US1824587A - Electrical condenser - Google Patents

Description

i 1T UIIIIIIEE-Ey w. M. BAILEY ELECTRICAL "CONDENSER.

Original Filed May 27, 1924 Sept. 22, 193i.

avwem Patented Sept. 22, 1931 NITED STATES PATENT OFFICE wnmm u. BAILEY/OI Lm, mssncnusnr'rs, ASSIGNOR r wmunrss SPECIALTY Arrmrus COMPANY, or BOSTON, mnsssorrusn'rrs, A conrona'mou or new YORK ELECTRICAL connnnsnn (Original application filed Kay 27, 1924, Serial No. 719,107.. Divided and thia-appllentiou flled March 30,

1926. Serial No. 93,411.

This up nlioation is a division of my upplieation serial No. 716,107, filed May 27, 192

This invention relates to improvements in Q electrical condensers, particularly of the type wherein sheets of dielectric and conducting foils are built up in a stack, the dielectric sheets being preferably at present of mica.

The invention relates more particularly to condensers designed. to carry high currents of, say, ten amperes more or less and upwardly to hundreds of amperes; although certain structures embodying the invention are useful also for high potential service Whether or not large currents be used. The inven times more expensive than metal), and inasmuch as the amount ofmice necessary to revent over-heating by the high currents increases very rapidly with the amperage employed, the cost in mica for such high current mica-and-foil condensers has been very high heretofore. The reason Why the use of a much larger quantity of dielectric sheets resulted in preventing undue heating of the condenser by high currents was the consequent reduction of current per sheet and therefore. the reduction of the Watt loss per sheet, the total watt loss being distributed throughout the increased number of sheets, thereby providing a larger dissipating surfuce of the stack, i. e., such surfaces comprising the edge of the mica sheets in the stack. In crderto maintain the originally desired capacity of the condenser when thus increasing the number of dielectric sheets, it was usually necessary to divide the stack into several serially connected sections whereby the voltage per section was reduced and Where by also were reduced the losses d .e to brushing resulting from high applied to the condense of the increase in dielectric shes over-heating by high currents such series-sectional.eoustri .on udnpted to preserve the some capacity notwithstanding the increase number of dielectric sheets.

The principal important object of the. present invention is to reduce. the quantity of dielectric, such as mice, in condensers de signed for high current duty, thereby obtain ing the desired capacity Without the necessity of providing a serieseectionel construction of stack. Other minor but valuable obiects voltage if such were to present was due to and results will be disclosed in connection with the drawings.

The invention consists, othe hings, of a foitstaolz condenser construction wherein the best developed by the high amperage alternating currents used is so efiiciently conducted away from the stuck from the conducting means as to make it unnecessary to increase the number of dielectric sheets (quantity of mica) for the purpose of causing a lower heat generation per sheet and a. greater total heat-dissipation from the exposed portions of the greater number of sheets. In a certain sense, the invention involves to a certain extent the substitution of masses of metal constituting heet-absor lug, heating-conducting and heat-dissipatmg means, in lieu. of the addition of much" -more expensive dielectric sheet-s.

dissipated insulated from one another by bushings I. Also, projecting from the single-section stack held compressed between clamps C1, C2, are four toil-bunches F1--F4, each of which is clamped between an auxiliary or foil clamp and a stack-clamp; foil-bunches F1 and F3 being clamped by auxiliary or foil clamps K1, K3 respectively to upper stack-clamp C1, and foil-bunches F2, F4, being clamped by auxiliary clamps K2, K; to lower stack-clamp C2. Each of the stack clampin members C1 and C2 is or may be provide with radiating fins or vanes N shown.

Fig. 3 shows the arrangement of dielectric sheets DS (as micas) and foils F1-F4 in the stack of Figs. 1-2, this being the arrange-' ment which makes possible the efiective construction of the four foil-bunches shown in Figs. 1-2. As shown in Fig. 3, one set of foils, distributed successively throughout the stack, is laid in the stack at right angles to another set of foils also distributed successively throughout the stack and alternatively with the first set of foils, so that there are four foil-bunches projecting beyond the active area of the stack as measured by the horizontal dimensions of the dielectric sheets DS; although pairs of oppositely projecting foil-bunches are ofthe same foils and therefore require only one circuit terminal. The foils of bunch F1 which is connected to stack clamp C1 are the same stack-foils as the bunch F3 connected to the same member C1. Also (and similarly) the foils projecting at F2 in a bunch and connected to stack clamp C2 are the same stack-foils as those oppositely projecting at F4 and also connected to the same stack clamp member C2. This connection of opposite ends of the same foils to the same metal stack clamp member is permitted (without efiective short-circuiting of any part of the condenser) by the above-described disposition of the foils shown in Fig. 3. Each foil is in heat-absorbing relation with two adjacent micas The clamping of the. respective foilbunches of Figs. 1-3 directly to the heatconducting and heat-dissipatin metal masses shown, permits use of high requency currents of as high current as 100 to 200 amperes; for not only is it possible for the heat developed in the stack by such high currents to get out to the projecting foils, but such heat is positively. rapidly and continuously drained-therefrom by means of the auxiliary clamping of the four projecting bunches of distributed foils, and such heat thence passes to the extended heat-dissipating surfaces of the stack-clamping means, so that it is possible to quarter the PR losses in the stack and keep it so cool. as to avoid all liability to injury or destruction thereof by heating from high currents. Dissipating fins N may eases? I clamps themselves, without any fins or the equivalent, may be sufiicient in many instances. I

The feature of Figs. 1-3, consisting of the four foil-bunches projecting from a given stack or stack-section, may be employed in connection with any other embodiment of the invention.

In general, condensers embodying this invention are designed for moderate to high capacity of each clamped unit, .005 to .2 microfaraclbeing obtained readily. With such range of capacity, almost any relation of -capacity, voltage and current may be obtained by employing a plurality of units in various relations of series, parallel, or series-parallel.

The following has been a practical result of placing the distributed projecting foilbunches in heat-conducting relation with one or more heat-dissipators of the below-specified order of exposed area. It has proven to be practicable to construct foil-stack condensers for high current duty with the same quantity of mica as for low current duty, and this whether the stack has only one or a plurality of sections. That is, by positively re moving from the stack, via the foil-bunches and the heat-dissipators, the heat developed in the stack by the use of high currents, there is obviated all need of increasing the quantity of mica for the purpose of ridding the stack of the heat so developed. And while, with the invention, some mica may be added to reduce losses in the stack, the need of the same is removed in proportion to the efiiciency of application of this invention. Prior to the use of said invention, the use of high currents required each section of a seriessectionalstack to contain additional sheets of mica (more than was needed to obtain a desired capacity), in order to avoid over-heating by such currents, and in order to maintain a given desired capacity for the condenser it was necessary to divide the stack so that a condenser for high current duty had very much more mica and a longer stack (of active condenser sheets) than a condenser for low current duty but/of the same capacity. By this invention, the number of sheets'of mica in a condenser of given capacity can be kept'substantially the same (for high or low current duty) whether the stack consists of a single section or of a plurality of sections connected in series. But the total length of a stack provided with the invention (whether in a singlesection or a plurality of sections) is not necessarily less than that of a stack adapted by increase of mica to operate without excessive heating under high current duty; because when the metal clamps for the condenser stack units are employed as in the invention, as the heat removal via the proj ecting foil bunches, the metal of such clamps occupies more or less the same order of stacklength as when extra micas were employed for heat-distribution, such length being sometimes much greater due to the dissipating vanes N when they are used. In effect, therefore, the invention involves the substitution of metal for mica,'the metal being very much cheaper. Various other advantages of the invention and of its various forms of embodiment have been specified above.

The efliciency of the invention in removing heat from a stack with which currents of very high amperage are employed may be dependent upon the efiiciency of dissipation of heat from the metal masses which conduct heat from the stack (dielectric sheets and foilarmatures) via the projecting bunches of stack-distributed foils. That is, the maintenance of efiiciency in continuously maintaining the conduction of heat from the interior of the stack at-a desirably 10w stacktemperature, is dependent upon the continuous maintenance of heat-dissipation from the heat-removing and dissipating metal masses. The following general instructions are given for the guidance of the designer or constructor, relative to this important matter of exposed area of the heat-dissipating means of the invention. This is for condensers of various designs, and condensers for various services as to amperage, frequencies and potential, in which the stack-generated heat may vary within wide limits. This is on the premise that the heat-dissipators are the stack-clamps (the best form of the invention) substantially enclosing the stack and thermally connected via the foils to the dielectric sheets distributed through the stack; and that substantially sole reliance is laced on the exposed surfaces of the clamps or the removal of heat from the stack at a desirable low temperature thereof, it being kept in mind that a higher stack-temperature than heretofore may be permitted by this invention on account of the permissive and preferred elimination of previously customary parafiin embedment of the stack. It should e noted that as the volume of the stack is increased (mica added for any reason), the exposed areas of heat-dissipation should be increased at a more rapid rate than the increase in external stack area corresponding to the increased stack volume. The object of the designer of a given condenser for desired conditions of service is to ensure the removal of the stack-generated heat at such rate as will prevent the temperature of the stack to rise above a given upper limit. Therefore in designing a given condenser to embody the invention for given service, there will be calculated the amount of heat generated in the stack per unit of time, and the definite rate at which heat must be removed from the stack without blowing the stack or exceeding the upper limit of stack temperature. Since the invention provides adequate means of conducting most rapidly from the interior of the stack, the heat generated therein, provided that after being so removed it is dissi ated from the removing means, therefore t e designer is concerns only in makin sure to provide sutlicient exposed area 0 the heat-dissipator in good thermal connection with the distributed foils. The designer therefore will provide such area suiiicient to dissipate the removed heat at the rate at which he has calculated that it will be generated in the stack. And while, in general, such area exposed to the cooling medium will be of substantially greater general order of magnitude than the exterior exposed area of the stack itself, yet it will vary within wide limits in various designs, on account of the several variables specified hereinbefore, including of course the kind of service and the amperage, frequency and potential to which the condenser .is to be subjected. Within such wide limits there is provided a control by the designer of the stack temperature which it may be desired to maintain. The area of the heat-dissipating meanswhich is exposed to the cooling medium and thermally connected to the specified foils is, in any instance, that which causes dissipation of the heat generated inside the stack at such rate as to maintain the desired low stack-temperature, depending on the nature of the cooling medium, i. e., whether it is still air, a forced draft or a liquid circulation; and, of course, depending on the conditions of service, as to potentia amperage and frequency; this referring to the area of the heat-dissipating projections or fins or vanes, if and when they are employed as they preferably will be in man instances, especially when still air is the coo ing medium.

I particularly point out and distinctly claim the part, improvement, or combination which I claim as my invention or discovery, as follows 1. A construction for an electrical condenser of the foil-stack type adapting it for high duty involving substantial internal heating, such construction including two substantially massive and rigid metal stackcompressing plates respectively engaging the entire surfaces of the end faces of the stack and extending laterally beyond four side portions of the stacked dielectric sheets, said compressing plates themselves having substantially large heat-dissipating surfaces and the plates being formed on their surfaces exposed from the stack with metal projections also having substantially large heatdissipating surfaces; a plurality of substantial metal rods cooperating with said four plate-extensions and insulated from at least one of the plates and compressing the surfaces of the stacked dielectric sheets into good thermal contact with the foil-sheets, and four foil-clamping devices located laterally of the stacked dielectric sheets and 15 between the two end plates and cooperating with said four plate-extensions; the two sets of foils which are in inductive relation to one another as armatures in the stack rojecting laterally from the stack in fbur bunches into positions adjacent the stackside surfaces of said four lateral plate-extensions and between said plate extensions and said foil-clam ing devices, whereby the individual foils each bunch are clamped w together and the several foil-bunches are clamped to said heat-dissipating plates in direct metallic thermal contact therewith.

2. A construction for an electrical condenser of the foil-stack type adapting it for high duty involving substantial internal heating, such construction including two substantially massive and rigid metal stackcompressing plates respectively engaging the entire surfaces of the end faces of the stack and extending laterally beyond four side portions of the stacked dielectric sheets, said compressing plates having substantially large heat-dissipating surfaces exposed from the stack; a plurality of substantial metal rods cooperating with said four plate-extensions and insulated from at least one of said plates and holding the surfaces of the stacked dielectric sheets and foil sheets in good thermal contact with one another in the stack between the plates; and four foil-clamping devices located laterally of the stacked dielectric sheets and between'the two end plates and cooperating with said four plate-extensions; the two sets of foils which are in inductive relation to one another as armatures in the stack projecting laterally from the stack in four bunches into positions adjacent the stack-side surfaces of said four lateral plate-extensions and between said plate extensions and said foil-clamping devices, whereby the individual foils of each bunch are clamped together and the several .foilbunches are clamped to said heat-dissipating plates in direct metallic thermal contact therewith.

3. A construction for an electrical con denser of the foil-stack type adapting it for high duty involving substantial internal heating, such construction including two substantially massive and rigid metal stackmeats? compressing plates respectively engaging the entire surfaces of the end faces of the stack and extending laterally beyond four side portions of the stacked dielectric sheets, said compressing plates having substantially large heat-dissipating surfaces exposed from the stack; means connecting said plates together mechanically but not electrically and holding the surfaces of the stacked dielectric sheets and foil-sheets between the plates in good thermal contact with one another; and four foil-clamping devices located laterally of the stacked dielectric sheets and between the two end plates and cooperating with the said four plate-extensions; the two sets of foils which are in inductive relation to one another as armatures in the stack projecting laterally from the stack in four bunches into positions adjacent the stack-side surfaces of said four lateral plate-extensions and between said plate extensions and said foil-clamping devices, whereby the indvidual foils of each bunch are clamped together and the several foil-bunches are clamped to said heatdissipating plates in direct metallic thermal contact therewith.

4. A construction for an electrical condenser of the foil-stack type adapting it for high duty involving substantial internal heating, such construction involving two substantially massive and rigid metal stackcompressing plates respectively engaging the entire surfaces of the endfaces of the stack and extending laterally beyond four slde portions of the stacked dielectric sheets, said compressing plates themselves having substantially large heat-dissipating surfaces exposed from the stack and being formed on their surfaces exposed from the stack with integral projections also having substantially large heat-dissipating projectrons; means connnecting said lates together mechanically but not electrically and holding the surfaces of the stacked dielectric sheets and foil sheets between the plates 1n good thermal contact with one another; and four foil-clamping devices located laterally of the stacked dielectric sheets and between the two end plates and cooperatmg with said four plate-extensions; the two sets of foils which are in inductive relat1on to one another as armatures in the stack projecting laterall from the stack in four bunches into POSlillODS adjacent the stack-side surfaces of said four lateral plate-extensions and between said plate extensions and said foil-clamping devices, whereby the individual foils of each bunch are clamped together and the several foilbunches are clamped to said heat-dissipating plates in direct metallic thermal con tact therwith.

5. A construction for an electrical condenser of the foil-stack type adapting it for angles to the other sheets,

tensions high duty involving substantial internal heating, such construction including tWo substantially massive and rigid metal stackcompressing plates insulated from one another and respectively engaging the entire surfaces of the end faces of the stack and extending laterally beyond four side portions of the stacked dielectric sheets, said compression plates having sufficient surfaces exposed from the stack to dissipate heat conducted to them from the interior of the stack; means connecting said plates together and holding the surfaces of the stacked dielectrics and 'foil sheets between. the lates in good "thermal contact with one anot er; four icihclainping devices located laterally of the stacked dielectric sheets and between the two end plates and cooperating with said :lonr plateextensions; the two sets of foils which are in inductive relation to one another as armatures in the stack rejecting laterally from the stack in four nnehes intopcsitions adjacent the stack-side surfaces said four lateral platecxtsnsions and between. said plate eX- and said ioihclamping devices, whereby he individual ioilsoi each bunch, are clamped together and the several foilhunches are clamped to said heat-dissipating plates in direct nectailic thermal contact therewith,

6. An electrical condenser adapted tore ceive an oscillating current tending to heat .itseriensly alcove normal and including a stack dielectric sheets and interleaved toils which project snhstantially their ,full width at each end beyond the dielectric sheets so as to form'four projecting hunches, a massive and rigid compression plate at each end of the staoa, means holding alternate foils at both rejecting ends in good thermal contact wit 1! and flat against one or said plates, other means holding the projecting ends of the other foils in good thermal contact with and fiat against the other of said pla es, extensions i ornoing cooling devices fast to said plates and exposed to the air be end the sides oi the steel: sufiiciently to dissipate heat de veloped in the stack,.and devices helcling said plates insulated from each other hut cosy pressing the pack between them 7. An electrical condenser adapted to receive an oscillating current tending to heat it'serionsiy above normai and including a stack of dielectric and interleaved foils which project substantially their ful.

"width at each end hey/end the dielectric sheets, alternate sheets projecting at right a massive end rigid compression plate at each end of the stack and forming part of stack compressing means, mechanical means also forming part of the stack, compressin means holding said plates together so that a ternate foils at-lioth projecting ends are in good thermal contact with andfiat against one of said lates, said mechanical means also holding t e projecting ends of the other ioils in good thermal contact with and flat against the other of said plates, and projections from said compresslng means forming heat-dissipating devices so that together with the lates and mechanical means heat is supphed chiefly through the projecting ends of the foils and is' effectively dissipated before the heat is seriously above normal.

8. An electrical condenser adapted toreceive an oscillating current tending to heat it seriously shove nesnial and including a stack of dielectric sheets interleaved foils

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