Dual voltage capacitive sensor

Abstract

Some embodiments provide a capacitive voltage sensor device including an electrical insulator; an elongated conductor at least partially embedded in the insulator; a first floating sensor electrode embedded in the insulator capacitively coupled to the elongated conductor and configured to provide a first output representative of a voltage of the elongated conductor; and a second floating sensor electrode embedded in the insulator capacitively coupled to the elongated conductor and configured to provide a second output representative of the voltage of the elongated conductor and configured to shield the first floating sensor electrode from electric fields that can come from sources outside the capacitive voltage sensor device. A capacitor can be embedded in the insulator and electrically connected with the first sensor electrode to form a capacitive voltage divider that provides the first output. The first output can provide an accurate LPVT output, and the second output can provide an output for a voltage presence indication system (VPIS) or a voltage detection indication system (VDIS).

Description

Technical Field

[0001] This disclosure relates to voltage sensing in power distribution systems, and more specifically to capacitive voltage sensors, some embodiments of which are particularly suitable for metering and / or protection and voltage presence indication in high voltage (HV) and / or medium voltage (MV) environments, such as in MV switchgear, control equipment and power transformers. Background Technology

[0002] Capacitive voltage sensors have been implemented in various components of power transmission and distribution systems. For example, in medium-voltage distribution systems, capacitive voltage sensors have been implemented as stand-alone capacitive voltage transformers (sometimes called capacitive low-power voltage transformers (LPVTs)) for voltage measurement for metering and / or protection (e.g., for protective relays). Capacitive sensors (e.g., configured as capacitive voltage dividers) have been incorporated into components such as bushings, insulators, and T-connectors, such as those used in MV switchgear, control equipment, and power transformers.

[0003] Designing capacitive sensors capable of providing the desired and / or required reliable and accurate voltage measurements (e.g., amplitude and phase) under variations in the monitored voltage (e.g., to provide linearity) and sensor temperature (e.g., due to temperature variations caused by external environmental factors and / or the monitored conductor current), as well as under stray high electric fields (e.g., due to adjacent phases) and potentially other sources of electromagnetic noise, remains technically challenging. Some known approaches attempting to address these challenges include, for example, sensor designs employing electrically grounded shielding (e.g., a Faraday cage) and / or external compensation (e.g., based on voltage measurements based on sensor temperature and / or apparent measurements).

[0004] The development and deployment of smart grids have further increased the demand for accurate capacitive sensors (e.g., IEC accuracy class 1, or perhaps 0.5 or 0.2 in some applications) for use throughout the distribution network, such as in secondary substations. To facilitate smart grid deployment, these capacitive sensors should be compact (e.g., to be fitted within available space in existing switchgear, control equipment, or power transformers) and preferably be implementable as standard-sized components (e.g., sleeves) that can easily replace existing components that do not contain sensors. The numerous smart sensors required for smart grids also create a specific need for accurate capacitive sensors that can be manufactured cost-effectively.

[0005] Therefore, there is still a need for improved capacitive voltage sensors that are well-suited to provide accurate voltage measurements (e.g., for protection or metering, such as smart metering sensors that may be needed to implement smart grid functions), are preferably well-suited for use in existing power distribution equipment, such as switchgear, control equipment, power transformers, and / or are preferably suitable for cost-effective manufacturing. Summary of the Invention

[0006] This disclosure describes various illustrative embodiments of a capacitive voltage sensor device, including several embodiments comprising: a capacitive voltage sensor device including an electrical insulator; an elongated conductor at least partially embedded in the insulator; a first floating sensor electrode embedded in the insulator, capacitively coupled to the elongated conductor and configured to provide a first output representing a voltage of the elongated conductor; and a second floating sensor electrode embedded in the insulator, capacitively coupled to the elongated conductor and configured to provide a second output representing a voltage of the elongated conductor, and configured to shield the first floating sensor electrode from electric fields that may originate from sources outside the capacitive voltage sensor device. A capacitor may be embedded in the insulator and electrically connected to the first electrical sensor to form a capacitive voltage divider providing the first output. In some embodiments, the first output provides a precise LPVT output and the second output provides a VPIS or VDIS output. Some of these embodiments are not only well-suited for providing accurate voltage measurements, but also, at least in which a separate grounded shielding electrode embedded within the capacitive voltage sensor device can be excluded, are also suitable for providing a compact and cost-effective sensor.

[0007] According to some embodiments, a capacitive voltage sensor device includes an electrical insulator (e.g., comprising epoxy resin) having an outer surface; an electrical conductor at least partially embedded in the insulator; a first terminal configured to electrically connect the electrical conductor to an external conductor to be sensed; a first conductive sensor electrode disposed in the electrical insulator between the electrical conductor and the outer surface of the electrical insulator, wherein the first conductive sensor electrode is electrically floated and capacitively coupled to the elongated electrical conductor; a second conductive sensor electrode disposed in the electrical insulator between the first conductive sensor electrode and the outer surface of the electrical insulator, wherein the second conductive sensor electrode is electrically floated and capacitively coupled to the electrical conductor and the first conductive sensor electrode, respectively; a first output terminal on the electrical insulator electrically coupled to the first conductive sensor electrode to provide a first output signal representing the voltage of the electrical conductor; a second output terminal on the electrical insulator electrically coupled to the second conductive sensor electrode to provide a second output signal representing the voltage of the electrical conductor; and a third terminal on the electrical insulator configured to be electrically connected to a reference potential.

[0008] In some embodiments, the capacitive voltage sensor may preferably further include a capacitor disposed within the electrical insulator and configured to electrically connect the first conductive sensor electrode to the third terminal, thereby forming a capacitive voltage divider. The capacitor may be disposed on or within a printed circuit board mounted on the second conductive sensor.

[0009] The second output terminal and the third terminal can be configured as the inner conductor and outer shielding conductor of the electrical connector connected to the printed circuit board, respectively.

[0010] In some embodiments, the electrical conductor is elongated and extends longitudinally within an insulator, wherein the first terminal is integral with a first longitudinal end of the electrical conductor exposed through the insulator.

[0011] In some embodiments, the second conductive electrode may be configured as a cylindrical housing coaxially disposed with the elongated electrical conductor and extending longitudinally along a second length, thereby defining an internal volume between the electrical conductor and the second conductive electrode, wherein the first sensor electrode is entirely disposed within the internal volume and has a longitudinal extent smaller than the second length. Furthermore, the first conductive electrode may be configured as a cylindrical housing coaxially disposed with and radially surrounded by the second conductive electrode. A corresponding cylindrical segment at each longitudinal end of the second conductive electrode may be separated from the electrical conductor by a corresponding portion of an insulator, which does not include a portion of the first conductive electrode, wherein the corresponding cylindrical segment is separated by a middle segment of the second conductive electrode having a second length and radially surrounding the first conductive electrode.

[0012] In some embodiments, the capacitive voltage sensor device is configured as a sleeve in which a first terminal is integral with a first longitudinal end of an electrical conductor exposed through an insulator, and wherein a second longitudinal end of the electrical conductor opposite to the first longitudinal end is exposed through an insulator and includes a second terminal configured to electrically connect the electrical conductor to a second external conductor to provide current conduction between the first and second external conductors via the electrical conductor.

[0013] In some embodiments, the first terminal is configured to be connected to a busbar, and the capacitive voltage sensor is configured as a low-power voltage transformer, a cylindrical insulator, or a bus support.

[0014] In some embodiments, the second sensor electrode has a capacitor configured to be coupled to a voltage presence indication system (e.g., VPIS or VDIS).

[0015] Some embodiments may also include a temperature sensor embedded in an electrical insulator, and a second connector disposed on the electrical insulator and electrically connected to the temperature sensor. The temperature sensor may be mounted on a second printed circuit board.

[0016] Those skilled in the art will recognize that the foregoing brief description and the following description with reference to the accompanying drawings are illustrations and explanations of some embodiments of the invention, and are neither intended to represent nor encompass all subjects and embodiments within the scope of the invention, nor are they intended to limit or characterize the invention, nor to limit the advantages that can be achieved by the embodiments of the invention, nor are they intended to require the invention to provide one or more of the advantages described herein with reference to certain embodiments. Therefore, the accompanying drawings, which are incorporated herein by reference and constitute a part thereof, illustrate some embodiments of the invention and, together with the detailed description, serve to explain the principles of some embodiments of the invention. Attached Figure Description

[0017] Considering the following description of non-limiting and non-exclusive embodiments in conjunction with the accompanying drawings, aspects, features, and advantages of some embodiments of the invention will be understood and will become more apparent in terms of structure and operation, in which the same reference numerals denote the same or similar parts, wherein:

[0018] Figure 1A A top view of a dual-voltage capacitive sensor configured as a sleeve according to some embodiments is schematically illustrated;

[0019] Figure 1B The illustration schematically depicts the view, according to some embodiments, in the direction indicated by reference B-B' in Figure A. Figure 1A The cross-sectional view of the sleeve shown;

[0020] Figure 1C The illustration schematically depicts the view, according to some embodiments, in the direction indicated by reference C-C' in Figure A. Figure 1A The cross-sectional view of the sleeve shown;

[0021] Figure 2A and Figure 2B The illustrations depict the respective corresponding embodiments according to some examples. Figure 1B and Figure 1C The view is a cross-sectional view used for illustrative alternative embodiments;

[0022] Figure 3 Similar to some embodiments are shown. Figure 1C However, the cross-sectional view is used for illustrative alternative embodiments;

[0023] Figure 4 The illustration depicts corresponding to some embodiments. Figure 1B The view is a cross-sectional view used to illustrate an alternative implementation.

[0024] Figure 5 The illustration schematically depicts what can be embodied according to some embodiments. Figure 1A-Illustrative capacitor model of a capacitive voltage sensor in an illustrative sleeve of C;

[0025] Figure 6 The illustration schematically depicts configurations for operation in a device or system according to some embodiments. Figure 5 A model of capacitive voltage sensor;

[0026] Figure 7A and Figure 7B These are illustrative schematic orthogonal cross-sectional views of an illustrative capacitive voltage sensor according to some embodiments; and

[0027] Figure 8A and Figure 8B These are illustrative schematic orthogonal cross-sectional views of illustrative alternative embodiments of a capacitive voltage sensor according to some embodiments. Detailed Implementation

[0028] Throughout the specification and claims, unless the context clearly specifies otherwise, the following terms shall have at least the meaning explicitly associated herein. The meanings defined below are not intended to limit the terms, but merely to provide illustrative examples.

[0029] The phrase “in one embodiment” as used herein does not necessarily refer to the same embodiment, although it may. Furthermore, the meanings of “a,” “an,” and “the” include plural reference; thus, for example, “embodiment” is not limited to a single embodiment but refers to one or more embodiments. Similarly, the phrase “one embodiment” does not necessarily refer to the same embodiment and is not limited to a single embodiment. As used herein, the term “or” is an inclusive “or” operator and is equivalent to the term “and / or” unless the context clearly specifies otherwise. The term “based on” is not exclusive but allows for basing on other factors not described unless the context clearly specifies otherwise.

[0030] Additionally, as used herein, unless the context explicitly specifies otherwise, the term "connection" refers to a direct or indirect connection via one or more intermediate components, and in some cases may also indicate or include an electrical connection, such as a conductive connection, a capacitive connection, and / or an inductive connection. Furthermore, "conductive connection," "electrical connection," and "electrical link," and similar variations, respectively refer to a connection via one or more intermediate components that allow energy transfer via conductive current, which may include direct current and alternating current, while "capacitive connection" refers to an electrostatic connection via one or more dielectric media and possibly also via one or more intermediate conductors (e.g., via a series of capacitive components), which allows energy transfer via displacement current rather than direct current between the connected components. Those skilled in the art will further understand that elements may be intentionally or unintentionally (e.g., parasiticly) capacitively connected, and in some cases, an element referred to as capacitively connected may refer to an intentional capacitive connection. Additionally, those skilled in the art will also understand that, in some cases, the term "connection" may refer to an operational connection made through direct and / or indirect connections. For example, a conductor referred to as being connected to a relay (e.g., an electrode or wire, etc.) can refer to a conductor operable to selectively operate the relay (e.g., switch / trigger), whether the conductor is indirectly (e.g., via intermediate passive and / or active circuits, etc.) and / or directly connected to the relay.

[0031] Furthermore, it will be understood that, with reference to the various views shown in the accompanying drawings, terms such as “top,” “upper,” “bottom,” “lower,” and “side” used herein are merely for convenience and ease of reference and do not otherwise impose any limitation on the overall design and / or curves of the dual-voltage capacitive sensor according to this disclosure.

[0032] Furthermore, for ease of reference, as used herein, the term "sensor electrode" refers to a conductive electrode having sufficient conductivity to be used as a capacitor electrode in the context of this invention. Similarly, for ease of reference, the terms "conductive" or "conductor" as used herein refer to electrical conductivity or electrical conduction (rather than, for example, thermal conductivity), unless the context clearly specifies otherwise. In this regard, it will be further understood that, as used herein, the term "conductor" refers to the electrical conductivity of a material or component (e.g., as opposed to an insulator or dielectric), rather than whether the material or component is actively conducting current or even configured to conduct current, although some conductors may be configured to conduct current. Thus, for example, a central conductive bar of a bushing (configured to connect and conduct current between a cable supplied by a medium or high voltage source and another electrical component) may be referred to as a conductor, regardless of whether the central conductive bar conducts current or is otherwise connected to the cable and the electrical component. Similarly, however, for example, the central conductive rod may also be referred to as a conductor in other components (e.g., LPVT or insulator), wherein the central conductive rod is not configured to conduct current through it, but is configured only to serve as an electrode (e.g., configured to be electrically connected to a bus provided by a medium or high voltage power supply without conducting current provided by the medium or high voltage power supply).

[0033] For clarity, although the terms “medium voltage” and “high voltage” may have different definitions in various standards, or may otherwise be understood to have different meanings, as used herein, “medium voltage” may refer to an alternating current (AC) root mean square (rms) voltage in the range of approximately 1 kV to approximately 52 kV, or a direct current (DC) voltage in the range of approximately 1.5 kV to approximately 75 kV; while high voltage may refer to an alternating current (AC) voltage greater than approximately 52 kV, or a direct current (DC) voltage greater than approximately 75 kV. However, as will be understood from the following disclosure, embodiments of this disclosure are not limited to specific voltages or voltage ranges.

[0034] As will be further understood from the following description, some embodiments provide a capacitive voltage sensor device comprising (i) an elongated conductor configured to be electrically connected to an external conductor (e.g., a medium-voltage conductor, such as a bus or input feeder of an MV switchgear, control device, or power transformer), (ii) a first floating sensor electrode configured to provide a capacitive voltage divider LPVT output signal (e.g., for metering and / or protection) representing the voltage of the elongated conductor (i.e., representing the voltage of the external conductor when the elongated conductor is connected to the external conductor), and (ii) a second floating sensor electrode configured to provide a voltage presence indication output signal (e.g., for a voltage presence indicator system (VPIS), such as according to IEC 61243-5 and / or IEC 62271 206 and / or IEC 62271-713 standards) representing the presence of voltage on the elongated conductor (e.g., the presence of voltage on the external conductor when the sensor device is connected to the external conductor), wherein the first floating sensor electrode is disposed between a portion of the elongated conductor and the second floating sensor electrode. First and second floating sensor electrodes, along with at least a portion of an elongated conductor, are embedded in an insulator. The insulator includes connector terminals on its outer surface, to which the first and second floating sensor electrodes are respectively connected to provide a corresponding LPVT output signal and a voltage presence indication output signal. In some embodiments, the second floating sensor is configured as a cylindrical housing surrounding at least a portion of the elongated conductor and the inserted first floating sensor electrode; in other embodiments, it may also be configured as a cylindrical housing.

[0035] Figure 1A -C schematically depicts a top view and cross-sectional view of an illustrative sleeve 100 including multiple capacitive voltage sensors according to some embodiments of the present disclosure. Although this illustrative embodiment relates to a sleeve, those skilled in the art will understand, in view of the present disclosure, that embodiments of the dual-voltage capacitive sensors according to the present disclosure are not limited to sleeves, and include, but are not limited to, alternative and additional implementations, such as separable connectors (e.g., T-body connectors, elbow connectors), reverse plugs of T-body connectors, cylindrical insulators, and independent low-power voltage transformers (LPVTs; for example, which may be electrically connected to a switchgear bus).

[0036] More specifically, Figure 1A This is a top view of sleeve 100. Figure 1B It is based on the reference arrow B-B' ( Figure 1A The illustrative cross-sectional view of sleeve 100 in the direction indicated by the arrow B-B' is shown, with reference arrow B-B' entering a plane containing axis 101 and perpendicular to reference arrow B-B'. Figure 1C It is based on the reference arrow C-C' ( Figure 1AThe cross-sectional view of sleeve 100 in the direction indicated by the arrow C-C' is shown, with reference arrow C-C' entering the plane containing axis 101 and perpendicular to reference arrow C-C'.

[0037] like Figure 1A As shown in -C, in some embodiments, the illustrative sleeve 100 may have a generally cylindrical shape about an axis 101 and includes the following: an insulator 102 having an externally threaded portion 103 for mounting the sleeve; a conductor 104 extending between opposite longitudinal ends of the sleeve and including openings 103 and 105 for connection to an external conductor; a cylindrical housing-shaped sensor electrode 106 spaced apart from and generally coaxial with the conductor 104; a cylindrical housing-shaped sensor electrode 108 spaced apart from and surrounding the sensor electrode 106 and generally coaxial with it; a printed circuit board (PCB) 110 mounted on the sensor electrode 108 via fasteners 113; and a solder joint 111 formed on the PCB 110 for electrical connection to one end of a conductor 119 (e.g., an insulated wire), the conductor 119 passing through an aperture or opening in the sensor electrode 108 or through the PCB. PCB 110 has an aperture or opening and is electrically connected (e.g., soldered) to the opposite ends of sensor electrode 106; capacitors 112 and 114 (e.g., thin-film chip capacitors) connected in parallel or series, mounted on PCB 110 with their first common terminal electrically connected to solder joint 111 (and thus to sensor 106); connector 107, mounted on PCB 110 with a portion exposed to the outside of insulator 102, its internal conductor electrically connected to solder joint 111 (and thus to sensor electrode 106 and to the first terminal of connected capacitors 112 and 114), and its external shielding conductor electrically connected to the second terminal of connected capacitors 112 and 114; and connector 109, electrically connected to sensor electrode 108 with a portion exposed to the outside of insulator 102. The external shielding conductor of connector 107 corresponds to a third terminal.

[0038] Thus, as further described below in the various components of sleeve 100, sensor electrode 106 and conductor 104 effectively form a capacitor connected in series with capacitors 112 and 114 in parallel or series, such that the signal provided across the inner and outer conductors of connector 107 is a voltage-divided representation of the voltage of conductor 104. Furthermore, sensor electrode 108 and conductor 104 effectively form a capacitor, and sensor electrode 108 is configured to (i) provide an output signal at connector 109 representing a separate measurement of the voltage of conductor 104 (corresponding to its capacitive connection with conductor 104), and (ii) shield electrode 106 from external electric fields. Such external electric fields may include, for example, near-field and / or quasi-static or low-frequency fields (e.g., possibly generated by a nearby phase), and high-frequency electromagnetic fields. This shielding of floating sensor electrode 108 helps electrode sensor 106 accurately sense the electric field generated by conductor 104, thereby facilitating accurate measurement of the voltage of conductor 104 (e.g., as required by metering and / or protection; e.g., IEC accuracy class 0.5).

[0039] As shown, the floating sensor electrode 108 not only shields electrode 106 from external electric fields but also provides an additional and independent output signal (at connector 107) representing the voltage across conductor 104. This independent output signal can be used, for example, for voltage presence indication (e.g., for safety reasons, such as according to IEC 62271 206). Therefore, in various embodiments, capacitive voltage sensors (e.g., sleeve 100) according to some embodiments of this disclosure can provide both VPIS and accurate LPVT output signals without requiring a dedicated electric field shield (e.g., a grounded shield surrounding the LPVT sensor) embedded within the sleeve.

[0040] Refer again Figure 1A-1C It is understood that in some embodiments, such as the illustrative sleeve 100 described herein, the insulator 102 may substantially enclose the sensor electrodes 106 and 108 (e.g., surrounding the electrodes (with a height indicated by arrow L2) comprising an annular region between sensors 106 and 108), except for the portion of sensor electrode 108 on which connector 109 is mounted). Furthermore, the insulator 102 may substantially enclose the conductor 104 (e.g., surrounding the conductor 104, except for the end portion of the conductor 104 which may be engaged at the outer end of the sleeve 100 for connection to an external conductor), thereby at least enclosing the portion of conductor 104 facing sensors 106 and 108. The insulator 102 may be composed of one or more dielectric materials, such as epoxy resin (e.g., (Including, for example, alicyclic epoxy resins), polyurethane resins, PTFE resins (e.g., (e.g., ceramic or other suitable insulating materials). In some embodiments, the sleeve 100 can be formed by performing a molding process (e.g., gravity casting or automated gelling (APG)) to... Figure 1A and 1B The component shown is encapsulated or substantially encapsulated in insulator 102.

[0041] In some embodiments, the insulator 102 may comprise a common dielectric constant throughout, while in some embodiments, the insulator 102 may comprise multiple regions having corresponding dielectric constants (e.g., different regions may comprise different compositions of the same or similar materials, and / or different regions may comprise different materials). As a non-limiting example, in some embodiments, the insulator 102 may be formed to provide an annular region (with a length indicated by arrow L2 and a thickness indicated by arrow d3) between sensors 106 and 108, whose dielectric constant is different from (e.g., lower than) the dielectric constant of the rest of the insulator 102. Alternatively or additionally, in some embodiments, the insulator 102 may be formed to provide at least a portion (with a length indicated by arrows L1 and L3) of an annular region between sensor electrode 108 and conductor 104, whose dielectric constant is different from the dielectric constant of the majority of the insulator 102 and is different from or substantially the same as the dielectric constant of the annular region between sensors 106 and 108.

[0042] Furthermore, those skilled in the art will understand that additional components may be embedded in the insulator 102 in various alternative embodiments. As a non-limiting example, in some embodiments, the insulator 102 may also enclose the thermal sensor as well as substantially enclose additional output connectors (e.g., similar to connectors 107 or 109) to provide output from the thermal sensor.

[0043] For example, Figure 2A and Figure 2B The diagrams depict the corresponding figures. Figure 1B and Figure 1C The figure shows a view, but is a cross-sectional view for an illustrative alternative embodiment, which includes a thermistor 202 mounted on a printed circuit board 204, which may be mounted on sensor electrodes 108 (e.g., similar to PCB 110). A connector 206 electrically connected to the thermistor 202 may be mounted on PCB 204 and extends externally to insulator 102 to provide a connection from the thermistor to excitation and voltage readout circuitry. As shown, in this illustrative embodiment, connector 109' corresponds to... Figure 1A-C connector 109, but with its azimuth offset by 90 degrees. Alternatively, connectors 107, 109, and 204 may be spaced approximately equidistant around the sleeve circumference at the same longitudinal position (e.g., spaced at 120-degree azimuths), and / or one or more connectors may be longitudinally displaced at different azimuths. In addition to temperature monitoring, in some embodiments, temperature measurement signals (e.g., if desired) may be used to compensate (e.g., based on pre-calibration) for temperature-dependent variations in the capacitive voltage divider transfer function. However, according to some embodiments (e.g.) Figure 1A - (illustrative embodiment of -C) Even for precise voltage measurements, such compensation may not be necessary because capacitors 112 and 114 are preferably embedded within insulator 102, and their temperature coefficient is sufficiently comparable to that of sensor electrode 106.

[0044] Although preferably embedded within insulator 102, in some alternative embodiments, capacitors 112 and 114 (or, for example, their equivalent single discrete capacitors) may be implemented outside insulator 102, for example in voltage measurement circuitry, or alternatively in an external module that may be removably connected directly to connector 107 and may include additional connectors for coupling to voltage measurement circuitry. Furthermore, although capacitors 112 and 114 may be implemented as surface-mount thin-film chip capacitors mounted on a PCB (as described above), alternative embodiments may employ, for example, one or more capacitors embedded in the PCB, or capacitors embedded in insulator 102 but not mounted on the printed circuit board.

[0045] As described, in some embodiments, conductor 104 may include openings 103 and 105 for connection to external conductors, such as input feed cables and electrical equipment in devices (e.g., switching devices, control devices, or power transformers) in which sleeve 100 is disposed. Thus, openings 103 and 105 (and, for example, end portions around insulating housing 102) can be configured according to various interface connections. For example, in some embodiments, openings 103 and / or 105 may be threaded for connection by bolts or threaded pins. Although conductor 104 can generally be implemented with a circular cross-section and a generally uniform diameter at approximately its central portion as shown, some embodiments according to this disclosure may include alternative shapes (e.g., an elliptical cross-section instead of a circle along its length, multiple longitudinal portions with different cross-sectional areas, etc.).

[0046] In some embodiments, for example Figure 1A and Figure 1BIn the illustrative embodiment, sensor electrodes 106 and 108 can be configured as substantially coaxial cylindrical conductors (e.g., they can be referred to as hollow cylindrical electrodes or cylindrical housing electrodes). The longitudinal ends of sensor electrodes 106 and 108 can be rounded, for example, by folding at their ends. Figure 1B and Figure 1C The dimensions indicated by arrows L1, L2, L3, d1, and d2 can be designed, for example, based on the desired or required capacitive connections between electrodes 106 and 108 and with conductor 104 to provide output at connectors 107 and 109 with the required electrical characteristics (e.g., voltage division, accuracy, and / or capacitance; as will be further understood in the following disclosure), reliability (e.g., with respect to leakage current, dielectric breakdown, etc.), and adequate shielding from external electric fields through electrodes 108 and 106.

[0047] One or both of the sensor electrodes 106 and 108 (whether configured as a cylindrical housing or other geometry) can be formed as an open mesh or sieve structure, which not only facilitates the insertion of the conductor 119 through the electrode 108 but also improves sleeve reliability and manufacturing yield. For example, during the molding process, such an open mesh or sieve structure can readily allow the material used to form the insulator 102 (e.g., epoxy resin) to flow freely through the sensor electrodes, thereby promoting conformal coverage. In some embodiments, the mesh or sieve structure can be formed by coating a plastic mesh with a conductor or by molding a conductive plastic including a conductive filler (e.g., nickel-coated graphite filler in nylon). In some embodiments, for example, one or more of the electrodes 106 and 108 can be formed as a continuous conductive sheet structure (e.g., formed from a metal sheet) that can be patterned, machined, or etched to include one or more orifices and / or grooves formed therein. The electrodes 106 and 108 can be formed from any of a variety of sufficiently conductive materials, such as aluminum, brass, copper, or other metals or metal alloys.

[0048] Despite Figure 1A In the illustrative embodiment of -C, sensor electrodes 106 and 108 are depicted as having a uniform radius, but in some embodiments, the radius of one or both of electrodes 106 and 108 may vary longitudinally (e.g., at least to some extent monotonically tapering). In some embodiments, electrodes 106 and 108 may have a uniform radius over length L2, while the radius of electrode 108 may vary in regions L1 and L3. In some embodiments, electrode 106, and possibly electrode 108, may not form a complete cylinder around conductor 104. For example, Figure 3 It shows something similar to Figure 1C The cross-sectional view shows that the electrode 106 partially surrounds the conductor 104.

[0049] In some embodiments, sensors 106 and 108 may be formed as an integrated module prior to a molding or casting process for forming insulator 102. For example, as shown in the cross-sectional view of Figure 4 , which corresponds to the illustrative embodiment of Figure 1B , prior to molding to form insulator 102, sensors 106 and 108 may be mechanically coupled by coaxial annular insulating members 302 and 304 (e.g., O-rings such as PTFE O-rings) to form an integrated module that helps maintain the desired spacing between sensors 106 and 108 during a subsequent molding or casting process for forming insulator 102 and sensors 106 and 108 embedded therein. In some embodiments, the pre-formed integrated module of sensors 106 and 108 may include forming an insulating material in the space between sensors 106 and 108 (which corresponds to the region of thickness d3 in Figure 1C ), which allows for further adjustment of the inter-sensor capacitance value and / or the inter-sensor spacing d3 by selecting an inter-sensor dielectric constant that may be different (e.g., potentially lower) than the dielectric constant of the material used to form insulator 102.

[0050] Referring to Figure 1B and Figure 1C , it can be seen that sensor electrode 106 is capacitively coupled directly (i.e., without an intermediate electrode) to conductor 104 via the dielectric material of insulator 102, and sensor electrode 106 and conductor 104 are thus effectively the corresponding electrodes of a capacitor, which for ease of reference is hereinafter referred to as the LPVT sensing capacitor. The LPVT sensing capacitance is proportional to the length L2 shown by arrow L2 (e.g., assuming an ideal cylindrical capacitor; ignoring fringe fields, stray fields, or parasitic fields, etc.). Similarly, in the regions identified by arrows L1 and L3 in Figure 1B , sensor electrode 108 is capacitively coupled directly to conductor 104 via the dielectric material of insulator 102, and sensor electrode 106 and conductor 104 are thus effectively the corresponding electrodes of a capacitor, which is herein referred to as the VPIS / VDIS capacitor (i.e., the VPIS or VDIS capacitor). The VPIS / VDIS capacitance is proportional to the sum of the lengths L1 and L3 shown by arrows L1 and L3. Additionally, sensor electrode 108 is capacitively coupled directly to sensor electrode 106 via the intermediate dielectric material of insulator 102, and sensor electrodes 106 and 108 are thus effectively the corresponding electrodes of a capacitor, which is herein referred to as the bridge capacitor. The bridge capacitance is proportional to the length L2. As is well known to those skilled in the art, each of these cylindrical capacitances is inversely proportional to ln(1 + d / a) (ln(1 + d / a) is approximately d / a since d << a), where a is the radius of conductor 104 and d is the radial spacing between the corresponding electrodes forming the capacitor; i.e., as Figure 1C As shown, for LPVT sensing, VPIS / VDIS and bridge capacitor respectively, d is equal to the distances d1, d2 and d3.

[0051] It should be noted that although sensor electrodes 106 and 108 are capacitively connected to each other (bridge capacitor), they are each capacitively connected to conductor 104. For clarity, as used herein, capacitively connecting (or similarly, “capacitively connected individually”) electrodes 106 and 108 to conductor 104 means that sensor electrode 108 is capacitively connected to conductor 104 via an intermediate dielectric region (excluding the dielectric region through which sensor electrode 106 is capacitively connected to conductor 104), and similarly, that sensor electrode 106 is capacitively connected to conductor 104 via an intermediate dielectric region (excluding the dielectric region through which sensor electrode 108 is capacitively connected to conductor 106).

[0052] As a non-limiting example, and for illustrative purposes only, when using... In some embodiments where a synthetic resin or similar material is used as the insulator 102, the diameter of the conductor 104 in the sensor region may be approximately 20 mm, d1 may be at least 4 mm and preferably at least 8 mm, d3 may be at least about 4 mm and preferably no more than about 12 mm, and each electrode sensor 106 and 108 may have a nominal thickness of 1 mm, corresponding to d2 at least about 8 mm and preferably no more than about 22 mm.

[0053] Now for reference Figure 5 An illustrative capacitive model of a dual-voltage sensor according to this disclosure is shown, which can be embodied in the above reference. Figure 1A -C describes the illustrative sleeve 100 of the embodiment. Thus, Figure 5 The various circuit elements and nodes in the circuit model are composed of Figure 1A -C contains numeric references to the corresponding components. For example, Figure 5 Nodes 106 and 108 in the diagram correspond to sensor electrodes 106 and 108, respectively; node 109 corresponds to connector 109. Figure 5 The region enclosed by element 102 in the diagram corresponds to insulator 102. Figure 5 Conductor 104 is shown as having terminals 403 and 405, which can represent Figure 1A and 1B The end portions of conductor 104 with openings 103 and 105. Terminals 407 and 417 respectively correspond to... Figure 1A and 1B The connector 107 in the middle has an inner conductor and an outer conductor.

[0054] Therefore, terminal 417 corresponds to the third terminal. Thus, it can be understood that the function of the third terminal is to provide a connection of the dual-voltage capacitive sensor to a voltage (e.g., "ground"), which provides a reference potential, for example, for a first output signal representing the voltage of an electrical conductor (provided via the first output terminal).

[0055] Furthermore, based on the foregoing discussion, it can be understood that (i) capacitor C1 represents the LPVT sensing capacitor, corresponding to the capacitive connection between sensor electrode 106 and conductor 104; (ii) capacitor C2 represents the VPIS / VDIS capacitor, corresponding to the capacitive connection between sensor electrode 108 and conductor 104; (iii) capacitor C3 represents the bridge capacitor, corresponding to the capacitive connection between sensor electrodes 106 and 108; and (iv) capacitor C0 is the low-voltage output capacitor of the capacitive voltage divider, for example, corresponding to... Figure 1A The capacitors 112 and 114 are connected in series or in parallel. As a non-limiting example, and for illustrative purposes only, in some embodiments, capacitors C0, C1, C2, and C3 may be designed to have values ​​within the following ranges: C1 may be approximately 10 to 20 pF, C2 may be approximately 10 to 50 pF, C3 may be approximately 65 to 75 pF, and C0 may be approximately 60 to 120 nF.

[0056] As will be understood, in some embodiments, for example, if the dual-voltage capacitive sensor according to this disclosure is implemented as a component not configured to conduct current (e.g., implemented as an insulator instead of a sleeve), one of terminals 403 and 405 can be removed from the model.

[0057] Figure 6 schematically depicted Figure 5 The dual-voltage capacitive sensor of the model, in this illustrative embodiment, is configured to (i) connect an output signal from the VPIS / VDIS capacitor C2 to the VPIS or VDIS circuit 440 representing the voltage across conductor 104, and (ii) connect the output signal (representing the voltage across conductor 104) of a capacitive voltage divider formed by the free LPVT capacitor C1 and the low-voltage output capacitor C0 to a metering circuit and / or a protective relay. As shown, conductor 104 is connected to an AC voltage source 415 via terminal 403. For example, in some embodiments, where the model represents a sleeve in a switching device including a metering circuit and / or a protective relay 430 and a VPIS or VDIS circuit 440, the AC voltage source 415 may represent an input feeder, and terminal 405 may be connected to other switching device electrical components (not shown).

[0058] like Figure 5 As shown in the model, and in Figure 6In the illustrative embodiment, electrode 108 is not grounded or at any other reference potential, but is floating and configured to provide a capacitively coupled output to conductor 104. That is, as described above, sensor electrode 108 is not coupled to any conductor of the dual-voltage capacitive sensor (e.g., sleeve 100) via a low-impedance path, which could be configured to ground or be connected to a reference potential when the dual-voltage capacitive sensor (e.g., embodied in sleeve 100 or other components) is mounted for intended operation. Additionally, as described above but not reflected in the circuit model, electrode 108 is also configured to shield electrode 106 from electric fields external to the capacitive sensor represented by the model.

[0059] Therefore, it can be understood that, by Figure 5 The model represents and can be embodied as Figure 1A The dual-voltage capacitive sensor (or, in other embodiments, such as an insulator) of sleeve 100 is configured such that sensor electrodes 106 and 108 are at their respective floating potentials and non-conductively connected to electrodes, terminals, or other conductors of sleeve 100, which are configured to be conductively connected (directly or indirectly) to ground potential or other reference potential via a low-impedance path (e.g., when the sleeve is mounted for operation, such as in a switchgear, controlgear, or power transformer). For example, connector 109 is configured to conductively connect the floating potential of sensor electrode 108 (e.g., via a shielded or unshielded single conductor wire that is plugged into or screwed into connector 109) to external circuitry (i.e., outside of sleeve 100), such as the external circuitry of a voltage presence indicator system (VPIS). In other words, connector 109 is configured to capacitively connect the voltage on conductor 104 to external circuitry via a VPIS capacitor formed by conductor 104 and sensor electrode 108.

[0060] Similarly, connector 107 is configured to conductively connect the floating potential of sensor electrode 106 to external circuitry, such as protection and / or metering circuitry. According to this illustrative embodiment, connector 107 may be configured as an electronic connector (e.g., a miniature BNC female connector) having, as described above, an external shielding conductor conductively connected to a second common terminal of capacitors 112 and 114 connected in parallel, the first common terminal of capacitors 112 and 114 being conductively connected to an internal conductor of connector 107 and sensor electrode 106.

[0061] As described above, embodiments of the capacitive voltage sensor according to this disclosure are not limited to sleeves, such as the illustrative sleeve embodiments discussed above. For example, Figure 7A and Figure 7BAn illustrative embodiment of a capacitive voltage sensor 700 is illustrated, which can be implemented as a dedicated sensor (e.g., LPVT and VPIS / VDIS) or as a cylindrical insulator or busbar support, for example, for use in MV switchgear, control equipment, or power transformers. The capacitive voltage sensor 700 is generally cylindrical. Figure 7A and 7B It is a cross-sectional view of an orthogonal plane containing the central longitudinal axis.

[0062] As shown in the figure, the capacitive voltage sensor 700 includes an insulator 702, which includes a shed 721; an elongated conductor 704 extending axially along the central axis of the insulator 702 and including an opening 703 for connection to an external conductor (e.g., a busbar); a cylindrical housing-shaped sensor electrode 706 spaced apart from and substantially coaxial with the conductor 704; a cylindrical housing-shaped sensor electrode 708 spaced apart from and surrounding the sensor electrode 706, and substantially coaxial with it; a printed circuit board (PCB) 710 mounted on a conductive base 722; a solder joint 711 formed on the PCB 710 for electrical connection to one end of a conductor 719 (e.g., an insulated wire), the conductor 719 passing through an aperture or opening in the conductive base 722 and through an aperture or opening in the PCB 710, and having an electrical connection (e.g., solder) to the opposite end of the sensor electrode 706; and a capacitor 712 (e.g., a thin-film chip capacitor) mounted on the PCB. A connector 707 is mounted on the PCB 710 and a portion of it is exposed outside the insulator 702. Its internal conductor is conductively connected to the solder joint 711 (and thus to the first terminal of the sensor electrode 106 and capacitor 712), and its external shielding conductor is conductively connected to the second terminal of capacitor 712. A connector 709 is electrically connected to the sensor electrode 708 via a conductor 724 (e.g., an insulated wire) and a portion of it is exposed outside the insulator 702. An opening 713 in the insulator 702 is configured to connect the conductive base 722 to a reference potential (e.g., ground), while in some embodiments, it provides mechanical fixation of the base of the capacitive voltage sensor.

[0063] In view of this disclosure, it will be understood that, with Figure 1AThe components of the capacitive voltage sensor 100 in the illustrative embodiment of -C, which generally correspond to the components of the capacitive voltage sensor 700, may have similar features and modifications. Furthermore, given this disclosure, those skilled in the art will further understand that various alternative embodiments of the capacitive voltage sensor 700 can be implemented. For example, alternatively, the PCB 710 (and the capacitor 712 mounted thereon) can be mounted to the sensor electrode 708, and conductors (e.g., wires) can be added to electrically connect the PCB to the connector 707. Additionally or alternatively, the connector 707 may be positioned closer to the periphery (e.g., a location similar to connector 707) rather than along the central axis.

[0064] Figure 8A and Figure 8B A cross-sectional view of an illustrative alternative embodiment of a capacitive voltage sensor 800 is shown, which generally corresponds to a capacitive voltage sensor 700, except that the conductive base 722 is removed and the external (e.g., VPIS / VDIS) sensor electrode is modified to have a closed conductive surface at its lower longitudinal end. More specifically, the sensor electrode 808 is generally a cylindrical housing with a closed lower longitudinal end (e.g., using the same conductive material structure as the cylindrical sidewall portion, which could be a conductive mesh). In other words, the sensor electrode 808 is generally cup-shaped. The closed lower portion of the electrode 808 provides sufficient shielding for the sensor electrode 706 and the conductor (electrode) 704 from external electric fields, such as those generated from the medium-voltage conductor electrically connected to the capacitive voltage sensor. Therefore, the conductive base 722 can be removed because its function is contained within the sensor electrode 808. In this regard, it should be noted that in order to ensure sufficient electric field shielding for the conductive base 722, it must typically be arranged very close to the lower portion of the VPIS / VDIS sensor electrode 708 (e.g., less than about 4 mm). Therefore, eliminating it in the capacitive voltage sensor 800 not only reduces manufacturing costs but also simplifies manufacturing, improves manufacturing yield, and increases lifespan and reliability.

[0065] In light of the foregoing, it can be understood that capacitive voltage sensors 700 and 800, like capacitive voltage sensor 100, can provide VPIS and accurate LPVT output signals (i.e., at connectors 709 and 707, respectively) without the need to embed a dedicated electric field shield (e.g., grounding shield) around the LPVT sensor. Furthermore, capacitive voltage sensor 800 does not require any additional electric field shield (e.g., conductive base 722).

[0066] While the foregoing description of illustrative embodiments of the invention and its various illustrative variations and features provides numerous details, these enabling details should not be construed as limiting the scope of the invention, and it will be readily understood by those skilled in the art that various modifications, adaptations, variations, omissions, additions, and equivalent implementations can be made to the invention without departing from its scope and without diminishing its incidental advantages. For example, the structure and / or function of a component may be combined into a single component or may be divided into two or more components. Furthermore, it is particularly conceivable that specific features described separately or as part of an embodiment may be combined with other separately described features or portions of other embodiments. It should also be noted that terms and expressions have been used as descriptive terms rather than restrictive terms. It is not intended to use these terms or expressions to exclude any equivalents of the features shown and described or portions thereof. Additionally, the invention may be practiced without necessarily providing one or more advantages described herein or otherwise understood in light of this disclosure and / or that may be realized in some embodiments thereof. Therefore, it is intended that the invention be limited to the disclosed embodiments, but should be defined according to the claims based on this disclosure, as such claims may be presented herein and / or in any patent application that claims priority to this disclosure, is based on this disclosure, and / or corresponds to this disclosure.

Claims

1. A capacitive voltage sensor, comprising: An electrical insulator with an outer surface; An electrical conductor that is at least partially embedded in the electrical insulator; The first terminal is configured to electrically connect the electrical conductor to a first external conductor to be sensed; A first conductive sensor electrode is disposed in the electrical insulator between the electrical conductor and the outer surface of the electrical insulator, wherein the first conductive sensor electrode is electrically floating and capacitively connected to the elongated electrical conductor; A second conductive sensor electrode is disposed in the electrical insulator between the first conductive sensor electrode and the outer surface of the electrical insulator, such that the first conductive sensor electrode is disposed between the electrical conductor and the second conductive sensor electrode, wherein the second conductive sensor electrode is electrically floating and capacitively connected to the electrical conductor and the first conductive sensor electrode respectively. A first output terminal is located on the electrical insulator and electrically connected to the first conductive sensor electrode to provide a first output signal representing the voltage of the electrical conductor. as well as A second output terminal is located on the electrical insulator and electrically connected to the second conductive sensor electrode to provide a second output signal representing the voltage of the electrical conductor. as well as The third terminal is on the electrical insulator and configured to be electrically connected to the reference potential.

2. The capacitive voltage sensor of claim 1 further includes a capacitor disposed within the electrical insulator and configured to electrically connect the first conductive sensor electrode to the third terminal, thereby forming a capacitive voltage divider.

3. The capacitive voltage sensor as claimed in claim 2, wherein the capacitor is disposed on or in a printed circuit board, and the printed circuit board is mounted on the second conductive sensor electrode.

4. The capacitive voltage sensor of claim 3, wherein the second output terminal and the third terminal are respectively configured as the inner conductor and the outer shielding conductor of an electrical connector connected to the printed circuit board.

5. The capacitive voltage sensor as claimed in any of the preceding claims, wherein the electrical conductor is elongated and extends longitudinally within the electrical insulator, and wherein the first terminal is integral with a first longitudinal end of the electrical conductor exposed through the electrical insulator.

6. The capacitive voltage sensor of claim 5, wherein the second conductive sensor electrode is configured as a cylindrical housing, which is coaxially disposed with the elongated electrical conductor and extends longitudinally in a second length, thereby defining an internal volume between the electrical conductor and the second conductive sensor electrode, wherein the first conductive sensor electrode is completely disposed within the internal volume and has a longitudinal extent smaller than the second length.

7. The capacitive voltage sensor of claim 6, wherein the first conductive sensor electrode is configured as a cylindrical housing, which is coaxially disposed with and radially surrounded by the second conductive sensor electrode.

8. The capacitive voltage sensor of claim 7, wherein a corresponding cylindrical segment at each longitudinal end of the second conductive sensor electrode is separated from the electrical conductor by a corresponding portion of the electrical insulator, the corresponding portion not including a portion of the first conductive sensor electrode, wherein the corresponding cylindrical segment is separated by a middle segment of the second conductive sensor electrode, the second conductive sensor electrode having the second length and radially surrounding the first conductive sensor electrode.

9. The capacitive voltage sensor of claim 5, wherein the capacitive voltage sensor device is configured as a sleeve, wherein the first terminal is integral with a first longitudinal end of the electrical conductor exposed through the electrical insulator, and wherein a second longitudinal end of the electrical conductor opposite to the first longitudinal end is exposed through the electrical insulator and includes a second terminal configured to electrically connect the electrical conductor to a second external conductor to provide current conduction between the first external conductor and the second external conductor via the electrical conductor.

10. The capacitive voltage sensor of claim 5, wherein the first terminal is configured to be connected to a bus, and the capacitive voltage sensor is configured as a low-power voltage transformer, a cylindrical insulator, or a bus support.

11. The capacitive voltage sensor of claim 1, wherein the second conductive sensor electrode has a capacitor configured to be connected to a voltage presence indication system or a voltage detection indication system.

12. The capacitive voltage sensor of claim 1, wherein the electrical insulator comprises epoxy resin.

13. The capacitive voltage sensor of claim 1, further comprising a temperature sensor embedded in the electrical insulator, and a second connector disposed on the electrical insulator and electrically connected to the temperature sensor.

14. The capacitive voltage sensor of claim 13, wherein the temperature sensor is mounted on the second printed circuit board.

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