Patent Publication Number: US-8110011-B2

Title: Method of processing high voltage capacitors

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application is a divisional of U.S. application Ser. No. 11/015,126, filed Dec. 17, 2004, entitled “A Method of Processing High Voltage Capacitors,” which claims priority from commonly assigned U.S. Provisional Application No. 60/575,597, filed May 28, 2004. Each of these applications is incorporated herein by reference in their entirety. 
     The present application is also related to U.S. application Ser. No. 12/960,481, filed Dec. 19, 2007, which is also a divisional application of U.S. application Ser. No. 11/015,126, filed Dec. 17, 2004, and claims priority from 60/575,597, filed May 28, 2004. 
    
    
     INTRODUCTION 
     The present invention is generally related to a capacitors and testing thereof and more particularly to HV capacitors and testing thereof. 
     BACKGROUND 
     The manufacture and/or testing of high voltage (HV) capacitors used in high voltage power transmission utilizes processes that in many respects can be improved. HV capacitors are typically very heavy and bulky; an exemplary HV capacitor weighs 50 Kg and is 2 meters long. In one variant, HV capacitors can be configured for use as a CVD (Capacitor Voltage Divider). 
     The manufacture of HV capacitors typically includes the assembly of a series string or stack of capacitor cells, which are subsequently inserted into an open capacitor housing. In the prior art, individual capacitor cells are joined in series by means of the introduction of additional material, which is used to form of a bond between the cells.  FIG. 6   b  illustrates bonding of two aluminum foils  10  of respective capacitor cells by use of additional material  12 , for example a solder, a conductive glue, a joining tab, etc. As represented by dashed lines in  FIG. 6   b , the additional material may act to deform an electrical field that is formed when an electrical potential is present across the aluminum foils; degraded performance may be one consequent result. In the prior aft, after insertion of cells in an unsealed housing, the housing is placed into a large oven chamber. With oven closed, the capacitor housing and capacitor cells within are subjected to one or more cycle of vacuum and/or high temperature so as to remove moisture form the cells and the interior of the housing. Increased oven drying throughput may be achieved by drying more than one HV capacitor housing (a batch) at a time, but the oven size needs to be increased accordingly. For example, in order to accommodate a batch of 125 HV capacitor housings, in one embodiment an interior of a drying oven is dimensioned to be on the order of about 3×5×5 meters. Although large ovens can permit a large number of capacitor housings to be dried at one time, a large amount of unused free volume remains within the oven, which requires that more air be evacuated and/or more air be heated to maintain a given temperature or vacuum within the oven; increased drying time and/or increased energy usage may be a consequent result. 
     After drying, the HV capacitor housings are physically removed from the oven for impregnation. The unsealed HV capacitor housings are removed from the oven and immersed or filled in their entirety in a vat or tank of impregnation fluid so as to fully impregnate the interior of the housings and capacitor cells therein. After the impregnation step, each capacitor housing is individually fitted and sealed with sealing end caps. Each sealing end cap may include terminals, with which external electrical access to the capacitor cells within the housing may be made. 
     In the prior art, impregnation of HV capacitors, whether individually or as a batch, is a very dirty and messy process that leaves residues of impregnation fluid on the exterior of each capacitor housing, as well, about the surrounding environment. Consequently, after sealing of a capacitor housing with sealing end caps, impregnation fluid typically needs cleaned from the housing exterior and other exposed apparatus. After impregnation and cleaning, the HV capacitor housings are reinserted into the oven, the temperature of which is raised again so as to increase the temperature of the impregnation fluid within the sealed housings. The increased temperature increases pressure within the now sealed capacitor housings. After an extended period of time, the HV capacitor housings are removed from the oven and inspected for leakage of impregnation fluid, particularly at sealed electrical connection points and end caps. If no leaks are detected, the HV capacitors are tested under application of a high voltage, and if the HV test is passed, the HV capacitors can be made available for use. 
     Variations in the order of testing, heating, and impregnation to that described above may exist in the prior art, but have in common that during each movement, test, and dis/assembly step, the HV capacitors and cells are exposed to impurities, moisture, and other undesired materials. The undesired materials may to some extent be reduced by extra time consuming drying and vacuum steps but, nevertheless, are always present. Performance of prior art capacitors is consequently negatively affected. 
     It is desired to improve upon one or more aspects of the prior art. 
     SUMMARY 
     In one embodiment, a method of processing high voltage capacitors comprises the steps of providing at least one sealed high voltage capacitor housing, the housing having an interior and an exterior; providing a fluid at the exterior of the sealed high voltage capacitor housing; and detecting with a detector, the presence or absence of the fluid in the interior of the sealed high voltage capacitor housing. The method may further comprise a step of applying a vacuum to the interior of each sealed high voltage capacitor housing. The fluid may comprise a low molecular weight gas. The detector may be coupled to each sealed high voltage capacitor housing at a sealable port. Each sealed high voltage capacitor housing may comprise at least one end cap. The at least one end cap may include the sealable port. The at least one end cap may be coupled to the housing by a seal disposed therebetween. The method may further comprise a step of placing each sealed high voltage capacitor housing within a chamber before performing a step of detecting. The fluid may be pressurized. 
     In one embodiment, a method of processing high voltage capacitors comprises the steps of providing at least one sealed high voltage capacitor housing, the housing having an interior and an exterior, and a sealable port; selectively passing a fluid between the exterior and the interior at the sealable port; and detecting with a detector the presence or absence of the fluid at the exterior of the housing. The method may further comprise a step of applying a vacuum to each sealed high voltage capacitor housing. The method may further comprise a step of applying a pressure to each sealed high voltage capacitor housing. The step of selectively passing a fluid may be facilitated by application of a pressure differential between the interior and the exterior. The fluid may comprise a liquid. The fluid may comprises impregnation fluid. Each sealed high voltage capacitor housing may be sealed by an end cap. The end cap may include the sealable port. Between the end cap and the housing there may be disposed a seal. The method may further comprise a step of placing each sealed high voltage capacitor housing within a chamber before performing the step of detecting with a detector. The fluid may be heated. The chamber may be heated. The chamber may comprise a vacuum chamber. 
     In one embodiment, a method of processing high voltage capacitors comprises the steps of providing at least one high voltage capacitor, the capacitor including a housing having an interior and an exterior, and sealing the interior from the exterior with at least one end cap; and passing a fluid between the exterior and interior through at least one selectively sealable port. The fluid may be an impregnation fluid. The method may further comprise a step of applying a vacuum to the interior of the capacitor. The method may further comprise a step of applying the vacuum through at least one sealable port. The method may further comprise a step of placing each high voltage capacitor within a chamber. At least one end cap may be fitted with at least one sealable port. The at least one high voltage capacitor may comprise a plurality of high voltage capacitors, and fluid from one source provides fluid to the plurality of high voltage capacitors. 
     In one embodiment, a method of processing a high voltage capacitor comprises the steps of providing a sealed high voltage capacitor, the capacitor having an interior and an exterior; providing a first fluid at the exterior of the capacitor; providing a first detector; detecting with the first detector the presence or absence of the first fluid at the interior of the housing; and providing a second fluid at the interior of the capacitor. The method may further comprise a step of detecting the presence or absence of the second fluid at the exterior of the housing. The second fluid may be an impregnation fluid. The first fluid is a gas. The method may further comprise a step of providing a chamber; disposing the high voltage capacitor in the chamber; performing the steps of detecting after disposing the capacitor in the chamber. The method may further comprise a step of applying a vacuum to the high voltage capacitor. The second fluid may be a gas. The second fluid may be heated. The sealed high voltage capacitor may comprise at least one selectively sealable port though which the first and second fluid are provided. 
     In one embodiment, a method of processing high voltage capacitors comprises the steps of providing at least one sealed high voltage capacitor, each high voltage capacitor having an interior and an exterior, and at least one selectively sealable port; and passing fluid between the exterior and the interior of each capacitor. The method may further comprise a step of passing fluid from the interior to the exterior of each capacitor at a sealable port. Fluid may be passed through a sealable port as a dry gas. Fluid may be passed through a sealable port as an impregnation fluid. Fluid may be passed through a sealable port as a low molecular weight gas. Each high voltage capacitor may be sealed by an end cap, wherein the end cap includes a seal and a selectively sealable port. The step of passing fluid may comprise a first step of passing a dry gas and a second step of passing an impregnation fluid. The fluid may originate from one source. The sealable port may comprise a coupler. The sealable port may be adapted to receive fluid via a hose. The method may further comprise a step of disposing each capacitor within a chamber prior to the step of applying fluid. The high voltage capacitor may comprise a plurality of fins. 
     Other variants, embodiment, benefits, and advantages will become apparent upon a reading of the Specification and related Figures. 
    
    
     
       FIGURES 
       In  FIG. 1 , there is seen a not to scale representation of a HV capacitor. 
       In  FIG. 2 , there is seen a not to scale cross-section of a rolled capacitor cell with exploded views of a right end and a left end of a cell. 
       In now to  FIG. 3 , there is seen not to scale representations of two capacitor cells connected in series. 
       In  FIG. 4 , there is seen a not to scale representation of a plurality of capacitor cells connected by aluminum foils at their ends. 
       In  FIG. 5 , there is seen a not to scale representation of a CVD. 
       In  FIG. 6   a  there is seen a mechanical bond that does not interfere with an electrical field. 
       In  FIG. 6   b , there is seen a prior art mechanical bond that interferes with an electrical field. 
       In  FIG. 7   a , there is seen a not to scale representation of a HV capacitor subject to a leak test. 
       In  FIG. 7   b , there is seen a not to scale representation of a HV capacitor subject to a leak test. 
       In  FIG. 8 , there is seen a not to scale representation of a HV capacitor subject to drying. 
       In  FIG. 9 , there is seen a not to scale representation of a HV capacitor subject to drying. 
       In  FIG. 10 , there is seen a not to scale representation of a HV capacitor subject to vacuum. 
       In  FIG. 11 , is seen a not to scale representation of a HV capacitor subject to impregnation. 
     
    
    
     INVENTION 
     Reference will now be made in detail to several embodiments of the invention that are illustrated in the accompanying drawings. Wherever practical, same or similar reference numerals are used in the drawings and the description to refer to the same or like parts or steps, however, to simplify the disclosure the same or similar reference numerals may in some instances refer to parts or steps that comprise variants of one another. The drawings are in simplified form and not to precise scale. For purposes of convenience and clarity directional terms, such as top, bottom, left, right, up, down, over, above, below, beneath, rear, front, and other terms may be used with respect to the accompanying drawings. These and similar directional terms should not be construed to limit the scope of the invention. The words “couple”, “connect” and similar terms with their inflectional morphemes are used interchangeably, unless the difference is noted or otherwise made clear from the context. These words do not necessarily signify direct connections, but may include connections through intermediate components and devices. Details in the Specification and Drawings are provided to enable and understand inventive principles and embodiments described herein and, as well, to the extent that would be needed by one skilled in the art to implement the principles and embodiments covered by the scope of the claims. The words “embodiment” refers to particular apparatus or process, and not necessarily to the same apparatus or process. Thus, “one embodiment” (or a similar expression) used in one place or context can refer to a particular apparatus or process; the same or a similar expression in a different place can refer to a different apparatus or process. The number of potential embodiments is not necessarily limited to one or any other quantity. 
     Referring to  FIG. 1 , there is seen a not to scale representation of a HV capacitor. In one embodiment, a HV capacitor  100  comprises a housing  101  and a plurality of capacitor cells  102  disposed within. The capacitor cells  102  are connected in a series string, with the number of capacitors in the string dictated by a desired nominal operating voltage of the capacitor  100 . Electrical access to ends of the series string of capacitor cells  102  is provided by sealed terminals  111   a ,  112   a . In a typical configuration, a HV capacitor  100  includes a plurality of ribs; the ribs facilitate cooling of the HV capacitor and, as well, provide a geometry and material to which impurities have difficulty adhering to. 
     Referring now to  FIG. 2 , and other Figures as needed, there is seen a not to scale cross-section of a rolled capacitor cell with exploded views of a right end and a left end of a cell. In one embodiment of the present invention, a capacitor cell  102  comprises a combination of insulator, separator, and conductor. In one embodiment, capacitor cell  102  is formed by disposing a layer of insulative polypropylene  104  over one or more layers of paper product separator  105 , and disposing the one or more layers of paper product separator over a layer of aluminum foil conductor  107 . In one particular embodiment, the polypropylene has a thickness of about 12.7 microns, the paper layers have a thickness of about 20 microns, and the aluminum foil has a thickness of about 10 microns. It is understood, however, that the present invention should not to be limited by dimensions disclosed herein as they may be changed in accordance with design requirements; for example, in other embodiments, the aluminum foil can vary in thickness between 5 um and 25 um. 
     Referring now to  FIG. 3 , and other Figures as needed, there is seen not to scale representations of two capacitor cells connected in series. As illustrated in  FIG. 3 , layers of polypropylene, paper, and aluminum foil  107  of a capacitor cells  102   a - b  are rolled in a manner that provides access to layers at a respective left end  106  and a right end  108  of each capacitor cell. A number of methods can be employed to provide a rolled capacitor cell as illustrated, including taking an initially unrolled length of the layers and folding the length such that the left end and the right end are initially adjacent to each other, and such that what would be an end opposite to the adjacent left and right ends is repeatably rolled as a length “Y” to a point where a certain length of the left end  106  and right end  108  remain unwound and exposed. In one embodiment, the length X at the left and right end that remains unwound is about 45 mm. Also illustrated in  FIG. 3  is a layer of aluminum foil  107  left unrolled at the left end  106  and positioned in a bottom orientation, and at the right end  108  a layer of aluminum foil  107  left unrolled in a top orientation. In these orientations, the left end of capacitor cell  102   a  is alignably disposed over a right end of a previously similarly rolled capacitor cell  102   b.    
     Referring now to  FIG. 4 , and other Figures as needed, there is seen a not to scale representation of a plurality of capacitor cells connected by aluminum foils at their ends. In one embodiment, capacitor cell  102   a  and capacitor cell  102   b  are bonded by a mechanical bond that joins exposed aluminum foil  107  of a right end  108  of capacitor cell  102   b  to exposed aluminum foil  107  of a left end  106  of capacitor cell  102   a . Repeated mechanical bonding of aluminum foils of respective capacitor cells can be used to form a series string or stack of electrically interconnected capacitor cells. In various embodiments, a nominal voltage rating for a string of capacitor cells is between about 10 KV and 420 KV, with individual nominal cell capacitance ranging between about 20 nf and 10 uf. Other ratings are within the scope of the present invention, as would determined by particular design specification. In one embodiment, 3 uf capacitor cells are connected in series to provide a 170 Kilovolt rated capacitor. In one embodiment, adjacently exposed aluminum foils of a right end of a cell  102   b  and a left end of a cell  102   a  are placed over a support  109 , and mechanical pressure is applied to press the foils against each other and the support. The mechanical pressure is of a value that allows a mechanical bond to be formed between the two conductors without causing damage or contamination to the conductors and other layers of material that may be present. With mechanical bonding, it is identified that aluminum oxide layers present on the aluminum foils may be penetrated and, thus, better electrical contact between the aluminum foils may be made. Formation of mechanical bonds by pressure applied to aluminum foils at a relatively low temperature is called by those skilled in the art as a “cold weld.” In one embodiment, a mechanical bond can also be formed at a raised or relatively high temperature. A mechanical bonding process can be repeated, wherein a bonded capacitor cell  102   b  is moved to a lower position under a stack of previously bonded cells, and an aluminum foil of a right end of an unbonded capacitor cell is placed next to an aluminum foil of a left end of a previously bonded cell  102   b , and the bonding process is repeated on the two foils. The process may be repeated until a desired number of capacitor cells have been bonded in series. Preferably, the dimension X disclosed in  FIG. 3 , is provided as a length that when cell  102   b  is moved under cell  102   a  to form a stack of cells, the right end  108  of cell  102   b  and the left end  106  of cell  102   a  can be manipulated and extended without causing damage to the cells  102   a  and  102   b , or bonds formed therebetween. 
     In one embodiment, mechanical pressure is applied to the positionally exposed aluminum foils of capacitors  102   a  and  102   b , for example, by a hardened metal cylinder that is moved or rolled across the exposed aluminum foils (represented by the two headed arrow). In one embodiment, the roller may comprise a surface that forces a patterned impression to be formed in the aluminum foils, for example, a cross hatch pattern, or the like. Patterned impressions may be used to help mechanically interlock the aluminum foils together and so as to add strength to the bond. The exposed aluminum foils of unconnected capacitors may be positioned and bonded by a manual and/or automated process. Although in one embodiment a roller is identified, in other embodiments, it is understood that exposed aluminum foils could be bonded by other force applying devices and mechanisms, for example, a mechanical press device, etc. Because the present invention does not utilize adhesives, solder, tabs, or other additional products to bond aluminum foils of capacitor cells together, the associated degradation in performance and reliability that occurs in the prior art is reduced or eliminated. As represented in  FIG. 6   a , without use of additional products to form a bond between conductors, an electrical field that can be formed by a potential applied across the conductors is minimally deformed and, thus, electrical performance of a HV capacitor  100  can be improved over that of the prior art. 
     Referring back to  FIG. 2 , it is identified that principles described above can be used in the assembly of a HV Capacitative Voltage Divider (CVD), a type of HV capacitor known to those skilled in the art. In a preferred embodiment, a capacitor cell  102  as used in a CVD includes one layer of polypropylene  104 , two layers of paper  105 , and one layer of aluminum foil  107 . In one embodiment, the polypropylene has a thickness of about 12.7 microns, each layer of paper has a thickness of about 10 microns, and the aluminum foil has a thickness of about 10 microns. Analysis and empirical results have identified that use of two layers of paper  105 , enables use of a CVD over a wider range of temperatures than a CVD that would use capacitor cells  102  made with one layer of paper of equivalent thickness. 
     Referring now to  FIG. 5 , there is seen a not to scale representation of a CVD. In one embodiment, a CVD differs from the HV capacitor  100  topology described above in at least one respect; an intermediate connection  103  is included to provide electrical access to an electrical point within a series string of capacitor cells  102 . In one embodiment, electrical connection and access at an intermediate connection may be provided by an appropriately dimensioned and positioned intermediate capacitor extending portion. Those skilled in the art will identify that the number of capacitor cells used to configure upper and lower legs of a CVD and, thus, the location of the intermediate connection, would vary according to desired specifications. 
     Referring back to  FIG. 1 , and other Figures as needed, there is seen capacitor cells disposed within a housing. After individual capacitor cells  102  are mechanically bonded in series, the resulting stack of cells is electrically coupled to one or more terminals provided with one or more end caps. In one embodiment, the electrically coupled stack is inserted into an appropriately sized housing  101 , and end caps  111 ,  112  are sealably attached to each open end of the housing. In one embodiment, between each end cap and the housing there is provided one or more seal, o-ring, gasket, or the like disposed to seal Scaling of a HV capacitor  100  with end caps at this point in a process facilitates shielding of the interior of the housing from external impurities during subsequent processing steps. With end caps attached to a housing, the resulting embodiment at this point in a process is understood to comprise a capacitor housing, a stack of serially bonded capacitor cells  102  disposed within, and ones one or more sealed end cap, but sans any impregnation fluid, or in other words, the interior of the HV capacitor  100  is without any electrolyte or oil. 
     Although HV capacitor  100  is sealed by its end caps, the present invention allows that selective access from the exterior to the interior (or interior to the exterior) of the capacitor may be made though one or more sealable port. Although illustrated in one embodiment as two selectively sealable ports  115  and  116 , each disposed at respective opposite end caps  111  and  112 , it will be understood that in other embodiments, one or more sealable port may be disposed at the same end cap. As well, in other embodiments, one or both end caps  111 ,  112  may comprise more than two sealable ports. As will be understood, unless a defect or failure is detected during some of the processes described further below, use of sealable ports allows that sealed end caps do not necessarily have to be removed and, thus, time consuming repositioning, dis/assembly, retesting, and/or cleaning steps may be avoided, as would be required in the prior art. Additionally, after sealable attachment of end caps is performed, damaging exposure to external moisture and impurities (as occurs during prior art end cap removal, repositioning, dis/assembly, and or cleaning steps) can be minimized. Exposure to impurities is reduced with the present invention because the interior of the HV capacitor  100  is exposed to an external environment during processing only as determined by a selective opening or closing of its sealable ports. Compare this to the prior art, wherein during required end cap removal process steps, the interior of a HV capacitor is always exposed to an external environment. 
     Referring now to  FIG. 7   a , there is seen a not to scale representation of a HV capacitor subject to a leak test. In embodiments described further herein, connections to selectively sealable ports, as well as sealable ports themselves, will be understood to utilize or comprise one or more coupler as are used by those skilled in the art to permit quick leak free seals, and/or dis/connections, to be made under pressure and/or vacuum. In one embodiment, the couplers may provide open-flow or no-flow functionality. In one embodiment, when closed, the couplers may provide sealing functionality. In one embodiment, one or more sealable port may be closed or sealed by a sealable insert or plug. 
     In one embodiment, a sealable port  115  is selectively closed and a sealable port  116  is coupled to a source of fluid or gas  118 , for example, a source of low molecular weight and/or inert gas such as helium, or the like. In one embodiment, with pressurized gas  118  applied at sealable port  116 , a gas leak detector  120  can be positioned about the HV capacitor  100  so as to verify that gas has or has not leaked out from within the capacitor. In one embodiment, the leak detector  120  comprises a helium leak detector as could be obtained and used by those skilled in the art. A detector  120  may be positioned to detect helium at possible points of leakage, for example, at interfaces between the housing, end caps, sealed ports, and/or electrical terminals. 
     Referring now to  FIG. 7   b , there is seen a not to scale representation of a HV capacitor subject to a leak test. In one embodiment, one or more HV capacitor  100  is coupled at a selectively sealable port to a gas detector  120  and, with other provided sealable ports sealed/closed, is exposed to an external source of gas  118 , for example, low molecular weight and/or inert gas such as helium, or the like. If no externally applied gas is detected by the gas detector  120 , the capacitor housing  101 , end caps  111 ,  112 , ports  115 ,  116  and terminals  111   a ,  112   a  may be considered as being sealed sufficiently against leakage of subsequently used impregnation fluid from within the HV capacitor  100 . 
     In one embodiment, it is identified that leak testing may be enhanced by placement of one or more HV capacitor  100  in a chamber  122 . In one embodiment, after placement of one or more HV capacitor  100  within chamber  122 , hoses and/or couplers  123  within or at walls of the chamber may be used to connect a leak detector  120  to a sealable port of HV capacitor(s) within the oven, and to a source of gas  118 . It is identified that if gas is introduced into a chamber  122  that is sealed, the chamber may become pressurized, and that the pressure may be used to accelerate any potential leakage of gas from outside to within the sealed interior of each HV capacitor  100 ; detection of the gas within a sealed capacitor housing can be used as an indication that the capacitor housing is not properly sealed. The amount of time required to determine if a HV capacitor  100  may be subject to leakage from subsequently used impregnation fluid may accordingly be reduced. 
     It has been identified that application of a vacuum to the interior of each sealed HV capacitor  100  at a sealable port may be used to accelerate leakage of an externally applied gas and, thus, detection of the gas within a HV capacitor that is improperly sealed. In one embodiment, gas detector  120  itself may comprise a vacuum source (not shown) with which gas from a gas source  118  can be potentially drawn into a leaking HV capacitor  100 . 
     In one embodiment, a gas source  118  or another source of heat may be used to introduce heat into chamber  122 . In one embodiment, chamber  122  may provide heating functionality. Cycled heating of the chamber  122  may be used to expand seals and joints of each HV capacitor  100  during leakage testing to better simulate actual operating conditions and possible failure modes that may occur during actual use. 
     It is identified that testing for leakage as described by the present invention above obviates the need for the extended high temperature testing of HV capacitors as is needed in the prior art. For example, in the prior art, leakage testing is performed by subjecting sealed and impregnation fluid filled HV capacitors to a high temperature for 48 hours; after cooling a subsequent visual inspection is performed to see if any leaked fluid is present outside the capacitor. Compared to the prior art, leakage testing of HV capacitors  100  in a manner as described by the present invention can be performed very cleanly and quickly, and such that testing throughput and reliability can be increased. Because a plurality of HV capacitors  100  may be easily connected at their sealable ports by means of a coupler, and subsequently quickly tested for leakage of a gas (not impregnation fluid as in the prior art), cleaning of leaked or spilled impregnation fluid can be eliminated. Furthermore, leakage testing of prior art HV capacitors requires that they be filled with impregnation fluid and tested in heating ovens for on the order of 48 hours, which contrasts with about 5 minutes as is made possible by the above described gas leak test processes. With the present invention, if leakage of gas is detected, an offending leaking HV capacitor  100  may be quickly disconnected at a sealable port from a source of gas and moved for subsequent disassembly and repair, which differs from the prior art, wherein a leaking HV capacitor, as indicated by leaking impregnation fluid, requires that the capacitor housing and impregnation fluid be cooled, that the capacitor be disassembled, that the impregnation fluid be removed from the housing, and that the capacitor be cleaned, before repair procedures can be implemented. 
     Referring now to  FIG. 8 , there is seen a not to scale representation of a HV capacitor subject to drying. Those skilled in the art will identify that in one embodiment, the drying process described herein could in addition to, or on its own, be performed before a gas leak test. If gas leakage testing is performed first, the source of pressurized gas  118  and/or gas leak detector  120  may be disconnected from a selectively sealable port/coupler at which it/they were applied, other sealable ports/couplers may be unsealed/opened, and a drying process may be initiated. 
     In one embodiment, a sealable port is coupled to a pressurized source of dry and/or inert gas  121 . In one embodiment, the gas is heated. The gas is applied at some temperature and/or pressure sufficient to expose and pass over, and through, the capacitor cells  102  within the capacitor housing  101  and such that most or all moisture and other impurities present within the housing is expelled from any unsealed/open port(s), for example, a port  115 . One or more of the HV capacitors  100  may be coupled to the same source of gas  121  in manner that allows all the capacitors to be dried at the same time. 
     Referring now to  FIG. 9 , there is seen a not to scale representation of a HV capacitor subject to drying. In one embodiment, it is identified that a drying process according to the present invention may also be performed by placement of one or more HV capacitor  100  in a chamber  122 . In one embodiment, chamber  122  provides oven functionality that may be utilized in conjunction with application of a source of dry and/or inert gas  121 . In one embodiment, after placement of one or more HV capacitor  100  within chamber  122 , one or more selectively sealable port is connected to a source of gas  121  via hoses and/or couplers  123  provided within or at walls of the chamber, such that gas applied from outside the chamber can be passed through each HV capacitor within the chamber. It is identified that if heated gas  121  is provided, the temperature of the interior of the HV capacitor(s)  100  may be raised independent of the temperature of chamber  122 . Accordingly, the amount of time chamber  122  needs to be maintained at a certain temperature to achieve a desired amount of drying of HV capacitor  100  may in many cases be reduced. In contrast, in the prior art, an entire volume of a drying oven needs to be heated in order to sufficiently raise the temperature of the interior of the unsealed open capacitor housings placed therein. Because with the present invention only the relatively small interior volume of each sealed HV capacitor  100 , and not the large volume of a chamber actually needs be dried, quicker testing and throughput may be achieved. 
     Referring now to  FIG. 10 , there is seen a not to scale representation of a HV capacitor subject to vacuum. In one embodiment, a HV capacitor  100  may be coupled at one or more selectively sealable port to a vacuum source  124 . In one embodiment, sealable ports not coupled to a vacuum source  124  may be sealed or closed. Connections made to vacuum source  124  may be achieved by means of vacuum tight couplers and connections as are know to those skilled in the art. Vacuum may be applied to bring moisture and/or impurity levels within the a sealed HV capacitor  100  to a desired level. In one embodiment, a plurality of HV capacitors  100  may be coupled to the same vacuum source  124  in a manner that allows evacuation of moisture and/or impurities from more than one housing  101  at a time. In one embodiment, vacuum may be applied to each HV capacitor  100  by means of a vacuum source  124  coupled to the chamber  122 . In one embodiment, the chamber  122  may provide vacuum functionality. 
     Referring now to  FIG. 11 , there is seen a not to scale representation of a HV capacitor subject to impregnation. In one embodiment, one or more HV capacitor  100  may have one or more selectively sealable port coupled to a source of fluid  125 . Fluid  125  is typically used to fill the capacitor housing  101  so as to impregnate capacitor cells  102  and/or to provide a medium with which to dissipate heat generated by the cells. In one embodiment, impregnation fluid  125  comprises an oil as would be used by those skilled in the art. In one embodiment, during filling, sufficient free volume of air is left to allow for expansion of impregnation fluid  127  within a sealed HV capacitor  100  under anticipated operating temperatures. Impregnation fluid  127  may be introduced by filling, under pressure, and/or under vacuum. In one embodiment, impregnation fluid  127  may be applied at one open sealable port and another sealable port may be selectively unsealed/opened sufficiently to allow fluid to be expelled. In one embodiment, expelled fluid and/or air may be directed by means of couplers and hoses to outside chamber  122  or to a container within the chamber. In one embodiment, fluid  127  may be drawn into a HV capacitor  100  at one sealable port with a vacuum applied at a sealable port. Because during impregnation all fluid preferably is contained within each HV capacitor  100 , or connections thereto, impregnation of a HV capacitor  100  with fluid  127  can be preferably performed with minimal or no spillage. In one embodiment, impregnation of HV capacitors  100  may be performed inside a chamber  122 . In one embodiment, fluids  127  may be introduced to within chamber  122  via hoses and/or couplers  123 . If other processing of HV capacitors  100  within a chamber  122  is desired, impregnation within a chamber  122  may be achieved without removal of any HV capacitors  100  from within the chamber before or after such processing, as minimal dis/connection of appropriate hoses to/from respective ports and couplers is all that would be required to change from one source of fluid to another source of fluid. Upon impregnation, if desired, all sealable ports can be quickly and easily selectively closed/sealed by an insert, a screwable plug, or by a coupler  119 . 
     It has, thus, been identified that in accordance with one or more embodiments described herein, a more reliable and better performing HV capacitor can be manufactured. It has further been identified that processing, testing, drying, and impregnation of HV capacitors can be performed in a much shorter period of time than previously possible. For example, the start to end time to process/test a batch of prior art HV capacitors takes 120 hours, whereas the start to end time to process/test the same number of HV capacitors  100  can take less than about 48 hours. Connections to selectively sealable ports of a plurality of HV capacitors  100  may be made quickly and easily in a batch mode using hose type connections and other appropriate fixtures. No or minimal cleanup is required during impregnation with the present invention because easy quick sealable connections are able to made to HV capacitors by means of one or more sealable port. Contrast this to the prior art, wherein after a HV capacitor housing is filled with impregnation fluid in a vat, and afterwards fitted and sealed with end caps, the exterior of prior art housing typically requires extensive cleaning. Also with the present invention, no or a minimal amount of impregnation fluid is wasted and/or contaminated as occurs during prior art immersion in, and removal from, impregnation vats. Because quick, easy, clean dis/connections can be made by and to sources of vacuum, heat, gas, and/or fluids via sealable ports of HV capacitors (outside and/or inside a test chamber), HV capacitor manufacture and testing throughput is increased. Drying, impregnation, and/or leakage tests can be performed without repeated removal of HV capacitors from within a chamber and/or impregnation vat. Because heat, and/or, vacuum, and/or pressurized gas can be applied to HV capacitors within a chamber from a source external to the chamber, the chamber itself may not necessarily require that it provide heat, pressure, and/or vacuum functionality. 
     Thus, the present invention and embodiments thereof should be limited only by the claims that follow and, as well, by their legal equivalents.