Electrical switch for on-load tap changer

Abstract

An electrical switch (1) for a load tap changer (2), the electrical switch (1) comprising: at least three electrical contacts (3a, 3b, 3c) connected to respective electrical conductors (4a, 4b, 4c); a switching device (5) configured to be movable between a plurality of positions (P1, P2), wherein the switching device (5) in each respective position (P1, P2) physically contacts a respective combination (C1, C2) of the electrical contacts (3a, 3b, 3c) to provide electrical contact between the electrical contacts in each respective combination (C1, C2) of electrical contacts (3a, 3b, 3c); a gas-tight sealed housing (6) providing an inner space (7) enclosing the electrical contacts (3a, 3b, 3c) and the switching device (5), the electrical conductors (4a, 4b, 4c) extending from the electrical contacts (3a, 3b, 3c) inside the inner space (7) of the housing (6) to outside the housing (6); and a control device (10) configured to control movement of the switching device (5). The inner space (7) is under vacuum or filled with arc suppressing gas. The control device (10) comprises an operating member (8) extending from outside the housing (6) into the inner space (7) of the housing (6), the operating member being operatively connected to the switching device (5) such that the operating member (8) is able to move the switching device (5) to the plurality of positions (P1, P2) depending on the position of the operating member (8). Further, the operating member (8) comprises an arm (9) rotatably attached to the housing (6) for rotation about an axis of rotation (11), wherein the switching device (5) is attached to an end portion of the arm such that the switching device (5) is movable along an arcuate path between the plurality of positions.

Description

Technical Field

[0001] This disclosure relates to on-load tap changers, and more particularly to an electrical switch for use as an on-load tap changer. Background Technology

[0002] Electrical switches are commonly used in on-load tap changers (OLTCs) to perform various functions, such as main switches, resistance switches, preselection switches, or changeover switches. The specific design of the switches can vary; for example, some switches are designed to be "on-first, then off-first," while others are designed to be "off-first, then on-load." On-load tap changers are typically used under voltage conditions where the switch is subjected to arcing when its position changes. Arcing can cause wear on the switch and thus contaminate surrounding components and / or the switch itself. For example, the insulating oil in the OLTC may become contaminated, losing some of its insulating properties.

[0003] EP1113548A1 discloses a power transmission and / or distribution substation connected to a multiphase power line, comprising: a transformer with a tank including a magnetic core, electrical windings, and a first dielectric fluid; a selector for regulating the transformer voltage ratio; and an integrated switchgear. The integrated switchgear includes a hermetically sealed housing.

[0004] JPHO677064A relates to an electrical device including a changeover switch, the changeover switch including an hermetically sealed housing.

[0005] EP2980820A1 discloses an on-load tap changer for dry-type transformers, comprising an electrically insulated hollow housing, which in one embodiment is hermetically sealed.

[0006] EP1113549A1 discloses a power transmission and / or distribution substation connected to a multiphase power line, the substation including a circuit breaker including a housing, which in one embodiment is hermetically sealed. Summary of the Invention

[0007] Accordingly, the purpose of this disclosure is to extend the service life of on-load tap changers and reduce their maintenance needs.

[0008] According to a first aspect of this disclosure, this and other objectives are achieved by the electrical switch according to claim 1, and by alternative embodiments set forth in the dependent claims. The electrical switch is used for on-load tap changing and includes at least three electrical contacts connected to respective electrical conductors. The electrical switch also includes a switching device configured to move between multiple positions, wherein the switching device at each respective position physically contacts a respective combination of the electrical contacts to provide electrical contact between the contacts in each respective combination. The physical contact controlled by the switching device can be direct contact between the contacts in each contact combination, or physical contact can be provided by contacting a portion of the switching device with the contacts in each contact combination to bridge between contact combinations. The electrical switch also includes a hermetically sealed housing that provides an internal space enclosing the electrical contacts and the switching device. The electrical conductors extend from the electrical contacts inside the internal space of the housing to the outside of the housing. The electrical switch also includes a control device configured to control the movement of the switching device. Additionally, the internal space is under vacuum or filled with an arc-suppressing gas.

[0009] The control device includes an operating member extending from the outside of the housing into the interior space of the housing. The operating member is operatively connected to a switching device, enabling the operating member to move the switching device to multiple positions depending on the position of the operating member.

[0010] The operating component includes an arm rotatably attached to the housing for rotation about an axis of rotation. A switching device is attached to the end portion of the arm, allowing the switching device to move along an arcuate path between the plurality of positions.

[0011] The switching device includes two electrically interconnected contacts or contact surfaces disposed on a movable carrier element mounted on an operating member for movement along the arcuate path, and the contacts or contact surfaces of the switching device are disposed at the same radial distance from the axis of rotation and are spaced at the same distance from the electrical contacts of each corresponding combination of electrical contacts.

[0012] For example, an electrical switch can be connected to multiple tap changers and a neutral terminal / load via corresponding conductors in the conductor. This allows the movable switching device to operate between different positions to connect a load to different tap changers among the multiple tap changers. This allows current to be routed through a first tap changer while regulating another tap changer, wherein the electrical switch is subsequently operated to be electrically connected to the other tap changer and disconnected from the first tap changer. By providing a hermetically sealed housing around the electrical contacts and switching device, and providing a vacuum or arc-suppressing gas inside the housing, the electrical contacts and switching device will be subjected to less arcing during operation of the electrical switch. Since the conductor is routed from the inside of the housing to the outside, the conductor is still accessible from the outside of the housing, and other suitable environments, such as air or electrical insulating oil, can be provided outside the housing. The ends of the conductor accessible from the outside of the housing can therefore be connected to the load and multiple tap changers. The housing specifically designed for the electrical switch contains any contaminants generated during operation of the electrical switch due to mechanical wear and arcing acting on the electrical contacts and switching device. By containing contaminants inside the electrical switch housing, the lifespan of other components of the on-load tap changer can be extended. Worn electrical switches can be easily replaced.

[0013] The internal space can be filled with SF6 arc-suppressing gas. SF6 gas is a suitable arc-suppressing gas and reduces arc discharge.

[0014] The switching device can be configured to be movable to a first position and movable to a second position, in which the switching device physically contacts a first electrical contact and a second electrical contact, and in the second position, the switching device physically contacts a second electrical contact and a third electrical contact.

[0015] As described above, a second aspect of this disclosure relates to an on-load tap changer comprising an electrical switch according to any one of claims 1 to 5.

[0016] The electrical switch of an on-load tap changer can be a switching switch, wherein one of the conductors is a neutral conductor, and wherein the remaining conductors are connected to the corresponding tap selection switch of the on-load tap changer. Attached Figure Description

[0017] Figure 1 Exemplary use cases of the electrical switches of this disclosure are schematically illustrated; specifically, Figure 1 An on-load tap changer is shown, which is equipped with an electrical switch in the form of a switching switch.

[0018] Figure 2a and Figure 2bA first embodiment of an electrical switch is schematically shown, characterized by a switching device that allows linear movement between two operating positions. Figure 2a An electrical switch in the first position is shown. Figure 2b An electrical switch in the second position is shown.

[0019] Figure 3a and Figure 3b A second embodiment of an electrical switch is schematically shown, characterized by a switching device that moves in an arcuate manner between two operating positions. Figure 3a An electrical switch in the first position is shown. Figure 3b An electrical switch in the second position is shown. Detailed Implementation

[0020] The embodiments of this disclosure will now be described in more detail with reference to the accompanying drawings.

[0021] As stated above, the purpose of this disclosure is to extend the service life of on-load tap changers and reduce the maintenance requirements of on-load tap changers.

[0022] According to this disclosure, this objective is achieved through a novel design of the provided electrical switch 1, which uses an hermetically sealed housing 6 to house only the internal components of the electrical switch 1 where arc discharge challenges exist. Therefore, the electrical conductors of the electrical switch 1 are routed to the outside of the housing 6 to connect to different electrical conductors of devices using the electrical switch 1.

[0023] In the on-load tap changer 2, the electrical switch 1 can have a variety of uses. For example, the electrical switch 1 can be used as a main switch, a resistance switch, a preselection switch, or a switching switch. The exemplary embodiments described below illustrate the electrical switch as a switching switch in the on-load tap changer 2. However, without departing from the inventive concept of this disclosure involving providing an hermetically sealed housing 6 containing a vacuum or arc-suppressing gas, alternative modifications can be made to the internal structure of the electrical switch 1, such as the number of electrical contacts 3a, 3b, 3c, the number of electrical conductors, and the provision of additional electrical components or alternative control devices 10 for controlling the switching of the electrical switch 1.

[0024] Figure 1 , Figure 3a and Figure 3b A first embodiment of the electrical switch 1 according to this disclosure is schematically shown. (As...) Figure 1As shown, the electrical switch 1 can be used as an on-load tap changer 2. The electrical switch 1 includes three electrical contacts 3a, 3b, 3c connected to corresponding electrical conductors 4a, 4b, 4c. The electrical switch 1 also includes a switching device 5 configured to move between multiple positions P1, P2, wherein the switching device 5 physically contacts corresponding combinations C1, C2 of the electrical contacts 3a, 3b, 3c at each corresponding position P1, P2 to provide electrical contact between the electrical contacts in each corresponding combination C1, C2 of the electrical contacts 3a, 3b, 3c. In other embodiments, a greater number of electrical contacts and conductors may be alternatively provided depending on the desired use and function of the electrical switch 1. For example, the design of a turn-on-break type electrical switch differs to some extent from the turn-off-turn-on type electrical switch schematically disclosed in the first embodiment.

[0025] The electrical switch 1 also includes a hermetically sealed housing 6, which provides an internal space 7 enclosing the contacts 3a, 3b, 3c and the switching device 5. Electrical conductors 4a, 4b, 4c extend from the contacts 3a, 3b, 3c within the internal space 7 of the housing 6 to the outside of the housing 6. Therefore, the housing 6 is a relatively small housing containing only the components of the electrical switch 1, and thus should not be confused with any surrounding housing that also encloses other components (such as a surrounding transformer tank, etc.). This is made clear in the appended claims by specifying that the electrical conductors 4a, 4b, 4c of the electrical switch 1 extend from the inside of the housing 6 to the outside of the housing 6.

[0026] The electrical switch 1 also includes a control device 10 configured to control the movement of the switching device 5. Furthermore, the internal space 7 of the housing 6 is either under vacuum or filled with an arc-suppressing gas (such as SF6).

[0027] like Figure 1As shown, the first electrical conductor of electrical switch 1 is connected to a plurality of tap selectors 9a, 9b and a load via corresponding conductors among the conductors. The movable switching device 5 is operated between different positions to connect the load to different tap selectors among the plurality of tap selectors 9a, 9b. This allows current to be routed through the first tap selector 9a while the second tap selector 9b is switched / operated to another position, wherein electrical switch 1 is subsequently operated to be electrically connected to the second tap selector 9b and disconnected from the first tap selector 9a. By providing an hermetically sealed housing 6 surrounding the electrical contacts 3a, 3b, 3c and the switching device 5, and by providing a vacuum or arc-suppressing gas inside the housing, the electrical contacts 3a, 3b, 3c and the switching device 5 will be subjected to less arc discharge when operating electrical switch 1. Since the electrical conductors are routed from inside the housing to outside the housing, the electrical conductors can still be accessed from outside the housing, and other suitable environments, such as air or electrical insulating oil, can be provided outside the housing. The ends of the electrical conductors accessible from the outside of the housing can therefore be connected to the load and multiple tap changers 9a, 9b. The housing specifically designed for the electrical switch 1 houses any contaminants generated during operation of the electrical switch 1 due to mechanical wear and arcing acting on the contacts 3a, 3b, 3c and the switching device 5. By containing these contaminants inside the housing of the electrical switch 1, the service life of other components of the on-load tap changer 2 can be extended. Worn electrical switch 1 can be easily replaced.

[0028] The control device 10 includes an operating member 8 extending from the outside of the housing 6 into the internal space 7 of the housing 6. The operating member 8 is operatively connected to the switching device 5, enabling the operating member 8 to move the switching device 5 to multiple positions P1, P2 depending on its position. In this embodiment, the operating member 8 includes an arm 9 rotatably attached to the housing 6 for rotation about a rotation axis 11. The switching device 5 is attached to the end portion of the arm, allowing it to move along an arcuate path between the multiple positions. The switching device 5 includes two electrically interconnected contacts or contact surfaces disposed on a movable carrier element mounted on the operating member for movement along the arcuate path, and the contacts or contact surfaces of the switching device 5 have the same spacing as the contacts of each corresponding combination C1, C2 of electrical contacts.

[0029] In this embodiment, arm 9 is controlled by an actuator (not shown), but in other embodiments, arm 9 can be operated manually.

[0030] The switching device 5 is therefore configured to be movable to a first position P1 and movable to a second position P2. In the first position, the switching device 5 physically contacts the first electrical contact 3a and the second electrical contact 3b among the electrical contacts 3a, 3b, and 3c. In the second position, the switching device 5 physically contacts the second electrical contact 3b and the third electrical contact 3c among the electrical contacts 3a, 3b, and 3c.

[0031] like Figure 1 As shown, one of the electrical conductors 4a, 4b, and 4c, 4b, is a neutral conductor, while the other two connectors 4a and 4c are connected to the corresponding tap selector switches 9a and 9b.

[0032] In other embodiments, additional locations (such as intermediate locations where current flows through other electrical contacts) may be provided to provide a first-on, then-off function.

[0033] Accordingly, such as Figure 1 As shown, this disclosure also proposes to provide an on-load tap changer 2 having the electrical switch 1 as described above.

[0034] 1 electrical switches 2 On-load tap changer 3a, 3b, 3c electrical contacts 4a, 4b, 4c Electrical conductor 5 Switching device 6 (Airtight) housing 7 interior space 8 Operating components 9a, 9b Tap selector switch 10 Control device 11 axis of rotation

[0035] Appendix label table.

Claims

1. An electrical switch (1) for a load tap changer (2), the electrical switch (1) comprising: at least three electrical contacts (3a, 3b, 3c) connected to respective electrical conductors (4a, 4b, 4c), a switching device (5) configured to be movable between a plurality of positions (PI, P2), a gas-tight sealed housing (6) providing an inner space (7) enclosing the electrical contacts (3a, 3b, 3c) and the switching device (5), the electrical conductors (4a, 4b, 4c) extending from the electrical contacts (3a, 3b, 3c) inside the inner space (7) of the housing (6) to the outside of the housing (6), one (4b) of the electrical conductors (4a, 4b, 4c) being a neutral conductor, and a control device (10) configured to control the movement of the switching device (5), wherein the inner space (7) is under vacuum or filled with arc suppression gas, wherein the control device (10) comprises an operating member (8) extending from the outside of the housing (6) into the inner space (7) of the housing (6), the operating member (8) being operably connected to the switching device (5) such that the operating member (8) can move the switching device (5) to the plurality of positions (PI, P2) depending on the position of the operating member (8), and wherein the operating member (8) comprises an arm rotatably attached to the housing (6) to rotate about a rotation axis (11), wherein an end portion of the arm is attached to the switching device (5) such that the switching device (5) can be moved between the plurality of positions along an arcuate path, characterized in that the switching device (5) in each respective position (PI, P2) physically contacts a respective combination (CI, C2) of the electrical contacts (3a, 3b, 3c) to provide electrical contact between the electrical contacts in each respective combination (CI, C2) of electrical contacts (3a, 3b, 3c), the switching device (5) comprises two electrically interconnected contacts or contact surfaces arranged on a movable carrier element mounted on the operating member for movement along the arcuate path, and the contacts or contact surfaces of the switching device (5) are arranged at the same radial distance from the rotation axis (11) and at the same spacing from the electrical contacts of each respective combination (CI, C2) of electrical contacts.

2. The electrical switch (1) according to claim 1, wherein the inner space (7) is filled with SF6 arc suppression gas.

3. The electrical switch (1) according to any one of claims 1 to 2, wherein, The switch device (5) is configured to be movable to a first position (PI) in which it physically contacts a first one (3a) of the electrical contacts (3a, 3b, 3c) and a second one (3b) of the electrical contacts (3a, 3b, 3c) and to be movable to a second position (P2) in which it physically contacts the second one (3b) of the electrical contacts (3a, 3b, 3c) and a third one (3c) of the electrical contacts (3a, 3b, 3c).

4. An on-load tap changer (2) comprising an electrical switch (1) according to any one of claims 1 to 3.

5. The on-load tap changer (2) of claim 4, wherein, The electrical switch (1) is a switching switch, wherein the remaining conductors (4a, 4c) of the electrical conductors (4a, 4b, 4c) other than the neutral conductor (4b) are connected to a respective tap selection switch (9a, 9b).

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