EP4654236A1

EP4654236A1 - Bypass contact system, vacuum interrupter module and tap changer

Info

Publication number: EP4654236A1
Application number: EP24177262.3A
Authority: EP
Inventors: Petar MITEV; Plamen Danchev MARINOV; Martin Georgiev
Original assignee: Hitachi Energy Ltd
Current assignee: Hitachi Energy Ltd
Priority date: 2024-05-22
Filing date: 2024-05-22
Publication date: 2025-11-26
Also published as: WO2025242405A1

Abstract

A bypass contact system (10) for an interrupter module (1) for a tap changer comprises a first and a second bypass contact (11, 12) each with a first or second lever system (13, 14), a first or second carrier (16) and a first or second plurality of moveable contact elements (20), respectively. The respective contact elements (20) are attached to the associated carrier (16) which is pivotably coupled to the associated lever system (13, 14). Both the first and the second contact elements (20) each comprise a predetermined outer shape with at least two respective contact regions (23, 24) which are configured in coordination with contact elements (4, 6) of the interrupter module (1), so that in a first state, in which at least one contact region (23, 24) is free of contact with at least one contact element (4, 6) of the interrupter module (1), and a second state, in which all contact regions (23, 24) of the associated bypass contact (11, 12) are in contact with all associated contact elements (4, 6) of the interrupter module (1). In the respective second state, the corresponding contact regions (23, 24) of the associated contact elements (20) each establish at least a four-point electrical contact to the contact elements (4, 6) of the interrupter module (1).

Description

The present disclosure is related to a bypass contact system, a vacuum interrupter assembly for a power diverter switch, and a transformer load tap changer.
Vacuum interrupters are widely used in utility power transmission systems, power generation units and power-distribution systems for railways, for example. Therein, the vacuum interrupter realizes a switch of a medium-voltage circuit-breaker, generator circuit-breaker, or high-voltage circuit-breaker which uses electrical contacts.
In this respect, it is a challenge to provide stable and reliable mechanisms to carry high electrical current.
Embodiments of the present disclosure enable secure and reliable switching of electrical contacts of a vacuum interrupter and contribute to stably carry high electrical current.
According to an embodiment, a bypass contact system for an interrupter module for a tap changer comprises a first bypass contact and a second bypass contact. The first bypass contact includes a first lever system, a first carrier and a first plurality of moveable contact elements attached to the first carrier. The first carrier is pivotably coupled to the first lever system. The second bypass contact includes a second lever system, a second carrier and a second plurality of moveable contact elements attached to the second carrier. The second carrier is pivotably coupled to the second lever system. Both the first and the second contact elements each comprise a predetermined outer shape with at least two respective contact regions which are configured in coordination with contact elements of the interrupter module, so that both the first bypass contact and the second bypass contact are configured to establish a respective first and second state.
In the first state at least one contact region of the associated bypass contact is free of contact with at least one contact element of the interrupter module. In the respective second state all contact regions of the associated bypass contact are in contact with all associated contact elements of the interrupter module, wherein in the respective second state, the respective contact regions of the first and/or the second contact elements of the first and/or the second bypass contact each establish at least a four-point electrical contact to the contact elements of the interrupter module.
Due to the described configuration a bypass contact system for a vacuum interrupter module and a vacuum reactance load tap changer is feasible which each enable stable carrying of high electrical current and secure and reliable switching of electrical contacts.
According to an embodiment of the bypass contact system, the first and the second bypass contact each comprise a respective first and a respective second lever which are pivotably coupled to each other and pivotably coupled to a drive unit so that the respective first and second lever and the associated carrier with its contact elements are drivable by means of the drive unit.
According to a further embodiment of the bypass contact system, the number of the moveable contact elements of the respective first and/or second bypass contact is configured in coordination with the current to be conducted in the interrupter module. Preferably, the respective first and/or second bypass contact each comprise at least five moveable contact elements configured to carry a current between 1250 up to 1750 A, e.g. about 1500 A. Alternatively, the respective first and/or second bypass contact each comprise seven moveable contact elements configured to carry a current between 2000 up to 3000 A, e.g. about 2500 A. Alternatively, the respective first and/or second bypass contact can comprise less than five or six or more than seven moveable contact elements configured to carry a current in a given range. It is further possible, that the first and second bypass contact comprise a different number of moveable contact elements.
According to a further embodiment of the bypass contact system, the moveable contact elements of the respective first and/or second bypass contact are each plate-shaped with a given outer shape which is configured in coordination with the contact elements of the interrupter module so that the contact regions are formed as respective contact recesses configured to surround the contact elements of the interrupter module in the second state. Preferably, the respective contact recesses are curved limited by a contact side of the respective contact element in coordination with a shape of the interacting contact elements of the interrupter module formed as respective curved contact columns.
Alternatively, the contact elements of the interrupter module comprise respective contact recesses and the moveable contact elements of the respective first and/or second bypass contact are formed to fit into the associated contact recess.
According to a further embodiment of the bypass contact system, one contact region of the respective contact elements of the first and/or second bypass contact is configured to be in permanent electrical contact to one associated contact element of the interrupter module in the first and the second state.
According to a further embodiment of the bypass contact system, the moveable contact elements of the first and/or second bypass contact each comprise an inner axle recess and a respective axle extending through the respective axle recesses so that the associated contact elements are arranged on top of each other. Such a sandwich structure allows for a clear and space-saving design of the respective bypass contact.
According to a further embodiment of the bypass contact system, the moveable contact elements of the first and/or second bypass contact each are coupled to one or more force elements which are configured to act on the associated contact element in a direction towards the associated contact element of the interrupter module, when the interrupter module is assembled ready for operation. Preferably, the respective force element is formed or comprises one or more spring elements which are coupled to a back side of the associated contact element opposite the respective contact side of the contact element.
According to a further embodiment of the bypass contact system, the respective contact element comprises one or more spring recesses at its back side and the one or more spring elements are arranged in the associated spring recess between the carrier and the associated contact element.
According to an embodiment, an interrupter module for a tap changer comprises an embodiment of the described bypass contact system, and an insulation plate with a plurality of contact elements, whose outer shape and number is configured in coordination with the outer shape of the first and second moveable contact elements. The bypass contact system is coupled to the insulation plate so that the first and the second state of both bypass contacts are adjustable. The interrupter module can be realized as a vacuum interrupter assembly for a power diverter switch.
According to an embodiment, a tap changer for a transformer comprises an embodiment of the described bypass contact system. Alternatively or additionally, the tap changer comprises an embodiment of the described interrupter module. The tap changer can be realized as a transformer on-load tap changer for setting a gear ratio comprising a tank that encloses a fluid and at least one embodiment of the aforementioned interrupter module power forming a power diverter switch arranged inside the tank and immersed in the fluid.
Such a configuration of the interrupter module and the tap changer using an embodiment of the described bypass contact system with improved electrical contacting enables secure and reliable switching and carrying of electrical current. As a result of that the interrupter module and the tap changer comprise an embodiment of the bypass contact system, described features and characteristics of the bypass contact system are also disclosed with respect to the interrupter module and the tap changer and vice versa. Thus, the present disclosure comprises several aspects, wherein every feature described with respect to one of the aspects is also disclosed herein with respect to the other aspect, even if the respective feature is not explicitly mentioned in the context of the specific aspect.
It is a recognition of the present disclosure that conventional designs for power diverter switches or bypass systems included in reactor step regulators, like VRLTC and RMV-II, only have a very limited number of contact points which, in turn, limit the current that can be transferred from one point to another. By use of the described bypass contact system of the present disclosure, it is possible to counteract the aforementioned adverse effects and to improve the performance of the system and the life of the interacting elements. The increased number of electrical contact points between static parts and moving elements in the bypass contact system also allows to increase the current and voltage carried or transferred in the bypass contact system as well as the corresponding interrupter module and tap changer.
Exemplary embodiments are explained in the following with the aid of schematic drawings and reference numbers. The figures show:

Figures 1-5 an embodiment of a bypass contact system in different views and states, and
Figures 6-10 an embodiment of a movable contact element of the bypass contact system in different views.

The accompanying figures are included to provide a further understanding. It is to be understood that the embodiments shown in the figures are illustrative representations and are not necessarily drawn to scale. Identical reference numbers designate elements or components with identical functions. In so far as elements or components correspond to one another in terms of their function in different figures, the description thereof is not repeated for each of the following figures. For the sake of clarity elements might not appear with corresponding reference symbols in all figures possibly.
The Figures 1 to 5 illustrate an embodiment of a power diverter switch assembly or a vacuum interrupter module 1 for transformer load tap changer in different views and different states. The figures 1 and 2 show an equal perspective view of the interrupter module 1 but with different reference sign in part for the sake of clarity and better illustration. The figures 3 to 5 show a top view of the interrupter module 1 in different states.
The vacuum interrupter module 1 comprises an insulation plate 3 and current transformer 2 attached to the insulation plate 3. The insulation plate 3 forms a support structure of the interrupter module 1 and may be composed of a rigid dielectric material, such as fiber-reinforced dielectric plastic. On a front side of the insulation plate 3 a bypass contact system 10 is mounted. A back-side of the insulation plate 3 can be used for carrying copper bars used for schematic connection. Incoming motion from a selector can be transferred to a cam end of a control cam or driving unit 5 through means of insulation shafts. The driving unit 5 is configured to actuate the bypass contact system 10 through corresponding bypass levers 13, 14.
The vacuum interrupter module 1 comprises the bypass contact system 10 including a first bypass contact 11 and a second bypass contact 12. The first bypass contact 11 comprises a first lever system with a first lever 13 and a second lever 14 acting as an insulation lever. The first bypass contact 11 further comprises a first housing or carrier 16 and a first plurality of moveable contact elements 20 attached to the first carrier 16. The second lever 14 is pivotably coupled to the first lever 13 and the first carrier 16. The first lever 13 is pivotably coupled to the driving unit 5. The interaction components are pivotable around a respective rotation axis R (see Fig. 2).
The second bypass contact 12 is formed analogously to the first bypass contact 11 and basically symmetrically identical with respect to a longitudinal axis L of the insulation plate 3. Thus, the second bypass contact 12 comprises a second lever system with a first lever 13 and a second lever 14, a second housing or carrier 16 and a second plurality of moveable contact elements 20 attached to the second carrier 16. The second lever 14 is acting as an insulation lever and is pivotably coupled to the first lever 13 and the second carrier 16. The first lever 13 is pivotably coupled to the driving unit 5. The interaction components are pivotable around a respective rotation axis R (see Fig. 2).
Both the first and the second contact elements 20 each comprise a predetermined outer shape with two respective contact regions formed or limited as contact recesses 23, 24 at a respective contact side 21 of the corresponding contact element 20 (see Figs. 6-10). The contour of the contact side 21 limiting the contact recesses 23, 24 is configured in coordination with an outer shape of the contact elements of the interrupter module 1 which are formed as cylindrical contact columns 4, 6. Accordingly, the contact recesses 23, 24 are both curved shaped or circularly limited.
Both the first bypass contact 11 and the second bypass contact 12 are configured to establish a respective first state and a second state. In the first state the associated contact column 4 of the interrupter module 1 is not arranged in the respective first contact recess 23 of the associated bypass contact 11, 12 and hence is in this region free of contact with the respective contact side 21 of the contact elements 20. In the second state the associated contact column 4 of the interrupter module 1 is arranged in the respective first contact recess 23 of the associated bypass contact 11, 12 and hence is in contact with the respective contact side 21 of the contact elements 20. The further contact column 6 is surrounded by a portion of the associated carrier 16 and is in permanent contact with the contact elements 20 of the bypass contacts 11, 12 in the first state and in the second state.
With respect to the figure 3, the first bypass contact 11 is in the first state and the second bypass contact 12 is in the second state, or in other words open left. With respect to the figure 4, the first bypass contact 11 is in the second state and the second bypass contact 12 is in the second state, or in other words closed. With respect to the figure 5, the first bypass contact 11 is in the first state and the second bypass contact 12 is in the first state, or in other words open right.
In the respective second state all contact regions of the associated bypass contact 11, 12 are in contact with the associated contact columns 4, 6 of the interrupter module. The bypass contact system 10 enables secure and reliable transfer of high current and/or voltage by means of establishing a four-point electrical contact between each of the contact elements 20 of the respective bypass contact 11 and/or 12 and the associated contact columns 4, 6 of the interrupter module 1. Alternatively or additionally, the contact elements 20 of the respective bypass contact 11 and/or 12 and the associated contact columns 4, 6 can be configured to make a five- or more-point contact and/or a line contact.
The contact columns 4 and 6 can be different in construction. The contact columns 4 which are free of electrical contact in the first state of the respective bypass contact 11, 12 can be made of copper entirely. The contact columns 6 which are in electrical contact in the first and the second state of the respective bypass contact 11, 12 can include metal-ceramic material.
When closing or opening the respective bypass contact 11, 12 an electric arc can occur between the contact elements 20 and the column 4. On the top of the columns 4, 6 there can be formed an additional tip comprising a metal-ceramic alloy, e.g. sintered tungsten copper WCu 70-30. The construction of the uppermost movable contact element 20, to which an element similar in shape and the same in material, is soldered is similar. Such elements can be formed or implemented due to the finding that an electric arc is formed right between such metal-ceramic parts which have much better durability under these conditions, thus extending the life of the copper contacts, respectively the bypass contacts 11, 12 and the corresponding bypass contact system 10. Accordingly, the bypass contact system 10 can further contribute to an arc extinguishing model in a corresponding tap changer.
Each of the bypass contact 11, 12 comprises a predetermined number of moveable contact elements configured in coordination with the current to be conducted in the interrupter module 1. According to an embodiment, the bypass contacts 11, 12 each may comprise at least five moveable contact elements 20 configured to carry a current between 1250 up to 1750 A, for example. According to another embodiment, the bypass contacts 11, 12 each may comprise at seven moveable contact elements 20 configured to carry a current of 2500 A, for example.
The Figures 6 to 10 illustrate an embodiment of a plate-shaped movable contact element 20 of the bypass contact system 10 in different views. The contact elements 20 are stacked above each other partly arranged inside the associated housing or carrier 16. The contact elements 20 comprise an inner axle recess 25 in a middle region formed to accommodate an axle 15 so that the associated contact elements 20 are arranged and hold in place on top of each other.
The moveable contact elements 20 further comprise recesses 26 at their respective back side 22 to accommodate a respective force element which is configured to act on the associated contact element 20 in a direction towards the associated contact elements 4, 6 of the interrupter module 1. According to the embodiment illustrated in the figures 6 to 10, the contact elements 20 each comprise four recesses 26 to accommodate a respective spring element 17 forming the force element (see Fig. 7). A number and position of the spring elements 17 can be varied depending on the desired force and its acting direction.
The four spring elements are coupled to the back side 22 of the associated contact element 20 opposite the respective contact side 21 and are arranged inside the associated spring recess 26 partially at least between the carrier 16 and the associated contact element 20. For example, in view of a stack of seven contact elements 20 of the respective bypass contact 11, 12 there can be twenty-eight spring elements 17 arranged in the corresponding carrier 16.
The described bypass contact system 10 interacts with two branches with static contacts which are realized by the contact columns 4 through which a certain current must flow. This is enabled by means of the sets of movable contact elements 20 driven by a lever and cam system that gives the necessary consistency and alternation for electrical switching.
The moveable contact elements 20 comprise a specific form with kind of a double V-shape which enables a beneficial four-point electrical contact, two-point contact to each column 4 and 6, when the respective bypass contact 11, 12 is in the second state. The specific asymmetric plate-shape provides one beneficial set up to contribute to reliable rotation, guidance and stability of the interaction components, mechanically and electrically. The spring elements 17 provide a given contact pressure and contribute to reliably establish the aforementioned electrical contact. In addition, a clearance is set between the contact elements 20 and their associated driving axle 15 inside the axle recess 25. The clearance can be realized, for example, by a gap of 1-4 mm or 2-3 mm between the axle 15 and the contact elements 20, which allows for a distance to be able to apply a beneficial pressure from the spring elements 17. Such a clearance and erosion during the switching operations further allows for a self-adjustment in the bypass contact system 10. In particular, the motion from a cam wheel of the driving unit 5 is transferred by means of the first lever 13, which can form a steel lever, the second lever 14, which can be form an insulation lever, the axle 15, bushings, the housing or carrier 16, which can form a sheet metal carrier, the spring elements 17, and finally the contact elements 20, which can be formed as copper contacts.
The bypass contact system 10 constructed in this way further simply allows to add or remove movable contact elements 20 so that a balance between the number of contact elements 20 and the required current to be transferred can be achieved, depending on the type of tap changer, like a vacuum reactance load tap changer (VRLTC).
The embodiments shown in the Figures 1 to 10 as stated represent exemplary embodiments of the improved bypass contact system 10, vacuum interrupter module 1 10, the power diverter switch or vacuum interrupter module 1 and the transformer load tap changer 100, respectively. Therefore, they do not constitute a complete list of all embodiments. Actual arrangements may vary from the embodiments shown in the figures.

Reference Signs

1: interrupter module
2: current transformer
3: insulation plate
4: contact column
5: driving unit
6: contact column
10: bypass contact system
11: first bypass contact
12: second bypass contact
13: first lever
14: second lever / insulation lever
15: axle
16: carrier / housing
17: spring element
20: movable contact element
21: contact side of the contact element
22: back side of the contact element
23: contact region / first contact recess
24: Contact region / second contact recess
25: axle recess
26: spring recess

L: longitudinal axis of the insulation plate
R: axis of rotation

Claims

Bypass contact system (10) for an interrupter module (1) for a tap changer, comprising:
- a first bypass contact (11) with a first lever system (13, 14), a first carrier (16) and a first plurality of moveable contact elements (20) attached to the first carrier (16), wherein the first carrier (16) is pivotably coupled to the first lever system (13, 14), and

- a second bypass contact (12) with a second lever system (13, 14), a second carrier (16) and a second plurality of moveable contact elements (20) attached to the second carrier (16), wherein the second carrier (16) is pivotably coupled to the second lever system (13, 14),
wherein both the first and the second contact elements (20) each comprise a predetermined outer shape with at least two respective contact regions (23, 24) which are configured in coordination with contact elements (4, 6) of the interrupter module (1), so that both the first bypass contact (11) and the second bypass contact (12) are configured to establish a respective first state, in which at least one contact region (23, 24) of the associated bypass contact (11, 12) is free of contact with at least one contact element (4, 6) of the interrupter module (1), and a respective second state, in which all contact regions (23, 24) of the associated bypass contact (11, 12) are in contact with all associated contact elements (4, 6) of the interrupter module (1), and wherein in the respective second state, the respective contact regions (23, 24) of the first and/or the second contact elements (20) of the first and/or the second bypass contact (11, 12) each establish at least a four-point electrical contact to the contact elements (4, 6) of the interrupter module (1).
Bypass contact system (10) according to claim 1, wherein the first and the second bypass contact (11, 12) each comprise a respective first and a respective second lever (14) which are pivotably coupled to each other and pivotably coupled to a drive unit (5) so that the respective first and second lever (13, 14) and the associated carrier (16) with its contact elements (20) are drivable by means of the drive unit (5).
Bypass contact system (10) according to any of the preceding claims, wherein the number of the moveable contact elements (20) of the respective first and/or second bypass contact (11, 12) is configured in coordination with the current to be conducted in the interrupter module (1).
Bypass contact system (10) according to claim 3, wherein the respective first and/or second bypass contact (11, 12) each comprise at least five moveable contact elements (20) configured to carry a current between 1250 up to 1750 A.
Bypass contact system (10) according to any of the preceding claims, wherein the moveable contact elements (20) of the respective first and/or second bypass contact (11, 12) are each plate-shaped with a given outer shape which is configured in coordination with the contact elements (4, 6) of the interrupter module (1) so that the contact regions are formed as respective contact recesses (23, 24) configured to surround the contact elements (4, 6) of the interrupter module (1) in the second state.
Bypass contact system (10) according to claim 5, wherein the respective contact recesses (23, 24) are curved limited by a contact side (21) of the respective contact element (20) in coordination with the contact elements (4, 6) of the interrupter module (1) formed as respective contact columns.
Bypass contact system (10) according to any of the preceding claims, wherein one contact region (23) of the respective contact elements (20) of the first and/or second bypass contact (11, 12) is configured to be in permanent electrical contact to one associated contact element (4, 6) of the interrupter module (1) in the first and the second state.
Bypass contact system (10) according to any of the preceding claims, wherein the moveable contact elements (20) of the first and/or second bypass contact (11, 12) each comprise an inner axle recess (25) and a respective axle (15) extending through the respective axle recesses (25) so that the associated contact elements (20) are arranged on top of each other.
Bypass contact system (10) according to any of the preceding claims, wherein the moveable contact elements (20) of the first and/or second bypass contact (11, 12) each are coupled to one or more force elements which are configured to act on the associated contact element (20) in a direction towards the associated contact element (4, 6) of the interrupter module (1), with respect to an assembled state of the interrupter module (1).
Bypass contact system (10) according to claim 9, wherein the respective force element comprises a spring element (17) that is coupled to a back side (22) of the associated contact element (20) opposite a respective contact side (21) of the contact element (20).
Bypass contact system (10) according to claim 10, wherein the respective contact element (20) comprises a spring recess (26) at its back side (22) and the spring element (17) is arranged in the spring recess (26) between the carrier (16) and the associated contact element (20).
Interrupter module (1) for a tap changer, comprising:
- an embodiment of the bypass contact system (10) according to any of the preceding claims, and

- an insulation plate (3) with a plurality of contact elements (4, 6), whose outer shape and number is configured in coordination with the outer shape of the first and second moveable contact elements (20), wherein the bypass contact system (10) is coupled to the insulation plate (3) so that the first and the second state of both bypass contacts (11, 12) are adjustable.
Tap changer for a transformer, comprising:
- an embodiment of the bypass contact system (10) according to any of the claims 1 to 11, and/or

- an interrupter module (1) according to claim 12.