WO2021061153A1

WO2021061153A1 - Capacitive voltage sensor

Info

Publication number: WO2021061153A1
Application number: PCT/US2019/053525
Authority: WO
Inventors: Alberto Bauer
Original assignee: G & W Electric Company
Priority date: 2019-09-27
Filing date: 2019-09-27
Publication date: 2021-04-01

Abstract

A capacitive voltage sensor includes a first component extending along a longitudinal axis and configured as an electrode, and a second component extending along the longitudinal axis and surrounding at least a portion of the first component. The second component includes a ring and a plurality of fingers extending from the ring, each finger of the plurality of fingers separated from an adjacent finger of the plurality of fingers by a respective gap. The capacitive voltage sensor further includes a dielectric material molded over the first component and the second component such that the dielectric material at least partially encapsulates the first component and the second component. The second component includes an inner layer made of an insulating material and an outer layer made of a conductive material. The inner layer faces the first component. The first component and the outer layer of the second component define a capacitive coupling.

Description

CAPACITIVE VOLTAGE SENSOR

FIELD OF THE DISCLOSURE

[0001] The present disclosure relates to voltage sensors, and more particularly to capacitive voltage sensors.

BACKGROUND

[0002] Currently known capacitive voltage sensors have several drawbacks.

[0003] For example, typical capacitive voltage sensors may include a resin dielectric material arranged around the components. During manufacturing, this resin dielectric material is typically molded over the components of the sensor. This process requires costly equipment, including costly fixtures to ensure that components of the sensors do not move relative to one another before the resin dielectric material cures.

[0004] The resin dielectric material used in typical capacitive voltage sensors may also lead to defects that can cause undesirable partial discharges. For example, during molding the resin dielectric material is susceptible to the formation of air bubbles. The resin dielectric material may not fully adhere to the elements of the capacitive voltage sensor, and the resin material may gradually detach from the elements of the capacitive voltage sensor over time, particularly when the capacitive sensor is exposed to an environment in which the operating temperature varies between hot and cold temperatures.

SUMMARY

[0005] The present disclosure provides, in one aspect, a capacitive voltage sensor including a first component extending along a longitudinal axis, the first component configured as an electrode, and a second component extending along the longitudinal axis and surrounding at least a portion of the first component. The second component includes a ring and a plurality of fingers extending from the ring, each finger of the plurality of fingers separated from an adjacent finger of the plurality of fingers by a respective gap. The capacitive voltage sensor further includes a dielectric material molded over the first component and the second component such that the dielectric material at least partially encapsulates the first component and the second component. The second component includes an inner layer made of an insulating material and an outer layer made of a conductive material. The inner layer faces the first component. The first component and the outer layer of the second component define a capacitive coupling.

[0006] Other features and aspects of the disclosure will become apparent by consideration of the following detailed description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0007] FIG. 1 shows schematically and in axial section a capacitive voltage sensor according to an embodiment of the present disclosure.

[0008] FIGS. 2 and 2A are top perspective exploded views of the capacitive voltage sensor of FIG. 1.

[0009] FIGS. 3 and 3 A are bottom perspective exploded views of the capacitive voltage sensor of FIG. 1.

[0010] FIG. 4 is a perspective view illustrating a component of the capacitive voltage sensor of FIG. 1.

[0011] FIG. 5 is a cross-sectional view illustrating another component of the capacitive voltage sensor of FIG. 1.

[0012] Before any embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. DETAILED DESCRIPTION

[0013] FIG. 1 illustrates a capacitive electric voltage sensor S.300 having a main body S.300b that extends along a longitudinal axis YS300, from a first axial end YaS300 (e.g., a proximal end) to a second axial end YbS300 (e.g., a distal end). In the illustrated embodiment, the longitudinal axis YS300 is a central axis of the sensor S.300, and the sensor S.300 has rotational symmetry about the longitudinal axis YS300.

[0014] The illustrated capacitive voltage sensor S.300 includes a first component 310, a second component 320, and a mass of dielectric insulating material 330. The first component 310 and the second component 320 may be made of electrically conductive material (e.g., copper). The first component 310 may be configured as an electrode, and more particularly as a source electrode able to emit an electric field. Alternatively, the first component 310 may be configured as a sensor electrode able to detect an electric field. The second component 320 may be configured as an electrode, and more particularly as a source electrode able to emit an electric field. Alternatively, the second component 320 may be configured as a sensor electrode able to detect an electric field.

[0015] The first component 310 is positioned proximate the first axial end YaS300 and extends towards the distal end YbS300 of the sensor S.300. In the illustrated embodiment, the first component 310 has a generally cylindrical shape that is elongated along a central axis Y310. The central axis Y310 of the first component 310 is preferably coaxial with respect to the axis YS300 of the sensor S.300. The first component 310 has a proximal end 310. v adjacent the first axial end YaS300 of the sensor S.300 and a distal end 310. d opposite the proximal end 310. v. In the illustrated embodiment, the distal end 310. d of the first component 310 is nearer the second axial end YbS300 of the sensor S.300 than the first axial end YaS300. The first component 310 may include a blind axial hole 3 lO.h extending from the proximal end 3 lO.v toward the distal end 310.d.

[0016] With continued reference to FIG. 1, the second component 320 is positioned proximate the second axial end YbS300 of the sensor S.300 and has a tubular shape, extending along a longitudinal axis Y320 that is arranged coaxially with respect to the axis YS300 of the sensor S300 and with axis Y310 of the first component 310. The second component 320 is positioned around the first component 310, and more particularly around the distal portion 3 lO.d of the first component 310. The second component 320 includes a proximal end 320. v and a distal end 320. d opposite the proximal end 320.v. The proximal end 320.v is nearer the first axial end YaS300 of the sensor S.300 than the distal end 310. d of the first component 310 such that the first component 310 and the second component 320 at least partially overlap along the longitudinal axes Y310, Y320, YS300.

[0017] In the illustrated embodiment, the mass of dielectric insulating material 330 at least partially encapsulates the first component 310 and the second component 320. In addition, the dielectric insulating material 330 is disposed between the first component 310 and the second component 320. In some embodiments, the dielectric insulating material 330 may be molded over the first component 310 and the second component 320. In some embodiments, the dielectric insulating material 330 may be made of a moldable dielectric resin (e.g., a dielectric epoxy resin).

[0018] The illustrated second component 320 includes a plurality of first elements or fingers 321a, 321b, etc., which are each axially elongated along respective longitudinal axes 321a.y, 321b. y, etc. In the illustrated embodiment, the longitudinal axes 321a.y, 321b. y, etc. are parallel to the axes YS300, Y310, Y320, but the axes 321a.y, 321b.y, etc. may vary in orientation in other embodiments. Each of the first elements, 321a, 321b, etc., has a respective free end 321a.v and a respective base end 321a.d. The first elements 321a, 321b, etc., are arranged circumferentially side by side to each other in order to configure a tubular body 320 and are supported at their base ends 321a.d, 321b. d, etc. in a cantilevered manner. Specifically, the base ends 321a. d, 321b. d, etc. are connected to each other by a circular ring 323 which acts as a support foot. In the illustrated embodiment, the first elements 321a, 321b, etc. are integrally formed with the circular ring 323.

[0019] Preferably, the first elements 321a, 321b, etc. are circumferentially spaced from each other, in order to form gaps or openings 322 between adjacent elements 321a, 321b, etc. The openings 322 have a width such as to allow the resin 330 in its liquid/uncured state (i.e. during the pouring/molding of the resin 330) to flow between the openings 322 from the outside towards the inside of the second component 320, as well as from the inside towards the outside of the second component 320 to at least partially encapsulate the components 310 and 320 without gaps or discontinuities that could lead to undesirable partial discharges or otherwise negatively affect performance of the sensor S.300. The openings 322 may also facilitate forming the second component 320 into its tubular shape. For example, in some embodiments, the second component 320 may be formed as a flat sheet and subsequently bent into the shape illustrated in FIGS. 1-3 A.

[0020] In addition, the respective free ends 321a.v, 321b.v, etc. are free to move and/or flex during the molding and solidification of the resin 330 used for forming the mass of dielectric material 330. This construction advantageously allows the respective free ends 321a.v, 321b. c, etc. to follow thermal expansions and/or contractions of the resin 330 during molding and cooling phases.

[0021] With reference to FIG. 4, the first elements 321a, 321b, etc. may include a first layer or inner layer 324 made of insulating material configured to form a self-supporting structure and a second layer 325 made of conductive material applied to the outer surface of the first layer 324 (the terms “inner” and “outer” used hererin with reference to the tubular shape of second component 320 as illustrated in FIGS. 1-3 A). In some embodiments, the second layer 325 may be thinner than the first layer 324. For example, the second layer 325 may be coated on the first layer 324. The second layer 325 of conductive material is able to form a second electrode 325 for the capacitive sensor S.300. In some embodiments, the second component 320 may be formed from a copper-plated base, such as a single-sided copper plated printed circuit board.

[0022] Referring to FIGS. 3A and 5, in some embodiments, the capacitive voltage sensor S.300 may further include a third component 350, which in the illustrated embodiment has a disc shape. The third component 350 extends across an interior of the second component 320 generally transverse to the longitudinal axes Y310, Y320, YS300. The third component 350 may be positioned adjacent the distal end 320. d of the second component 320. For example, the third component 350 may be positioned within the circular ring 323 in order to stabilize and/or brace the tubular shape of the second component 320. In some embodiments, the third component 350 may be partially or entirely made of a conductive material and configured to function as an electrode and, more particularly, as a source electrode able to emit an electric field. Alternatively, the third component 350 may be configured as an electrode sensor able to detect an electric field, the third component 350 may be solely a structural component (e.g., made of an insulating material).

[0023] The third component 350 is preferably provided with through openings or slots 356, which have a width sufficient to allow the resin 330, in its liquid/uncured state, (i.e. during the pouring/molding of the resin 330), to flow between the openings 356 from the outside towards the inside and/or from the inside towards the outside of the second disk-shaped body 350. The openings 356 thus improve the flow of resin 330 during molding to allow the resin 330 to at least partially encapsulate the components 310, 320 and 350.

[0024] With reference to FIG. 5, in some embodiments, the third component 350 may include a first layer or inner layer 354 made of insulating material configured to form a self- supporting structure and a second layer 355 made of conductive material applied on the outer surface of the first layer 354 (the term “inner” used with reference to the assembly of the third component 350 with the second component 320 as illustrated in FIG. 1). In some embodiments, the second layer 355 may be thinner than the first layer 354. For example, the second layer 355 may be coated on the first layer 354. The second layer 355 of conductive material is preferably configured to perform the function of electrode. In some embodiments, the third component 350 may be formed from a copper-plated base, such as a single-sided copper plated printed circuit board.

[0025] Referring to FIG. 1, in some embodiments, the layer of conductive material 355 of the third component 350 is electrically isolated from the layer of conductive material 325 of the second component 320 (e.g., by the layer of insulating material 324). In other embodiments, the layer of conductive material 355 may be electrically connected with the layer of conductive material 325. For example, in such embodiments, a portion of the layer of insulating material 324 may be removed, or conductive material may extend across the insulating layer 324 to electrically connect the conductive layers 325, 355.

[0026] In some embodiments, the outer edge 351 of the third component 350 can be joined or coupled to the inner periphery of the tubular ring 323 in order to form a non-deformable self- supporting structure. For example, with reference to FIGS. 1, 2 and 3, the second component 320 having a tubular shape and the third component 350 having a disc-like shape are coupled together to form an assembly having a shape of a cup, in which the first elements 321a, 321b, etc. and the ring 323 of the second component 320 form the axially-extending sidewall of the cup, and the third component 350 forms the bottom portion or base of the cup, extending generally transverse to the sidewall.

[0027] The capacitive sensor S.300 may provide a first and second operative configurations.

[0028] For example, in the first operating configuration, the first component 310 may act as a source electrode able to emit an electric field, and the second component 320, and more particularly the outer conductive layer 325, (which forms a capacitive coupling with the first component 310) may act as an electric field sensor electrode suitable for detecting the electric field emitted by the first component 310. A controller or measuring device may be coupled to the second component 320 in order to determine the voltage of the first component 310 based on the detected electric field. In some embodiments, the outer conductive layer 355 of the third component 350 may alternatively or additionally act as the electric field sensor, and the controller or measuring device may alternatively or additionally be coupled to the third component 350.

[0029] In the second operating configuration, the second component 320 and, more particularly, the outer conductive layer 325 may act as the source electrode, and the first component 310 may act the electric field sensor able to detect the electric field emitted by the second component 320. A controller or measuring device may be coupled to the first component 310 in order to determine the voltage of the second component 320 based on the detected electric field.

[0030] Various features of the disclosure are set forth in the following claims.

Claims

CLAIMS What is claimed is:

1. A capacitive voltage sensor comprising: a first component extending along a longitudinal axis, the first component configured as an electrode; a second component extending along the longitudinal axis and surrounding at least a portion of the first component, the second component including a ring and a plurality of fingers extending from the ring, each finger of the plurality of fingers separated from an adjacent finger of the plurality of fingers by a respective gap; and a dielectric material molded over the first component and the second component such that the dielectric material at least partially encapsulates the first component and the second component, wherein the second component includes an inner layer made of an insulating material and an outer layer made of a conductive material, the inner layer facing the first component, and wherein the first component and the outer layer of the second component define a capacitive coupling.

2. The capacitive voltage sensor according to claim 1, wherein the first component is a source electrode configured to emit an electric field, and wherein the second component is configured to detect the electric field emitted by the first component.

3. The capacitive voltage sensor according to claim 1, wherein the second component is a source electrode configured to emit an electric field, and wherein the first component is configured to detect the electric field emitted by the second component.

4. The capacitive voltage sensor according to any of claims 1-3, wherein the plurality of fingers extend from the ring parallel to the longitudinal axis.

5. The capacitive voltage sensor according to any of claims 1-4, further comprising a third component extending across an interior of the second component.

6. The capacitive voltage sensor according to claim 5, wherein the third component is shaped as a disc.

7. The capacitive voltage sensor according to claim 5 or 6, wherein the third component is positioned within the ring.

8. The capacitive voltage sensor according to any of claims 5-7, wherein the ring is coupled to an external perimeter of the third component.

9. The capacitive voltage sensor according to any of claims 5-8, wherein the third component includes an inner layer made of an insulating material and an outer layer made of a conductive material.

10. The capacitive voltage sensor according to claim 9, wherein the outer layer of the third component is electrically connected to the outer layer of the second component.

11. The capacitive voltage sensor according to claim 9, wherein the outer layer of the third component is electrically isolated from the outer layer of the second component.

12. The capacitive voltage sensor according to any of claims 5-11, wherein the third component includes a plurality of openings, and wherein the plurality of openings is configured such that the dielectric material may flow through the plurality of openings during molding.

13. The capacitive voltage sensor according to any of claims 1-12, wherein the second component has a generally tubular shape.

14. The capacitive voltage sensor according to any of claims 1-13, wherein the plurality of fingers is integrally formed with the ring.

15. The capacitive voltage sensor according to any of claims 1-14, wherein the plurality of fingers is configured to flex during molding of the dielectric material.

16. The capacitive voltage sensor according to any of claims 1-15, wherein each respective gap is sized such that the dielectric material may flow through the gaps between adjacent fingers during molding.