WO2012100810A1

WO2012100810A1 - A cooling component for a transformer comprising ceramic

Info

Publication number: WO2012100810A1
Application number: PCT/EP2011/050878
Authority: WO
Inventors: Martin Wuethrich; Frank BUERVENICH
Original assignee: Schaffner Emv Ag
Priority date: 2011-01-24
Filing date: 2011-01-24
Publication date: 2012-08-02

Abstract

According to the present invention there is provided a cooling component having one or more channels defined therein, wherein the cooling component comprises ceramic. There is further provided a corresponding method for manufacturing such a cooling component; a transformer comprising such a cooling component; and a corresponding method of manufacturing such a transformer.

Description

A COOLING COMPONENT FOR A TRANSFORMER COMPRISING CERAMIC

Field of the invention

[0001] The present invention relates to a cooling component, and in particularly, but not exclusively to a cooling component which is suitable for liquid cooling of a core of a transformer or reactor (thereafter named "transformer" only).

Description of related art

[0002] Various means for cooling the core of a transformer are in use today. The most effective cooling means which are currently in use involve liquid cooling. To liquid cool a core of a transformer, a cooling body through which a cooling fluid flows, is positioned proximate to the core of the transformer. Heat generated by the core is conducted through the cooling body and is absorbed by the cooling fluid which flows in the cooling body. Having absorbed the heat generated by the core, the cooling fluid flows out of the cooling body thus removing the heat energy away from the core.

[0003] The cooling body through which cooling fluid flows is usually composed of aluminium, or stainless steel. Such materials are robust and offer high resistance to corrosion which may be caused by cooling fluids. However, each of these materials have disadvantages; in the case of aluminium cooling bodies strong eddy currents are created in the aluminium cooling bodies by the magnetic field exhibited from the core of the transformer, especially at higher frequencies (fPWM / switching frequency). The creation of strong eddy currents leads to high losses (eddy current losses). Although less eddy currents are created in the case of stainless steel cooling bodies, stainless steel cooling bodies offer a different disadvantage in that stainless steel has low thermal conductivity and a high density; thus stainless steel cooling bodies a not effective at conducting heat away from the core of the transformer to the cooling fluid which flows within said stainless steel cooling body. Plastic cooling bodies, which are not common, but are sometimes used are not capable of withstanding high temperatures. The cores and windings of transformers which are currently in use can reach temperatures of above 200°C, thus plastic cooling bodies are susceptible to melting and failure when used to cool the cores of modern transformers.

[0004] It is further necessary to electrically isolate these cooling bodies from the windings of a transformer. Typically expensive electrically insulating material, such as Nomex™, is wound around the outer surface of the body; the electrically insulating material electrically isolates the cooling body from the windings of the transformer. Due to the high electrical conductivity of aluminium and steel, over twelve layers of electrically insulating material is required to be applied to the outer surface of the cooling body to electrically isolate the cooling body from the windings of the transformer (the windings may conduct a DC-link voltage of up to1080V, which is the common voltage for windmill applications). The requirement for so many layers of electrically insulating material increases the expense and labour time of transformers which use such cooling bodies.

[0005] It is an aim of the present invention to obviate or mitigate one or more of the aforementioned disadvantages

Brief summary of the invention

[0006] According to the present invention there is provided a cooling component having one or more channels defined therein, wherein the cooling component comprises ceramic. [0007] "Ceramic" in as referred to in the present invention, is aluminium oxide (AI203).

[0008] Cooling fluid can flow in the one or more channels; the cooling fluid can absorb heat energy from the core of a transformer thus cooling the core and winding of the transformer. Advantageously, as the cooling component comprises ceramic, it ensures that no eddy currents are be created in the cooling component by the magnetic field exhibited from the core of the transformer. Furthermore, ceramic is a good heat conductor thus is effective at conducting heat away from the core and winding of the transformer to any cooling fluid which flows within the one or more channels defined in the cooling component. Additionally, Ceramic can withstand high temperatures thus is not susceptible to melting due to high temperatures which are generated in the core and winding of a

transformer. Furthermore, since ceramic is a good electrical insulator, only two layers of electrically insulating material e.g. Nomex™, are required to be applied to the outer surface of the cooling component to electrically isolate the cooling component from the windings of a transformer, which means to ensure the correct creepage (over surface) and clearance (through air) distances between the cooling component and windings. Accordingly the requirement for less layers of electrically insulating material decreases the expense of transformers which use cooling components according to the present invention.

[0009] The cooling component may be configured such that it can cooperate with a core of a transformer so that it is in thermal communication with the core of the transformer. The cooling component may be

configured such that it can co-operate with a winding of a transformer so that it is in thermal communication with the winding of the transformer.

[0010] Preferably, the cooling component comprises two or more channels defined therein. [0011] The cooling component may comprise a first part and second part which are co-operable. This allows for easier construction of the cooling component. The first part and second part may be co-operable to define the one or more channels. The first and second part may be secured together by means of one or more fasteners, for example one or more screw members. Alternatively, the first and second part may be held in cooperation with one another by means of electrically insulating material which is applied to an outer surface of the cooling component. For example, the first and second part may be held in co-operation with one another by means of electrically insulating material which is wound around an outer surface of the cooling component. The first and second part may be held in co-operation with one another by means of windings of a transformer. In the latter two cases, advantageously, no fasteners are required.

[0012] The cooling component may further comprise one or more conduit members. It should be understood that the cooling component may comprise any number of conduit members. The conduit members may each take any suitable shape, aspect or design. The or each conduit member may be positioned within the one or more channels which are defined in the cooling component. The or each conduit member may be a pipe.

[0013] The cooling component may comprise a U-shaped conduit member.

[0014] The cooling component may comprise two or more conduit members. Preferably the cooling component comprises two conduit members. The cooling component may further comprise an intermediate conduit member. The intermediate conduit member may fluidly connect two conduit members. The intermediate conduit member may fluidly connect two conduit members to form a U-shaped conduit member.

[0015] The or each conduit member may comprise any suitable material. Preferably, the or each conduit member will comprise at least one material selected from the group of materials comprising, stainless steel, copper, aluminium.

[0016] The or each conduit member may comprise an inner diameter of length between 6mm-20mm. Preferably, the or each conduit member may comprise an inner diameter of length 8mm or bigger. The thickness of a wall of the or each conduit member may be between 1 .5mm-4mm.

However, it will be understood that the or each conduit member may comprise an inner diameter of any suitable length and the thickness of the wall of the or each conduit member may be of any suitable dimension. Preferably, the inner diameter dimension and the wall thickness dimension are chosen to ensure that the difference between the pressure of the cooling fluid which is inputted to the conduit member and the pressure of the cooling fluid which is outputted to the conduit member, is below a predetermined pressure difference. This ensures that the pressure loss in the cooling fluid as it flows through the conduit is not too large.

[0017] The cooling component may further comprise a conducting paste. The conducting paste may facilitate the elimination of air pockets which may occur due uneven surfaces of the cooling component. For example, air contained within a slight depression on the surface of the cooling component will act as a thermal insulator, compromising the transfer of heat to the cooling component; the conducting paste when applied to the surface of the cooling component will fill the depression so to eliminate the air pocket. The conducting paste may be provided on an outer surface of the cooling component. This will facilitate the elimination of air pockets which may occur between the cooling component and electrically insulating material which is provided on the surface of the cooling component, and thus ultimately facilitating the elimination of air pockets which exist between the cooling component and a core of a transformer which the cooling component has been arranged to cool. The conducting paste maybe provided on a first part of the cooling component. The conducting paste maybe provided on a second part of the cooling component. The conducting paste maybe provided at an interface between the first part and second parts. The conducting paste may be provided on a surface of the one or more channels. The conducting paste may be provided on a surface of the one more conduit members. The conducting paste may be provided at an interface between the one or more channels and the one or more conduit members.

[0018] The conducting paste may be Elantron PU4284 TX. [0019] The cooling component may further comprise resin. The resin may provide structural strength to the cooling component. The resin may be impregnated into the cooling component.

[0020] The cooling component may further comprise a cooling fluid. The cooling fluid may comprise at least one selected from the group

comprising, water, glycol and oil. The cooling fluid may be provided within the one or more channels defined in the cooling component. The cooling fluid may be provided within the one or more conduit members which are located in the one or more channels defined in the cooling component. [0021] According to the present invention there is further provided a transformer comprising any one of the afore-mentioned cooling

components.

[0022] The transformer may comprise a plurality of the afore-mentioned cooling components. [0023] The transformer may further comprise electrically insulating material which electrically isolates a cooling component from windings of a transformer. The electrically insulating material may be provided on a surface of the cooling component. The electrically insulating material may be wound around a surface of the cooling component. [0024] The transformer may further comprise a winding casing which is impermeable to fluid, wherein the winding casing comprises a putty material. The winding casing will prevent any leaking cooling fluid from contacting the winding. The putty material may arranged to prevent any leaking fluid from damaging the windings of the transformer. The putty material may comprise CW2243 compound and HY2966 hardener, which when mixed becomes a bisphonel A epoxy resin.

[0025] The transformer may further comprise a temperature sensor, which detects and monitors the temperature of the core. If the core reaches a temperature which exceeds a predetermined threshold temperature, the senor may emit an alarm and/or the transformer may be shut down.

[0026] The transformer may further comprise a detector which detects cooling fluid flowing within the cooling component. The detector may be configured to emit an alarm when the cooling fluid is not flowing as desired. For example, the detector may be arranged to detect cooling fluid following out of conduit members which are positioned in the one or more channels defined in the cooling component; if the detector detects that no cooling fluid is flowing out of the conduit members, this will indicate that there is a leak somewhere in the system and the detector will operate to emit and alarm and/or shut down the operation of the transformer.

[0027] The transformer may further comprise resin. The resin may provide structural strength to the transformer. The resin may be

impregnated into the transformer. [0028] According to the present invention there is further provided a method of manufacturing a cooling component, the method comprising the steps of,

co-operating a first piece comprising ceramic with a second price comprising ceramic, to define one or more channels;

providing at least one conduit in the one or more channels.

[0029] The method may further comprise the step of, providing conducting paste so as to reduce the amount of air which exists between components of the cooling component.

[0030] The method may further comprise the step of, providing conducting paste at an interface between the first piece comprising ceramic and second price comprising ceramic.

[0031] The method may further comprise the step of, providing conducting paste at an interface between walls which define the one or more channels and the at least one conduit. [0032] The method may further comprise the step of providing conducting paste at a surface of the at least one conduit so as to reduce the amount air which can exist between the at least one conduit and the first and second pieces which are co-operated to define one or more channels. [0033] According to the present invention there is further provided a method of manufacturing a transformer, comprising the step of, providing one or more cooling components according to any one of the aforementioned cooling components, proximate to a core and winding of a transformer, such that the one or more cooling components are in thermal communication with the core of the transformer. The one or more cooling components may be arranged between the core of the transformer and windings of the transformer.

[0034] The method of manufacturing a transformer may further comprise the step of providing conducting paste on an outer surface of the one or more cooling components so as to reduce the amount of air which can exist between a core of the transformer and the one or more cooling components.

[0035] The method of manufacturing a transformer may further comprise the step of providing electrically insulating material on a surface of the one or more cooling components to electrically isolate the cooling components from windings of the transformer. The electrically insulating material may be provided on a surface of the cooling component. The electrically insulating material may be wound around a surface of the cooling component. Brief Description of the Drawings

[0036] An embodiment of the present invention will now be described, by way of example only, with reference to the following figures in which;

Figure 1 shows an exploded view of a cooling component according one embodiment of the present invention; Figure 2 provides a perspective view of the cooling component shown in figure 1 when assembled;

Figure 3 provides a perspective view of a transformer according to an embodiment of the present invention; Figure 4 provides a perspective view of a cooling component according to a further embodiment of the present invention.

Detailed Description of possible embodiments of the Invention

[0037] Figure 1 shows an exploded view of a cooling component 1 according one embodiment of the present invention. [0038] The cooling component 1 comprises a first part 3 and a second part 5 which are co-operable. Each of the first part 3 and second part 5 are composed of ceramic (AI203). Each of the first part 3 and second part 5 comprise grooves 7; the first part 3 and second part 5 are shown to comprise two grooves 7, however it will be understood they could comprise any number of grooves 7.

[0039] The cooling component 1 further comprises two conduit members in the form of pipes 1 1 a, 1 1 b. It should be understood that the cooling component 1 may comprise any number of conduit members and that the conduit members may each take any suitable shape, aspect or design. In this particular example the pipes 1 1 a,1 1 b are straight and have a circular cross section. Each pipe 1 1 a, 1 1 b is composed of copper, however the pipes 1 1 a,1 1 b may comprise any suitable material such as stainless steel, copper, aluminium or a mixture thereof. Each pipe 1 1 a, 1 1 b comprises an inner diameter 'd' of length 8mm. The thickness T' of a wall 15 of each pipe 1 1 a, 1 1 b is 4mm. It will be understood that the pipes 1 1 a,1 1 b may comprise an inner diameter of any suitable length and a wall thickness T' of any suitable dimension. [0040] Figure 2 provides a perspective view of the cooling component 1 shown in figure 1 , when assembled.

[0041] As can be seen from figure 2, when the first part 3 and second part 5 are brought into co-operation with one another, the grooves 7 in each part 3, 5 co-operate to define channels 13a, 13b. It should be understood that any number of channels may be provided. The pipes 1 1 a,1 1 b located within channels 13a,13b respectively.

[0042] The cooling component may further comprise a conducting paste 17; in the present example the cooling paste is Elantron PU4284 TX. The conducting paste 17 is provided; at an interface 19 between the first part 3 and second part 5 of the cooling component 1 ; at an interface 21 between the pipe 1 1 a, 1 1 b and walls 23 which define the channels 13a,13b. The conduction paste will eliminate any air-pockets that may exist between the first part 3 and second part 5 of the cooling component 1 and between the pipes 1 1 a, 1 1 b and walls 23 which define the channels 13a,13b; air pockets may occur, for example, due to uneven surfaces; as air is a thermal insulator, the presence of air-pockets can make the cooling component 1 less efficient at absorbing heat energy; the presence of conducting paste in the cooling component 1 of the present invention helps eliminate this problem.

[0043] The conducting paste 17 may also be provided on an outer- surface 25 of the cooling component 1 ; the conducting paste on the outer- surface 25 of the cooling component 1 will eliminate any air pockets that exist between the outer-surface 25 of the cooling component 1 and electrical isolation material (not shown) which is wrapped around the outer-surface 25 of the cooling component 1 to electrically isolate the cooling component 1 and to hold the first part 3 and second part 5 of the cooling component 1 in co-operation.

[0044] The cooling component 1 is configured to have a substantially flat surface 15 such that it can co-operate with a flat surface of a core of a transformer. This flat surface 15 will enable the cooling component 1 to abut a flat surface of a core, thus enabling the cooling component 1 to be brought into thermal communication with the core of a transformer.

[0045] The first part 3 and second part 5 of the cooling component 1 are held in co-operation with one another by means of electrically insulating material (not shown) e.g. Nomex™, which is wound around the an outer surface 25 of the cooling component 1 . The electrically insulating material will further act to electrically isolate the cooling component 1 , thus enabling the cooling component 1 to be safely positioned close to the windings of a transformer. As the first part 3 and second part 5 comprise ceramic (AI203), and since ceramic is an electrical insulator material, the amount of insulating material required to electrically isolate the cooling component 1 is reduced compared to that required to electrically isolate existing cooling components. The first part 3 and second part 5 may optionally be fastened together using fasteners (not shown). [0046] The pipes 1 1 a,1 1 b are held within the channels 13a,13b of the cooling component 1 by frictional forces which exist between the pipes 1 1 a,1 1 b and the walls 23 which define the channels 13a,13b.

[0047] The cooling component 1 further comprises a resin (not shown) which is integral thereto. The resin is impregnated into the cooling component 1 during the manufacturing stage. The resin may provide structural strength to the cooling component 1 .

[0048] The cooling component 1 illustrated in figures 1 and 2 is suitable for use in a transformer, to cool the core of the transformer. Figure 3 provides a perspective view of a transformer 50 according to the present invention which comprises a six cooling components 1 a-d (only four of which are shown) of the type shown in figures 1 and 2.

[0049] The transformer 50 comprises three cores 51 a-c around which are wound three windings (not shown) respectively. The three cores 51 a-c are held together by means of a clamp member 57. The windings are encased by casings 53a-c and are therefore not visible. The casings 53a-c are impermeable to fluid; thus the casings 53a-c will prevent the windings of the transformer 50 from being damaged by any leaking cooling fluid. Each casing 53 may further comprise a putty material to seal the casings 53a-c at their extremities 55a, 55b. The putty material may comprise CW2243 compound and HY2966 hardener. The putty material is impermeable to fluid.

[0050] The transformer 50 can be 3-phase or single phase application. 3- phase applications have normally 3 cores where to put the cooling elements. Single phase transformers have 2 cores to put the cooling elements. The transformer 50 may take any other suitable configuration, for example the transformer 50 may comprise any number of cores, for example the transformer 50 may comprisebetweenl and 5 cores.

[0051] Flanked on either side of each of the cores 51 a-c is a cooling component 1 a-d. Each cooling component 1 a-d is arranged such that its flat surface 15 abuts a core 51 a-c so that the cooling component 1 a-d is in thermal communication with a core 51 a-c of the transformer 50. Electrically insulating material (not shown) e.g. Nomex™, is wound around an outer surface 25 of each of the cooling components 1 a-d; this serves to electrically isolate the cooling components 1 a-d, from the windings (not shown) of the transformer 50 (as previously discussed the insulating material also serves to hold the components of each cooling component 1 a-d in co-operation).

[0052] A multi-duct supply component 59 is provided, which is in fluid communication with each of the pipes 1 1 a,1 1 b in each of the six cooling components 1 a-d. Cooling fluid may be supplied to each of the pipes 1 1 a,1 1 b in each of the six cooling components 1 a-d, via the multi-duct component 59. A drain component 60 is further provided which is in fluid communication with each of the pipes 1 1 a,1 1 b in each of the six cooling components 1 a-d. Cooling fluid which has flowed through the pipes 1 1 a,1 1 b in each cooling component 1 a-d may be drained out of the pipes 1 1 a,1 1 b into the drain component 60. The drain component 60 directs drained cooling fluid away from the cores 51 a-c of the transformer 50. In an alternative embodiment the position of the multi-duct supply component 59 and the drain component 60can be exchanged.

[0053] Optionally, resin may be impregnated into the transformer 50 to improve the structural strength of the transformer 50. [0054] When the transformer 50 is in use, each of the cores 51 a-c will heat. The cooling components 1 a-d will each operate to prevent the cores 51 a-c from overheating. Cooling fluid (not shown) in the form of cooling water, glycol and/or oil, for example, is supplied from a reservoir (not shown) to the multi-duct supply component 59 via a supply aperture 61 . The cooling fluid is feed from the multi-duct supply component 59 to each of the pipes 1 1 a,1 1 b located within the channels 13a, 13b of each of the cooling components 1 a-d. The cooling fluid will flow along the pipes 1 1 a,1 1 b of each cooling component 1 a-d. As the cooling fluid flows along the pipes 1 1 a,1 1 b, heat from the cores 51 a-c of the transformer 50 is conducted through the ceramic first part 3 and second part 5 of each the cooling components 1 a-d and into the cooling fluid which flows in the pipes 1 1 a,1 1 b. The heat energy is absorbed by the cooling fluid thus providing cooling of the cores 51 a-c of the transformer 50. The now heated cooling fluid drains out of each of the pipes 1 1 a, 1 1 b into drain component 60; from there the heated cooling fluid directed to flow away from the cores 51 a-c so that the heat energy is removed from the transformer 50. Optionally, the heated cooling fluid can be collected and cooled; once cooled it can be reused to cool the cores 51 a-c of the transformer 50 during a further operation of the transformer 50. [0055] As the cooling component comprises ceramic this ensures that no eddy currents are be created in the cooling components 1 a-d by the magnetic field exhibited from the cores 51 a-c of the transformer 50 during operation. Furthermore, ceramic is a good heat conductor thus is effective at conducting heat away from the cores 51 a-c of the transformer 50 to the cooling fluid which flows within the pipes 1 1 a,1 1 b. Ceramic can withstand high temperatures, thus is not susceptible to melting when the cores 51 a-c of the transformer 50 reach high temperatures during operation. Furthermore, since ceramic is a good electrical insulator, less electrically insulating material e.g. Nomex™, is required to be applied to the outer surface of the cooling components 1 a-d to electrically isolate them from the windings (not shown) of the transformer 50; the requirement for less insulating material reduces the overall cost of the transformer 50.

[0056] The transformer 50 may further comprise a temperature sensor (not shown), which detects and monitors the temperature of the cores 51 a- c. If the cores 51 a-c reaches a temperature which exceeds a predetermined threshold temperature, the temperature sensor (not shown) may emit an alarm and/or the transformer 50 may be shut down.

[0057] The transformer 50 may further comprise a detector (not shown) which monitors the cooling fluid flow within the pipes 1 1 a,1 1 b of each of the cooling components 1 a-d. The detector may be configured to emit an alarm when the cooling fluid is not flowing as desired. For example, the detector may be arranged to detect cooling fluid following out of the pipes 1 1 a,1 1 b into the drain component 60; if the detector detects that no cooling fluid is flowing out of the pipes 1 1 a,1 1 b into the drain component 60 this will indicate that there is a leak somewhere in the system and the detector will operate to emit and alarm and/or shut down the operation of the transformer 50.

[0058] Variations on the cooling component 1 described above are possible; Figure 4 provides a perspective view of a cooling component 10 according to a further embodiment of the present invention. The cooling component 10 has many of the same features as the cooling component 1 shown in figures 1 and 2, and like features are awarded the same reference numerals. The cooling component 10 comprises an intermediate conduit member 71 which fluidly connects conduits 13a,13b. Alternatively, the two conduits 13a,13b fluidly connected by an intermediate conduit member 71 could be replaced by a single, U-shaped, conduit member. [0059] As before the cooling component 10 is suitable for use in a transformer, to cool the core of a transformer. During use cooling fluid can flow along conduit 13a, as the cooling fluid flows along the conduit 13a it will absorb heat energy from a core of a transformer. Unlike the previous embodiments, in the present embodiment, the cooling fluid then enters the intermediate conduit member 71 where it is directed to flow back along conduit 13b. As the cooling fluid flows back along conduit 13b it absorbs more heat energy from the core of the transformer. Thus, in the embodiment shown in figure 4 the cooling fluid flows twice along a conduit 13a,13b before it is drained away from the transformer.

[0060] Various modifications and variations to the described

embodiments of the invention will be apparent to those skilled in the art without departing from the scope of the invention as defined in the appended claims. Although the invention has been described in

connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiment.

Claims

1 . A cooling component having one or more channels defined therein, wherein the cooling component comprises ceramic.

2. A cooling component according to claim 1 , wherein the cooling component is configured such that it can co-operate with a core of a transformer so that it is in thermal communication with the core and/or winding.

3. A cooling component according to claim 1 or 2, wherein the cooling component comprises two or more channels defined therein.

4. A cooling component according to any one of the preceding claims, wherein the cooling component comprises a first part and second part which are co-operable.

5. A cooling component according to claim 4 wherein the first and second part are secured together by means of electrically insulating material which is applied to an outer surface of the cooling component.

6. A cooling component according to any one of the preceding claims, wherein the cooling component further comprises one or more conduit members.

7. A cooling component according to claim 6, wherein the cooling component comprises two conduit members.

8. A cooling component according to claim 6 or 7, wherein the cooling component further comprises an intermediate conduit member which fluidly connects two conduit members.

9. A cooling component according to any one of the preceding claims, wherein the cooling component further comprises a conducting paste.

10. A cooling component according to claim 9, wherein the conducting paste is provided on an outer surface of the cooling

component.

1 1 . A cooling component according to claim 9 or 10, wherein the conducting paste is provided at an interface between a first part and second part of the cooling component.

12. A cooling component according to any one of claims 9-1 1 wherein the conducting paste is provided at an interface between walls which define the one or more channels and one or more conduit members.

13. A transformer comprising a cooling component according to any one of claims 1 -12.

14. A method of manufacturing a cooling component, the method comprising the steps of,

co-operating a first piece comprising ceramic with a second piece comprising ceramic, to define one or more channels;

providing at least one conduit in the one or more channels.

1 5. A method according to claim 14 further comprising the step of, providing conducting paste so as to reduce the amount of air which can exist between components of the cooling component.

16. A method of manufacturing a transformer, comprising the step of,

providing one or more cooling components according to any one of claims 1 -12, proximate to a core of a transformer, such that the one or more cooling components are in thermal communication with the core of the transformer.