High-voltage sensor with axially overlapping electrodes and local field sensors

Patent metadata

Field	Value
Publication number	US-9279834-B2
Application number	US-201213707987-A
Country	US
Kind code	B2
Filing date	Dec 7, 2012
Priority date	Jun 7, 2010
Publication date	Mar 8, 2016
Grant date	Mar 8, 2016

Abstract

A voltage sensor includes an insulator with mutually insulated electrodes embedded therein. The electrodes are coaxial and cylindrical and overlap axially along part of their lengths. They are mutually staggered and control the surfaces of electric equipotential such that there is a substantially homogeneous electric field outside the insulator and a substantially homogeneous but higher field within a sensing cavity within the insulator. A field sensor is arranged within the sensing cavity to locally measure the field. This design allows for the production of compact voltage sensors for high voltage applications.

First claim

What is claimed is:

1. A high-voltage sensor for measuring a voltage between a first contact point and a second contact point, the high-voltage sensor comprising:
an insulator composed of an insulating material extending along an axial direction between the first and second contact points, and including a sensing cavity;
a plurality of conductive electrodes arranged in the insulator, the conductive electrodes being mutually separated by the insulating material and capacitively coupled to each other; and
at least one electric field sensor arranged in the sensing cavity of the insulator, wherein:
for at least part of the conductive electrodes, each conductive electrode axially overlaps at least one other one of the conductive electrodes;
the conductive electrodes are configured to steer an electric field in the sensing cavity so that the electric field has a mean field strength larger than the voltage between the first and second contact points divided by a distance between the first and second contact points;
the at least one electric field sensor is a local electric field sensor configured to measure the field over only part of an axial extension of the sensing cavity,
the high-voltage sensor comprises at least a first primary electrode electrically connected to the first contact point and a second primary electrode electrically connected to the second contact point; and
the conductive electrodes form a capacitive voltage divider between the first and second primary electrodes.

2. The high-voltage sensor of claim 1 , wherein the at least one electric field sensor includes at least one optical sensor configured to introduce a field-dependent phase shift Δφ between a first sensor polarization or sensor mode and a second sensor polarization or sensor mode of light passing through the at least one optical sensor, and
wherein the at least one optical sensor comprises one of:
an electro-optical device with field-dependent birefringence, or a poled waveguide exhibiting a Pockels effect; and
a piezo-electric device and a waveguide carrying at least two modes, the waveguide being connected to the piezo-electric device such that a length of the waveguide is field-dependent.

3. The high-voltage sensor of claim 2 , comprising:
a plurality of the optical sensors arranged optically in series.

4. The high-voltage sensor of claim 2 , comprising:
a control unit configured to determine a voltage from a phase shift between light passing through the at least one optical sensor in the first sensor polarization or sensor mode and light passing through the at least one optical sensor in the second sensor polarization or sensor mode; and
a Faraday rotator arranged between the control unit and the at least one optical sensor, the Faraday rotator configured to cause a nonreciprocal rotation of the light by 45° for each pass.

5. The high-voltage sensor of claim 4 , comprising:
at least one first and at least one second polarization maintaining fiber section arranged optically in series and connected to guide the light between two passes through the Faraday rotator, wherein main axes of the first and second polarization maintaining fibers sections are mutually rotated by 90°.

6. The high-voltage sensor of claim 5 , comprising:
a plurality of sensing modules arranged optically in series, wherein each sensing module comprises at least one of the first and at least one of the second polarization maintaining fiber sections and at least one optical sensor.

7. The high-voltage sensor of claim 2 , comprising:
a polarization maintaining fiber having at least a first polarization mode, wherein the polarization maintaining fiber is connected to the at least one optical sensor such that (i) light passing the at least one optical sensor in the first sensor polarization or sensor mode, and (ii) light passing the at least one optical sensor in the second sensor polarization or sensor mode are both partially coupled into the first polarization mode of the polarization maintaining fiber; and
a detector unit connected to the polarization maintaining fiber, the detector unit comprising at least a first light detector measuring light passing through the first polarization mode of the polarization maintaining fiber.

8. The high-voltage sensor of claim 2 , wherein a temperature derivative of an electro-optic effect of the at least one optical sensor has an opposite sign to a temperature derivative ∂|E z,mean |∂T of a mean absolute value of an axial electrical field component in the at least one optical sensor.

9. The high-voltage sensor of claim 2 , wherein the at least one optical sensor comprises a waveguide.

10. The high-voltage sensor of claim 2 , wherein the at least one optical sensor is of a III-V-semiconductor.

11. The high-voltage sensor of claim 1 , wherein:
the sensing cavity is symmetrical with respect to a reference plane extending perpendicularly to the axial direction; and
a position of the at least one electric field sensor is symmetrical with respect to the reference plane.

12. The high-voltage sensor of claim 1 , wherein:
the sensing cavity is symmetrical with respect to a reference plane extending perpendicularly to the axial direction; and
a plurality of the electric field sensors are arranged symmetrically with respect to the reference plane.

13. An assembly of several high-voltage sensors of claim 1 .

14. The assembly of claim 13 , comprising:
several of the high-voltage sensors arranged in at least one of series and parallel to each other.

15. The assembly of claim 13 , comprising at least one of for the high-voltage sensors:
a common light source; and
a signal processor.

16. The high-voltage sensor of claim 1 , wherein at least one of the conductive electrodes is a shield electrode radially surrounding the sensing cavity.

17. The high-voltage sensor of claim 1 , wherein:
the conducting electrodes comprise a first set of electrodes E 1 i with i=1 . . . N 1 , and a second set of electrodes E 2 i with i=1 . . . N 2 ;
the electrodes E 1 i of the first set are arranged in a first region of the insulator, the first region extending from a reference plane of the sensing cavity to the first contact point;
the electrodes E 2 i of the second set are arranged in a second region of the insulator, the second region extending from the reference plane to the second contact point; and
the reference plane extends radially through the sensing cavity.

18. The high-voltage sensor of claim 17 , wherein a first electrode E 1 1 of the first set forms the first primary electrode, and a first electrode E 2 1 of the second set forms the second primary electrode.

19. The high voltage sensor of claim 17 , wherein:
for each set j of electrodes, the electrodes Ej i and Ej i+1 and axially overlap along an overlapping section; and
in the overlapping section, the electrode Ej i+1 is arranged radially outside from the electrode Ej i .

20. The high-voltage sensor of claim 17 , wherein, for each set j of electrodes:
each electrode has a center end facing the reference plane and a contact end arranged axially opposite to the center end;
the center end of the electrode Ej i+1 is closer to the reference plane than the center end of the electrode Ej i , and the contact end of the electrode Ej i+1 is closer to the reference plane than the contact end of the electrode Ej i ;
the center end of the electrode Ej i+1 has an axial distance Bj i from the center end of the electrode Ej i , and the contact end of

Assignees

• Abb Research Ltd

Inventors

• Eriksson Göran
• Bohnert Klaus
• Marchese Sergio Vincenzo
• Wildermuth Stephan

Classifications

• G01R19/0046 Primary

  characterised by a specific application or detail not covered by any other subgroup of G01R19/00 · CPC title

• G01R15/242 Primary

  based on the Pockels effect, i.e. linear electro-optic effect · CPC title

• G01R15/18 Primary

  using inductive devices, e.g. transformers · CPC title

• G01R19/00

  Arrangements for measuring currents or voltages or for indicating presence or sign thereof (G01R5/00 takes precedence; for measuring bioelectric currents or voltages A61B5/24) · CPC title

• G01R15/14

  Adaptations providing voltage or current isolation, e.g. for high-voltage or high-current networks · CPC title