Electrical switch for on-load tap changer

Abstract

An electrical switch (1) for an on-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); switching means (5) configured to be movable between a plurality of positions (P1, P2), where the switching means (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 the electrical contacts (3a, 3b, 3c); a hermetically sealed housing (6) providing an inner space (7) enclosing the electrical contacts (3a, 3b, 3c) and the switching device (5), said 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); and a control device (10) configured to control the movement of the switching device (5). The inner space (7) is under vacuum or filled with an arc suppression gas. The control device (10) comprises an operating member (8) extending from the outside of the housing (6) into the interior space (7) of the housing (6), which operating member is operatively connected to the switching device (5) such that the operating member (8) is able to move the switching device (5) to a plurality of positions (P1, P2) depending on the position of the operating member (8). Furthermore, 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 between the plurality of positions along an arcuate path.

Description

Technical Field

[0001] The present disclosure relates to on-load tap changers, and more particularly to an electrical switch for an on-load tap changer. Background Art

[0002] Electrical switches are often used in on-load tap changers (OLTCs) to fulfill different functions, such as main switches, resistance switches, pre-selector switches or diverter switches. The specific design of the switches can vary; for example, some switches are designed to be "make before break" and some are designed to be "break before make". On-load tap changers are often used at voltages where they are subject to arcing when the electrical switch position is changed. Arcing can lead to wear of the electrical switch and thus contaminate components around the OLTC and / or contaminate the electrical switch. For example, the insulating oil in the OLTC can become contaminated and lose some of its insulating properties. Summary of the invention

[0003] Accordingly, it is an object of the present disclosure to extend the service life of an in-line tap changer and reduce the need for maintenance thereof.

[0004] According to a first aspect of the present disclosure, this object and other objects are achieved by an electrical switch according to claim 1, and alternative embodiments set forth in the dependent claims. The electrical switch is used for an on-load tap changer, and the electrical switch includes at least three electrical contacts connected to respective electrical conductors. The electrical switch also includes a switching device configured to be movable between a plurality of positions, wherein the switching device in each respective position physically contacts a respective combination of the electrical contacts to provide electrical contact between the electrical contacts in each respective combination of the electrical contacts. The physical contact controlled by the switching device may be direct contact between the contacts in each contact combination, or the physical contact may be provided by contacting a portion of the switching device with the contacts in each contact combination to bridge between the contact combinations. The electrical switch also includes a hermetic sealed housing providing 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. In addition, the internal space is under vacuum or filled with an arc suppression gas.

[0005] 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 operably connected to the switch device so that the operating member can move the switch device to a plurality of positions according to the position of the operating member.

[0006] The operating member includes an arm rotatably attached to the housing to rotate about a rotation axis. A switch device is attached to the end portion of the arm so that the switch device can move between the plurality of positions along an arc path.

[0007] For example, the electrical switch can be connected to a plurality of tap selector switches and a neutral terminal / load via corresponding conductors in the conductors. The movable switch device is operated between different positions to connect the load to different tap selector switches in the plurality of tap selector switches. This enables the current to be routed through the first tap selector switch while adjusting another tap selector switch, wherein the electrical switch is then operated to be electrically connected to the other tap selector switch and disconnected from the first tap selector switch. By providing a hermetic sealed housing around the electrical contacts and the switch device, and providing a vacuum or arc suppression gas inside the housing, the electrical contacts and the switch device will be subjected to less arc discharge when the electrical switch is operated. Since the conductor is routed from the inside of the housing to the outside of the housing, the conductor can still be touched from the outside of the housing, and some other suitable environment, such as air or electrical insulating oil, can be provided outside the housing. The end of the conductor that is accessible outside the housing can therefore be connected to the load and a plurality of tap selector switches. The housing provided specifically for the electrical switch accommodates any contaminants generated by mechanical wear and arc discharge acting on the electrical contacts and the switch device when the electrical switch is operated. By containing the contaminants inside the electrical switch housing, the service life of the other components of the on-load tap-changer can be extended. A worn electrical switch can be easily replaced.

[0008] The switching device comprises one of the electrical contacts. One of the electrical contacts can thus be moved together with the switching device so that it moves into direct contact with one or more other electrical contacts depending on the position of the switching device. Figure 4a to Figure 4b as well as Figure 5a to Figure 5b Such an embodiment is shown in .

[0009] The inner space may be filled with SF6 arc suppression gas. SF6 gas is a suitable arc suppression gas and reduces arc discharge.

[0010] The switch device can be configured to be movable to a first position, in which the switch device physically contacts a first one of the electrical contacts and a second one of the electrical contacts, and to a second position, in which the switch device physically contacts the second one of the electrical contacts and a third one of the electrical contacts.

[0011] As described above, the second aspect of the present disclosure relates to an on-load tap changer, which includes the electrical switch according to any one of claims 1 to 5.

[0012] The electrical switch of the on-load tap changer may be a changeover switch, wherein one of the conductors is a neutral conductor and wherein the remaining conductors are connected to a respective tap selector switch of the on-load tap changer. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 Schematically illustrates an exemplary use case of the electrical switch of the present disclosure; specifically, Figure 1 An on-load tap changer is shown which is provided with an electrical switch in the form of a diverter switch.

[0014] Figure 2a and Figure 2b A first embodiment of an electrical switch is schematically shown, which features a switching device for linear movement between two operating positions. Figure 2a shows an electrical switch in a first position, Figure 2b The electrical switch is shown in a second position.

[0015] Figure 3a and Figure 3b A second embodiment of an electrical switch is schematically shown, the electrical switch featuring a switching device that performs an arcuate movement between two operating positions. Figure 3a shows an electrical switch in a first position, Figure 3b The electrical switch is shown in a second position.

[0016] Figure 4a and Figure 4b A third embodiment of an electrical switch is schematically shown, the electrical switch featuring a switching device comprising one of the electrical contacts. The switching device is movable in an arc between two operating positions. Figure 4a shows an electrical switch in a first position, Figure 4b The electrical switch is shown in a second position.

[0017] Figure 5a and Figure 5b A fourth embodiment of an electrical switch is schematically shown, the electrical switch featuring a switching device comprising one of the electrical contacts. The switching device is movable along a linear path between two operating positions. Figure 5a shows an electrical switch in a first position, Figure 5b The electrical switch is shown in a second position. DETAILED DESCRIPTION

[0018] Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings.

[0019] As stated above, an object of the present disclosure is to extend the service life of an on-load tap changer and reduce the need for maintenance of the on-load tap changer.

[0020] According to the present disclosure, this object is achieved by providing a new design of an electrical switch 1 that uses a hermetically sealed housing 6 to contain only the internal components of the electrical switch 1 that present arc discharge challenges. Thus, the electrical conductors of the electrical switch 1 are routed to the outside of the housing 6 to connect to different electrical conductors of the device in which the electrical switch 1 is used.

[0021] In the on-load tap changer 2, the electrical switch 1 can have many uses. For example, the electrical switch 1 can be used as a main switch, a resistance switch, a pre-selection switch or a changeover switch. The exemplary embodiment below shows that the electrical switch is used as a changeover switch of the on-load tap changer 2. However, the interior 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, can be changed alternatively without departing from the inventive concept of the present disclosure involving providing a hermetically sealed housing 6 containing a vacuum or arc suppression gas.

[0022] Figure 13, a and Figure 3b A first embodiment of an electrical switch 1 according to the present disclosure is schematically shown. Figure 1 As shown, the electrical switch 1 can be used for 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 be movable between multiple positions P1, P2, wherein the switching device 5 physically contacts the 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, according to the desired use and function of the electrical switch 1, a larger number of electrical contacts and electrical conductors can also be alternatively provided. For example, the design of the make-before-break type electrical switch is different to some extent from the break-before-make type electrical switch schematically disclosed in the first embodiment.

[0023] The electrical switch 1 further comprises a hermetically sealed housing 6 which provides an internal space 7 enclosing the contacts 3a, 3b, 3c and the switching device 5. The electrical conductors 4a, 4b, 4c extend from the contacts 3a, 3b, 3c inside the internal space 7 of the housing 6 to the outside of the housing 6. The housing 6 is thus a relatively small housing containing only the components of the electrical switch 1 and should therefore not be confused with any surrounding housing (such as a surrounding transformer tank etc.) which also encloses other components. 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.

[0024] The electrical switch 1 further comprises a control device 10 configured to control the movement of the switching device 5. Further, the inner space 7 of the housing 6 is under vacuum or filled with an arc suppression gas such as SF6.

[0025] like Figure 1 As shown, the first electrical conductor of the electrical switch 1 is connected to a plurality of tap selector switches 9a, 9b and a load via a corresponding electrical conductor in the electrical conductor. The movable switch device 5 is operated between different positions to connect the load to different tap selector switches in the plurality of tap selector switches 9a, 9b. This enables the current to be routed through the first tap selector switch 9a, while the second tap selector switch 9b is switched / operated to another position, wherein the electrical switch 1 is then operated to be electrically connected to the second tap selector switch 9b and disconnected from the first tap selector switch 9a. By providing a hermetic sealed housing 6 around the electrical contacts 3a, 3b, 3c and the switch device 5, and providing a vacuum or arc suppression gas inside the housing, when operating the electrical switch 1, the electrical contacts 3a, 3b, 3c and the switch device 5 will be subjected to less arc discharge. Since the electrical conductor is routed from the inside of the housing to the outside of the housing, the electrical conductor can still be touched from the outside of the housing, and some other suitable environment, such as air or electrical insulating oil, can be provided outside the housing. The ends of the electrical conductors accessible outside the housing can thus be connected to the load and the plurality of tap selector switches 9a, 9b. The housing provided specifically for the electrical switch 1 contains any contaminants generated by mechanical wear and arc discharges acting on the contacts 3a, 3b, 3c and the switching device 5 when the electrical switch 1 is operated. By containing the contaminants inside the housing of the electrical switch 1, the service life of the other components of the on-load tap changer 2 can be extended. A worn electrical switch 1 can be easily replaced.

[0026] The control device 10 includes an operating member 8 extending from the outside of the housing 6 to the interior space 7 of the housing 6. The operating member 8 is operably connected to the switch device 5 so that the operating member 8 can move the switch device 5 to multiple positions P1, P2 according to the position of the operating member 8. In this embodiment, the operating member 8 includes an arm 9, which is rotatably attached to the housing 6 to rotate around the rotation axis 11. The switch device 5 is attached to the end portion of the arm so that the switch device 5 can move between the multiple positions along an arc path. In other embodiments, a mechanical linkage device or a transmission device can be provided instead of the arm 8.

[0027] Alternatively, an actuator may be provided within the interior space 7 of the housing 6 , said actuator being operably connected to an internal operating member 8 not extending outside the housing 6 , wherein the actuator is powered by a cable extending from the interior space 7 of the housing 6 to the outside of the housing 6 .

[0028] In this embodiment, the arm 9 is controlled by an actuator (not shown), but in other embodiments, the arm 9 may be manually operated. Figure 2a and Figure 2b As shown, the movement path of the switching device 5 may alternatively be rectilinear, or have any other suitable extent, but requiring a suitable adaptation of the control device 10 .

[0029] like Figure 4a to Figure 4b as well as Figure 5a to Figure 5b As shown, the switch device 5 may include one of the electrical contacts 3b. The switch device 5 may be movable between two operating positions P1, P2 in an arcuate movement. Figure 4a and Figure 5a The electrical switch 1 is shown in a first operating position P1, Figure 4b and Figure 5b The electrical switch is shown in a second operating position P2.

[0030] exist Figure 4a to Figure 4b In the embodiment of the present invention, the second conductor 4b is a conductor provided separately from the control device 10, but in other embodiments (such as Figure 5a to Figure 5b In an embodiment of the present invention, the control device 10 may be electrically conductive and thus act as the second conductor 4b.

[0031] The switching device 5 is therefore configured to be movable to a first position P1 and to a second position P2, wherein in the first position the switching device 5 physically contacts the first electrical contact 3a among the electrical contacts 3a, 3b, 3c and the second electrical contact 3b among the electrical contacts 3a, 3b, 3c, and in the second position the switching device 5 physically contacts the second electrical contact 3b among the electrical contacts 3a, 3b, 3c and the third electrical contact 3c among the electrical contacts 3a, 3b, 3c.

[0032] like Figure 1 As shown, one 4b of the electrical conductors 4a, 4b, 4c is a neutral conductor, while the remaining two connectors 4a, 4c are connected to respective tap selector switches 9a, 9b.

[0033] In other embodiments, additional positions (such as intermediate positions where current flows via other electrical contacts) may be provided to provide a make-before-break functionality.

[0034] Accordingly, if Figure 1 As shown, the present disclosure therefore also proposes to provide an on-load tap changer 2 having an electrical switch 1 as described above.

[0035] 1 Electrical switches 2 On-load tap-changer 3a, 3b, 3c Electrical contacts 4a, 4b, 4c Electrical Conductor 5 Switchgear 6 (Heat-tight seal) housing 7 Interior Space 8 Operation components 9a, 9b Tap selector switch 10 Controls 11 Rotation axis

[0036] Reference numerals list

Claims

1. An electrical switch (1) for an on-load tap changer (2), the electrical switch (1) comprising: at least three electrical contacts (3a, 3b, 3c), the at least three electrical contacts being connected to respective electrical conductors (4a, 4b, 4c), A switch device (5) configured to be movable between a plurality of positions (P1, P2), wherein the switch 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 the electrical contacts (3a, 3b, 3c), a hermetically sealed housing (6), the hermetically sealed housing providing an internal 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 internal space (7) of the housing (6) to the outside of the housing (6), and a control device (10) configured to control the movement of the switch device (5), wherein the inner space (7) is in a vacuum or filled with an arc-suppressing gas, The control device (10) comprises 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) being operably connected to the switch device (5), so that the operating member (8) can move the switch device (5) to the plurality of positions (P1, P2) according to the position of the operating member (8), and The operating member (8) comprises an arm (9) which is rotatably attached to the housing (6) so as to rotate about a rotation axis (11), wherein the switch device (5) is attached to an end portion of the arm so that the switch device (5) can move between the plurality of positions along an arc path.

2. The electrical switch (1) according to claim 1, wherein: The switching device (5) comprises one of the electrical contacts (3b).

3. The electrical switch (1) according to any one of claims 1 to 2, wherein: The inner space (7) is filled with SF6 arc suppression gas.

4. The electrical switch (1) according to any one of claims 1 to 3, wherein: The switch device (5) is configured to be movable to a first position (P1) and to be movable to a second position (P2), wherein in the first position, the switch device physically contacts a first electrical contact (3a) among the electrical contacts (3a, 3b, 3c) and a second electrical contact (3b) among the electrical contacts (3a, 3b, 3c), and in the second position, the switch device (5) physically contacts the second electrical contact (3b) among the electrical contacts (3a, 3b, 3c) and a third electrical contact (3c) among the electrical contacts (3a, 3b, 3c).

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

6. The on-load tap changer (2) according to claim 5, wherein: The electrical switch (1) is a changeover switch, wherein one (4b) of the electrical conductors (4a, 4b, 4c) is a neutral conductor and wherein the remaining conductors (4a, 4c) are connected to respective tap selector switches (9a, 9b).

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