Contact ring unit for tap changer and tap changer

Abstract

A contact ring unit (2) for a tap changer (1) comprises a ring support structure (3) and a plurality of electrically fixed contacts (4) coupled to the ring support structure (3). The contact ring unit (2) further comprises a shaft element (15) configured to provide a rotational driving force about a rotational axis (L), and at least one movable contact unit (10), the at least one movable contact unit is coupled to the shaft element (15) and is configured to establish electrical contact with a respective fixed contact (4) for electrical switching between the two fixed contacts (4) with interaction with the shaft element (15). The ring support structure (3) is configured to hold the fixed contacts (4) in place such that the fixed contacts (4) are arranged along a closed line comprising a non-circular overall shape.

Description

Technical Field

[0001] This disclosure relates to a contact ring unit for a tap changer and a corresponding tap changer. Background Technology

[0002] Tap changers implement a mechanism in transformers that allows, for example, the selection of a variable turns ratio in discrete steps. Providing a stable and reliable mechanism with low wear and low stress is a challenge, given the movable and stationary electrically engaged contacts.

[0003] Therefore, the objective is to provide contact units and tap switches for tap changers, each achieving size reduction and a stable and reliable mechanism for the interaction of components. Summary of the Invention

[0004] According to an embodiment, a contact ring unit for a tap changer (e.g., an on-load or off-load tap changer) includes a ring support structure and a plurality of fixed electrical contacts coupled to the ring support structure. The ring support structure may form an insulating carrier for the fixed contacts. The contact ring unit also includes a shaft element configured to provide rotational driving force about a rotational axis. The contact ring unit also includes one or more movable electrical contact units coupled to the shaft element and configured to establish electrical contact with corresponding fixed contacts to electrically switch between two fixed contacts upon interaction with the shaft element. The ring support structure defines a structure that holds the fixed contacts in corresponding predetermined positions such that the fixed electrical contacts are arranged along a circumferential line that differs from a complete circular integral shape. In other words, the fixed electrical contacts are arranged following a closed-formed or virtual path that includes a non-circular integral shape. The fixed contacts and movable contact units are arranged radially relative to the rotational axis to face each other, and the distance between two adjacent fixed contacts along the ring support structure is different from the distance between another two adjacent fixed contacts along the ring support structure.

[0005] By using the described contact ring unit, components for tap changers are feasible, enabling safe and reliable operation. The ring support structure allows for a stationary contact system with two or more fixed contacts configured to interact with corresponding movable contact units to provide current transfer in the selector of a power switching device for on-load tap changers. Furthermore, due to the non-circular integral shape or positional specifications of the fixed contacts, reductions in the size of the contact ring, the corresponding tap changer, and the corresponding transformer are possible. The contact ring unit is also suitable for other types of tap changers, such as off-load tap changers.

[0006] Due to the non-circular shape or positional specifications of the ring support structure, and the fixed contacts spaced at uniform angles, improved dielectric distance can be achieved between selected adjacent fixed contacts. The corresponding tap changer may include multiple contact layers, each layer comprising a corresponding contact ring unit with a non-circular overall shape. The contact ring unit or ring support structure may include any shape on each contact layer that does not conform to a complete circular shape. In the following description, the ring support structure may be described as including a non-circular shape, but it may include any shape such that the positional specifications of the associated fixed contacts are arranged along a self-enclosed line or path with a non-circular shape.

[0007] The described contact ring unit arrangement also reduces the overall tap changer size, and thus helps to reduce the overall transformer volume including one or more tap changers. The non-circular shape of the ring support structure can also improve the insulation distance between adjacent phases of the tap changer. Each phase may include one or more contact ring units, which can be arranged vertically to each other, and each contact ring unit is connected to an insulating rod. This insulating rod provides support for the ring support structure, and the fixed contacts are fixed to the corresponding ring support structure rather than the insulating rod. The described contact ring units can be assembled separately in selectors, preselectors (such as on-load tap changers), and selector switches or de-energized tap changers, thereby providing the aforementioned improvements.

[0008] According to embodiments of the contact ring unit, the ring support structure includes at least one segment having a shape that does not follow a circular segment. The ring support structure may include one or more segments that are, for example, circular segments relative to a top or bottom view along the axis of rotation. Between these circular segments, there may be linear, elliptical, or any other shape different from the circular segments, such that the ring support structure includes a non-circular overall shape. In particular, the ring support structure may include an overall elliptical shape.

[0009] According to a further embodiment of the contact ring unit, the ring support structure includes a first maximum extension along a first direction and a second maximum extension along a second direction, the second direction being perpendicular to the first direction relative to a plane extending along a non-circular integral shape, and wherein the second maximum extension is greater than the first maximum extension. This configuration can achieve an elliptical shape for the ring support structure, wherein the first maximum extension corresponds to the minor axis and the second maximum extension corresponds to the major axis of the ellipse.

[0010] This disclosure recognizes that the selector mechanism in a tap changer is typically designed with a circular shape on each contact layer. For example, the fixed contacts are placed at a uniform angle, and the insulation distance between any two adjacent contacts is the same. When the fixed contacts are numbered according to the regulating circuit diagram, typically two adjacent fixed contacts receive the first and last terminals from the regulating winding of the transformer.

[0011] The described contact ring unit takes into account the insulation distance requirements between adjacent fixed contacts, so that the distance between the first and last terminals of the regulating winding from the transformer can be set to be larger than the insulation distance between other adjacent pairs or fixed contacts.

[0012] The fixed contact and the movable contact unit are arranged radially relative to the axis of rotation, facing each other. For example, the ring support structure is implemented as a peripheral non-circular component, such that the electrical contact fixed thereon protrudes inward toward the central region. The movable electrical contact unit protrudes outward toward the ring support structure. The shaft element can be arranged at the center and can be implemented as a central shaft that drives and rotates the movable contact unit.

[0013] The distance between two adjacent fixed contacts along the ring support structure differs from the distance between another two adjacent fixed contacts along the ring support structure. The non-circular ring support structure allows for a non-equidistant arrangement of fixed contacts, but they have the same rotation angle between adjacent fixed contacts. Specifically, adjacent fixed contacts with the highest voltage difference should be arranged further apart from each other compared to contacts with lower voltage differences.

[0014] According to a further embodiment, the contact ring unit includes a drive cam coupled to the movable contact unit and configured to guide the contact unit to rotate about a rotation axis, wherein the drive cam has a shape that matches the shape of the ring support structure. This drive cam can be implemented as a stabilizing guide to achieve safe and reliable rotation and / or proper positioning of the associated movable contact unit.

[0015] According to a further embodiment of the contact ring unit, each of the corresponding contact units includes a drive and guide device and one or more radially movable contact elements relative to a rotation axis, the one or more radially movable contact elements being configured to establish electrical contact with a corresponding contact surface of an associated fixed contact. These contact units may each include a spring element, a roller element, a bushing element, and / or a slider element, such that the radially movable contact elements can extend and retract telescopically. According to the above-described possible embodiments of the contact unit, a safe and reliable electrical connection can be established even when the distance between the contact and the contact unit differs. According to the above-described possible embodiments of the contact unit, a safe and reliable electrical connection can be established even when the distance between the fixed contact and the rotatable or movable contact unit differs.

[0016] According to embodiments, the tap changer includes embodiments of the described contact ring unit. Specifically, the tap changer may include two different or identical embodiments of the described contact ring unit, which are coupled to one or more insulating rods such that a given height distance is set between the contact ring units along the direction of the axis of rotation. When the contact ring units are arranged vertically to each other, the axis of rotation may also be considered as the longitudinal or vertical axis of the tap changer. Since the tap changer includes embodiments of the contact ring unit as described above, the features and characteristics disclosed for the contact ring unit are also disclosed for the tap changer, and vice versa.

[0017] By implementing selector or contact ring units with a non-circular (e.g., elliptical) integral shape on the corresponding contact layers of the tap changer, adjacent fixed contacts can be arranged further apart than other adjacent contacts, which beneficially affects the insulation characteristics of the tap changer. The fixed contacts can be positioned at a uniform angle. At each switching step, a movable contact unit is coupled to the associated fixed contact, for example, following a given cam profile that radially controls the placement of the movable contact unit. The movable contact unit preferably has the capability of radial reciprocating movement to achieve radial translation or telescopic translation via guide elements (e.g., rollers).

[0018] Due to the non-circular shape of the contact ring unit, there is potential to reduce the overall size of the tap changer. Furthermore, the designed modular fixed contact ring unit allows for improved insulation distances between adjacent phases of the tap changer. This also enables improved insulation distances in the transformer tank and the transformer oil containing the tap changer assembled therein. Attached Figure Description

[0019] Exemplary embodiments are explained below with the aid of schematic diagrams and reference numerals. The accompanying drawings illustrate:

[0020] Figures 1 to 2 Embodiments of the tap changer are shown in different views. Figure 3 An embodiment of a contact ring unit for a tap changer is shown in top view, and Figure 4 The diagram is shown in bottom view according to Figure 3 An embodiment of the contact ring unit. Detailed Implementation

[0021] The accompanying drawings are included to provide further understanding. The same reference numerals denote elements or parts that have the same function. As long as elements or parts correspond to each other in function in different drawings, their description will not be repeated for each subsequent drawing. For clarity, elements may not have corresponding reference numerals in all drawings.

[0022] Figure 1 The diagram illustrates a side view of a transformer tap changer 1, which allows for selection of a variable turns ratio at different stages (e.g., during tap changes without power interruption). For example, the illustrated embodiment could belong to an on-load or off-load tap changer 1, which includes one or more contact ring units 2 associated with one or more individual phases N...N+1, configured to perform tap changes and power transfer. The contact ring units 2 are connected to an insulating rod 16 and arranged vertically relative to each other with respect to the longitudinal axis L of the tap changer 1. The longitudinal axis L also forms the axis of rotation of one or more rotatable or movable contact units 10 associated with the contact ring units 2. A given height distance H is arranged between the contact ring units 2 of adjacent phase layers N and N+1, which can advantageously influence the insulation distance through the configuration of the respective contact units 2. Figure 1 In the illustrated embodiment, the tap changer 1 includes four contact ring units 2a-2d. According to a further embodiment, the tap changer 1 may include more or fewer contact ring units 2, such as two, three, or more contact ring units 2. This can be applied, for example, to an off-load tap changer. For an on-load tap changer, the number of contact ring units 2 per phase may include, for example, one, two, three, or four.

[0023] Figure 2 The diagram shows a perspective view of tap changer 1 taken from an angled bottom view. Figure 3 A top view of an embodiment of the corresponding contact ring unit 2 is shown. Figure 4 The corresponding bottom view is shown. The contact ring unit 2 includes a ring support structure 3 and multiple electrically fixed contacts 4a-4(n+1) connected to the ring support structure 3. According to... Figure 3 and Figure 4In the embodiment shown, the contact ring unit 2 includes six fixed electrical contacts 4. According to a further embodiment, the contact ring unit 2 may include more than six or fewer than six fixed contacts 4 (e.g., two, three, four, five, seven, eight or more fixed contacts 4).

[0024] The contact ring unit 2 also includes at least one movable contact unit 10 coupled to a centrally arranged shaft element 15, which is configured such that the movable contact unit 10 provides rotational driving force about a rotational axis L. The movable contact unit 10 is configured to establish electrical contact with a corresponding fixed contact 4 for electrical switching in interaction with the shaft element 15. The movable contact unit 10 follows a given guide rail formed by a drive cam 6. According to... Figures 1 to 4 In the embodiment shown, the contact ring unit 2 includes a movable contact unit 10.

[0025] The ring support structure 3 has a non-circular integral shape, particularly an elliptical shape. The ring support structure 3 is formed as a peripheral component and substantially defines the shape of the corresponding contact ring unit 2. The drive cam 6 is arranged between the ring support structure 3 and the central shaft element 15, and may also include a non-circular integral shape, such as an elliptical shape. Due to the non-circular shape of the ring support structure 3 and the angularly spaced fixed contacts 4, an improved insulation distance can be achieved between selected adjacent fixed contacts 4.

[0026] Furthermore, the size of the contact ring unit 2, the corresponding tap changer 1, and the transformer can be reduced. Due to the non-circular shape of the ring support structure 3, the contact ring unit 2 includes a first extension D1, which is smaller than a second extension D2, and the direction along which the second extension D2 is substantially perpendicular to the direction of the first extension D1 (see...). Figure 3 Therefore, compared to conventional contact systems with a circular shape (which may include a diameter equal to the second extension D2), the described contact ring unit 2 can be formed thinner or narrower in at least one direction, and thus achieves a size reduction in addition to the aforementioned beneficial effects (improved insulation distance between selected adjacent fixed contacts 4).

[0027] The ring support structure 3 is formed as an insulating carrier, on which fixed contacts 4a-4(n+1) are mounted. The central shaft element 15 is configured to initiate the rotational switching of the movable contact unit 10. Each movable contact unit 10 includes a guide and drive device as well as further components such as a roller element 11, a carrier element 12, a current collector terminal 13, and a telescopic finger element 14 (see...). Figure 2 The rotational and radial movements achieved by contact unit 10 are... Figure 4 The corresponding arrow indicates this.

[0028] The movable contact unit 10 follows the non-circular contour of the drive cam 6 and switches from the fixed contact 4, for example, from contact 4b to contact 4c (see...). Figure 3 and Figure 4 Even when the distance between the movable contact unit 10 and the corresponding fixed contact 4 differs, switching is possible because the drive and guide mechanism of the movable contact unit 10 allows radial displacement via the telescopically guided carrier element 12 and finger element 14. The current collector terminal 13 and the finger assembly 14 are assembled to the carrier element 12 and move with it. Flexible or sliding connections attached to the current collector terminal may exist, leading the current to the neutral point or the next stationary point.

[0029] The movable contact unit 10 is moved by the same angle for each switching process. For example, the angle between fixed contacts 4b and 4c can be set to be the same as the angle between fixed contacts 4a and 4b, but the finger element 14 travels a different distance. Compared to the insulation distance between fixed contacts 4a and 4b, the non-circular shape can increase the insulation distance between fixed contacts 4b and 4c (see...). Figure 3 and Figure 4 Furthermore, the fixed contact 4a-4(n+1) is mounted to the insulating ring support structure 3 instead of the insulating rod 16, which achieves better insulation between adjacent phases N and N+1 in terms of height distance H. This height distance can be measured by the transformer oil in which the tap changer components are immersed, rather than by the insulating surface.

[0030] As mentioned above, Figures 1 to 4 The embodiments shown represent exemplary embodiments of the improved contact ring unit 2 and the corresponding tap changer 1; therefore, they do not constitute a complete list of all embodiments according to possible arrangements. The actual arrangement of the contact ring unit 2 and / or tap changer 1 may differ from the embodiments shown in the figures.

[0031] Figure Labels 1 Tap switch / Non-circular selector switch 2(n) Corresponding contact ring unit 3-ring support structure 4(n) Corresponding fixed contacts 6 drive cams 10 Corresponding Movable Contact Units 11-roller element 12 load-bearing elements 13 collector terminals 14 finger-shaped elements 15 central shaft elements 16 insulating rods The first extension of the D1 contact ring The second extension of the D2 contact ring The height distance between H phase layers Longitudinal axis / rotation axis of L-tap switch

Claims

1. A contact ring unit (2) for a tap changer (1), comprising: - Ring support structure (3). - Multiple electrically fixed contacts (4) connected to the ring support structure (3). - A shaft element (15) configured to provide a rotational driving force about a rotational axis (L), and - A movable contact unit (10), which is coupled to the shaft element (15) and configured to establish electrical contact with a corresponding fixed contact (4) to electrically switch between two fixed contacts (4) in interaction with the shaft element (15), wherein the ring support structure (3) is configured to hold the fixed contact (4) in place such that the fixed contact (4) is arranged along a closed line including a non-circular integral shape. The fixed contact (4) and the movable contact unit (10) are arranged to face each other radially relative to the axis of rotation (L), and the distance between two adjacent fixed contacts (4) along the ring support structure (3) is different from the distance between two other adjacent fixed contacts (4) along the ring support structure (3).

2. The contact ring unit (2) according to claim 1, wherein, The ring support structure (3) forms at least one line segment for positioning the fixed contact (4), the shape of which does not follow a circumferential segment.

3. The contact ring unit (2) according to any one of the preceding claims, wherein, The ring support structure (3) forms a closed line for positioning the fixed contact (4), the closed line including an elliptical shape.

4. The contact ring unit (2) according to any one of the preceding claims, wherein, The ring support structure (3) forms the closed line such that it includes a first maximum extension (D1) along a first direction and a second maximum extension (D2) along a second direction, the second direction being perpendicular to the first direction with respect to a plane extending along the non-circular integral shape, and wherein the second maximum extension (D2) is greater than the first maximum extension (D1).

5. The contact ring unit (2) according to any one of the preceding claims, comprising: A drive cam (6) is coupled to the movable contact unit (10) and configured to guide the rotational movement of the contact unit (10) about the rotation axis (L), wherein the drive cam (6) includes a shape that matches the line predetermined by the ring support structure (3).

6. The contact ring unit (2) according to any one of the preceding claims, wherein, The contact unit (10) includes drive and guide devices (11, 12) and one or more contact elements (14) that are radially movable relative to the axis of rotation (L), the radially movable contact elements being configured to establish electrical contact with the corresponding contact surface of the associated fixed contact (4).

7. The contact unit (10) according to any one of the preceding claims, wherein, The contact unit (10) includes a spring element, a roller element, a bushing element and / or a slider element, such that the radially movable contact element (14) can extend and retract telescopically.

8. A tap changer (1), comprising: - Contact ring unit (2) according to any one of the preceding claims. - Another contact ring unit (2) according to any one of the preceding claims, and - One or more insulating rods (16) are connected to the contact ring unit (2) such that a given distance (H) is set between the contact ring units (2) in the direction of the rotation axis (L).

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