Electrical device having encapsulated spaces cooled with different intensity

Abstract

An electrical device for connecting to a high-voltage network has a vessel, which is filled with an insulating fluid, an active part, which is arranged in the vessel and which has a magnetizable core and partial windings for producing a magnetic field in the core, and a cooling apparatus for cooling the insulating fluid. The electrical device can be operated at high temperatures. At least one barrier system is provided, which at least partly delimits encapsulated spaces, in each of which at least one partial winding is arranged, the barrier system guiding the insulating fluid cooled by the cooling apparatus across the encapsulated spaces in such a way that different encapsulated-space temperatures arise in the encapsulated spaces.

Claims

1. An electrical device for connecting to a high-voltage network, the electrical device comprising: a vessel filled with an insulating fluid; an active part disposed in said vessel, said active part having a magnetizable core and partial windings for generating a magnetic field in said core; and a cooling device for cooling the insulating fluid; a barrier system disposed to at least partially delimit encapsulating spaces, in which at least one of said partial windings is respectively arranged, the barrier system guiding said insulating fluid cooled by the cooling device across said encapsulating spaces to cause different temperatures of the insulating fluid and/or of said partial windings in said encapsulating spaces; and each said encapsulating space being connected to a further encapsulating space, to thereby form a series of encapsulating spaces arranged one behind another in a direction of flow of the insulating fluid, with a first encapsulating space of said series forming an inlet opening and a last encapsulating space of said series forming an outlet opening; said barrier system having core connecting ducts formed therein, which extend from an encapsulating space arranged last in the direction of flow of the insulating fluid, and cooling ducts of said core.

2. The electrical device according to claim 1, wherein said barrier system is disposed to guide the insulating fluid through said encapsulating spaces one after another.

3. The electrical device according to claim 1, wherein said partial windings include a first partial winding being a low-voltage winding and a second partial winding being a high-voltage winding, said first and second partial windings being arranged concentrically in relation to one another and in relation to a core portion extending through an inner said winding being said low-voltage winding.

4. The electrical device according to claim 1, wherein insulations of different insulating materials are arranged in said encapsulating spaces.

5. The electrical device according to claim 1, wherein said partial windings are designed for different operating voltages, a temperature of the insulating fluid and/or of said partial winding in a respective said encapsulating space in which a partial winding designed for higher voltage is arranged being lower during normal operation than a temperature of the insulating fluid and/or of said partial winding in a respective said encapsulating space in which a partial winding designed for a comparatively lower voltage is arranged.

6. The electrical device according to claim 1, wherein said cooling device has a control unit with temperature sensors, said control unit having a threshold value for each encapsulating space or each temperature region (25.1-25.4) of one of said partial windings and being configured for controlling a cooling output of said cooling device in dependence on a respective threshold value.

7. The electrical device according to claim 6, wherein said temperature sensors are configured for sensing a temperature of a partial winding and/or for sensing a temperature of the insulating fluid in a partial winding.

8. The electrical device according to claim 1, wherein said barrier system comprises at least one insulating portion configured for reducing electrical field strengths.

9. The electrical device according to claim 8, wherein said barrier system delimits vertical flow ducts running parallel to one another with opposite directions of flow, at least one of said vertical flow ducts being arranged as a return duct between insulating portions respectively surrounding a partial winding.

10. The electrical device according to claim 9, wherein a wall of said barrier system between respective said vertical flow ducts running parallel to one another with opposite directions of flow has a thermal insulation.

11. The electrical device according to claim 1, wherein at least one partial winding forms temperature regions in which insulating materials that have differing degrees of thermal loadability are arranged.

12. The electrical device according to claim 11, wherein at least two said temperature regions are respectively provided with a thermal sensor for measuring a hotspot temperature of said at least one winding in the respective said temperature region.

13. The electrical device according to claim 1, wherein said barrier system forms flow ducts that run parallel to one another at least in certain portions.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) Further expedient embodiments and advantages of the invention are the subject of the following description of exemplary embodiments of the invention with reference to the figures of the drawing, in which

(2) FIGS. 1 to 4 schematically illustrate exemplary embodiments of the electrical device according to the invention in a side view.

DESCRIPTION OF THE INVENTION

(3) FIG. 1 of the drawing shows an exemplary embodiment of the electrical device 1 according to the invention, which is configured as a transformer 1. The transformer 1 has an active part 2, which is formed by a core 3, a low-voltage winding 4 and a high-voltage winding 5. The low-voltage winding 4 and the high-voltage winding 5 are arranged concentrically in relation to a leg 6 of the core 3, only one side of the windings being illustrated in FIG. 1. It should however be noted that both the low-voltage winding and the high-voltage winding run around the leg 6 as partial windings in a circumferentially closed manner, that is to say in the form of a ring.

(4) The active part 2 is arranged within a vessel 7, which is filled with an insulating fluid 8, in the exemplary embodiment shown a vegetable ester. Fastened on the vessel 7 is a cooling device 9, which has a cooling register 10, a circulating pump 11, a supply line 12 and a return line 13. The transformer 1 is intended for connection to a high-voltage network, with the result that, during the operation of the transformer, the high-voltage winding 5 is at a high-voltage potential, that is to say is subjected to a voltage of over 50 kV. A barrier system 14, which almost completely encloses both the low-voltage winding 4 and the high-voltage winding 5 respectively with one of its insulating portions, serves for controlling the electrical field thereby occurring. The barrier system 14 is at least partially produced from pressboard or some other cellulose-based material and has curved portions 15 and cylindrical portions 16, which are arranged in relation to one another in such a way that the high-voltage winding 5 and the low-voltage winding 4 are respectively arranged in encapsulating spaces 17 and 18, which are fluidically connected to one another. The encapsulating spaces 17, 18 are not completely fluid-tight. Some insulating fluid 8 can therefore also leave the barrier system 14 from the inside to the outside above the high-voltage winding 5. These “unintentionally” escaping amounts of fluid can however be ignored with regard to the cooling. The main proportion of the flow of the insulating fluid is guided through the barrier system 14. In this case, the barrier system 14 forms under the high-voltage winding 5 an inlet opening 19, through which the cooled insulating fluid escaping from the supply line 12 of the cooling device 9 enters the barrier system 14. In addition, the barrier system 14 also forms an outlet opening 21, which in the example shown is arranged above the low-voltage winding 4. The encapsulating spaces 17 and 18 are in addition hydraulically coupled to one another.

(5) The circulating pump 11 ensures that the insulating fluid 8 flows through the active part 2 and the vessel 7 in the direction illustrated by flow arrows 23. Each partial winding 4 and 5 has grading rings 24, which are arranged at its upper and lower ends for field control.

(6) By circulating by means of the circulating pump 11, the insulating fluid 8, that is to say the ester, is guided over the cooling register 10 and cooled down, cooled insulating fluid 8 leaving the outlet opening 20 of the supply line 12 entering the barrier system 14 through the inlet opening 19. There, the insulating fluid 8 is deflected a number of times, that is to say is guided in a meandering form, until it reaches the lower end of the high-voltage winding 5, in which cooling ducts are formed. In these cooling ducts, which are not represented in the figures, the lost heat of the high-voltage winding 5 is transferred to the insulating fluid 8 flowing through the cooling ducts. This causes a continual warming up of the insulating fluid 8. The high-voltage winding 5 forms two temperature regions 25.1 and 25.2, which are indicated in FIG. 1 by a different patterning. In these temperature regions 25.1 and 25.2, the winding 5 is provided with different insulating materials, which are for example assigned to different thermal classes.

(7) The gradually warming-up insulating fluid 8 enters the encapsulating space 18 of the low-voltage winding 4 from the encapsulating space 17 of the high-voltage winding 5. The barrier system 14 then guides the insulating fluid 8 over the low-voltage winding 4, which likewise has cooling ducts and temperature regions 25.3 and 25.4 with different insulating materials. Finally, the insulating fluid 8, which is once again warmed up here, passes through the outlet opening 21 into the interior space of the vessel. From there, the insulating fluid 8 is supplied once again to the cooling register 10 by way of the return line 13 and the circulating pump 11. The cooling cycle begins once again.

(8) Since the insulating fluid 8 is guided through the encapsulating spaces 17 and 18 one after the other, different encapsulating temperature regions form in the temperature regions 25.1, 25.2, 25.3 and 25.4. Thus, the encapsulating space temperature, that is to say the temperature of the winding 5 and of the insulating fluid 8, in the temperature region 25.1 is on average lower than in the temperature region 25.2 and in particular than in the temperature regions 25.3 and 25.4.

(9) Unnecessary costs are avoided by the arrangement of insulating materials with different heat resistance in the respectively appropriate temperature regions of the partial windings.

(10) An exemplary assignment of the thermal classes to the winding regions 25.1-25.4 represented in the exemplary embodiment is indicated below. In the exemplary embodiment, an ester oil is used as the insulating fluid.

(11) Design example of the partial windings 4, 5 as shown in FIG. 1 (thermal classes of the insulating materials in accordance with EN 60085:2008)

(12) TABLE-US-00001 Temperature region 25.1 25.2 25.3 25.4 Conductor insulation E B F H (120° C.) (130° C.) (155° C.) (180° C.) Spacer A E B F (105° C.) (120° C.) (130° C.) (155° C.) Barrier system/potential A A E B control rings (105° C.) (105° C.) (120° C.) (130° C.) Spacers comprise: Radial and axial spacers (bars, riders intermediate layers) Barrier system comprises: Barriers, angle rings, caps, disks, insulating cylinders

(13) The gradation of the thermal capability of the insulating materials can also be undertaken within the thermal classes in accordance with EN 60085, a large number of possibilities existing here, with for example a gradation in temperature increments of less than 10 K also being possible.

(14) FIG. 2 shows an exemplary embodiment of the electrical device 1 according to the invention represented in a simplified form, the barrier system 14 being particularly clear to see. The barrier system 14 is designed to the extent that it can be used for guiding and deflecting the flow of the insulating fluid 8. For this purpose, the barrier system 14 again has cylindrical portions 16, 16.1, 16.2, 16.3, disk-shaped portions 26.1, 26.2, 26.3 and curved portions 15, 15.1, 15.2, 15.3 and 15.4, the latter also being referred to as angle rings or caps.

(15) According to the invention, the barrier system 14 is designed in such a way that encapsulated winding spaces form, referred to here as encapsulating spaces 17, 28. For this purpose, the usually present, outer horizontal disk-shaped barriers, that delimit a flow duct for the insulating fluid are replaced by closed disks 26.2, 26.3, with the result that the inflow and outflow of the insulating fluid 8 into and out of the encapsulating spaces 17 and 18 takes place in a controlled manner by way of the inlet opening 19 and outlet opening 21. In this case, the encapsulating spaces 17 and 18 are fluidically connected to one another, in that the gap between the cylindrical portions 16.2 and 16.3 is used as a return duct 27 for the insulating fluid. In the exemplary embodiment, the inlet opening 19 is formed in the so-called winding base.

(16) The outlet opening 21 lies in the disk-shaped portion 26.1. In the exemplary embodiment shown, the gap between the curved portions 15.3 and 15.4 is used for deflecting the flow 23, or in other words reversing the direction of the flow 23, of the insulating fluid 8.

(17) In terms of high voltage, the construction of closed barrier surfaces as perpendicularly as possible to the direction of the field should be preferred. Advantageously, the curved barriers should also accordingly follow approximately the path of the equipotential lines. The resultant largely parallel arrangement also of the curved portions 15, 15.2 is conducive to use as a flow duct 27 for deflecting the flow of the insulating fluid 8, with the result that only slight flow-related changes are necessary. At transitions at which the number of electrically required curved barrier portions 15.4, 15.5 do not allow a reversal of the direction of the flow of the insulating fluid, additional curved barriers 15.3 that guide the flow and outwardly seal the winding space are inserted.

(18) In the exemplary embodiment shown, an additional curved barrier 15.3 that serves for diverting the flow of the insulating fluid has the effect of an overlaying of a number of solid insulations at the interface between the cylindrical and curved barrier portions. To avoid unfavorable field conditions due to an excessive overall thickness of the solid insulations forming the electrical barrier, at the interface between the curved barriers and the cylindrical barriers respectively scarfed angle rings 15.2 and unscarfed angle rings of a small wall thickness 15.3 are arranged in a combined and opposing manner at the cylindrical portion 16.3.

(19) FIG. 3 shows an exemplary embodiment in which only one of the encapsulating spaces 17, 18 has a partial winding with a number of temperature regions 25.1 and 25.2. The thermal class of the conductor insulation 26 increases from encapsulating space 17 to encapsulating space 18 and in the latter in turn from temperature region 25.1 to temperature region 25.2. The transition of the temperature regions takes place after reaching a winding height H1.

(20) To increase the dielectric strength, it is known that the oil gaps of the insulating construction are divided by the barrier system 14 into narrower vertical ducts 27 and horizontal ducts 28. According to the invention, these ducts 27, 28 are used for conducting the insulating fluid 8 to the partial winding 4 arranged downstream in the direction of flow 23. In the exemplary embodiment, a number of these ducts 27, 28 extend parallel to one another, in order to achieve the cross section required for the flow of the insulating fluid 8. The cross section or exact cross-sectional area and the number of interconnected vertical ducts 27 and horizontal ducts 28 may deviate from one another within the scope of the invention. To avoid bypasses, the ducts 29, which are not used as flow ducts, may be completely or partially closed at the lower end by shims 30 of insulating material.

(21) In the exemplary embodiment shown, traditional disk windings are represented within the temperature regions 25.1 and 25.2. The insulating fluid 8 flows from an outer vertical duct through a number of horizontal ducts into a second outer duct, where the direction of flow of the insulating fluid 8 is deflected, so that the insulating fluid 8 continues to flow in the opposite direction, with the result that the direction of flow changes a number of times along the height of the winding. The embodiment according to the invention of the barrier system 14 and insulation is however analogously transferable to all other types of winding.

(22) In the exemplary embodiment shown, the partial windings are provided with thermal sensors 31 at so-called hotspots of their respective temperature regions 5, 25.1 and 25.2. The sensors 31 are connected to a control unit that is not represented in the figures.

(23) Arranged at the outlet opening 21 of the last partial winding 4 thermally connected in series is a further sensor 32 for measuring the maximum temperature of the insulating fluid 8. If need be, checking the maximum temperature of the insulating fluid 8 in the upstream partial winding 5 is also possible by way of the sensor 33.

(24) FIG. 4 shows an exemplary embodiment in which the core 3 is incorporated in the cooling circuit. This is advantageous when a great temperature span of the insulating fluid 8 is provided. Designing the core 3 for higher temperatures requires only a very small effort since no moldings are required and an electrical field loading does not have to be taken into consideration. Therefore, the core 3 is put at the end of the fluidic series connection of the components to be cooled of the electrical device 1. In the exemplary embodiment as shown in FIG. 4, the windings 5 and 4 are flowed through by the insulating fluid 8 one after the other, and subsequently the core 3. The cooling ducts of the partial windings 4, 5 and cooling ducts 34 of the core 3 are thermally and fluidically connected in series. In the exemplary embodiment, the barriers are designed such that the main flow of the insulating fluid 8 within the encapsulating spaces 17 and 18 and in the core 3 is in each case directed from the bottom upward, that is to say directed in the same sense as the proper motion of the insulating fluid 8 caused by warming up. The return of the insulating fluid 8 takes place in each case in the vertical ducts 27 between the barriers of the insulating arrangement, which are referred to here as insulating portions of the barrier system 14.

(25) In the exemplary embodiment, the vertical portions 16 of the barrier system 14, which delimit ducts 27 with opposed directions of flow, are provided with an additional thermal insulation 35 in regions with a high temperature difference of the insulating fluid 8. In the simple case, this may take place by increasing the wall thickness. In the regions near the reversal in the direction of the insulating fluid 8, the temperature difference is small. Therefore, no measures are required there.