EP4468319A1

EP4468319A1 - Vacuum interrupter

Info

Publication number: EP4468319A1
Application number: EP23174866.6A
Authority: EP
Inventors: Michael Weuffel; Soeren EMLER; Patrick Rumpelt
Original assignee: ABB Schweiz AG
Current assignee: ABB Schweiz AG
Priority date: 2023-05-23
Filing date: 2023-05-23
Publication date: 2024-11-27
Also published as: CN119028756A

Abstract

The present invention relates to a vacuum interrupter (10), comprising:
- a movable contact (50);
- a fixed contact (60);
- a metal shield (70); and
- a conductive lid (20); and
- an isolation part (30);
wherein the metal vapour shield surrounds at least the fixed contact and/or the movable contact;
wherein an outer housing of the vacuum interrupter is at least partially formed from the conductive lid and the isolation part (30); and
wherein a conductive material overlay (40) covers at least part of an outer surface of the outer housing.

Description

FIELD OF THE INVENTION

The present invention relates to a vacuum interrupter in low, or medium, or high voltage switchgear, and a method of manufacturing a vacuum interrupter.

BACKGROUND OF THE INVENTION

Vacuum interrupters (Vls) are often designed to fulfil dielectric ratings in freestanding applications, for example when AC PFW or LI voltages are applied. In this situation, the potential of the metal shield, such as a metal vapour shield, is usually approximately half of the applied total potential, e.g. that being applied to the movable contact for the fixed contact of the VI grounded, along with the corresponding distribution of the electric field inside and outside the VI.
However, when such a VI is placed in a surrounding gas insulated switchgear (GIS) encapsulation, or in the vicinity of other structures that have live, ground or floating potential, the dielectric performance can be influenced and/or affected because the potential distribution of the overall assembly, including the potential distribution of the VI, will change due to capacitive coupling of parts of the VI to other parts or structures different to the VI. Consequently, the distribution of the electric field inside the VI will change and can result in high stressed areas, for example roundings of shields, edges of contact discs etc.
Operation of the VI in such a situation, will lead to capacitive dis-grading of the VI and therefore to a decrease of the dielectric performance of the VI.
Normally, cost intensive bespoke designs are required dependent upon the specific utilisation of the VI to optimise the VI and its electric field distribution and take into account the operational requirements of the VI placed within a GIS encapsulation or in the vicinity of neighbouring equipment.
There is a need to address these issues.

SUMMARY OF THE INVENTION

Therefore, it would be advantageous to have an improved Vacuum Interrupter.
The object of the present invention is solved with the subject matter of the independent claims, wherein further embodiments are incorporated in the dependent claims.
In a first aspect, there is provided a vacuum interrupter, comprising:

a movable contact;
a fixed contact;
a metal shield; and
a conductive lid; and
an isolation part.

The metal shield surrounds at least the fixed contact and/or the movable contact. An outer housing of the vacuum interrupter is at least partially formed from the conductive lid and the isolation part. A conductive material overlay covers at least part of an outer surface of the outer housing.
In an example, the metal shield is a metal vapour shield.
In an example, the metal shield surrounds at least both the fixed contact and the movable contact.
In an example, the vacuum interrupter comprises one or more further metal shields that surround a part of the vacuum interrupter other than the fixed contact and the movable contact.
In an example, the conductive material overlay directly contacts at least part of an outer surface of the isolation part.
In an example, the conductive material overlay directly contacts at least part of an outer surface of the conductive lid.
In an example, the conductive material overlay is electrically connected to the movable contact.
In an example, the conductive material overlay is electrically connected to the fixed contact.
In an example, the conductive material overlay is capacitively coupled to the metal shield.
In an example, the conductive material overlay is galvanically isolated from the metal shield.
In an example, the conductive material overlay comprises a shrinkage tube, applied by shrinking onto the at least part of an outer surface of the outer housing.
In an example, the conductive material overlay comprises a paint or lacquer, applied by spraying, brushing, painting or sprinkling onto the at least part of an outer surface of the outer housing.
In an example, the conductive material overlay comprises a metal coating, applied by plasma coating or sputtering onto the at least part of an outer surface of the outer housing.
In an example, the conductive material overlay comprises a manchette.
In a second aspect, there is provided a low, or medium, or high voltage switchgear comprising a vacuum interrupter according to the first aspect.
In a third aspect, there is provided a method of manufacturing a vacuum interrupter, comprising:

providing a movable contact;
providing a fixed contact;
providing a metal shield that surrounds at least the fixed contact and/or the movable contact;
providing an outer housing of the vacuum interrupter at least partially formed from a conductive lid and an isolation part; and
covering at least part of an outer surface of the outer housing with a conductive material overlay.

In an example, the metal shield is a metal vapour shield.
In an example, the metal shield surrounds at least both the fixed contact and the movable contact.
In an example, the method comprises capacitively coupling the conductive material overlay to the metal shield.
In an example, the method comprises galvanically isolating conductive material overlay from the metal shield.
The above aspect and examples will become apparent from and be elucidated with reference to the embodiments described hereinafter.

BRIEF DESCRIPTION OF THE DRAWINGS

Exemplary embodiments will be described in the following with reference to the following drawing:
Fig. 1 shows a schematic representation of a vacuum interrupter.

DETAILED DESCRIPTION OF EMBODIMENTS

Fig. 1 shows a schematic representation of an example of vacuum interrupter 10.
In an example, vacuum interrupter 10, comprises:

a movable contact 50;
a fixed contact 60;
a metal shield 70; and
a conductive lid 20; and
an isolation part 30.

The metal shield surrounds at least the fixed contact and/or the movable contact. An outer housing of the vacuum interrupter is at least partially formed from the conductive lid and the isolation part 30. A conductive material overlay 40 covers at least part of an outer surface of the outer housing.
That the conductive material overlay covers at least part of an outer surface of the outer housing can mean that the conductive overlay can be slightly spaced from the outer surface of the outer housing and/or there could be another layer between the conductive material overlay and the outer surface of the outer housing. That the conductive material overlay covers at least part of an outer surface of the outer housing can mean that the conductive overlay is in contact with the outer surface of the outer housing.
In an example, the metal shield 70 is a metal vapour shield.
In an example, the metal shield 70 surrounds at least both the fixed contact 50 and the movable contact 60.
Thus, the metal shield 70 can be a metal vapour shield that protects the isolation part 30, for example insulation ceramic or ceramics, from metal vapour. The metal shield can additionally or alternatively be a utilized for electric field distribution control.
In an example, the isolation part comprises at least one insulation ceramic.
According to an example, the conductive material overlay directly contacts at least part of an outer surface of the isolation part.
According to an example, the conductive material overlay directly contacts at least part of an outer surface of the conductive lid. Thus, in Fig. 1 the conductive material overlay 40 is shown slightly spaced from the conductive lid 20, but as detailed here it can be in direct contact with the lid.
According to an example, the conductive material overlay is electrically connected to the movable contact.
According to an example, the conductive material overlay is electrically connected to the fixed contact.
According to an example, the conductive material overlay is capacitively coupled to the metal shield.
According to an example, the conductive material overlay is galvanically isolated from the metal shield.
In an example, the vacuum interrupter comprises one or more further metal shields that surround a part of the vacuum interrupter other than the fixed contact and the movable contact.
In an example, the conductive material overlay is capacitively coupled to the one or more further metal shields.
In an example, the conductive material overlay is galvanically isolated from the one or more further metal vapour shields.
According to an example, the conductive material overlay comprises a shrinkage tube, applied by shrinking onto the at least part of an outer surface of the outer housing.
According to an example, the conductive material overlay comprises a paint or lacquer, applied by spraying, brushing, painting or sprinkling onto the at least part of an outer surface of the outer housing.
According to an example, the conductive material overlay comprises a metal coating, applied by plasma coating or sputtering onto the at least part of an outer surface of the outer housing.
According to an example, the conductive material overlay comprises a manchette.
A low, or medium, or high voltage switchgear comprising a vacuum interrupter can then have one or more of such a vacuum interrupter 10 as described above.
An exemplar means of manufacturing a vacuum interrupter 10, comprises:

providing a movable contact 50;
providing a fixed contact 60;
providing a metal shield 70 surrounds at least the fixed contact and/or the movable contact,
providing an outer housing of the vacuum interrupter at least partially formed from a conductive lid 20 and an isolation part 30; and
covering at least part of an outer surface of the outer housing with a conductive material overlay (40).

In an example, the metal shield is a metal vapour shield.
In an example, the metal shield surrounds at least both the fixed contact and the movable contact.
In an example, the isolation part comprises at least one insulation ceramic.
In an example, the method comprises directly contacting at least part of an outer surface of the isolation part with the conductive material overlay.
In an example, the method comprises directly contacting at least part of an outer surface of the conductive lid with the conductive material overlay.
In an example, the method comprises electrically connecting the conductive material overlay to the movable contact.
In an example, the method comprises electrically connecting the conductive material overlay to the fixed contact.
According to an example, the method comprises capacitively coupling the conductive material overlay to the metal shield.
According to an example, the method comprises galvanically isolating conductive material overlay from the metal shield.
In an example, the method comprises providing one or more further metal shields that surround a part of the vacuum interrupter other than the fixed contact and the movable contact.
In an example, the method comprises capacitively coupling conductive material overlay to the one or more further metal shields.
In an example, the method comprises galvanically isolating the conductive material overlay from the one or more further metal shields.
In an example, the conductive material overlay comprises a shrinkage tube, and the method comprises applying the conductive material overlay by shrinking the shrinkage tube onto the at least part of an outer surface of the outer housing.
In an example, the conductive material overlay comprises a paint or lacquer, and the method comprises applying the conductive material overlay by spraying, brushing, painting or sprinkling the paint or lacquer onto the at least part of an outer surface of the outer housing.
In an example, the conductive material overlay comprises a metal coating, and the method comprises applying the conductive material overlay by plasma coating or sputtering the metal coating onto the at least part of an outer surface of the outer housing.
In an example, the conductive material overlay comprises a manchette, and the method comprises applying the conductive material overlay by applying the manchette around the at least part of an outer surface of the outer housing.
Thus, the inventors realised that a new design of vacuum interrupter could be provided for capacitive grading of the shield potential, that differs to existing designs of Vls in that the new VI described has a conductive element (conductive material overlay) arranged at the outer side surface of the VI, the conductive element connected to one electrode of the VI (fixed or movable contact) and capacitively coupled to a metal shield, that can be a metal vapour shield of the VI and galvanically isolated from the metal shield..
In the new VI deign, the shield potential can be effectively controlled and problems caused by known resistive connections to the metal (vapour) shield can be avoided. The resistance of the conductive element is not critical; it can be a good (low resistance) conductor.
In the new design, the other terminal (fixed/movable contact) of the VI is isolated from the conductive element. Also, the conductive element does not need to extend along the whole length of the outer side surface of the VI.
Continuing with Fig. 1, instead of the costly design changes of the VI and space consuming additional grading electrodes, as shown the new design utilises a simplified, electrically conductive part (conductive material overlay) directly attached to an outer surface of the VI. This conductive part (conductive material overlay) can be a coating, painting or a strip applied on the VI outer surface. As an alternative, and overlaid manchette directly attached to the VI outer surface can be used.
The application of such an electrically conductive part (conductive material overlay) can be seen as a modular, specific, cost-effective add-on feature, with a design that depends on the individual application of the VI.
The additional electrically conductive part (conductive material overlay) leads to a different capacitive coupling of the metal (vapour) shield to the surrounding electrodes, so that the potential distribution inside the VI is again made symmetric, and thus the electric field stress correspondingly is locally reduced. Due to this, the VI can withstand high dielectric stress and dielectric ratings, for example inside the GIS.
Thus, in summary the new design involves a partial coverage of a VI on its outer surface with an electrically conductive material (conductive material overlay), in order to capacitively grade the potential of the metal (vapour) shield inside the VI. Features can be:
The electrically conductive medium (conductive material overlay) is directly applied on the surface of the isolating parts (i.e. the ceramics) of the VI, it can be also applied onto the surface of the conductive parts of the VI (i.e. the VI lids).
The electrically conductive medium (conductive material overlay) can be a shrinkage tube, applied by shrinking onto the outer VI surface.
The electrically conductive medium (conductive material overlay) can be a paint or lacquer, applied by spraying, brushing, painting or sprinkling.
The electrically conductive medium (conductive material overlay) can be a metal coating, applied by e.g. plasma coating or sputtering.
The electrically conductive medium (conductive material overlay) can be a manchette, applied by putting-over, sleeve, shrinkage, gluing, and other attaching methods.
The electrically conductive medium is electrically connected with moving or fixed contact of the VI, i.e. having the potential of the moving or fixed contact.
The VI, which incorporates the above mentioned electrically conductive medium , (conductive material overlay) can be covered by an additional insulating material (e.g. silicone embedding), to give additional outer dielectric strength and mechanical protection.
The application of the electrically conductive medium (conductive material overlay) can be seen as application specific as well as phase specific (in multi-phase system, e.g. 3-phase system). As an example, in a freestanding application the VI can be used without the (conductive material overlay) whereas in an application inside of a GIS, the (conductive material overlay) is utilized with the VI. Due to this, a reduced number of VI variants are needed, where a basic VI design can be used with/without the conductive material overlay.
The medium, conductive material overlay for example in the form of a manchette or other alternative embodiments, can be pre-manufactured to allow an easy and cost-efficient add-on.
The application length of the applied conductive medium (conductive material overlay) on the longitudinal isolation length (for example on the ceramics) can be varied dependent on the specific application of the VI and the degree of symmetry that needs to be achieved. This can be determined through several test runs with conductive material overlay applied at different lengths to the outside of the VI.

Claims

A vacuum interrupter (10), comprising:
- a movable contact (50);

- a fixed contact (60);

- a metal shield (70); and

- a conductive lid (20); and

- an isolation part (30);
wherein the metal shield surrounds at least the fixed contact and/or the movable contact;

wherein an outer housing of the vacuum interrupter is at least partially formed from the conductive lid and the isolation part (30); and

wherein a conductive material overlay (40) covers at least part of an outer surface of the outer housing.
Vacuum interrupter according to claim 1, wherein the conductive material overlay directly contacts at least part of an outer surface of the isolation part.
Vacuum interrupter according to any of claims 1-2, wherein the conductive material overlay directly contacts at least part of an outer surface of the conductive lid.
Vacuum interrupter according to any of claims 1-3, wherein the conductive material overlay is electrically connected to the movable contact.
Vacuum interrupter according to any of claims 1-3, wherein the conductive material overlay is electrically connected to the fixed contact.
Vacuum interrupter according to any of claims 1-5, wherein the conductive material overlay is capacitively coupled to the metal shield.
Vacuum interrupter according to any of claims 1-6, wherein the conductive material overlay is galvanically isolated from the metal shield.
Vacuum interrupter according to any of claims 1-7, wherein the conductive material overlay comprises a shrinkage tube, applied by shrinking onto the at least part of an outer surface of the outer housing.
Vacuum interrupter according to any of claims 1-7, wherein the conductive material overlay comprises a paint or lacquer, applied by spraying, brushing, painting or sprinkling onto the at least part of an outer surface of the outer housing.
Vacuum interrupter according to any of claims 1-7, wherein the conductive material overlay comprises a metal coating, applied by plasma coating or sputtering onto the at least part of an outer surface of the outer housing.
Vacuum interrupter according to any of claims 1-7, wherein the conductive material overlay comprises a manchette.
A low, or medium, or high voltage switchgear comprising a vacuum interrupter according to any of claims 1-11.
A method of manufacturing a vacuum interrupter (10), comprising:
providing a movable contact (50);

providing a fixed contact (60);

providing a metal shield (70) surrounds at least the fixed contact and/or the movable contact,

providing an outer housing of the vacuum interrupter at least partially formed from a conductive lid (20) and an isolation part (30); and

covering at least part of an outer surface of the outer housing with a conductive material overlay (40).
Method according to claim 13, wherein the method comprises capacitively coupling the conductive material overlay to the metal shield.
Method according to any of claims 13-14, wherein the method comprises galvanically isolating conductive material overlay from the metal shield.