Load step switch and step transformer with load step switch

Description

[0001] The invention relates to a load tap changer for uninterrupted load switching between different winding taps of a tap transformer.

[0002] Furthermore, the invention relates to a step-down transformer with a load tap switch for uninterrupted load switching between different winding taps of the step-down transformer.

[0003] Load tap changers are known from the prior art and typically comprise a load changeover switch and a selector. The load changeover switch, with its vacuum switching tubes and switching resistors, is housed in a cylindrical container. The selector consists of a multitude of rods arranged in a circle. Contacts are arranged on these rods at different levels, serving as connections for the winding taps of a control winding. Inside the selector, two selector arms are mounted on a switching column. These arms make contact with the contacts on the rods. The load changeover switch and selector are interconnected via a gearbox.

[0004] The on-load tap changer is attached to the transformer cover. In the first step, the tap changer head is screwed to the underside of the transformer cover. In the second step, a tap changer cover is screwed onto the transformer cover over the tap changer. This type of installation is time-consuming, expensive, and unsuitable for smaller on-load tap changers.

[0005] DE 10 2012 103 489 A1 discloses a load tap changer for uninterrupted load switching with a flange module.

[0006] US 4 532 386 A and US 5 847 939 A disclose a changeover switch that is attached to a transformer cover or transformer wall by means of a union nut.

[0007] CN 105 977 002 A discloses a load tap changer that is attached inside a transformer housing by means of retaining elements. The object of the invention is to create a load tap changer that is simple and compact in design and can therefore be installed easily and in a space-saving manner in a tap transformer.

[0008] This problem is solved by a load tap changer according to claim 1. The features of the dependent claims constitute advantageous further developments of the invention.

[0009] A further objective of the invention is to create a step-down transformer with a load tap changer that is simple and compact in design.

[0010] This problem is solved with a step-down transformer according to claim 4. The features of the dependent claims constitute advantageous further developments of the invention.

[0011] According to a first aspect, the invention proposes a load tap changer for uninterrupted load switching between different winding taps of a tap transformer, comprising a flange module and a union nut, wherein the load tap changer can be attached to the tap transformer by means of the union nut and the flange module.

[0012] The simple solution of using a flange module and a union nut to secure the load tap changer in a step-down transformer makes installation particularly easy. The flange module is inserted from inside the step-down transformer through an opening in the housing wall. Part of the flange module protrudes from the housing. The union nut is then placed onto the flange module, pressing it against the inside of the housing wall from the outside.

[0013] The connection between the flange module outside the housing and the union nut is implemented as a thread or partial thread. This allows the union nut to be screwed onto the flange module. Furthermore, the connection between the union nut and the flange module is achieved through positive locking and / or frictional locking.

[0014] The union nut has an internal thread which is screwed onto an external thread of the flange module.

[0015] The flange module and / or the union nut can be made of an insulating material, preferably plastic.

[0016] It may be provided that at least one seal, such as a sealing ring, is arranged between the flange module and the housing. The seal can then be positioned, for example, between the inner wall of the housing and the flange of the flange module.

[0017] The load tap changer comprises a control unit and / or a communication unit, an actuator, a load switch, and a selector. The communication unit and / or the control unit are arranged in a first section of the flange module, which is located at least partially outside the tap changer.

[0018] The drive, load switch and selector are arranged in a second area of ​​the flange module, which is located at least partially inside the step-down transformer.

[0019] It may be provided that the load switch has several semiconductor switching elements and the selector has several mechanical switches.

[0020] It may be provided that the first area and the second area of ​​the flange module are separated from each other by a wall.

[0021] The load tap changer can be designed in any way and can, for example, be a conventional load tap changer with mechanical contacts or a hybrid tap changer with mechanical contacts and semiconductor switching elements.

[0022] According to a second aspect, the invention proposes a step-down transformer with a load tap changer, a housing and an active part with winding taps, wherein the load tap changer is designed according to the first aspect mentioned above.

[0023] Because the load tap changer can be attached via the flange module and the union nut, the installation of the tap changer is particularly easy. After inserting the active part, the load tap changer can be connected to the winding taps without much effort. The flange module is then inserted through an opening in the housing wall up to the flange and secured from the outside with the union nut. No special tools are required for installation.

[0024] The load tap changer may be arranged horizontally or vertically inside the tap transformer.

[0025] It may be provided that the load tap changer is located inside the tap transformer next to and / or above and / or below an active part.

[0026] The step-down transformer can be configured in any way and, for example, as a single- or multi-phase distribution transformer, pole-mounted transformer, service transformer, pad-mounted transformer, or pole-mounted transformer. This step-down transformer is preferably suitable for voltages up to 36 kV.

[0027] The invention and its advantages are described in more detail below with reference to the accompanying drawings. These show: Fig. 1 shows a load tap changer in a tap transformer; Fig. 2 shows a sectional view of the load tap changer.

[0028] Figure 1Figure 1 shows a load tap changer 1 for uninterrupted load switching between different winding taps 31 of a tap-changer 30. The load tap changer 1 is arranged horizontally inside the transformer 30 above the active part 32 and protrudes laterally from the housing 6 of the transformer 30. Alternatively, the load tap changer 1 can be arranged vertically, in which case it protrudes from the top of the housing 6 or the cover 7. The load tap changer 1 is connected to the respective winding taps 31 of the active part 32 via conductors.

[0029] The step-down transformer 30 is a single- or multi-phase distribution transformer, which can be configured in particular as a so-called mast transformer, service transformer, pad-mounted transformer or pole-mounted transformer. This step-down transformer is preferably suitable for voltages up to 36 kV.

[0030] Figure 2Figure 1 shows a detailed sectional view of the load tap changer 1 for uninterrupted load switching between different winding taps 31 of a tap changer 30. The load tap changer 1 has a flange module 2, which is essentially divided into two sections. The first section 10 is separated from the second section 20 by a wall 4. After installation of the load tap changer 1, the first section 10 of the load tap changer 1 is located outside the tap changer 30. The second section 20 of the load tap changer 1 is located inside the tap changer 30.

[0031] During the installation of the load tap changer 1, the flange module 2 of the load tap changer 1 is inserted through an opening 3 of the housing 6, here a wall 4 of the step-down transformer 30. This is possible because the flange module 2, and thus the load tap changer 1, has a smaller or approximately the same diameter in its first section 10 as the diameter of the opening 3 in the wall 4 of the step-down transformer 30.

[0032] The flange module 2 has a flange 5 whose diameter is larger than the diameter of the opening 3. The flange module 2 can only project through the opening 3 of the wall 4 up to this flange 5. The flange 5 has a first surface 5.1 that faces the inside 4.1 of the wall 4 or housing 6. Between the first surface 5.1 and the inside 4.1 of the wall 4, one or more seals in the form of one or more sealing rings 21 can be arranged when the tap changer 1 is mounted. Thus, the seal or sealing ring 21 is located between the flange module 2 and the housing 6. This prevents the escape of transformer oil located inside the tap changer 30.

[0033] The first section 10 of the flange module 2, located on the outer surface 4.2 of the step-down transformer 30, has a circumferentially extending thread 11 that is at least partially formed. The load tap changer 1 is fastened to the housing 6 of the step-down transformer 30 by means of a union nut 12, which has an internal thread 13. Tightening the union nut 12 presses the flange module 2, and thus the entire load tap changer 1, against the inner surface 4.1 of the housing 6, i.e., the wall 4. The connection between the union nut 12 and the flange module 2 can also be achieved by means of locking lugs or similar devices. In this case, the union nut 12 is always placed onto the flange module 2 to secure it. The flange 5 supports the flange module 2 against the inner surface of the wall 4 of the step-down transformer 30. In the embodiment shown here, a cover cap 14 is clipped onto the load tap changer from the outside.This serves as protection against the elements.

[0034] Flange module 2 forms part of the load tap changer 1. The control unit 40 and the communication unit 41 are located in the first section 10 of flange module 2. These are accessible from the outside, i.e., outside the tap changer 30. The drive unit 42, the load changeover switch 43, and the selector 44 are located in the second section 20, which is inside the tap changer 30. While the selector 44 consists of mechanical switches / contacts, the load changeover switch 43 has semiconductor switching elements. The load tap changer 1 is therefore a so-called hybrid load tap changer. Reference symbol list

[0035] 1 Load step switch 2 Flange module 3 Opening 4 Wall 4.1 Inside of 4 4.2 Outside of 4 5 Flange 5.1 First surface of 5 6 Housing 7 Cover 10 First area 11 Thread 12 Union nut 13 Internal thread 14 Cover cap 20 Second area 21 Gasket or sealing ring 30 Step transformer 31 Winding taps 32 Active part 40 Control unit 41 Communication unit 42 Actuator 43 Load step switch 44 Selector

Claims

1. An on-load tap-changer (1) for uninterrupted diverter switch operation between different winding taps of a tapped transformer (30), comprising: - a flange module (2) and a union nut (12); wherein - the tapped transformer (30) has a housing (6) with an inner side (4.1); - the flange module (2) has a flange (5); - the flange module (2) has a first region (10) and a second region (20); - the flange module (2) has an at least partially formed, circumferentially extending thread (11) in the first region (10); - a control unit (40) and / or a communication unit (41) are arranged in the first region (10); - the first region (10) is arranged at least partially outside the step transformer (30); - a drive (42), a diverter switch operation (43) and a selector (44) are arranged in the second area (20); - the second region (20) is arranged at least partially inside the tapped transformer (30); - the union nut (12) has an internal thread (13); - the on-load tap-changer (1) can be fastened to the tapped transformer (30) by means of the union nut (12) and the flange module (2) in such a way that, when the on-load tap-changer (1) is mounted, by attaching the union nut (12) to the flange module (2), the union nut (12) presses the flange (5) against the inside (4.1) of the housing (6) of the tapped transformer (30) by screwing and thus fixes the on-load tap-changer (1).

2. On-load tap-changer (1) according to claim 1, wherein - at least one seal (21) is arranged between the flange module (2) and the housing (6).

3. On-load tap-changer (1) according to one of claims 1 or 2, wherein - the diverter switch (43) comprises semiconductor switching elements and the selector (44) comprises mechanical switches.

4. A tapped transformer (30) with an on-load tap-changer (1) according to any one of claims 1 to 3, comprising: - a housing (6) with a cover (7); - an active part (32) with winding taps (31); wherein - the on-load tap-changer (1) is arranged on the cover (7) of the housing (6) above the active part (32) and / or on the housing (6) next to the active part (32).

5. Tap-changer transformer (30) according to claim 4 with an on-load tap-changer (1) according to one of claims 1 to 3, wherein - the on-load tap-changer (1) is aligned horizontally above the active part (32) or is aligned vertically.

6. A tapped transformer (30) according to any one of claims 4 or 5, comprising an on-load tap-changer (1) according to any one of claims 1 to 3, wherein the tapped transformer (30) is a single-phase or multi-phase distribution transformer.