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; an insulation fluid disposed within the insulation space and electrically insulating at least a part of the electrical component from the housing, the insulation fluid comprising a first organofluorine compound and a background gas, wherein the first organofluorine compound is selected from the group consisting of fluoroethers, fluoroketones, fluoroolefins, fluoronitriles, and mixtures thereof; a cooling element comprising a condenser, an evaporator and a cooling fluid to be circulated between the condenser and the evaporator, the evaporator being configured 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, the cooling fluid consisting of second organofluorine compound selected from the group consisting of fluoroethers, fluoroketones, fluoroolefins, fluoronitriles, and mixtures thereof, wherein the cooling fluid is devoid of a background gas, wherein the insulation fluid has a first condensation temperature and the cooling fluid has a second condensation temperature lower than the first condensation temperature.

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

3. The electrical apparatus according to claim 2, wherein at least one winding of the at least two windings is at least partially immersed in the cooling fluid in its liquid state.

4. The electrical apparatus according to claim 1, wherein the insulation fluid and the cooling fluid differ from each other in at least one of their composition or density.

5. The electrical apparatus according to claim 1, wherein a condensation temperature is lower than a condensation temperature of the insulation fluid.

6. 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.

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

9. The electrical apparatus according to claim 8, 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 first organofluorine compound is selected from the group consisting of hydrofluoromonoethers, perfluoroketones, hydrofluoroolefins, and perfluoronitriles, and mixtures thereof, and wherein the second organofluorine compound is selected from the group consisting of hydrofluoromonoethers, perfluoroketones, hydrofluoroolefins, and perfluoronitriles, and mixtures thereof.

11. The electrical apparatus according to claim 1, wherein the first organofluorine compound and the second organofluorine compound 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 background gas is 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 a second pressure of the cooling fluid in the evaporator is at least approximately equal to a first pressure of the insulation fluid in the insulation space.

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

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

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

18. The electrical apparatus according to claim 17, wherein the cooling fluid recirculation channel is disposed in a cooling fluid outlet region branching off from the condenser and arranged outside of the apparatus.

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

20. The electrical apparatus according to claim 1, wherein the cooling fluid forms 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 configured to produce heat upon exposure to electric or magnetic fields.

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

23. The electrical apparatus according to claim 1, further comprising 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; an insulation fluid disposed within the insulation space and electrically insulating at least a part of the electrical component from the housing, the insulation fluid comprising a first organofluorine compound and a background gas, wherein the first organofluorine compound is selected from the group consisting of fluoroethers, fluoroketones, fluoroolefins, fluoronitriles, and mixtures thereof; a cooling element comprising a condenser, an evaporator and a cooling fluid to be circulated between the condenser and the evaporator, the evaporator being configured 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, the cooling fluid consisting of second organofluorine compound selected from the group consisting of fluoroethers, fluoroketones, fluoroolefins, fluoronitriles, and mixtures thereof, wherein the cooling fluid is devoid of a background gas, wherein the insulation fluid has a first condensation temperature and the cooling fluid has a second condensation temperature lower than the first condensation temperature, the method comprising: 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; transferring the evaporated cooling fluid to the condenser; cooling down the evaporated cooling fluid below the condensation temperature, thereby causing the evaporated cooling fluid becoming liquid; transferring the liquid cooling fluid back to the evaporator; and repeating the transferring heat, the transferring the evaporated cooling fluid, the cooling down the evaporated cooling fluid, and the transferring the liquid cooling fluid to transfer heat away from the electrical component.

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

27. 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; an insulation fluid disposed within the insulation space and electrically insulating at least a part of the electrical component from the housing, the insulation fluid comprising a first organofluorine compound and a background gas, wherein the first organofluorine compound is selected from the group consisting of fluoroethers, fluoroolefins, fluoronitriles, and mixtures thereof; and a cooling element comprising a condenser, an evaporator and a cooling fluid to be circulated between the condenser and the evaporator, the evaporator being configured 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, the cooling fluid consisting of second organofluorine compound selected from the group consisting of fluoroethers, fluoroolefins, fluoronitriles, and mixtures thereof, wherein the cooling fluid is devoid of a background gas, and wherein the insulation fluid has a first condensation temperature and the cooling fluid has a second condensation temperature lower than the first condensation temperature.

Description

(1) The invention is further illustrated by the attached

(2) FIG. 1 showing a purely schematic sectional view of a gas-insulated electrical apparatus of the present invention.

(3) 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.

(4) 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.

(5) 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.

(6) The transformer 101 further comprises a cooling element 28 which comprises an evaporator 30.

(7) 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.

(8) 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.

(9) 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.

(10) 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.

(11) 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.

(12) 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

(13) 10; 101 fluid-insulated electrical apparatus, gas-insulated electrical apparatus; gas-insulated transformer, gas-insulated reactor 12 housing 14 interior space 16 electrical component 18 primary winding 20 secondary winding 22 magnetic core 24 insulation space 26 insulation fluid 28 cooling element 30 evaporator 31 evaporator wall 32 cooling fluid 33 evaporator interior space 34 cooling fluid outlet region, cooling fluid evaporator-outlet channel 36 condenser 38 uppermost region of the condenser 40 bottom region of the condenser 42 cooling fluid recirculation channel 44 bottom region of the evaporator, cooling fluid evaporator-inlet channel 46 uppermost region of the evaporator