Transformer and rail-bound vehicle

Abstract

The invention relates to a self-ventilating transformer (1). Furthermore, the invention relates to a rail-bound vehicle (19) having such a transformer (1).

Description

[0001] The invention relates to a transformer comprising a transformer active part, a tank accommodating the transformer active part and completely filled with transformer oil, a cover closing the tank, an expansion tank partially filled with transformer oil and partially filled with air, which is arranged laterally next to the tank and whose lower area filled with transformer oil is fluidically connected to the tank in such a way that flow in both directions is possible, and a vent with integrated dehumidifier, which is fluidically connected to the upper area of ​​the expansion tank filled with air.

[0002] Transformers of the type mentioned above are generally known in the prior art. They comprise an active transformer part arranged in a tank, which is normally a composite of core, windings, pressed parts, conductor, and possibly other components. Transformer oil is used to electrically insulate and cool the active part, and the tank is completely filled with it. During operation, the transformer oil in transformers used, for example, in rail vehicles is exposed to temperature amplitudes of up to 100 K. Since the volume of the transformer oil changes with temperature, the transformers are designed such that, in the event of expansion, excess fluid is collected in an expansion tank filled with transformer oil in the lower section and air in the upper section.The upper, air-filled section of the expansion tank is connected to the atmosphere via a vent with an integrated dehumidifier, allowing the air contained in the expansion tank to be displaced by the transformer oil flowing into the tank. The dehumidifier protects the transformer oil and prevents harmful moisture absorption from the ambient air. This prevents a reduction in the dielectric strength and the formation of condensate in the expansion tank.

[0003] Expansion tanks are typically positioned above the cover that seals the tank. The fluid connection between the tank and the expansion tank is preferably located at the highest point of the tank. This design has the advantage that any gases, such as air, that collect inside the tank during transformer operation and rise due to buoyancy can escape and be drained through the expansion tank.

[0004] However, arranging the expansion tank above the tank is not possible or at least undesirable in some applications due to the resulting great installation height, which is why expansion tanks are also positioned to the side of the tank. In this case, gases accumulating in the tank can no longer be fully diverted into the expansion tank. An increasing gas content in the tank leads to a drop in the transformer oil level. If this falls below a critical point, the necessary voltage clearances between electrical components of the active part can no longer be guaranteed. Accordingly, the tank must be manually vented at regular intervals. The success of the venting depends in particular on the position of the transformer during venting and on the expertise of the maintenance personnel.If the venting is not done properly, the transformer must be shut down before reaching the critical point to prevent lasting damage. This could potentially lead to the entire rail vehicle coming to a standstill during operation. The result is that the train must be towed to the nearest depot.

[0005] From the generic DE 19 51 917 A, a liquid-filled transformer with a laterally arranged expansion tank is known, in which the expansion tank is connected to the tank via a lockable pipe.

[0006] WO 2018 / 210 544 A1 discloses a high-voltage arrangement with a Buchholz relay and a specific piping arrangement between the transformer tank and the conservator.

[0007] Based on this prior art, it is an object of the present invention to provide a transformer of the type mentioned at the outset with an improved structure.

[0008] To achieve this object, the present invention provides a transformer comprising a transformer active part, a tank accommodating the transformer active part and completely filled with transformer oil, a lid closing the tank, an expansion tank partially filled with transformer oil and partially filled with air, which is arranged laterally next to the tank and whose lower region filled with transformer oil is fluidically connected to the tank in such a way that flow in both directions is possible, and a vent with integrated dehumidifier, which is fluidically connected to the upper, air-filled region of the expansion tank, characterized in that a first line provided with a first check valve is provided, which fluidically connects the tank to a region of the expansion tank filled with transformer oil,wherein the first check valve only allows flow through the first line in the direction of the boiler, and that an air trap container is provided above the cover, the lower region of which is fluidically connected to an upper region of the boiler via a second line, in particular to a highest upper region of the boiler, and the upper region of which is fluidically connected to the expansion tank via a third line provided with a second check valve, to a lower region of the expansion tank filled with transformer oil, wherein the second check valve only allows flow through the third line in the direction of the expansion tank.

[0009] The air trap tank serves to collect any gases that rise within the tank. For this purpose, it is located above the lid and its lower section is fluidly connected to the upper section of the tank via the second line, specifically to a point at the highest point in the upper section of the tank. To prevent manual venting of the air trap tank, the upper section of the air trap tank is also connected to the expansion tank via the third line, to a lower section of the expansion tank filled with transformer oil. To prevent air from "pulling back" in the event of compression, the third line is equipped with a second check valve. This ensures that when the tank cools down, only transformer oil from the fluid section of the expansion tank is drawn through the first line.If the transformer heats up during operation, the air is flushed from the air trap. During this operating state, the connection to the fluid area of ​​the expansion tank is blocked by the first check valve located in the first line.

[0010] A key advantage of the transformer according to the invention is that, despite the expansion tank being positioned to the side of the tank, manual venting of the tank is no longer necessary. The tank vents itself several times a day due to heating and cooling phases, preventing large amounts of gas from accumulating in the tank. This eliminates downtime and maintenance costs.

[0011] According to one embodiment of the present invention, the expansion tank comprises chambers whose lower, transformer oil-filled regions are each connected to one another via an oil connecting line, and whose upper, air-filled regions are each connected to one another via an air connecting line. Such chambers make it possible to divide the total volume of the expansion tank into several smaller volumes, thereby achieving considerable design flexibility.

[0012] Preferably, the chambers are positioned on opposite sides of the transformer, which ensures a uniform structure and thus an even weight distribution.

[0013] Furthermore, the present invention provides a rail-bound vehicle with a transformer according to the invention. Transformers according to the invention can be constructed flat, making them particularly suitable for use in rail vehicles.

[0014] Further features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. Fig. 1 is a schematic view of a transformer according to an embodiment of the present invention and Fig. 2 a schematic view of a rail-bound vehicle according to an embodiment of the present invention.

[0015] The transformer 1 comprises as main components a transformer active part 2, a tank 3, a cover 4 closing the tank 3, an expansion tank 5, a vent 6 with integrated dehumidifier and an air trap container 7.

[0016] The active transformer part 2, which is in particular a composite of core, windings, pressed parts, conductor, and possibly other components, is positioned within the tank 3, which is otherwise completely filled with transformer oil 8 to protect and cool the active transformer part. The expansion tank 5, which is partially filled with transformer oil 8 and partially filled with air 9, is arranged laterally next to the tank 3. More precisely, the expansion tank 5 is divided into two chambers 5a, 5b positioned on opposite sides of the tank 3, the lower regions of which, filled with transformer oil 8, are connected to one another via an oil connecting line 10, and the upper regions of which, filled with air 9, are connected to one another via an air connecting line 11.The vent 6, which communicates with the environment and has an integrated dehumidifier, is fluidly connected to the upper area of ​​the expansion tank 5, filled with air 9, via an air outlet line 12. The lower area of ​​the expansion tank 5, filled with transformer oil 8, is fluidly connected to the tank 3, in particular to a region of the tank 3 just below the cover 4, via a first line 14 provided with a first check valve 13. The first check valve 13 only allows flow through the first line 14 in the direction of the tank 3.

[0017] In the embodiment shown here, a sub-chamber 5c, completely filled with transformer oil 8, is separated from the chamber 5a that is fluidically connected to the tank 3 via the first line 14, into which sub-chamber 5c the first line 14 opens in the lower region. A further connecting line 15 is provided that connects the upper region of the sub-chamber 5c with the lower region of the chamber 5a of the expansion tank 5, filled with transformer oil 8. The air trap container 7 is arranged above the cover 4. A lower region of the air trap container 7 is fluidically connected to an upper region of the tank 3, in particular to a highest point of the tank 3, via a second line 16.An upper region of the air trap container 7 is fluidically connected to the expansion tank 5 via a third line 18 provided with a second check valve 17, with a lower region of the expansion tank 5 filled with transformer oil 8, wherein the second check valve 17 only allows flow through the third line 18 in the direction of the expansion tank 5.

[0018] If the transformer oil 8 in the tank 3 is heated during operation of the transformer 1, it expands and rises through the second line 16 into the air trap tank 7. Any gases, in particular air 9, that have collected in the tank 3 below the cover 4 are also pumped into the air trap tank 7 along with the transformer oil 8, so that the tank 3 is automatically vented. In this operating state, the connection to the fluid area of ​​the expansion tank 5 is blocked by the first check valve 13 arranged in the first line 14. From the air trap tank 7, transformer oil 8 and air 9 are then fed through the third line 18 into the expansion tank 5. A "backflow" of air 9 is prevented by the second check valve 17. The transformer oil level in the expansion tank 5 rises accordingly.Excess air 9 is vented from the expansion tank 5 into the atmosphere via the air outlet line 12 and the vent 6 with integrated dehumidifier. When the transformer oil contained in the tank 3 cools down again, transformer oil 8 is automatically pumped from the expansion tank 5 back into the tank 3 via the connecting line 15 and the first line 14, and ambient air is drawn from the atmosphere into the expansion tank 5 via the vent 6 with integrated dehumidifier.

[0019] Fig. 2 shows a rail-bound vehicle 19 according to an embodiment of the present invention, in this case a railcar of an express train, which has a transformer 1 according to the invention.

Claims

[1] Transformer (1) comprising a transformer active part (2), a tank (3) receiving the transformer active part (2) and completely filled with transformer oil (8), a cover (4) closing the tank (3), an expansion tank (5) partially filled with transformer oil (8) and partially filled with air (9), which is arranged laterally next to the tank (3) and whose lower area filled with transformer oil (8) is fluidically connected to the tank (3) in such a way that flow in both directions is possible, and a vent (6) with integrated dehumidifier, which is fluidically connected to the upper area of ​​the expansion tank (5) filled with air (9), characterized bythat a first line (14) is provided with a first check valve (13) and fluidically connects the boiler (3) to a region of the expansion tank (5) filled with transformer oil (8), wherein the first check valve (13) only allows flow through the first line (14) in the direction of the boiler (3), and that an air trap container (7) is arranged above the cover (4), the lower region of which is fluidically connected to an upper region of the boiler (3) via a second line (16), and the upper region of which is fluidically connected to the expansion tank (5) via a third line (18) provided with a second check valve (17), with a lower region of the expansion tank (5) filled with transformer oil (8), wherein the second check valve (17) only allows flow through the third line (18) in the direction of the expansion tank (5). [2] Transformer (1) according to claim 1, characterized by that the expansion tank (5) has chambers (5a, 5b), the lower regions of which are filled with transformer oil (8) and are each connected to one another via an oil connecting line (10), and the upper regions of which are filled with air (9) and are each connected to one another via an air connecting line (11). [3] Transformer (1) according to claim 2, characterized by that the chambers (5a, 5b) are positioned on opposite sides of the transformer (1). [4] Rail-bound vehicle (19) comprising a transformer (1) according to one of the preceding claims.

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