Transformer oil reclaiming device

Abstract

The present method refers to a transformer oil reclaiming device providing an improved transformer oil reclaiming, utilizing a cartridge system. Furthermore, the present invention refers to a cabinet

Description

The present method refers to a transformer oil reclaiming device providing an improved transformer oil reclaiming. Furthermore, the present invention refers to a cabinet containing such transformer oil reclaiming device. Additionally, the present invention refers to a method of transformer oil reclaiming . Transformers are essential parts of, for example, electrical power grids and in this context are necessary components of modern society. While they are already standards components being utilized for decades they are still subject to continuous improvements. Especially the requirements originating from changes of the demands, for example, originating from changes like the amount of renewable energy being introduced into such power grid and the change in electrical power demands in society results in additional burdens to be addressed. Exemplarily, it is referred to the increased power consumption of the society and the industry and the increased dependency from it. Only expected to increase, for example, based on the changes of heating systems like heat exchangers introduced as heating source for the common part of the society at home. Resulting in significant problems in case a power grid during high load operation goes down in winter leaving thousands of households without heating. An essential part of high power transformers as utilized in power grids is an isolator required to ensure a secure and efficient operation. Herein, such as oil needs to fulfill a significance number of requirements to operate at very high temperatures, provide cooling, provide insulation, To ensure long-term utilization of such oil it is required to reclaim such oil and remove contaminations as well as moisture to maintain the properties of said transformer oil. However, available methods of reclaiming the transformer oil still provide the opportunity to be further improved. For example, existing methods suffer from problems like the possibility to swiftly adapt to the corresponding demands as well as providing highly reliable transformer oil reclaiming securing highest quality transformer oil being able to be utilized over very long time periods. These and further problems are solved by the products and methods as disclosed hereafter and in the claims. Further beneficial embodiments are disclosed in the dependent claims and the further description and figures. These benefits can be used to adapt the corresponding solution to specific needs or to solve additional problems. According to one aspect the present invention refers to a transformer oil reclaiming device for reclaiming transformer oil containing at least one, more preferred at least two, oil cleaning cartridge and at least one oil drying cartridge, wherein the at least one oil cleaning cartridge has a height of at most 180cm and a width of at most 30cm, wherein the aspect ratio of height to width is at most 12:1, wherein the at least one oil drying cartridge has a height of at most 180cm and a width of at most 30cm, wherein the aspect ratio of height to width is at most 12:1, wherein the at least one oil cleaning cartridge contains fuller earth to absorb contaminations from the oil, wherein the at least one oil drying cartridge contains molecular sieve to absorb moisture from the oil. Surprisingly, the inventive system of a combination of such oil cleaning cartridges of a specified size containing fuller earth and oil drying cartridges of a specified size containing molecular sieves provides improved effects even compared to other systems containing, for example, absorbent that are deemed to provide a higher performance like activated alumina, Bentonite, diatomaceous earth, silica gel, activated carbon or the like. The inventors noted that surprisingly uti lizing such cartridges a flexible and especially highly efficient transformer oil reclaiming can be realized. Not only it becomes possible to realize small scaled transformer oil reclaiming devices easily fitting into existing facilities and enabling to retrofit such facilities with a continuous oil reclaiming providing, for example, providing significant benefits compared to a discontinuous oil reclaiming. Also, it becomes possible to easily handle the corresponding cartridges utilizing existing equipment and increasing the overall security for personal tasked with operating said transformer oil reclaiming devices. Especially, it was noted that the reliability of the oil reclaiming utilizing the disclosed transformer oil reclaiming device is surprisingly high. Typically, one should have expected that utilizing especially such small scaled cartridges primarily require a high number of exchanges only increasing the effort without benefit. But providing such cartridge based system even allowing to adapt according to the specific needs noted on a short term surprisingly compensates for such replacement requirements. Even adaption strategies can be provided as it was noted that real life application provide a change of the required drying and cleaning capacities. For example, it was noted that the drying requirements typically become lower over time when most moisture was already removed. In such cases the number of oil cleaning cartridges can be increased to adapt to such changing requirements. While in case, for example, certain service actions require replacements of the transformer or the transformer oil an increased number of oil drying cartriges can be utilized again to adapt to this requirement. Herein, the use of the fuller earths and molecular sieves in combination with the specified size provide an optimum combination to provide such beneficial transformer oil reclaiming process. According to a further aspect the present invention refers to a cabinet containing an inventive transformer oil reclaiming device . According to a further aspect the present invention refers to a method of transformer oil reclaiming, wherein the method utilizes an inventive transformer oil reclaiming device, wherein the method contains the step of removing contaminations from the transformer oil using the at least one oil cleaning cartridge, and wherein the method contains the step of removing contaminations from the transformer oil using the at least one oil drying cartridge . To simplify understanding of the present invention it is referred to the detailed description hereafter and the figures attached as well as their description. Herein, the figures are to be understood being not limiting the scope of the present invention, but disclosing preferred embodiments explaining the invention further. Fig. 1 shows a schematic drawing of a cabinet containing the transformer oil claiming device. According to one aspect the present invention refers to a transformer oil reclaiming device as described above. Fuller earths are known to the skilled person being various clays used as an absorbent, filter, or bleaching agent. Examples of fuller earths that have been noted to be especially beneficial for transformer oil reclaiming processes are COFERMIN Bauxit, PETROCHEM Bauxit, Newport Bauxit, BOUD Minerals Bauxit, OILDRI Fuller's Earth, Curimbaba Fuller's Earth, Porocel Fuller's Earth, JVI Minerals Fuller's Earth, Ashapura Fuller's Earth, and READE Fuller's Earth.lt was noticed that Fuller earths are especially suitable to be utilized for typical transformers is utilized in power grids. The contaminations noted in these applications are very well absorbed and very effectively removed from the corresponding transformer oil. Resulting in the especially high quality oil reclaiming even at the end of the lifetime of the corresponding transformer oil cleaning cartridge. According to further embodiments it is preferred that the molecular sieve is a 3 A molecular sieve and / or a 4 A molecular sieve. Corresponding molecules sieves where noted to be very suitable for typical application cases. According to further embodiments it is preferred that the transformer oil reclaiming device contains a moisture sensor. Integrating a corresponding moisture sensor allows to further improve the possibilities to monitor the state of corresponding cartridges and eventually detect irregularity and increased moisture removal requirements from such oil. While it seems simple, it was noted, that in real life applications such simple additional sensor allows to you detects an abnormal moisture contents of the transformer oil. Rendering such typically less beneficial additional sensor based on the typically well predictable behavior and moisture content of the transformer oil being highly beneficial based on indirect deductions that can acquired from it. Typical origins of such moisture like paper utilized in such transformer slowly setting free moisture over time due to depolymerization allow to simply calculate the time a corresponding moisture absorbant can be utilized. Rendering such sensor less beneficial. However, it was noted that corresponding deviations from such calculated behavior can be utilized to identify problems at an early stage and even prevent problems to develop. Typically, it is preferred that the moisture sensor is located after the at least one transformer oil drying cartridge. According to further embodiments it is preferred that the transformer oil reclaiming device contains at least one moisture sensor before the at least one transformer oil drying cartridge and at least one moisture sensor after the at least one transformer oil drying cartridge based on the intended flow direction of the transformer oil through the at least one transformer oil drying cartridge. Allowing to additionally securely provide data regarding the drying behavior of the transformer oil drying cartridges to provide further insight like a saturation of the transformer oil drying cartridges with other substances providing further insight into the transformer . According to further embodiments it is preferred that the at least one oil cleaning cartridge has a height of at least 70cm, measured from an oil cleaning cartridge top to an oil cleaning cartridge bottom and a width of at least 10cm, wherein the aspect ratio of height to width is at least 4:1, wherein the at least one oil drying cartridge has a height of at least 70cm measured from an oil drying cartridge top to an oil drying cartridge bottom and a width of at least 10cm, wherein the aspect ratio of height to width is at least 4:1, wherein the at least one oil cleaning cartridge has a height of at least 80cm and a width of at least 12cm, wherein the at least one oil drying cartridge has a height of at least 80cm and a width of at least 12cm, more preferred wherein the at least one oil cleaning cartridge has a height of at least 100cm and a width of at least 15 cm, wherein the at least one oil drying cartridge has a height of at least 100cm and a width of at least 15cm. While their flexibility and possibility to adapt to spontaneous demands still is a core of the invention it was noted that increasing the size of this cartridges provides far lower loss of such flexibility than expected. Simultaneously, for typical applications like high performance transformer is utilized in power grids it allows to significantly reduce the number of required replacements required for reclaiming the transformer oil easily compensating the loss originating from, for example, in early replacements of a partially used cartridge. Rendering such designs especially for power grids applications very beneficial. According to further embodiments it is preferred that the aspect ratio of height to width is preferred at least 5:1, even more preferred at least 6:1. While a higher aspect ratio should be expected to also provide contradicting effects it was noted that typically utilizing such high aspect ratio is beneficial. According to further embodiments it is preferred that the at least one oil cleaning cartridge has a height of at most 155cm and a width of at most 24cm, wherein the at least one oil drying cartridge has a height of at most 155 cm and a width of at most 24cm, wherein the aspect ratio of height to width is at most 10:1, more preferred wherein the at least one oil cleaning cartridge has a height of at most 140cm and a width of at most 2 2 cm, wherein the at least one oil drying cartridge has a height of at most 140cm and a width of at most 22cm, wherein the aspect ratio of height to width is at most 9:1. It was noted that such designed oil cleaning cartridges and oil drying cartridges are especially suitable to be utilized in a cabinet allowing to easily access the cartridges. While it should be expected that utilizing bigger cartridges are to be preferred allowing to reduce the number of replacements. Yet, it was found that such sizes and especially the utilization of a cabinet solution is very suitable for transformer oil reclaiming as under real life conditions the typical persons responsible for such transformers finds it very beneficial to utilize such sized solution. Especially, taking into account the recent demand to decrease the staff responsible based on the improved possibilities to monitor corresponding transformers remotely and the increased reliability based on improved transformers it becomes mandatory to provide solutions allowing a simpler handling with less persons and decreased risk of grave injuries in case of minor mistakes during handling. According to further embodiments it is preferred that the transformer oil reclaiming device provides a transformer oil entry and a transformer oil exit based on a flow direction the transformer oil reclaiming device is adapted to provide for a transformer oil to be reclaimed flowing through the transformer oil reclaiming device, wherein the oil drying cartridge in case the at least one oil drying cartridge is only one oil drying cartridge or at least one of the at least one drying cartridge in case the at least only oil drying cartridge is two or more oil drying cartridges are located at the transformer oil exit. It was noted that letting the transformer oil flowing lastly through an oil drying cartridge seems to improve the drying process significantly increasing the drying speed of the oil. For typical embodiments it is preferred that at least two oil drying cartridges in case the transformer oil reclaiming device contains at least two oil drying cartriges, more preferred at least three oil drying cartridges in case the transformer oil reclaiming device contains at least three oil drying cartridges are located at the transformer oil exit. While single oil drying cartridges can be located at the beginning and especially between the at least one oil cleaning cartridge placing more oil drying cartridges at the end were surprisingly beneficial. Especially, it can be preferred that all oil drying cartridges are located at the transformer oil exit of the transformer oil reclaiming device based on a flow direction of the transformer oil during the transformer oil reclaiming . According to further embodiments it is preferred that the transformer oil reclaiming device provides a transformer oil entry and a transformer oil exit based on a flow direction the transformer oil reclaiming device is adapted to provide for a transformer oil to be reclaimed flowing through the transformer oil reclaiming device, wherein the oil cleaning cartridge in case the at least one oil cleaning cartridge is only one oil cleaning cartridge or at least one of the at least one cleaning cartridge in case the at least only oil cleaning cartridge is two or more oil cleaning cartridges is located at the transformer oil entry. It was noted that in typical application cases it is sometimes difficult to secure a low moisture content of the fuller earths. Placing at least one oil cleaning cartridge at the entry of the transformer oil path through the transformer oil reclaiming device allows to easily secure that the drying effect of the subsequent oil drying cartridges are fully made use off. Allowing to also remove moisture set free by the fuller earth. Posing a real problem under real life conditions based on, for example, changing moisture contents of the fuller earths or other deviations. For typical embodiments it is preferred that at least two oil cleaning cartridges in case the transformer oil reclaiming device contains at least two oil cleaning cartriges, more preferred at least three oil cleaning cartridges in case the transformer oil reclaiming device contains at least three oil cleaning cartridges are located before the at least one oil drying cartridge based on the flow direction of the transformer oil the transformer oil reclaiming device is adapted to provide. While it was possible to also place oil cleaning cartridges between the at least one oil drying cartridge it was typically preferred to place at least a majority in front of the oil drying cartridges. Especially, it can be preferred that all oil cleaning cartridges are located before the at least one oil drying cartridge based on the flow direction of the transformer oil the transformer oil reclaiming device is adapted to provide. According to further embodiments of the preferred that cleaning cartridge fastening system and the at least one oil drying cartridge is fastened by a drying cartridge fastening system, wherein the cleaning cartridge fastening system and / or the drying cartridge fastening system are adapted to enable an exchange of the at least one cleaning cartridge and / or the at least one drying cartridge without the use of the tool. Utilizing the cartridge system as specified was noted to require a repeated replacement of the cartridges rendering such type of fastening mechanism typically beneficial. While additional efforts to, for example, fastening corresponding cartridges utilizing a wrench is no tremendous additional effort it was noted that such different fastening systems not requiring specific tool are surprisingly beneficial. Especially, tests provided indications that personal tasked with operating corresponding transformer oil reclaiming devices tended to forget or misplace the corresponding tool. Resulting in increased safety related issues in case the corresponding personal tries to hold the cartridge in place while reaching out for a tool being a bit too distanced. To be easily solved by a fastening system as described above. In this context, it was noted that fastening systems as described above especially provided in safety improvement in the real life conditions . According to further embodiments it is preferred that the transformer oil reclaiming device contains a filter located before or after, preferably after, the at least one oil cleaning cartridge, based on a flow direction the transformer oil reclaiming device is adapted to provide for a transformer oil to be reclaimed flowing through the transformer oil reclaiming device. Typically, it is preferred that such filter is located before or after, preferably after, the at least one oil cleaning cartridge and the at least one oil drying cartridge. It was noted that such apparently simple addition of a filter allows to significantly increase the reliability of providing high quality reclaimed transformer oil. While it should be expected that small particles should already be securely remove when passing through the cartridges as specified it was noted that this still provides a significant improvement. Especially surprising when placing the filter after the cartridges. While the invention cannot be deemed limited based upon this theory, but the inventors assume that very small particles are passing through the fuller earths of the cleaning cartridges or are set free from them. Rendering such filter beneficial even in case at least one oil drying cartridge is located after the at least one oil cleaning cartridge . According to further embodiments it is preferred that the filter providing a pore size less than 10 Micron, more preferred less than 6 Micron, even more preferred less than 5 Micron. Such pore size can be determined using commonly available methods like also, for example, specified by ISO 16889. It was noted that surprisingly such very fine particles were available in the transformer oil. Especially after the specified cartridges. While typically corresponding filters for particle sizes of 30-40 Micron were to be preferred. Providing a surprising and quite significant further improvement of the transformer oil reclaiming for the inventive transformer oil reclaiming device utilizing such filter as specified. According to further embodiments it is preferred that the transformer oil reclaiming device contains at least two oil cleaning cartridges. It was noticed, that utilizing a plurality of cleaning cartridges provides the surprising benefit that even rare problems transformer oil cleaning cartridges providing channels inside the fuller earths resulting in decreased oil cleaning effect can be easily compensated by such. As corresponding problems are deemed to originate, for example, from incorrect storage or bad handling of the cartridges such modification is surprisingly beneficial. As it allows to secure a reliable removal of contaminations even in case one cartridges provides an impaired filter effect. Herein, it was noted that such impaired filter effect seems to remedied over time. Maybe resulting from channels being closed over the time of usage. Rendering such simple solution to guarantee an effective reclaiming right from the beginning even more beneficial. Enabling, for example, to easily store corresponding replacements transformer oil cleaning cartridges locally in a significant number. Taking into account past delivery problems as noted, for example, during Corona times and the like showed that increasing the reliability of corresponding cartridges by such means provides a significant benefit contributing to the overall value of such solution. According to further aspects of the present invention refers to a cabinet as described above. According to a further aspect of the present invention refers to a method as described above. According to further embodiments it is preferred that the transformer oil last flows through the oil drying cartridge in case the at least one oil drying cartridge is only one oil drying cartridge or at least one of the at least one drying cartridge in case the at least only oil drying cartridge is two or more oil drying cartridges before exiting the transformer oil reclaiming device. Figure 1 shows a schematic drawing of a cabinet 2 containing the transformer oil claiming device being used to reclaim the transformer oil over high performance transformer utilized in the power grid distributing electrical power on a country scale. The cabinet 2 comprising transformer oil claiming device contains oil cleaning cartridges la, lb as well as one oil drying cartridge 1c. The oil cleaning cartridges la, lb as well as the oil drying cartridge 1c provide a height of 120cm and a width of 15cm. The oil cleaning cartridges contain fuller earth and the oil drying cartridge contains molecular sieve. A pump 4 provide the flow of the transformer oil through the transformer oil reclaiming device. The embodiment as shown in figure 1 shows such pump before the oil cleaning cartridges la, lb and the oil drying cartridge 1c based on the flow direction of the transformer oil. Small particles like sand sized particles or the like resulting from, for example, some material like paper or metal inside the transformer being ripped off are removed from the transformer oil by means of the filter 4. The transformer oil flows through said filter 4 like in the shown case the the transformer oil typically typically flows through one cleaning cartridge 1c and the drying cartridges la, lb. Allowing to ensure that the oil flowing into the transformer is free from particles . After passing the first transformer oil cleaning cartridge la and the second transformer oil cleaning cartridge lb the transformer oil enters the transformer oil drying cartridge 1c. Inside the transformer oil drying cartridge 1c molecular sieve being a 3 A molecular sieve removes the moisture from the transformer oil. Unless there is an irregularity or defect there is typically a constant but low setting free of moisture in such transformer. Not shown in figure 1 is the moisture sensor located after the at least one transformer oil drying cartridge. The transformer oil cleaning cartridges la, lb are fastened by a cleaning cartridge fastening system and the transformer oil drying cartridge 1c is fastened by a drying cartridge fastening system. Herein, the cleaning cartridge fastening system and the drying cartridge fastening system require a wrench to securely fasten the cartridges in the transformer oil reclaiming device. According to alternative inventive embodiments the cleaning cartridge fastening system and / or the drying cartridge fastening system can be adapted to enable an exchange of the transformer oil cleaning cartridge and / or the at least one transformer oil drying cartridge without the use of the tool. The present invention was only described in further detail for explanatory purposes. However, the invention is not to be understood being limited to these embodiments as they represent embodiments providing benefits to solve specific problems or fulfilling specific needs. The scope of the protection should be understood to be only limited by the claims attached.

Claims

1. Transformer oil reclaiming device for reclaiming transformer oil containingat least one, more preferred at least two, oil cleaning cartridge (la, lb) and at least one oil drying cartridge (1c), wherein the at least one oil cleaning cartridge (la, lb) has a height of at most 180cm and a width of at most 30cm, wherein the aspect ratio of height to width is at most 12:1,wherein the at least one oil drying cartridge (1c) has aheight of at most 180cm and a width of at most 30cm, wherein the aspect ratio of height to width is at most 12:1,wherein the at least one oil cleaning cartridge (la, lb) contains fuller earth to absorb contaminations from the oil, wherein the at least one oil drying cartridge (1c) contains molecular sieve to absorb moisture from the oil.

2. Transformer oil reclaiming device according to any of the aforementioned claims, wherein the molecular sieve is a 3 A molecular sieve and / or a 4 A molecular sieve.

3. Transformer oil reclaiming device according to any of the aforementioned claims,wherein transformer oil reclaiming device contains a moisture sensor.

4. Transformer oil reclaiming device according to any of the aforementioned claims, wherein the Transformer oil reclaiming device according to any of the aforementioned claims, wherein the at least one oil cleaning cartridge (la, lb) has a height of at least 70cm, measured from an oil cleaning cartridge (la, lb) top to an oil cleaning cartridge (la, lb) bottom and a width of at least 10cm, wherein the aspect ratio of height to width is at least 4:1, wherein the at least one oil drying cartridge (1c) has a height of at least 70cm measured from an oil drying cartridge(1c) top to an oil drying cartridge (1c) bottom and a width of at least 10cm, wherein the aspect ratio of height to width is at least 4:1, wherein the at least one oil cleaning cartridge (la, lb) has a height of at least 80cm and a width of at least 12cm, wherein the at least one oil drying cartridge (1c) has a height of at least 80cm and a width of at least 12cm, more preferred wherein the at least one oil cleaning cartridge (la, lb) has a height of at least 100cm and a width of at least 15cm, wherein the at least one oil drying cartridge (1c) has a height of at least 100cm and a width of at least 15cm.

5. Transformer oil reclaiming device according to any of the aforementioned claims, wherein the aspect ratio of height to width is preferred at least 5:1, even more preferred at least 6:1.

6. Transformer oil reclaiming device according to any of the aforementioned claims, wherein the Transformer oil reclaiming device according to any of the aforementioned claims, wherein the at least one oil cleaning cartridge (la, lb) has a height of at most 155cm and a width of at most 24cm, wherein the at least one oil drying cartridge (1c) has a height of at most 155 cm and a width of at most 24cm, wherein the aspect ratio of height to width is at most 10:1, more preferred wherein the at least one oil cleaning cartridge (la, lb) has a height of at most 140cm and a width of at most 22cm, wherein the at least one oil drying cartridge (1c) has a height of at most 140cm and a width of at most 22cm, wherein the aspect ratio of height to width is at most 9:1.

7. Transformer oil reclaiming device according to any of the aforementioned claims, wherein the transformer oil reclaiming device provides a transformer oil entry and a transformer oil exit, based on aflow direction the transformer oil reclaiming device is adapted to provide for a transformer oil to be reclaimed flowing through the transformer oil reclaiming device, wherein the oil drying cartridge (1c) in case the at least one oil drying cartridge (1c) is only one oil drying cartridge (lc) or at least one of the at least one drying cartridge (1c) in case the at least only oil drying cartridge (lc) is two or more oil drying cartridge (lc)s are located atthe transformer oil exit.

8. Transformer oil reclaiming device according to any ofthe aforementioned claims,wherein the transformer oil reclaiming device provides a transformer oil entry and a transformer oil exit based on a flow direction the transformer oil reclaiming device is adapted to provide for a transformer oil to be reclaimed flowing through the transformer oil reclaiming device, wherein the oil cleaning cartridge (la, lb) in case the at least one oil cleaning cartridge (la, lb) is only one oil cleaning cartridge (la, lb) or at least one of the at least one cleaning cartridge (la, lb) in case the at least only oil cleaning cartridge (la, lb) is two or more oil cleaning cartridge (la, lb)s is located at the transformer oil entry.

9. Transformer oil reclaiming device according to any of the aforementioned claims, wherein the at least one transformer oil cleaning cartridge (la, lb) is fastened by a cleaning cartridge (la, lb) fastening system and the at least one transformer oil drying cartridge (lc) is fastened by a drying cartridge (lc) fastening system, wherein the cleaning cartridge (la, lb) fastening system and / or the drying cartridge (lc) fastening system are adapted to enable an exchange of the at least one cleaning cartridge (la, lb) and / or the at least one drying cartridge (lc) without the use of the tool.

10. Transformer oil reclaiming device according to any of the aforementioned claims, wherein the transformer oil reclaiming device contains at least two oil cleaning cartridge (la, lb)s.

11. Transformer oil reclaiming device according to any of the aforementioned claims, wherein the transformer oil reclaiming device contains a filter (4) located before or after, preferably after, the at least one oil cleaning cartridge (la, lb) and the at least one oil drying cartridge (1c), based on a flow direction the transformer oil reclaiming device is adapted to provide for a transformer oil to be reclaimed flowing through the transformer oil reclaiming device.

12. Transformer oil reclaiming device according to claim 11, wherein the filter (4) providing a pore size less than 10 Micron, more preferred less than 6 Micron, even more preferred less than 5 Micron.

13. Cabinet (2) containing a transformer oil reclaiming device according to any of the aforementioned claims.

14. Method of transformer oil reclaiming, wherein the method utilizes a transformer oil reclaiming device according to any of claims 1 to 10 or a cabinet (2) according to claim 11, wherein the method contains the step of removing contaminations from the transformer oil using the at least one oil cleaning cartridge (la, lb), and wherein the method contains the step of removing contaminations from the transformer oil using the at least one oil drying cartridge (1c).

15. Method according to claim 12, wherein the transformer oil last flows through the oil drying cartridge (1c) in case the at least one oil drying cartridge (1c) is only one oil drying cartridge (1c) or at least one of the at least one drying cartridge (1c) in case the at least only oil dryingcartridge (1c) is two or more oil drying cartridge (lc)s before exiting the transformer oil reclaiming device.19

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