DD151238A5 - ELECTRIC CAPACITOR AND HIGH VOLTAGE LIGHTING CAPACITOR - Google Patents

Abstract

The invention relates to an improved power capacitor dielectric system comprising the combination of electrode films having a raised green pattern on their surfaces and only polypropylene film as a dielectric, the polypropylene film having a texture or fiber pattern on a surface.

Description

'2 1 9 ι & U Berlin, 1.8.1980

56 773/17

Electric capacitor and high voltage phase shifter capacitor

A field of application of the invention;

The invention "relates to an improved capacitor grade aluminum foil and an improved capacitor incorporating the same, and more particularly relates to a capacitor filled with a dielectric fluid, solid synthetic resin dielectric strips, and foil strips having mutually corresponding roughened and patterned boundary and Have contact surfaces that keep their distance relationships stable and facilitate the ingress of fluid therebetween.

Characteristics of the known tech nical solutions

Fluid-saturated capacitors constructed of alternating electrode foil and synthetic resin film strips wound in a tight winding fashion have heretofore been difficult to impregnate or impregnate with dielectric pluid; In fact, although winding a capacitor winding with a certain looseness, known as winding factor, the pluid must penetrate not only the winding from its ends, but also the interfaces between the film strips which stick together and between the film strips. and film tapes which also stick together * In order to overcome this known and common problem, a number of solutions have been proposed which include complex soaking operations and roughening of the film and / or film.

  2 1 S 1 60 -2- 1 * 8.1980

56 773/17

or film surfaces through various surface finishing methods, including mechanical and chemical methods, such as B. embossing, grinding and coating of foil and etching of PiIm ₀

The problems that have arisen in these approaches have been numerous, ranging from poor overall fluid saturation and poor results of electrical testing, undesirable thickening of the capacitor winding without correlation to the required winding factor of the capacitor, to poor economy due to the additional required Processing. It is even more important that the reliability and reproducibility in the appropriate electrical tests for capacitors produced with standard manufacturing techniques have been worsened by these solutions. "

Aim of the invention;

The aim of the invention is to avoid the lack of reliability and poor economy in the production «

presentation; the nature of the Erfindu ng

The object of the invention is to provide a capacitor in which the total penetration is secured with fluid that can be produced economically and reliably tested _e

According to the invention, it has been found that the problems mentioned can be overcome or minimized by winding a polypropylene film with a special uniquely

21 9 1SO _ ₃ - 1-8.1980

56 773/17

This combination also facilitates winding of a coil with Pluid when preferred pluid is used, resulting in an improved, more stable capacitor with a uniform winding factor, wherein a synthetic resin film, ζ, is also referred to as a " turbid film ". Β »a polypropylene film, the only dielectric between the polar electrodes *

The electrical capacitor according to the invention comprising a housing having electrical terminals thereon and one or more capacitor windings in the housing connected to the terminals and a dielectric sheet in the housing impregnating the windings are characterized by being combined with each other

a) the winding comprises a pair of spaced apart (metallic electrode striplets) metallic electrode foil strips and a dielectric therebetween consisting of only one synthetic resin and comprising at least one resin strip;

b) the electrode foil strips have a double pattern of continuous uniform dimpled structures adjacent to one another on their surface;

c) the dimple-like structures have a thickness of poles,

which is about 2 to 10 times the original thickness before winding in the winding;

21 91S0 -4- 1.8.1980

56 773/17

ά) the synthetic resin strip contains or consists of polypropylene and has on one of its surfaces a roughened texture giving a film winding factor greater than about 3 % ; and

e) the fluid is selected from the group consisting of esters and hydrocarbons *.

In an advantageous embodiment of the invention, the number of dimples is more than about 100 per 2.54 cm film length and the depth of the dimples is substantially equal to their base diameter. "

The fluid suitably contains an ester as an ingredient *

It can also be a fluid with a hydrocarbon advantage *

The electrical capacitor of the present invention comprises a dielectric having a pair of polypropylene film strips each having a roughened surface and a smooth surface arranged such that a rough surface is adjacent a smooth surface.

The hydrocarbon used as a fluid contains diarylalkane or consists of «

It may also be advantageous for the hydrocarbon to contain or consist of isopropyl diphenyl. "

19 16-0 -5- 1 · 8 · 1980

56 773/17

In a further advantageous embodiment of the invention, it may be appropriate that

a) the winding comprises a pair of spaced aluminum foil electrodes and a dielectric therebetween consisting of a synthetic resin only and having a pair of adjacent polypropylene film strips each having surface irregularities on its one surface, and wherein the irregularities have a film winding factor of about 10 up to 30 % yield;

b) the electrode foil strips have a double pitting pattern on each surface of very small, closely spaced dimples adjacent to one another on its surfaces;

c) the dimples give a film thickness which is 2 to 5 times the original thickness of 6 ^ around the film before being wound on the winding

The winding factor of the assembled and saturated capacitor according to the invention is approximately 5 to 10 % »

The dimples may also be advantageously arranged in a substantially continuous pattern of about 100 to 500 dimples per running 2.54 cm of electrode foil. "

It may also be expedient that the aluminum foil electrodes, which have a smooth and a frosted surface, are arranged in the winding in such a way that a smooth surface opposes a matted surface,

»Ϊ ^ö « -6- 1.8.1980

56 773/17

and that a filmstrip has its rough surface adjacent to a smooth surface of a next polystyrene strip. "

In a further advantageous embodiment of the invention, the inner and outer surfaces of the dimples are smoothed by the interaction of steel dimples or steel humps on a roller which slidably pushes the poles into a plastic roller between them by pulling the poles between them Rolling is working.

A high-voltage phase-shifter capacitor according to the invention, which is dimensioned at 50 to 400 kvar, characterized in that

a) it has a housing with electrical connections thereon and one or more Kondensationsv- icklungen in the housing, which are connected to the terminals;

b) it has a dielectric Pluid in the housing, which soaks through the windings;

c) the windings comprise a pair of spaced apart aluminum foil electrode strips with one or more resin strips therebetween;

d) the synthetic resin strips have irregularities in the shape of a cloudy surface, resulting in a winding power factor of about 10 to 30 % ;

2 1 9 1 BO -7- 1.8.1930 ,,

56 773/17

e) the electrode strips have a regular pattern of raised dimples on each of their opposite surfaces contiguous with etv / a from 100 to about 500 dimples per 2.54 cm pole length; each of their surfaces;

f) the depth of the pits and the base diameter of the pits substantially correspond to each other;

g) the dimples have an increased polishing thickness of about 2 to 5 times the original film thickness of less than about 6 Aim ·

Exemplary embodiment .

The invention will be explained in more detail below with reference to embodiments. In the accompanying examples:

FIG. 1 is a schematic representation of a partially unwound Porm capacitor winding to show the arrangement of dielectric film and electrode foil; FIG.

Pig. FIG. 2: a representation of an electrical capacitor using a single capacitor winding according to Pig · 1; FIG.

FIG. 3 is an illustration of a high voltage phase shifter capacitor in which a plurality of capacitor convolutions according to Pig. 1 is used;

.-219IbQ -8- 1.8.1980.

56 773/17

Fig. 4 is a plan view of a portion of a foil electrode showing the pattern arrangement of the electrode foil

Fig. 5i is a cross-sectional view in linear form of a patterned electrode foil according to Fig. 4;

Fig. 6 is a schematic representation of the arrangement of patterned electrode foil and turbid film in a smooth-roughness relationship as a single dielectric in a capacitor;

Fig. 7 is a modification of the embodiment of Fig. 6, showing the arrangement of two haze film strips in a rough-roughened surface relationship;

Fig. 8i shows a modification of the embodiment according to Fig. 7, showing the arrangement of two clouding film strips in a smooth-slat and a head-to-head relationship, respectively;

Fig. 9 is a modification of the embodiment of Fig. 6 showing the arrangement of three haze film strips in a smooth-rough relationship;

219 160 _ ₃ _ i .8.1980 /

56 773/17

Pig. 10: a modification of the embodiment according to FIG. 6 with a folded film;

11 shows a schematic representation of a winding device for embossing an electrode film, which is arranged on a capacitor winding device or capacitor winding device;

FIG. 12 shows a modification of the device of FIG.

FIG. 1 shows a capacitor winding 10 in partially unwound form. Winding 10 includes a pair of spaced metal foil strip electrodes 11 and 12 and intervening polypropylene film strips 13. Additional polypropylene film strips 15 and 16 complete the winding such that pairs of polypropylene film strips are located between the metal foil electrode strips throughout the winding. Tap strips 17 and 18 are inserted into the winding 10 such that they are adjacent the electrode strip and serve as electrical connections for the electrodes.

One or more capacitor windings 10 are inserted into a suitable housing, which fills the housing with a dielectric fluid and allows the fluid to penetrate and penetrate the winding so as to penetrate both the interstices between the winding turns and the polypropylene itself. Such a capacitor 19 is shown in FIG. 2, where a single winding 10 in a nozzle or in a

• 2 191 _1ό

56 773/17

see fluid 21 (not shown) is filled. The housing 20 includes a pair of electrical terminals 22 and 23 »to which the taps 17 and 18 are connected. Lid 24, which is sealed to housing 20, has a small opening (not shown) which is used to introduce the fluid into housing 20 and then close it with solder represented by solder 25.

Another capacitor, referred to as a power capacitor 26, is shown in FIG. 3; The invention is particularly applicable to this capacitor. In FIG. 3, the capacitor 26 has a plurality of windings 10 which can be arranged in upper and lower rows in a double-pack type with all windings immersed in the fluid 21. The container 20 may exceed 65.0 cm in height, and the windings 10 may have about 25.4 cm to 30.5 cm in length . The windings 10 further include taps 17 and 18 electrically connected to one another and to the terminals 27 and 28 are connected. When using a single pack type of packing, the windings are referred to as wide turns and may be about 60 cm or more in length. The taps 17 and 18 may be omitted using an exposed film embodiment, wherein each one of the windings The foil windings at each end are soldered together and thereafter connect to the terminals 27 and 28.

Due to the narrowness of the windings of the windings 10 and because the metal foil strip electrodes have a substantially

2 1 9 1 SQ -n- '1.8.1980.

56 773/17

the fluid must pass through the coil ends 29 (FIGS. 1) and 30 (FIG. 3). At this point, due to the elevated temperatures which have been used both in the vacuum drying of the coils and in the penetration operation, the overlapping polypropylene film strip edges at the winding ends fuse together and seal against the electrode strips and swell so that they abut closely against the adjacent strips as they absorb fluid, thereby inhibiting fluid from entering the winding ·

In accordance with the present invention, the combination of polypropylene suspending film strips and specially patterned metal foil strips provides a controlled permeable spacer and means for permeating the fluid into the windings 10 from the coil ends in a unique and economical manner. Turbidity film is described in U.S. Patent Application No. 686,832.

Turbid film comprises a polypropylene film obtained in the production of a blown pipe in which the temperatures and velocities are controlled such that the polypropylene straw or polypropylene pipe emerging from the extruder has a continuous and extensive (coextensive) surface on its outer surface ) has a uniform layer of crystal structures predominantly of type III, often referred to as β-crystals. Subsequent inflation of the straw into a bubble shape results in surface irregularities or craters, sometimes referred to as

'219160' ~ ¹² - 1.8.1980

56 773/17

Surface fibrils are referred to and which extend completely over a surface of the film. These fibrils may rise about 2 to 3 / um on the surface of the base film. Accordingly, the clouding film according to the invention has a fairly roughened surface, and the opposite surface may be said to be smooth or glossy. The roughness can be measured by the ASTM tests D2457-70 or D10003, although one prefers a measurement taking into account the open space of a rough surface (the winding factor). This irregular surface texture or texture on the capacitor film strips in the windings 10 provides a winding factor in the form of fluid paths between an adjacent foil electrode and a dielectric strip or between adjacent dielectric strips and facilitates fluid penetration. Modified forms of turbid film can be obtained with other film production methods, including pulling and clamping method (draft and tentering process) and the Filmgußmethode _β Although the invention other films with a roughened surface can-use, provided their surface roughness and its winding factor reasonably similar to those of turbid film , you prefer cloudy film.

Turbid film has not only a high degree of surface irregularity but also a highly desirable high winding factor. The winding factor is a term that refers to the measured additional volume fraction, for example, of a measured volume of turbid film strips stacked one on top of the other

2 1 9 1 SO -13- 1.8.1980

56 773/17. ·

The desired roughness is thus associated with a maximum peak-to-valley distance or summit-valley extent with fewer peaks and valleys (which has a high winding factor and high Soakability) compared to a maximum number of peaks and valleys of lesser extent which gives a lower winding factor. With known film forming conditions, the surface roughness can be related empirically to the winding factor by measuring the light transmission through the piIm, for example with ASTIi test D 10003, and the resulting measurement is expressed as haze.

The use of special patterned poled electrodes together with turbid film results in an improved, impregnable condensate structure. Although the capacitor electrode foils may be of different metals, aluminum foil is the main electrode material currently used. In general, these electrodes have a thickness of about 5.0 to 6.1 Jum and are made of soft annealed or tempered aluminum. It is known to roughen the surface of aluminum electrodes in capacitor windings to facilitate soaking of the winding, e.g. By deformation, etching, grinding, etc .; US Pat. No. 3,746 describes such a method. Many such roughened electrode films showed serious drawbacks in that the roughening methods formed irregular peaks or sharp edges, or caused larger apertures of the film, giving sharp edges, and the sharp edges are areas of high voltage stress and corona discharge in a capacitor. Furthermore, these sharp edges cause incision in the adjacent polypropylene film, which increases the dielectric strength

2Ί9 160 -14- 1.8.1980

56 773/17

Another drawback is that when using films which are believed to require a high degree of roughness, such as those obtained with crimping and corrugation methods, these roughened films become one maintained too high winding factor in the winding «

According to the invention, it has been found that an improved, uniquely patterned and preconditioned film minimizes the aforementioned saturation and winding factor problems

FIG. 4 shows a section of a foil strip electrode 11, which schematically shows an embossed and raised pattern of dimple-like depressions 31 and elevations 32. The raised dimple pattern is a pattern that protrudes evenly and oppositely on both sides of the fabric relative to the starting material such that the total thickness is substantially greater than the original thickness. The dimpling structure is shown more clearly in FIG. 5. FIG. 5 shows a cross-section in a linear form of the film 11 of FIG. 4. According to one embodiment of the invention, the dimples are identical to each other, have a monohedral cross-section and extend etv / a 12.7 μm each side of the centerline of the filmstrip. Each dimple has a base diameter of less than about 0.254 Åun, and the dimple base centerpoints are about 0.508 μm apart, as shown in FIG. 4. * Any dimple is in its preferred Embodiment has a circular base and progressively decreasing horizontal round cross-sections bounded in a rounded or egg-shaped form. The surfaces defining the dimples are smoothly flowing curvilinear and continuous surfaces of one

2 1916 0 _ ₁₅ - 1.8.1980-

56 773/17

Dimple, As Elevation, Next Dimple, Well · The vertical cross section approximates an electrical sine waveform, indicating that there are no sharp corners or breaks in the curve line from the surface of one pit to the other. Other forms of curvilinear bases and cross sections can also be used if there are no sharp corners or ridges. The described circular shape is preferred. This preference is based in part on the fact that the deformation of the polyhedron to achieve such a large dimple may include a method that actually smooths, polishes and solidifies the polyp and preconditions it for use in the condenser. The polie described is called a polypure with a pitted pattern. This double pitting pattern incorporates the entire capacitor surface of the polie into the pattern and there are no substantially undeformed areas therebetween. The pattern is referred to as 100/100 or 120/120, indicating that there are 200 or 240 pits per running 2.54 cm electrode film. The curvilinear surfaces therefore extend substantially continuously over the poles and are not interrupted. According to the invention, the pattern can be extended to more than 120/120 as the conditions permit. Preferably, however, each dimple has the same general extent as an adjacent dimple so as to obtain a regular pattern with rows of dimples which are perpendicular to each other.

The double pit pattern structure according to the invention gives maximum space between adjacent stripes

-16- 1 .8.1980

56 773/17

the aluminum foil and the dielectric film strip with a minimal overall increase in the winding factor. This feature is achieved by the unique structure of the film. As shown in Figure 5, the coupling structure of the dimples significantly increases the thickness of the aluminum foil from an original thickness of about 5 »5 /» to about 25.0 ». This is about five times the original thickness and a total thickness which, if the film were incompressible or rigid, would not be well applicable in the present invention. It is also a property not easily obtained by etching, corrugating or grinding an aluminum foil strip However, dimpling provides increased or reduced resistance to crushing and flattening of the dimples when winding the foil under winding voltage to a capacitor winding. However, it allows a considerable amount of desirable springing and flattening in the reeling work so that, despite its original thickness, the condensate development of the final product is within the design tolerances. A thickness range is according to the invention an increase to about 2 to 5 times the original thickness, with a preferred thickness being about 2 to 3 times the original thickness. The metal electrode according to the invention will become a variable and flexible thickness spacer in both the Winding operation of the capacitor winding as well as in the capacitor end product. This flexible or variable thickness is related to the applied forces encountered in capacitor fabrication so that a desired thickness is maintained in the capacitor end product. In the winding, because of the smooth curved dimple profiles, there are no apertures or sharp edges present, which could penetrate the film dielectric or as stress accumulation areas

²¹⁹¹⁶⁰ -17- 1.8.1980-

56 773/17

could serve «

The invention relates to a basic arrangement of embossed film samples for use in oil-filled capacitors according to the invention, the arrangement having two features. First, there is a practical limitation on the summit-valley extension of the dimples, because excessive expansion results in a larger winding factor, which makes winding the winding rather difficult and contributes to early electrical failure. The maximum peak-valley extension also limits Second, the linear extent from pit peak to pit peak should generally be equal to the base diameter of the pit, and thereby the number of pits per unit length of the poles is also limited.

Said arrangement causes the pattern on the film to be related to the winding factor desired in the capacitor, a higher winding factor allowing for a greater pit depth but a smaller pit count and a lower winding factor for a smaller pit depth but more pits per unit length An important feature is that the sinusoidal pattern should be maintained as narrow as possible both in the longitudinal expansion and in the width expansion with full inclusion of the film.

According to the invention, the winding factor of the capacitor according to the examples and claims is the winding factor measured in a capacitor after full swelling of the polypropylene film by the infiltrating fluid. The basic measure of the capacitor winding factor is the winding factor of the polypropylene screen film -

-18- 1.8.1980

, -56 773/17

The winding factor of the polypropylene support film is the ratio of the theoretical fixed volume of a film strip to the measured volume, if a theoretical plane surface rests along the roughened surface »The ratio is given in percent of the fixed volume, so that a winding factor of 10 % indicates a volume where the space is 10 % of the solid mass. The film winding factor increases to an extent that indicates the swelling of the film by the fluid used at appropriate treatment temperatures. The increase is related to Probability _c skurve, which includes the various tolerance limits in manufacturing methods and materials, and a winding factor of the final assembly, or the capacitor end product, is determined to be greater than the measured film winding factor described above.

The Wicklvmgsfaktor in the capacitors of the invention is critical and detects all deviations in the expansion tolerances of the substances and the different temperature coefficients in the expansion of the substances and the swelling of the substances by the fluid or the Fluids · A K icklungsfaktor is necessary before soaking with the Fluid to provide a space for removing water and other volatiles when drying the condenser in vacuum at elevated temperatures, and further having sufficient space through which the infiltrating fluid passes and substantially fully, constantly the capacitor winding is saturated «

The winding factor should be uniform throughout the entire winding, d _e h · it is a certain minimum of Y / icklungsfaktor such, B _e Mittelwerts- a transit or

21 9 IS © ^ 1.8.1980

56 773/17.

throughout the winding, and this winding factor should be maintained and controlled throughout the winding and flattening operation, as the capacitor is flattened, as shown in FIG.

The mere provision of rough adjacent PiIm or foil surfaces to provide space for fluid ingress is not fully sufficient for capacitor fabrication. One must avoid too small a winding factor and too large a winding factor However, this results in a loss of uniformity of the required winding factor and a softer winding, both of which result in critical areas for failure of the capacitor during winding under tension and when flattening the winding.

The combination of a patterned film with a clouding film will advantageously exploit the winding factor of the clouding film and adjust the winding factor in the capacitors of the invention in an adjustable manner. The amount of winding factor that can be achieved with currently available polypropylene support films, ie, about 3.0 to about 30%, is insufficient and sometimes generally undesirable when ah, the entire required winding factor is intended to serve, for example, in power capacitors; if the winding factor is available in the film, it is expected to vary slightly in the manufacture of the capacitor because of the swelling of the film. Furthermore, the roughness of the polypropylene film may not be perfectly uniform, and certain areas may

2 1 S 1 SO -20- 1.8.1980

56 773/17

have a higher roughness and others a lower roughness, this property not being related to the clearance in the film and film thickness, which adds to the problem of achieving a uniform winding factor of quite satisfactory value throughout the capacitor winding Therefore, in order to control the winding factor, the use of the double-pored pattern film of the present invention is sufficient if sufficient winding factor is already present in the polypropylene filmstrip. The patterned film serves as an adjustable spring and gives a desired amount of winding factor uniformly Entire Winding, The dimple structure requires a steadily increasing flattening force due to its unbroken dome structure and adapts itself to the varying pressures or forces throughout the winding and winding of the winding and preserves the unveiling The design space factor · The structure is deformable under pressure and selective even at a single dome, and, more importantly, the entire capacitor area of the foil is included in the pattern. This means that each dome makes the piim such contributes that the PiIm does not touch the film between the domes and so reduces the winding factor or blocks the ingress of the fluid.

In the practice of the invention, the turbid film and the double bitterness film may be wound into a capacitor winding in various arrangements. A preferred arrangement uses only haze film as the strips 13 to 16 of the dielectric material between the foil electrodes 11 and 12. Such an arrangement is shown in FIG. 6 in a sham-insulated manner with the film and poliestril strips in spatial proximity.

2 1 91 SO _ ₂₁ _ _{l # 8 # 1980}

56 773/17

shown in a friendly position ·

In Fig. 6, the assembly 33 comprises a pair of patterned or dimpled films 34 and 35 and two intermediate films of turbidity 36 and 37. In the industrial production of aluminum foil, one surface is generally quite smooth and shiny, and the other surface is referred to as a rough or frosted surface. The film winding operation involves inserting two superimposed film strips between the rollers, and the surface between the strips will be different, i. rougher than the surface adjacent to the rolls. It has been found that the frosted surface actually enhances soaking due to the additional winding factor provided by the frosted surface. Accordingly, as a further aid for impregnation, the aluminum foil is placed in such a way that the smooth or shiny surface is located next to the rough surface of the thin film. This was called a smooth-rough-draw. Cloudy film strips may have the required surface irregularities or required surface roughness on one or both sides. However, the clouding film, as described in more detail in this connection, has only one surface, which is rough. Therefore, if two polypropylene film strips are used, they are arranged In this way, each electrode film strip has a smooth surface adjacent to a rough surface of a film of turbidity throughout the winding, resulting in a more uniform soaking of the winding facilitated"

<I 9 I OU ^ _22- 1.8.1980

56 773/17

A further modification of the embodiment of Figure 6 is shown in Figure 7. In Figure 7, the assembly 38 includes a pair of opacifying film strips 36 and 37 arranged in a rough-roughened surface relationship. In this arrangement, one or both rough surfaces of the electrode film strips may be adjacent to a smooth film strip surface, although preferably one from the other The penetrating fluid is allowed to penetrate the rough surface areas between the film strips and then penetrate laterally through the film strips into the areas between the film strips and the film strips. The fluid also penetrates this area from the winding ends along the surfaces of the electrodes. denfolie "

Another modification is shown in FIG. 8. In FIG. 8, the assembly 39 comprises a pair of dimple electrode sheets 34 and 35 separated by a pair of opaque film strips 37 and 37 arranged in a smooth-smooth surface relationship. In this modification, the arrangement of the smooth and rough surfaces of the electrode foil strips is relatively unimportant, although it is preferred that one is inverted over the other.

A further modification is shown in FIG _e 9. In Fig. 9, the assembly 40 comprises a pair of dimpled sheets 34 and 35 separated by three opacifying film strips 36, 37 and 41. The filmstrips are all arranged in the smooth-roughness relationship as a preferred embodiment, although one is also a blend The use of three filmstrips of FIG. 9 instead of two filmstrips of FIG. 6 can provide an additional advantage ν ^ - ^ Λ r -, -, Λ Λ ^ -f - ^ - r. TM ·? 4- viKVior>oT> TiHT ¹ P-In «π M affafes tis"

1Q160

^TS ' ^Ό ™ -23- 1.8.1980

56 773/17

It is obvious that you can use more than three filmstrips as well as a single filmstrip. "

In some cases and in some of the described embodiments, it may be desirable to fold an edge of a foil electrode strip because of the increased stress on the foil edge. Electrode foil edges are generally said to be sharp-edged, and this property is obtained by bending the foils to a predetermined width This splitting is generally achieved with a knife edge, and the resulting electrode foil edge is sharp and sometimes irregular due to burr-like elevations which become the points for the beginning of a corona. As can be seen from Fig. 3, a field of high voltage loading is formed. The electrode foil strips 34 and 35 at the coil ends 29 and 30, and any sharp edges or other irregularities cause or assist the onset of a corona. These regions are more susceptible to corona discharge when using lower dielectric fluids constant used, for. B · Fluids with a dielectric constant in the range of 2.0 to 3.0, compared to fluids with a dielectric constant of more than about 3 »0, such as chlorinated biphenyls and esters, because the fluids under higher loads in these areas FIG. 10 shows an embodiment which minimizes these high loading effects.

Referring to Figure 10, the assembly 42 includes a wider electrode strip 43 and a narrower electrode foil strip 44 disposed in opposing axial relationship to each other and supporting the electrode films.

-. .219160 _ ₂₄ _ 1.8.1980

56 773/17

is sometimes referred to as upper electrode foil 43 and lower electrode foil 44. In such an arrangement, the measured distance between the opposing electrode foil edges is increased. However, it is known that a narrower electrode causes a higher stress load in the region of the edge of the narrower electrode. As shown in Figure 10, the narrower electrode sheet 44 has a folded edge 45 "that passes through the entire winding." This folded edge 45 exhibits a smooth, rounded surface in the high load area and reduces field loading at the rounded surface. Further, the folded edge decreases the fluid film between the curled edge and the adjacent polypropylene film strip, and accordingly reduces the propensity for breakthrough of the lower dielectric constant fluid in this range. "

When folding the electrode film at its edges, it is important to fold the film electrode also in the width of its leading edge and in the width of its end edge, or to take other measures to reduce the stress at these locations. A folded edge of about 0.3175 to 0.127 cm achieves satisfactory results and a range of 0.635 to 0.95 cm is preferred. An additional amount of winding factor can be used to accommodate the folded edge. "The best results are achieved with the invention or without a folded electrode foil when the final development factor is equal to or greater than a value allowing total and unrestricted swelling of the polypropylene film by the fluid in the condenser. Usually, the described polypropylene films in capacitors, as in the examples below, swell in FIG Range of about

219180 -25- 1.8.1980

56 773/17

It is important that the entry and exit of a fluid into a condenser or into the polypropylene film or into the intervening spaces is not hindered by a limitation by swelling of the film.

Many capacitor fluids can be used according to the invention »Examples of which are esters, hydrocarbons and synthetic fluids, such as. As alkanes and biphenyls. The dielectric constant of these fluids can vary from about 2.5 to more than about 5 · The stress on the dielectric system is divided proportionally to the dielectric constant of the individual substances. A higher dielectric constant fluid shifts more stress on the film. With a polypropylene film having a dielectric constant of about 2.5 v / a, a fluid having a lower dielectric constant is more highly stressed, and the Koran conditions at the winding edges may be deteriorated.

Examples of such fluids are alkylbenzene, alkylnaphthalene, alkyldiphenyl, alkylpolyphenyl, alkylaryl ethers and alkyl substituted derivatives thereof, diarylalkanes and alkyl substituted derivatives thereof and diaryl ethers and alkyl substituted derivatives thereof, wherein the alkyl radicals and alkanes have from 1 to about 20 carbon atoms and wherein the aryl radicals are phenyl, ilaphthyl -, biphenyl or polyphenyl, and the polyphenyls contain from 3 to about 5 phenyl radicals. A fluid used in the invention is diarylalkane (phenylcyclohexyl).

Another specific fluid is monoisopropyl biphenyl (MIPB), which is a meticulously blended mixture of the m- and p-substituted biphenyl derivatives.

2 f 91 S0 -26- 1.8.1980

56 773/17

MIPB has the following formula:

with the cumulant CL ^ H-g and a molecular weight of 196.3.-

Other higher-dielectric constant fluids are, for example, the chlorobenzenes, chlorodiphenyloxides and the mixtures of esters and chlorinated aromatic compounds.

The saturation of the capacitors according to the invention can be carried out according to the usual methods which are common in polypropylene film capacitors and are described, for example, in US Pat. No. 3,363,156. However, it is preferably a method with a drying at a low temperature and under vacuum in the range of about 30 to 110 ⁰ C, preferably 90 to 110 C and less than about 80 / obar pressure and a! Blending mode, wherein the capacitor has a temperature of 30 Thereafter, the capacitors may be placed in an oven and their temperature may be in the range of about 40 to 100 ^° C., and preferably about 60 to 90 ^° C., for more than 80 ^° C., and the fluid has a temperature of 30 to 50 ^° C. increase as 40 h.

In the following, the invention will be further illustrated by examples. The applied capacitor winding factor ranged from about 5 to about 8%. The roughness of the clouding film varied from about 10 to 30 % winding factor of

²¹⁹¹⁶⁰ -27-, 8/8/80

56 773/17

Polypropylene Film Alone The fluids used were Fluid A, which contained about 97 % diarylalkane in equilibrium with a mixture of isomers, and MIPB. In each case, the fluid was carefully purified to high purity and about 0.6 to 0.8% by weight of an epoxide and about 0.01 to 0.10% by weight of an antioxidant, such as ζζΒ, were added , 2,6-di-t-butyl-p-cresol.

Example I

A number of capacitors were constructed according to the arrangements of Figures 3, 5 and 6 and the aforementioned preferred modes of operation. The capacitor windings had a length of 26.97 cm and comprised patterned aluminum foil electrodes of about 5.6 μm thick with dimples 50/50 per 2.54 cm and 2 sheets of polypropylene support film with a winding factor of about 10 to 30%, one stripe one Thickness of 18 ^ un and the other of 25.4 / um. Each capacitor had a height of the order of about 66.0 cm.

The assembled capacitors were dried in an oven at a temperature ranging from 85 to 100 ⁰ O lind a vacuum of less than 80 / ubar about 26 hours. Thereafter, the capacitors were allowed to cool to a temperature range of about 50 to 80 ⁰ C and then introduced adenetrating fluid having a temperature of about 40 to 50 ⁰ C in the condenser under vacuum. After filling, the capacitors were placed in an oven and the temperature raised to a range of about 65 to 85 ° C. Once the temperature became constant, the capacitors were left in the oven for about 20 hours, after which the temperature was reduced to room temperature.

j "B 9 ν _-2a " 1.8.1980

, 56 773/17

This pulling Let repeating a second time for an additional 20 h _e Then they brought the capacitors to room temperature, locked it and subjected to certain electrical tests.

DIV is the discharge start voltage, also known as the corona start voltage, and the indicated values are the mean of three readings. DEV is the discharge extinction voltage, also known as the coronal voltage. dissipation factor) is in % DP or tan theta (loss angle) and is expressed in percent watt loss. The results show repeatable excellent capacitors, although the design and testing criteria of these capacitors were extremely stringent:

Diel · Diel, testing tiF DIV DIV DEV DEV DEV DIV tem-

Thick Volt volt 'Wick- (Mit- (250 250 1000 1000 pe

In the middle of the long haul

worth) value) door

35.0 1680 35.0 1680 35.0 1680 35.0 1680 43.0 1990

43.0 1990

43.0 1990

43.0 1990

1990

7 3100 2600 3700 3300 3200 3100 25 7 3200 2500 3400 2700 3000 2700 25 7 3300 2600 3800 3500 25 7 3100 2500 3300 3000 25 4 3700 3000 3000 25 3200 2700 3100 80 4 3000 2400 25 3400 3100 80 4 3900 3000 25 4250 2200 80 4 , 3900 3200 25 5200 4300 80 4 3600 25 3600 25

2 19 16 0

«Vw _-29 _ 1.8.1980

56 773/17

Diel · Diel · Test pF DIV DEY DIVDEVDIV DEV Tem-

Thick Volt volt% ick- (co- (with- 250 250 1000 1000 pe

/ um lung tel- h h h h ra

worth) value) door

3700 3100 3600 3400 3500 3000 3800 3400

As can be seen from the above data, these capacitors were subjected to a severe stress load and showed very high and stable and more repeated DIV and DEV values. When these units were subjected to Hennspannung for life testing, a first retest was performed 250 h before, which showed that no units had failed, and no significant changes had occurred. The life test was then continued for a total time of 1000 hours and retested on exemplary units for each example. The DIV and DEV values remained satisfactory for overall improvement. The distribution factor and capacitance tests showed excellent values, with the distribution factor improving with time, ie 120 % of rated voltage for 1000 h and about 0.01% at 85 ° ^C C was.

Example II

Another group of 7 capacitors were prepared according to Example I, using a winding width of 57 »15 cm * The dielectric had a thickness of 18 μm and a thickness of 25.4 μm in its thickness. These capacitors were rated at 52 μP and 75 kvar at a voltage of 1990 V on the dielectric system through the films. These capacitors were subjected to a life test at voltages in the range from 2350 to 166 V and in the temperature range from room temperature to 70 ° C.

1.8.1980 56 773/17

All such capacitors tested survived more than 500 hours at higher voltages than the rated voltages and thus showed improved performance of the dielectric system,

Example III

Further groups of capacitors of different rated voltages were prepared and tested according to Example I * Group No. 6 had a wide winding of 57.15 cm "The other windings were 28.75 cm wide" The buffer voltage (pad voltage), d. The thickness of the dielectric between the electrode foils was in the range of 38 / um and 43 / um. The total winding factor of the entire capacitor winding ranged from 20 to 30 % before soaking "The results show the repeatability and safety of the capacitors made according to the invention"

Number of kvar 200 Nominal span DP 85 C Overvoltage 60 h 120 % rated voltage V failed Units 200 V checked lives 0 36 200 9960 021 36 36 0 48 200 14400 018 9 9 0 30 200 7620 021 9 9 0 30 7620 025 7 7 - 27 12470 015 - - Example IV

Various capacitors were made according to the method of Example I * The capacitors had windings of 28.75 cm in length and 4 / ul? Capacity on «

, 2 19 160 -31- 1.8.1980

56 773/17

The capacitors were measured for 1990 V on the foils. As in Pig. 8, one of the inner foils at each edge was folded 0.95 cm. Electrical tests of these capacitors showed a remarkable increase in DIV and DEV values as compared to the non-folded design.

Example V

In this example, special test capacitor units were made from 38.1 cm wraps of patterned foil having 120/120 dimples per 2.54 cm as shown in FIG. The capacitor winding factor was 5 to 10%. "The windings were designed for 1670V. A web of film 16.5 / ^mi-t 5 to 10% winding factor was used and a web of 17.7 / im film with 5 to 10 % winding factor in the dielectric system according to Figures 3, and 6. Das Soaking was carried out according to the method of Example I.

These capacitor units were subjected to tests on the corona starting voltage in the range of -40 to 25 ⁰ C at more than 180 % of the Hennspannung. The corona extinction voltage was tested and found to be about 160 % of the nominal precision; both values are excellent values for total film capacitors.

The use of the double pitted pattern film of the invention and the opacifying film facilitates penetration of a total film capacitor, provides security to infiltration, and enhances the soaking method. In use, the combination of opacifying film and painted film provides the required safety and repeatability of the results. and the film and the film are

2 1916® -32- 1.8.1980

56 773/17

support yxia. complement each other in areas where each other's part could be inadequate. This, for example, achieves the desired high DEV values «

The combination mitigates the saturation parameters that have become so stringent for overall film capacitors, and achieves a structure that can be adapted to widely different soaking methods, including those of manifold fill and flood fill fillings For example, as with other synthetic resin films, it is easy to produce with a surface roughness lower or greater than that of the preferred opacifying film of the invention, for example, less than about 5.0%. The pattern film according to the invention achieves its unique results as a spacer over the entire range of surface roughness of the synthetic resin film from about 5jO % to more than 30.0 %. " The winding factor of the dimpled film can be increased with the winding factor of the film in high-low or higher Relationship, as the case requires. The preferred range is about 5.0 to 30.0% for the winding factor of the film and about 2 to about 5 times the original thickness for the film thickness. "Examination of a double pitted film removed from assembled capacitors. showed areas of minimum thickness and few areas of maximum thickness, indicating that the film adapts to available space and prints, where haze variations, unmatched tolerance limits, or uneven winding are scarcely due. Such studies also showed that the smaller dimples, with a larger number per 2.54 cm, are fairly resistant to extinction and are highly enduring during manufacturing. The investigation also showed that excessive erasure would cause the extinguishing

1 9 1 60 _33 "1.8.1980

56 773/17

Accordingly, a pit density greater than about 100/100 is preferred. Most of the capacitors of the above examples were high voltage phase-shift capacitors. Such capacitors can be sized to greater than about 600 to more than about 13800 V AC, and their capacitance dielectric systems are subject to a high voltage load. These capacitors are rated for a kilovolt-ampere reactive power (kvar) of approximately 50 to 400 kvar and more. In these capacitors, the invention is particularly applicable and particularly desirable.

While it is extremely desirable to use turbid film according to the invention because of the safety that it gives to the winding factor achieved with it, one can produce a satisfactory overall film capacitor alone with the double pitted pattern film of the present invention, particularly the low winding width capacitors however, cases where it appears that either the patterned film according to the invention or the haze film gives improved results. Their combined use sometimes obscures the amount of one over the other, which, as I said, can be attributed to their complementary punctuations. The following examples provide an indication of the individual contributions of the patterned film or the cloudy film.

Example YI

In this example, the formation of the capacitor and the treatment were the same as in Example I, except that the capacitor windings had a narrow width of 26.9 mm and a relatively smooth film, e.g. B .. included a lower winding factor (LS)

Z Ί y Ί 9.V-34- 1.8.1980

56 773/17

with a high winding factor (HS) had an average winding factor of about 20 % . The winding factor of the capacitor was about 5 %. · The nominal voltage of the dielectric was moderate, ie about 1200 V, «Gs means DC, Ws means AC, Vr means Hennspannung _e The capacitors are measured to 7960 V and kvar« ";

Movie Gs Ws 250 h Gs

6.5 σ Vr 3 σ.Yr 6, 25 σ Yr 6 , 25 σ Vr

LS 1/6 0/3 0/3 1/3 HS 3/6 0/3 0/3 0/3

Example VII

Double sets of total polypropylene film capacitors were prepared, the only difference being that one group contained patterned film and the other did not. The test results are given below and indicate that the patterned film gave better results:

Capacitor Test Tempe- Time h voltage test checks says

V ° .C (number)

flat foil 600 Ws 80 18 4 1700

patterned

Foil 660 Ws 80 20 0 1700

One of the main reasons for the wide Anv / extension region of the film with the Doppelgrübchenmuster the smoothness and the suspension effect of the dimple ₀ Other projections or depressions, which are formed by crimping, embossing, corrugating or by sandgestehlte rollers cause elevations

• * 2 1 9 1 SO -35- 1.8.1980

56 773/17

with sharp edges in the film and many cracks and holes, all of which are highly detrimental in a high voltage loaded total film capacitor because of said corona. The dimple or hillock shape of the recesses and protrusions of the patterned film according to the invention has smooth flowing surfaces Limiting geometrical ovoid shapes that are extremely resistant to complete deformation or complete compression. These dimples protrude evenly from both sides of the film plane and form a geometric or regular and repeating pattern of equally spaced dimples and rows, such as shown. The pattern is continuous and consistent with the effective film surface in a condenser. The use of dimple patterns provides an additional safety factor in the capacitors of the invention and a more reliable capacitor in terms of the many minor disturbances that can occur in capacitor operation. Dielectricity under alternating current indicated increased dielectric strength.

In particular, the forming of the dimples on the winding apparatus used to wind up the capacitor windings is performed. The main advantage of this operation is that it avoids the need to wind the patterned film from a winding for subsequent winding to a capacitor winding Weaving and hewing exposes the dimples to possible damage, especially by crushing. The practical application of a draw to the foil to drive the embossing rolls gives the dimples and the pattern coherence and uniformity.

In the improved film according to the invention occurs

1.8.1980 56 773/17

Combining the deformation of the entire area of the film and polishing or physically processing the film in selected areas extending adjacent each other across the film surface. This improved film can be made according to two important working methods, which will be explained below with reference to FIGS. 11 and 12. In both cases, use is made of a commercially available heat-treated aluminum foil of a purity of more than 90.43 #.

Referring to Fig. 11, a capacitor winding device 4-6 has a suitable embossing device 47 disposed thereon. In the device 47, the roller 48 is a steel roller having on its surface 49 a protruding dimple pattern having the desired number of dimples per 2.45 cm, preferably more than about 100. Each dimple structure shows the same general structure as that of FIG Dimple is described in Figures 4 and 5, and all dimple depths are preferably equal to one another. A second roller 50 is arranged in the device 46 parallel to the roller 48. The outer surface of the roller 50 is made of a hard but elastic material. This fabric may be a plastic or rubber-like fabric, and excellent results were obtained with a hard rubber school having a hardness of about 60 to 80 (measured with a hardness tester). The roller 50 is biased against the embossing roll 48 with a suitable biasing means or spring 51 ,

The aluminum foil 57 is pulled out from a feed roller 52 and between the rollers 48 and 50 with the guide or condenser roller 53. Other feed rollers feed the other strips of the film electrode and the polypropylene dielectric to the condenser roller 53. The penetration depth of the protruding dimples of the embossing roll 48 into the

2 19160 -37- 1.8.1980- ·

, 56 773/17

Rubber of roll 50 ranges from about 5.0 μm to about 25 -4 μm. Accordingly, assuming a thickness of the aluminum foil of about 5 -6 to 6.0-μm, the final thickness of the embossed foil 57 is in the range of about 2 to 5 times the original thickness of the aluminum foil.

The winding factor for total film capacitors according to the invention (not soaked) in which part of the winding factor is taken from the textured or opacified polypropylene film indicates that the dimple pattern according to the invention ranges from about 100/100 pits per 2.54 cm of film length to should be about 500/500 pits per 2.54 cm film length.

The embossed pattern impressed on the film in this way is a sinusoidal pattern in cross-section, as shown in Fig. 5, with the individual dimples close to each other; they press into the elastic roller surface and obtain a rounded dimple tip, and the elastic material of the roller 50 is slightly pressed up into the area between the adjacent dimples. In this connection, one does not obtain the full depth of the dimples on the embossing roller 48 in this embossing method. The pit depth may be in the range of 50.0 μm or more, although the penetration is limited to a part thereof. Accordingly, the embossing operation changes the original surface of the film, and bumps are also generated on the side of the film facing the surface with the raised dimple pattern. Accordingly, in cross-section, an assumed plane passes through the centers of the dimples, and the cross-sectional view of FIG. 5 or a sinusoidal pattern is obtained. The distance between the centerlines of adjacent dimples is about 200 microns. Further, the entire film surface is included in the embossed dimple pattern because the

, .219160 .38- "1.8.198O

56 773/17

Dimples are formed twice, and the original plane of the film is changed ·

With more than 14,000 pits per 6.45 cm, the film surface and the outer surfaces of the pits are machined, polished, and smoothed, and light apertures or tear edges and other film imperfections are also smoothed, resulting in a better electrical performance of the film. The film according to the invention is referred to as a pre-exposed film due to the processing and polishing of substantially the entire film surface and in particular due to the processing and hardening of the dimple pits which press into the propylene film dielectric »

Tests show that a Grübchenkonzentration of 120/120 dimples per 2.54 cm film is superior along with the method of Figure 11, a lower Grübchenkonzentration and the method of Figure 12 in many respects and accordingly preferred is _e result is a flattening of the lower Dimple and easier winding of the coil, and yet the arrangement of an elastic spacer is maintained * A preferred range of dimple starts above about 100/100, the upper limit being the practical upper limits of film processing, with clear patterns while maintaining a desirable Depth of the Pattern "In general, this limit is about 500/500 pits per 2.54 cm. ₀ As the pebble number increases, the total thickness of the finished film may be slightly less than twice the original thickness." By changing the winding method and the train, one can however the education maintain a resilient spacer «

The method and apparatus of the US patent application

-39- 1.8.1930

56 773/17

No. 952,947, which is shown in FIG. 12, can also be used to produce the film according to the invention.

In Fig. 12, the broken-line outline indicates the outline of the capacitor winding device 46 in which a film patterning device 54 is suitably arranged. * The device 54 comprises a pair of embossing rolls 55 and 56 arranged in rotation in the device 46. Each roll surface is made of steel and Etched or engraved with precision so that hill-like elevations were achieved. Optionally, either one or both rolls of non-metallic material may be such, B · hardened plastic or rubber · The roll surfaces, _€ arranged precisely with suitable adjustment means, are brought to mutual engagement, so that the elevations of one roller between the elevations fit the matching roll. An externally toothed gear or a gearbox from the outside (external gearing) couples the rollers to one another and maintains the overlay. In cross-section, the roller elevations, which are called hill-like elevations, engage in a slight manner into the corresponding elevations on the opposite roller , The Y / alts can be adjustable so that their spacing can be varied and a dimple structure in the film of about 63.5 / μm distance of the vertex of the dimple from the film plane achieved. When adjusting the rollers 55 and 56, there is a clearance which is considerably larger than the film thickness so that only a part of a dimple protrudes on the roller into the film.

91Q160

d. | j to « _{-40 <-} 1.8.1980

57 773/17

The apparatus of Figure 12 does not achieve the type of preconditioning achieved by the method of Pigur 11 because the pits of the pits are not attacked on their outer surface by an opposing surface that processes, smoothes, and polishes the metal.

Claims (1)

1 * 8160 -41- '1.8.1980 57 773/17 invention claim An electric capacitor comprising a housing having electrical terminals thereon and one or more capacitor windings in the housing connected to the terminals and a dielectric fluid in the housing impregnating the windings, characterized in that they are combined with each other a) the coil (10) comprises a pair of spaced (metallic electrode volumetric strips) metallic electrode pads (11; 12; 34; 35; 43; 44) and a dielectric therebetween consisting of only one resin and at least a synthetic resin strip (13; 14; 15; 16; 36; 37; 41); the electrode foil strips (11; 12; 34; 35; 43; 44) have a double pattern of continuous uniform dimpled structures adjacent to one another on their surface; c) the dimple-like structures have a film thickness, the etv / a is 2 to 10 times the original thickness before winding in the winding (10); d) the synthetic resin strip (13; 14; 15; 16; 36; 37; 41) contains or consists of polypropylene and has a roughened texture on one of its surfaces giving a film winding factor greater than about 3.0 % ; and ² * ⁹¹⁶⁰ -42- -1.8.1980 ' 57 773/17 e) the fluid (21) is selected from the group consisting of esters and hydrocarbons. 2. The electrical capacitor according to item 1, characterized in that the number of dimples is more than about 100 per 2.54 cm foil length, and the depth of the dimples is substantially equal to its base diameter * 3 * Electrical condenser according to item 1 or 2, characterized in that the fluid (21) contains an ester as an ingredient. 4 · Electrical condenser according to item 1 or 2, characterized by a fluid (21) with a hydrocarbon « Electric capacitor according to one of the preceding points, in particular item 4, characterized by a dielectric comprising a pair of polypropylene film strips (13; 14; 15; 16; 36; 37; 41), each having a roughened surface and a smooth surface, and the are arranged such that a rough upper surface is adjacent to a smooth surface 6 «Electrical capacitor according to one of the preceding points, in particular point 4 or 5j, characterized in that the hydrocarbon contains or consists of diarylalkane © Electric capacitor according to one of the preceding points, in particular point 4 or 5 »characterized in that the hydrocarbon contains or consists of an isopropyldiplienyl« 2 19 16 0 -43- 1.8.1980 57 773/17 Electric capacitor according to one of the preceding points, characterized in that a) the winding (10) comprises a pair of spaced apart aluminum foil electrodes (11; 12; 34; 35 »43; 44) and a dielectric therebetween consisting of only a synthetic resin and a pair of adjacent polypropylene film strips (13; ; 15; 16; 36; 37; 41), each having surface irregularities on its one surface, and wherein the irregularities give a film winding factor of about 10 to 30 % ; b) the electrode foil strips (11; 12; 34; 35; 43; 44) "have a double pitting pattern on each surface of very small, closely spaced dimples adjacent to one another on its surfaces; c) the dimples give a film thickness which is the 2 to 5 times the original thickness of 6 / on the film (57) before winding on the winding (10) « 9 · Electrical capacitor according to one of the preceding points, in particular point 8, characterized by a winding factor of the assembled and impregnated capacitor of about 5 to 10 % « 10, electric capacitor according to one of the preceding points, in particular points 8 and 9 _9, characterized in that the dimples in a substantially continuous Huster of about 100 to 500 dimples per run- , -AI 9 I uv _ ₄₄ "1.8.1980 57 773/17 the 2.54 cm of the electrode foil (11; 12; 34; 35; 43; 44) are arranged. Electric capacitor according to one of the preceding points, in particular items 8 to 10, characterized in that the aluminum foil electrodes (11; 12; 34; 35 »43; 44) have a smooth and a matted surface, and in that way in the winding (10) are arranged such that a smooth surface opposes a frosted surface, and in that a film strip (13; 14; 15; 16; 36; 37; 41) has its rough surface adjacent to a smooth surface of a nearest (3) Poliestreifens ( 11, 12, 34, 35, 43, 44). Electric capacitor according to one of the preceding points, in particular items 8 to 11, characterized in that the inner and outer surfaces of the dimples have been smoothed by the interaction of steel dimples or steel bumps on a roller (48) forming the poles (57) in pushing a plastic roller (50) in sliding relation caused by the withdrawal of the poles (11; 12; 34; 35; 43; 44; 57) between said rollers (48; 50). 13 * High-voltage phase-shifter capacitor rated at 50 to 400 kvar, characterized in that a) it has a housing (20) with electrical connections (22; 23; 27; 28) thereon and one or more capacitor windings (10) in the housing (20); which are connected to the terminals (22; 23; 27; 28); , 2 1 9 1 SO -45- 1.8.1980 57 773/17 "b) it has a dielectric fluid (21) in the housing (20) so that the windings (10) soak through; c) the windings (10) comprise a pair of spaced apart aluminum foil electrode strips (11; 12; 34; 35; 43; 44) with one or more synthetic resin strips (13; 14; 15; 16; 36; 37; 41). in between; d) the synthetic resin strips (13; H; 15; 16; 36; 37; 41) Irregularities in the form of a cloudy surface on iron giving a film winding factor of about 10 to 30 % ; e) the electrode strips (11; 12; 34; 35; 43; 44) have a regular pattern of raised dimples, each of their facing surfaces contiguous with about 100 to about 500 dimples per 2.54 cm of film length on each of their surfaces ; f) the depth of the pits and the base diameter of the pits substantially correspond to each other; g) the dimples have an increased film thickness of about 2 to 5 times the original film thickness of less than about 6 / μm (0.25 mil) · Eeldiöiiriäen