Gas-tight compartment and optical voltage sensor with coated electro-optic crystal

Patent metadata

Field	Value
Publication number	US-10416198-B2
Application number	US-201715708968-A
Country	US
Kind code	B2
Filing date	Sep 19, 2017
Priority date	Mar 19, 2015
Publication date	Sep 17, 2019
Grant date	Sep 17, 2019

Abstract

The invention relates to an assembly of a gas-tight compartment and an optical voltage sensor that further comprises a module. The module comprises an electro-optic crystal and electrodes, wherein the electro-optic crystal is the only element of the module to mechanically connect the two electrodes and to bridge the potentials of the two electrodes. The assembly is particuarly suited to measure direct current voltages.

First claim

The invention claimed is:

1. An assembly, comprising an optical voltage sensor and a gas-tight compartment,
the optical voltage sensor comprising a module, with the module comprising first and second electrodes, for applying a potential difference defining the voltage to be measured, and an electro-optic crystal having a first facet electrically connected to the first electrode and a second facet electrically connected to the second electrode, with the gas-tight compartment and the module designed so that the module is mounted in the gas-tight compartment,
wherein the electro-optic crystal is the only element of the module that mechanically connects the two electrodes and bridges the potentials of the two electrodes with the first and second facet of the electro-optic crystal being coated, partially or completely, with electrically conductive layers that are transparent at both facets, or are transparent at one facet and reflective at the other facet,
wherein surface parts of the electro-optic crystal exposed to a voltage potential drop when a voltage is applied to the module are coated partially or completely with a layer having a moderate electrical conductivity, which is larger than the conductivity of the electro-optic crystal and is smaller than the conductivity of the electrically conductive layers at the first and second facets.

2. The assembly of claim 1 , wherein the module does not comprise an insulating tube or an insulator with a bore, which surrounds the electro-optic crystal.

3. The assembly of claim 1 , wherein the gas-tight compartment does not comprise an insulating tube or an insulator with a bore, which bridges the potentials of the two electrodes and surrounds the electro-optic crystal along its full length, when the module is mounted in the gas-tight compartment and a potential difference is applied to the electrodes.

4. The assembly of claim 1 , wherein the gas-tight compartment comprises a first outer electrode, shaped to fit the first electrode of the module, and a second outer electrode, shaped to fit the second electrode of the module.

5. The assembly of claim 4 , wherein at least one electrode of the module is connectable to the corresponding outer electrode, the module being a plug-in module.

6. The assembly of claim 4 , wherein the first outer electrode is electrically connected to a conductor guided into the gas-tight compartment through an insulating wall.

7. The assembly of claim 4 , wherein the second outer electrode is electrically connected with conducting walls of the gas-tight compartment.

8. The assembly of claim 1 , wherein any portion of the gas-tight compartment bridging the potential of the electrodes are in a distance to the electro-optic crystal exceeding the length of the electro-optic crystal, when the module is mounted in the gas-tight compartment and a potential difference is applied to the electrodes.

9. The assembly of claim 1 , wherein the module has a longitudinal axis, a lateral extension of each of the first and second electrodes of the module exceeding the extension of the first and second facets corresponding thereto at least by a factor of two.

10. The assembly of claim 1 , wherein portions of the gas-tight compartment are exposed at its outside to ambient air.

11. The assembly of claim 1 , wherein probe light propagates along a light path at least once through the electro-optic crystal from one of the first and second facets to the other of the first and second facets, and the crystal class of the electro-optic crystal and its crystal orientation with respect to the light path are chosen so that an electro-optical phase shift is proportional to a line integral of the electric field along the light path through the electro-optic crystal.

12. The assembly of claim 1 , with at least one base element being attached to at least one of the facets.

13. The assembly of claim 12 , with at least one of the at least one base element being of a material of lower elasto-optic coefficient than the electro-optic crystal.

14. The assembly of claim 13 , with the at least one of the at least one base element being of a material of lower elasto-optic coefficient than the electro-optic crystal.

15. The assembly of claim 13 , with the at least one of the at least one base element being of BK7 glass, flint glass, or fused silica.

16. The assembly of claim 13 , with at least one of the at least one base element having surfaces that are partially or completely coated with conductive layers that are in electrical contact with the first or second facet corresponding thereto.

17. The assembly of claim 12 , with the at least one base element having a higher fracture toughness than the electro-optic crystal and/or having a thermal expansion coefficient within a percentage range of [50%, 200%] of the thermal expansion coefficient of the electro-optic crystal.

18. The assembly of claim 12 , with at least one optical arrangement attached to the at least one base element, the optical arrangement comprising at least one optical element selected from the group consisting of: a Faraday rotator, a collimating lens, a graded index lens, a phase retarder, a mirror, a retroreflector, a beamsplitter, a polarizer, a polarizing beam splitter, an optical fiber, or combinations thereof.

19. The assembly of claim 12 , with an elastic fixation between the at least one base element and the electrode that is electrically connected with the first or second facet corresponding thereto, with the elastic fixation comprising at least one element selected from the group consisting of: o-ring, conductive o-ring, elastic adhesive, conductive elastic adhesive, silicone adhesive, mechanical spring, and combinations thereof.

20. The assembly of claim 12 , with a contact area between the electro-optic crystal and the at least one base element being smaller than the area of the first or second facet corresponding thereto of the electro-optic crystal.

21. The assembly of claim 12 , wherein an electrically conductive path is formed between at least one of the electrodes and the corresponding first or second facet via a conductive wire, conductive adhesive, or a conductive o-ring connecting the at least one electrode with a base element that is in electrical contact with the corresponding facet, wherein the conductive wire, the conductive adhesive, or the conductive o-ring reside(s) on the field-averted side of the electrode, when the module is mounted within the gas-tight compartment and a potential difference is applied to the electrodes.

22. The assembly of claim 1 , for measuring a direct current (DC) voltage, a high direct current (DC) voltage, an alternating current (AC) voltage, a high alternating current (AC) voltage, voltages larger than 50 kV, or a combination thereof.

23. The assembly of claim 1 , being incorporated into or attached to a gas-insulated switchgear.

24. The assembly of claim 1 , with the gas-tight compartment being filled with gas, an insulation gas, a dielectric insulation medium, SF 6 , N 2 , CO 2 , or a gas mixture.

25. The assembly of claim 24 , with the surface parts of the electro-optic crystal exposed to the voltage potential drop when the module is mounted in the gas-tight compartment and the voltage is applied to the first and second electrodes, being in direct contact with the medium or gas inside the gas-tight compartment.

26. The assembly of claim 24 , with the surface of the electro

Assignees

• Abb Schweiz Ag

Inventors

• Marchese Sergio Vincenzo
• Gu Xun
• Büyükkavir Burak
• Bohnert Klaus
• Erford Tobias

Classifications

• G01R15/242 Primary

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