conductor 31 of the cable 30 on one side and to electrical equipment (not shown) external to the GIS terminal, such as a power transformer, overhead medium or high voltage lines, etc., on the other side.

[0100] The insulator 10 may include a metal insert 14 configured to be electrically connected to the electrical conductor 31 of the cable 30 on one side and to be electrically connected to the bare conductor 70 on the other side. In other words, the metal insert 14 is intended to establish an electrical connection between the cable 30 and the bare conductor 70. In the embodiment shown, the metal insert 14 is provided with a plug element 71 intended to be fixed to the electrical conductor 31 of the cable 30. In this particular embodiment, the metal insert 14 includes a housing configured to receive the plug element 71, and the metal insert 14 is electrically connected to the electrical conductor 31 of the cable 30 via the plug element 71.

[0101] According to the terminal assembly of the present disclosure, it is also possible to configure Figure 7 and Figure 8 Part of a fluid-filled or dry outdoor terminal, respectively, as shown in FIG.

[0102] In particular, as in Figure 7 As can be observed in FIG. 1 , the fluid-filled outdoor terminal further comprises a tubular housing 80 made of an insulating material suitable for housing the insulator 10 and a bare conductor 70 configured to be installed in the tubular housing 80 and electrically connected to the electrical conductor 31 of the cable.

[0103] The tubular housing 80 can be fixed to a flange 61 provided at the second longitudinal end 13 of the insulator by screws 62 or other fixing means. The space between the tubular housing 80 and the insulator can be filled with a fluid, such as silicone oil or SF6 gas, or with a gel, such as silicone, or with a foam, such as polyurethane foam.

[0104] In the illustrated embodiment, the insulator 10 includes a metal insert 14 that is configured to be electrically connected to the electrical conductor 31 of the cable 30 on one side and to the bare conductor 70 on the other side. Figure 7 In the embodiment, the metal insert 14 is provided with a plug element 71 intended to be fixed to the electrical conductor 31 of the cable 30. The metal insert 14 includes a housing configured to receive the plug element 71, and the metal insert 14 is electrically connected to the electrical conductor 31 of the cable 30 through the plug element 71.

[0105] like Figure 8 As can be observed in FIG. 1 , the dry outdoor terminal also includes a bare conductor 70 configured to be installed in the insulator 10 and electrically connected to the electrical conductor 31 of the cable. The insulator 10 includes a metal insert 14 configured to be electrically connected to the electrical conductor 31 of the cable 30 on one side and to be electrically connected to the bare conductor 70 on the other side. Figure 8 , the metal insert 14 is provided with plug elements 71a, 71b intended to be fixed to the electric conductor 31 of the cable 30. The metal insert 14 includes a housing configured to receive the plug element 71, and the metal insert 14 is electrically connected to the electric conductor 31 of the cable 30 through the plug element 71. The cable termination system 100 according to the present disclosure includes the cable 30 and a terminal (GIS or outdoor) coupled to the cable 30. In particular, the electric field control element 50 is assembled to the cable 30, and the insulator 10 is coupled to the electric field control element 50 in a manner of at least partially surrounding the electric field control element 50.

Claims

1. An insulator (10) for a cable terminal assembly, comprising: - a body (11) of insulating material extending along a longitudinal direction X and having a cylindrically symmetrical shape with a first longitudinal end (12) and a second longitudinal end (13) opposite one another, said body (11) being suitable for being fitted on a cable; - an annular electrode (20) made of a mesh of conductive material integrated in said body (11) at a predetermined distance from said first end (12), said annular electrode (20) being configured to be connected to an external voltage detector.

2. The insulator (10) according to claim 1, wherein: The annular electrode (20) is provided with at least one protrusion (21), which is made of a conductive material and extends from the annular electrode (20) to the outer surface of the body (11).

3. An insulator (10) according to claim 1 or 2, wherein: The at least one projection (21) has a threaded bushing (24) made of an electrically conductive material at its free end.

4. The insulator (10) according to one or more of the preceding claims, wherein: The annular electrode (20) comprises an annular metal mesh plate (22).

5. Insulator (10) according to one or more of the preceding claims, wherein: The annular electrode (20) has a folded edge (23) proximally relative to the first end (12).

6. Insulator (10) according to one or more of the preceding claims, wherein: The web of conductive material has a covering factor between 0.2 and 0.

5.

7. Insulator (10) according to one or more of the preceding claims, wherein: The main body (11) is made of epoxy resin.

8. The insulator (10) of claim 7, comprising a metal insert (14) configured to be electrically connected to an exposed electrical conductor of the cable on one side and to a bare conductor on the other side.

9. A terminal assembly for a cable (30), comprising: - an electric field control element (50) intended to be fitted to said cable (30); - Insulator (10) according to one or more of the preceding claims, wherein said insulator (10) is intended to be coupled to said electric field control element (50) in such a way as to at least partially surround said electric field control element (50).

10. Gas insulated substation terminal, including: - A terminal assembly according to claim 8; - a tubular housing (60) adapted to be fixed to said insulator and to house said insulator (10); - a bare conductor (70) configured to be mounted within the tubular housing and electrically connected to the electrical conductor (31) of the cable (30).

11. A cable termination system (100), comprising: - a cable (30); - an electric field control element (50) mounted to said cable (30); - Insulator (10) according to one or more of claims 1 to 8, wherein the insulator (10) is coupled to the electric field control element (50) in such a way that it at least partially surrounds the electric field control element (50).

12. The cable termination system (100) according to claim 11, wherein: The annular electrode (20) and the cable electrical conductor (31) are electrically insulated from each other, thereby realizing a first capacitor, wherein a voltage detector (40) is electrically connected to the annular electrode (20), the voltage detector (40) comprising a second capacitor connected in series with the first capacitor.

13. The cable termination system (100) according to claim 11, wherein: The ring electrode (20) and the cable electrical conductor are electrically insulated from each other to realize a first capacitor, the insulator (10) comprises a second capacitor connected in series to the first capacitor, and wherein a voltage detector (40) is electrically connected to the second capacitor.

14. The cable termination system (100) according to claim 12 or 13, wherein: The voltage detector is configured to detect whether the cable electrical conductor (31) is undervoltage and / or the presence of partial discharges on the cable or the cable termination system.

15. A method for monitoring a cable termination assembly, comprising: - connecting the annular electrode (20) of the insulator (10) for a cable termination assembly according to one or more of claims 1 to 8 applied on a cable (30) to a voltage detector; - detecting a voltage signal using the voltage detector (40); - Analyzing the voltage signal by the voltage detector (40) and determining whether the cable has insufficient voltage and / or detecting the presence of partial discharge.

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