High-voltage sensor with axially overlapping electrodes

Patent metadata

Field	Value
Publication number	US-9291650-B2
Application number	US-201213707263-A
Country	US
Kind code	B2
Filing date	Dec 6, 2012
Priority date	Jun 7, 2010
Publication date	Mar 22, 2016
Grant date	Mar 22, 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 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 comprising an insulating material extending along an axial direction between the first and the second contact points, the insulator including at least one 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 at least one 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 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 contact point and the second contact point; and
for each sensing cavity, the conductive electrodes include a first set of electrodes in a first region of the insulator that extends from a reference plane of the sensing cavity to the first contact point and a second set of electrodes in a second region of the insulator that extends from the reference plane of the sensing cavity to the second contact point, the reference plane extending radially through the sensing cavity.

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

3. The high-voltage sensor of claim 1 , comprising:
a first primary electrode electrically connected to the first contact point; and
a second primary electrode electrically connected to the second contact point,
wherein the conductive electrodes form a capacitive voltage divider between the first and the second primary electrodes.

4. The high-voltage sensor of claim 3 , wherein the at least one electric field sensor axially overlaps with the first primary electrode and with the second primary electrode.

5. The high-voltage sensor of claim 1 , wherein 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 at least one sensing cavity.

6. The high-voltage sensor of claim 1 , wherein:
the first set of electrodes corresponds to electrodes E 1 i with i=1 . . . N1 and the second set of electrodes corresponds to electrodes E 2 i with i=1 . . . N2.

7. The high-voltage sensor of claim 6 , comprising:
a first primary electrode electrically connected to the first contact point; and
a second primary electrode electrically connected to the second contact point, wherein:
the conductive electrodes form a capacitive voltage divider between the first and the second primary electrodes;
a first electrode of the first set forms the first primary electrode; and
a first electrode of the second set forms the second primary electrode.

8. The high-voltage sensor of claim 6 , wherein, for each set j of conductive electrodes, the conductive electrodes Ej i and Ej i+1 axially overlap along an overlapping section such that, in the overlapping section, the electrode Ej i+1 is arranged radially outside from the electrode Ej i .

9. The high-voltage sensor of claim 6 , wherein, for each set j of conductive electrodes,
each conductive electrode has a center end facing the reference plane and a contact end 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 the electrode Ej i+1 has an axial distance Cj i from the contact end of the electrode Ej i ; and
the electrodes Ej i and Ej i+1 axially overlap between the contact end of the electrode Ej i+1 and the center end of the electrode Ej i .

10. The high-voltage sensor of claim 9 , wherein, for each set j of electrodes, at least one of:
(i) the axial distance Bj i is smaller than the axial distance Cj i ; and
(ii) each set j of electrodes has at least one of a different i-th axial distance Bj i and a different i-th axial distance C 1 i .

11. The high-voltage sensor of claim 9 , wherein, for each set j of electrodes, at least one of:
(i) the axial distances Bj i are substantially equal to a common distance B, and
(ii) the axial distances Cj i are substantially equal to a common distance C.

12. The high-voltage sensor of claim 6 , wherein:
at least one of the conductive electrodes is a shield electrode radially surrounding the at least one sensing cavity; and
the shield electrode axially overlaps with at least one electrode of the first set and at least one electrode of the second set.

13. The high-voltage sensor of claim 6 , wherein at least one of:
the conductive electrodes are arranged non-symmetrically with respect to the reference plane; and
the conductive electrodes are embedded in insulator material including different dielectric constants on either side of the reference plane.

14. The high-voltage sensor of claim 6 , wherein for at least one sensing cavity, the first set of electrodes forms a first capacitance, and the second set of electrodes forms a second capacitance.

15. The high-voltage sensor of claim 14 , wherein at least one of:
the first capacitance and the second capacitance is made larger than any stray capacitance present in a mounted state of the high-voltage sensor; and
a ratio of the first and second capacitances is in the range of 1.1 to 1.5.

16. The high-voltage sensor of claim 14 , wherein for increasing the first capacitance over the second capacitance, at least one of:
the first set of electrodes E 1 i includes i-th electrodes E 1 i having longer axial lengths than the i-th electrodes E 2 i of the second set;
the first set of electrodes E i includes a different number of electrodes than the second set of electrodes E 2 i ;
the first set of electrodes E 1 i includes a different spacing between the electrodes E 1 i as compared to the second set of electrodes E 2 i ;
selected neighbouring electrodes in at least one of the first and second sets are electrically short-circuited; and
the first set of electrodes E 1 i includes insulation material of higher dielectric constant than insulation material of the second set of electrodes E 2 i .

17. The high-voltage sensor of claim 6 , wherein:
the electrodes E 1 i of the first set are equally spaced in the radial direction; and
the electrodes E 2 i of the second set are equally spaced in the radial direction.

18. The high-voltage sensor of claim 6 , wherein the conductive electrodes are arranged symmetrically with respect to the reference plane.

19. The high-voltage sensor of claim 1 , wherein at least part of the conductive electrodes are at least one of (i) substantially cylindrical and (ii) substantially coaxial to each other.

20. The high-voltage sensor of claim 1 , wherein the at least one field sensor includes an optical sensor configured to introduce a field-dependent phase shift between a first polarisation or mode and a second polarization or mode of li

Assignees

• Abb Research Ltd

Inventors

• Wildermuth Stephan
• Bohnert Klaus
• Koch Norbert
• Czyzewski Jan
• Marchese Sergio Vincenzo

Classifications

• G01R15/242 Primary

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

• G01R19/0046 Primary

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

• G01R1/06

  Measuring leads; Measuring probes (G01R19/145, G01R19/165 take precedence) · 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

• G01R15/18 Primary

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