GAS-INSULATED ELECTRICAL APPARATUS, IN PARTICULAR GAS-INSULATED TRANSFORMER OR REACTOR

Abstract

The present invention relates to gas-insulated electrical apparatuses, in particular gas-insulated transformers or reactors, comprising a housing enclosing an interior space, in which an electrical component comprising a winding is arranged, at least a portion of the interior space defining an insulation space which is filled with an insulation fluid electrically insulating at least a part of the electrical component from the housing. According to the invention, the electrical apparatus further comprises a cooling element comprising a condenser, an evaporator and a cooling fluid to be circulated between the condenser and the evaporator. The evaporator is designed such that at least a part of the electric component is immersed in the cooling fluid in its liquid state, thus being in direct contact with the cooling fluid.

Claims

1. A fluid-insulated electrical apparatus, comprising: a housing enclosing an interior space, in which interior space an electrical component comprising at least one winding is arranged, at least a portion of the interior space defining an insulation space which is filled with an insulation fluid electrically insulating at least a part of the electrical component from the housing, a cooling element comprising a condenser, an evaporator and a cooling fluid to be circulated between the condenser and the evaporator, the evaporator being designed such that at least a part of the electrical component is immersed in the cooling fluid in its liquid state, thus being in direct contact with the cooling fluid, wherein the cooling fluid and the insulation fluid comprise independently from each other an organofluorine compound selected from the group consisting of fluoroethers, fluoroketones, fluoroolefins, fluoronitriles, and mixtures thereof, the cooling fluid is devoid of a background gas and consists of the organofluorine compound or a mixture of the organofluorine compounds, and the insulation fluid comprises the organofluorine compound in combination with a background gas.

2. The electrical apparatus according to claim 1, wherein it is a fluid-insulated transformer, the electrical component comprising at least two windings including a primary winding and a secondary winding and further comprising a magnetic core.

3. The electrical apparatus according to claim 1, wherein the insulation fluid and the cooling fluid differ from each other in their composition and/or density.

4. The electrical apparatus according to claim 1, wherein a composition and/or density for the cooling fluid is chosen such that its condensation temperature is lower than a condensation temperature of the insulation fluid.

5. The electrical apparatus according to claim 1, wherein the evaporator is surrounded by the insulation space and comprises an evaporator wall enclosing an evaporator interior space separated from the insulation space, said evaporator wall being impermeable for both the insulation fluid and the cooling fluid.

6. The electrical apparatus according to claim 1, wherein at least one winding is at least partially immersed in the cooling fluid in its liquid state.

7. The electrical apparatus according to claim 1, wherein the cooling fluid has a boiling point lower than the maximally allowed hotspot temperature at the at least one winding.

8. The electrical apparatus according to claim 1, wherein the cooling fluid has a boiling point lower than 100° C., at the maximum pressure expected inside the electrical apparatus, during standard operation of the electrical apparatus.

9. The electrical apparatus according to claim 1, wherein the maximum pressure expected inside the electrical apparatus, during standard operation of the electrical apparatus is 6 bar at most.

10. The electrical apparatus according to claim 1, wherein the cooling fluid and/or the insulation fluid comprises independently from each other an organofluorine compound selected from the group consisting of hydrofluoromonoethers, perfluoroketones, hydrofluoroolefins, and perfluoronitriles, and mixtures thereof.

11. The electrical apparatus according to claim 1, wherein both the cooling fluid and the insulation fluid comprise the same organofluorine compound.

12. The electrical apparatus according to claim 1, wherein the cooling fluid is at least approximately devoid of air or an air component.

13. The electrical apparatus according to claim 1, wherein the insulation fluid comprises the organofluorine compound in combination with a background gas selected from the group consisting of: air, an air component, nitrogen, oxygen, carbon dioxide, a nitrogen oxide, and mixtures thereof.

14. The electrical apparatus according to claim 1, wherein the pressure of the cooling fluid in the evaporator is at least approximately identical to the pressure of the insulation fluid in the insulation space.

15. The electrical apparatus according to claim 1, wherein the condenser is designed to transfer heat to the outside of the electrical apparatus, and is arranged outside of the apparatus.

16. The electrical apparatus according to claim 1, wherein an auxiliary cooling element is allocated to the condenser.

17. The electrical apparatus according to claim 1, wherein the condenser and the evaporator are fluidically connected by a cooling fluid recirculation channel, that allows a flow of the condensed cooling fluid from the condenser in direction to the evaporator.

18. The electrical apparatus according to claim 1, wherein the cooling fluid recirculation channel in a cooling fluid outlet region branching off from the condenser is arranged outside of the apparatus.

19. The electrical apparatus according to claim 1, wherein the electrical apparatus is a gas-insulated transformer or a gas-insulated reactor.

20. The electrical apparatus according to claim 1, wherein the cooling fluid is a dielectric insulating material.

21. The electrical apparatus according to claim 1, wherein the immersed part of the electrical component is a bare or barely insulated part producing heat upon exposure to electric or magnetic fields.

22. The electrical apparatus according to claim 1, wherein the cooling element is a heat sink.

23. The electrical apparatus according to claim 1, which further comprises means for creating a turbulent flow of the liquid cooling fluid inside the cooling element.

24. The electrical apparatus according to claim 23, wherein the means are or are part of the immersed part of the electrical component.

25. A method of cooling a fluid-insulated electrical apparatus, comprising: a housing enclosing an interior space, in which interior space an electrical component comprising at least one winding is arranged, at least a portion of the interior space defining an insulation space which is filled with an insulation fluid electrically insulating at least a part of the electrical component from the housing, a cooling element comprising a condenser, an evaporator and a cooling fluid to be circulated between the condenser and the evaporator, the evaporator being designed such that at least a part of the electrical component is immersed in the cooling fluid in its liquid state, thus being in direct contact with the cooling fluid, wherein the cooling fluid and the insulation fluid comprise independently from each other an organofluorine compound selected from the group consisting of fluoroethers, fluoroketones, fluoroolefins, fluoronitriles, and mixtures thereof, the cooling fluid is devoid of a background gas and consists of the organofluorine compound or a mixture of the organofluorine compounds, and the insulation fluid comprises the organofluorine compound in combination with a background gas; the method comprising: a) transferring heat in the evaporator from the electrical component to the cooling fluid, at least a portion of which cooling fluid being in its liquid state, in which liquid cooling fluid at least a part of the electrical component immersed, whereby at least a portion of the liquid cooling fluid evaporates, b) transferring the evaporated cooling fluid generated in step a) to the condenser, where the evaporated cooling fluid is cooled down below the condensation temperature, thereby becoming liquid, and c) transferring the liquid cooling fluid obtained in step b) back to the evaporator.

26. The method according to claim 25, wherein a turbulent flow of the liquid cooling fluid inside the cooling element around the immersed part of the electrical component, is created.

Description

[0063] The invention is further illustrated by the attached

[0064] FIG. 1 showing a purely schematic sectional view of a gas-insulated electrical apparatus of the present invention.

[0065] The gas-insulated electrical apparatus 10 shown in FIG. 1 is in the form of a gas-insulated transformer 101 comprising a housing 12 enclosing an interior space 14, in which an electrical component 16 comprising a primary, low-voltage winding 18 and a secondary, high voltage winding 20 is arranged.

[0066] In the specific embodiment shown, the windings 18, 20 are arranged concentrically and are wound around a magnetic core 22 designed in the “core form”.

[0067] The interior space 14 of the transformer 101 defines an insulation space 24 which is filled with an insulation fluid 26 electrically insulating the windings 18, 20 and the core 22 from the housing 12. In the embodiment shown, the insulation fluid is in its gaseous state. However, also two-phase systems, in which at least some of the components are partially present in liquid phase apart from the gaseous phase, are thinkable.

[0068] The transformer 101 further comprises a cooling element 28 which comprises an evaporator 30.

[0069] In the embodiment shown, the evaporator 30 is in the form of an encapsulation 301 in which the windings 18, 20 are enclosed. Specifically, the evaporator 30 is surrounded by the insulation space 24 and comprises an evaporator wall 31 enclosing an evaporator interior space 33 separated from the insulation space 24.

[0070] Specifically, the encapsulation 301 is in the form of a hollow cylinder arranged around the magnetic core 22, the axis of the hollow cylinder running parallel to the respective portion of the magnetic core 22.

[0071] The evaporator interior space 33 has a volume which is only slightly greater than the volume defined by the outer contour of the windings 18, 20 and is filled with a cooling fluid 32, which is at least partially in its liquid state. In embodiments, the evaporator wall 31 is impermeable for both the insulation fluid 26 and the cooling fluid 32.

[0072] In its uppermost region 46, the evaporator 30 opens into a cooling fluid outlet channel 34, which extends from the interior space 14 of the transformer 101 through the housing 12 to the outside and fluidically connects the evaporator 30 with a condenser 36 arranged outside of the housing 12. Specifically, the cooling fluid outlet channel 34 enters the condenser 36 in its uppermost region 38. In its bottom region 40, the condenser 36 opens into cooling fluid recirculation channel 42 extending again into the interior space 14 of the transformer 101, where it enters the evaporator 30 in its bottom region 44.

[0073] In operation, the liquid cooling fluid, which is in direct contact with the windings 18, 20 immersed therein, is heated by the losses generated in the windings. When reaching the evaporation temperature, the cooling fluid 32 enters the gaseous state. The evaporated cooling fluid thereby formed is emitted into the cooling fluid outlet channel 34, by means of which it is transferred into the condenser 36.

[0074] Upon entering the condenser 36, the evaporated cooling fluid is cooled down below the condensation temperature, thereby becoming liquid again. The resulting cooling fluid liquid is then again transferred to the evaporator 30 by means of the cooling fluid recirculation channel 42, thus closing the recirculation cycle.

LIST OF REFERENCE NUMERALS

[0075] 10; 101 fluid-insulated electrical apparatus, gas-insulated electrical apparatus; gas-insulated transformer, gas-insulated reactor [0076] 12 housing [0077] 14 interior space [0078] 16 electrical component [0079] 18 primary winding [0080] 20 secondary winding [0081] 22 magnetic core [0082] 24 insulation space [0083] 26 insulation fluid [0084] 28 cooling element [0085] 30 evaporator [0086] 31 evaporator wall [0087] 32 cooling fluid [0088] 33 evaporator interior space [0089] 34 cooling fluid outlet region, cooling fluid evaporator-outlet channel [0090] 36 condenser [0091] 38 uppermost region of the condenser [0092] 40 bottom region of the condenser [0093] 42 cooling fluid recirculation channel [0094] 44 bottom region of the evaporator, cooling fluid evaporator-inlet channel [0095] 46 uppermost region of the evaporator