US3829744A

US3829744A - Gas filled measuring condenser

Info

Publication number: US3829744A
Application number: US00344146A
Authority: US
Inventors: F Raupach
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-03-24
Filing date: 1973-03-23
Publication date: 1974-08-13
Anticipated expiration: 1991-08-13
Also published as: CH558589A; DE2214288B1; GB1363219A; DE2214288C2; AT320812B

Abstract

A condenser, especially for measurement purposes, in which the high voltage electrode and the low voltage electrode are arranged on the inside of an insulating casing housing filled with a gas; the space between the high voltage electrode and the low voltage electrode or a space enclosed by an auxiliary electrode surrounding the high voltage and low voltage electrodes is closed off insulatingly gas-tight and the pressure of the gas in this space is higher than the pressure of the gas in the space formed between such electrodes and the insulating casing housing.

Description

United States Patent 1191 Raupach [4 1 Aug. 13, 1974 [76] inventor! Friedrich Raupach, Wildensorget 933,351 9/1955 Germany 317/244 Strasse 9, Bamberg, Germany 22 Filed; Man 23 1973 Primary ExaminerE. A. Goldberg Attorney, Agent, or Firm-Craig & Antonelli [21] Appl. No.: 344,146

[57] ABSTRACT [30] Foreign Application Priority Data A condenser, especially for measurement purposes, in Mar. 24, 1972 Germany 2214288 which g Voltage electrode and the low voltage electrode are arranged on the inside of an insulating 52 us. 01 317/244, 317/242, 317/246 Casing housing filled with a gas; the Space between the 511 1m. 01 HOlg 5/02 high voltage electrode and the low voltage electrode [58] Field of Search 317/242, 245, 244, 246 Or a Space enclosed y an auxiliary electrode rounding the high voltage and low voltage electrodes 5 References Cited is closed off insulatingly gas-tight and the pressure of UNITED STATES PATENTS the gas in this space is higher than the pressure of the 2 900 585 H K H 317/244 gas in the space formed between such electrodes and e Cl 3,242,397 3/1966 Jennings 317/245 the msulatmg casmg housmg' 3,405,559 10/1968 Moffatt 317/246 x 34 Claims, 2 Drawing Figures II I PATENIEU Am 1 31914 9,7

sum

2 or 2 FIG 2 GAS FILLED MEASURING CONDENSER The present invention relates to a condenser, and in particular to a condenser used for measuring purposes in which the high voltage electrode and the low voltage electrode are arranged on the inside of an insulating casing filled with a gas.

With the frequently used pressure gas condensers according to Schering-Vieweg for high and very high voltages, as are required for measurements, especially for loss factor measurements, instrument transformer calibrations, etc., the high voltage electrode and the low voltage electrode consist of metallic cylinders coaxially surrounding one another which are accommodated in an insulating tube or pipe filled with pressure gas, i.e., with a compressed gas. As a rule, the high voltage electrode is secured at the metallic cover of the insulating tube which is at the high voltage potential whereas the cylindrical low voltage electrode surrounded by the high voltage electrode is carried by a column secured on the grounded floor plate of the insulating tube.

These prior art compressed gas condensers distinguish themselves by a low loss factor and by a practically non-measurable independence from external or foreign fields. However, the external insulation offers difficulties since the field is not controlled by intermediate electrodes but instead the potential is reduced in a single stage. Furthermore, a coaxial cylindrical field is more unfavorable electrostatically than, for example, a field which forms between approximately flat electrodes. For achieving a high dielectric strength, it is therefore necessary to improve the insulating properties of the pressure gas which has been achieved with the heretofore customary constructions by the use of a high pressure in the pressure gas container approximately at a magnitude of 14 atm. (atmosphere gauge) (Keller: Konstanz der Kapazitaet von Pressgaskondensatoren, ETZ-A Volume 80, 1959, pages 757-761). J

To avoid these difficulties, a high voltage condenser for measuring purposes has been disclosed which is characterized in that the two preferably spherically shaped or semi-spherically electrodes thereof are arranged one above the other in the axial direction of the insulating tube on the inside of an essentially cylindrical intermediate electrode which is secured approximately at half the height in the insulating tube and is held at a potential lying between the potential of the high voltage electrode and the low voltage electrode (German Offenlegungsschrift 1,514,203).

With such a condenser, the external insulation problem becomes considerably more simple because the voltage is reduced at two places of the insulating tube. With the same insulating tube diameter and the same permissive surface field strength, one can therefore control approximately twice the voltage than with the pressure gas condensers according to Schering-Vieweg as mentioned hereinabove. It is also of advantage that the gas pressure in the pressure gas container can be kept lower than necessary heretofore. With the use of sulfurhexafluoride one is able to get along even with a pressure of 2-3 atm. (atmospheric excess pressure). While one does not obtain a'complete independence from external fields as with the condensers having mutually coaxial high and low voltage electrodes, the external field influence nonetheless is so slight that it does not disturb or cause any problems.

The present invention relates to a condenser, especially for measurement purposes, in which the high voltage electrode and the low voltage electrode are arranged on the inside of an insulating casing housing filled with gas.

The present invention is concerned with the task to so construct such a condenser that it excels by a slight requirement in insulating gas, a high operational reliability and safety and small dimensions.

The underlying problems are solved according to one embodiment of the present invention in that the space between the high voltage electrode and of the low voltage electrode is closed off insulatingly gas-tight and that the pressure of the gas in the space formed by the high voltage electrode and the low voltage electrode is higher than the pressure of the gas in the space between the electrodes and the insulating casing housing.

By the subdivision of the condenser into a measurement condenser spaced formed by the high voltage electrode and the low voltage electrode and into a leadin space disposed outside of the electrodes and delimited by the insulating casing housing, whereby exclusively the measuring condenser space is provided with the higher gas pressure required for the rated voltage whereas the lead-in space has a considerably lower gas pressure, one achieves a considerable saving in insulating gas. The gas pressure can be selected relatively high in the comparatively small measurement condenser space. As a result thereof, the radial distance between the electrodes, on the one hand, and between the electrodes and the insulating casing housing, on the other, can be reduced because dielectric strength increases with the pressure of the insulating gas, which enables a slender design and small construction. The over-all insulating gas expenditure is relatively small compared with the known condensers of this type because the gas pressure in the lead-in space which has a considerably larger volume than the measurement condenser space, can be relatively low. The pressure may preferably amount to about 1 ata in the lead-in space.

The subdivision of the condenser space according to the present invention into a measurement condenser space with higher gas pressure and into a lead-through space with lower gas pressure is applicable with advantage not only to condensers which are designed according to the constructional principle of Schering-Vieweg, i.e., with mutually coaxial high voltage and low voltage electrodes but with the same or similar advantages also to condensers having electrodes arranged axially one above the other and an auxiliary electrode according to Kind.

The present invention according to a further embodiment therefore also relates to a condenser, especially for measurement purposes, in which the high voltage electrode and the low voltage electrode are surrounded far-reachingly by an auxiliary electrode which is at approximately half the high voltage potential whereby the auxiliary electrode is arranged either completely or partially on the inside of an insulating casing housing filled with a gas. According to the present invention, the space between the high voltage electrode and the auxiliary electrode, on the one hand, and between the low voltage electrode and the auxiliary electrode, on the other, is closed off insulatingly gas-tight whereby the pressure of the gas in the space constituted by the high voltage electrode, the low voltage electrode and the auxiliary electrode is higher than the pressure of the gas in the space or spaces between the electrodes and the insulating casing housing. In addition to the advantages described above, the further advantage is achieved thereby that the axial distance between the high voltage electrode and the low voltage electrode can be reduced whence the capacity of the condenser is increased which is frequently desirable.

Accordingly, it is an object of the present invention to provide a condenser, especially for measurement purposes which avoids byv simple means the aforementioned shortcomings and drawbacks encountered in the prior art.

Another object of the present invention resides in a condenser of the type described above in which the external insulation problem is considerably simplified while at the same time a significant saving in insulating gas is realized.

A still further object of the present invention resides in a pressure gas condenser which is extraordinarily reliable in operation and distinguishes itself by small dimensions.

Another object of the present invention resides in a condenser of the type described above in which the capacity of the condenser can be increased.

These and further objects, features and advantages of the present invention will become more apparent from the following description when taken in connection with the accompanying drawing which shows, for purposes of illustration only, two embodiments in accordance with the present invention, and wherein:

FIG. 1 is a longitudinal cross-sectional view through a condenser in accordance with the present invention with high voltage and low voltage electrodes arranged coaxially to one another; and I FIG. 2 is a longitudinal cross-sectional view through a condenser according to the present invention with high voltage and low voltage electrodes arranged one above the other in the axial direction of the insulating casing as well as with an auxiliary electrode surrounding the same.

Referring now to the drawing, and more particularly to H0. 1, the condenser illustrated in this figure, preferably a pressure gas condenser for high and very high voltages, includes an insulating casing 1 consisting of casting resin or any other suitable insulating material as known in the art, which is closed off at the top by a metallic cover 2 having a shielding hood 3 and at the bottom by a metal bottom 4. A low voltage electrode 5 is completely shielded by a high voltage electrode 6 surrounding the same. The high voltage electrode 6 is extended downwardly relatively far and terminates in a bulged or beaded ring 7 that has such a small distance from a grounded tubular member 8 carrying the low voltage electrode 5 that no external field lines can penetrate onto the measurement layer. A feed line leading to the measurement electrode (low voltage electrode) 5 is designated by reference numeral 9 which is disposed within the grounded support pipe 8. A support ring 10 is secured at the high voltage electrode 6; one

7 end of a conical-disk-shaped supporting-type insulator The space closed off gas-tight by the supporting-type bushing 11 between the low voltage electrode 5 and the highvoltage electrode 6 is filled with an inert gas, for example, nitrogen or with an electro-negative gas, preferably sulfur hexafluoride having a higher pressure. The gas pressure P of the insulating gas in the measurement condenser space formed by the electrodes 5 and 6 may preferably be within the range between about i and 10 atm.,, The gas pressure P in the lead-in space disposed on the outside of the electrodes 5 and 6 may amount preferably to about 1 ata. Also, the leadin space is filled preferably with an inert or electronegative gas, preferably sulfur hexafluoride. As a result of the subdivision of the condenser according to the present invention into the two pressure spaces, the expenditure in insulating gas is considerably reduced compared to the known constructions. Since the electrode distances can be kept small in the measurement condenserspace, one additionally obtains a very compact, slender type of construction.

The condenser illustrated in FIG. 2 includes also an insulating casing 21 which is closed off at the top by a metal cover 22 with a shielding hood 23 and at the bottom by a metal bottom 24. Approximately at half the height of the insulating casing 21 are located the

electrodes

25 and 26 disposed one above the other in the direction of the casing axis and, for example, provided with a Rogowski-profile or plate-shaped. The high voltage electrode 25 is secured at the cover 22 by means of a pipe or tubular member 27 whereas the low voltage electrode 26 is carried by a pipe or tubular member 28 secured at the bottom 24. The high voltage and

low voltage electrodes

25 and 26 are surrounded by an auxiliary electrode 29 closed off in a gas-tight manner and filled with an insulating gas of higher pressure. The auxiliary electrode 29 arranged on the inside of the insulating casing 21 consists of two approximately semispherically shaped shells 30 and 31 which are provided each with an

aperture

32 and 33 for the tubular support members or

pipes

27 and 28 of the

electrodes

25 and 26, respectively. The

apertures

32 and 33 of the housing shells 30 and 31 are closed off gas-tight by coneshaped supporting-

type insulator bushings

34 and 35 tapering in the upward and downward direction respectively and preferably consisting of casting resin of any suitable known type.

Support rings

36 and 37 consisting preferably of insulating casting resin and secured at the housing shells 30 and 31 are provided as abutment surfaces for the conically shaped supporting-

type bushings

34 and 35. The insulating casing 21 is subdivided into two insulating

casing portions

38 and 39 which are provided with

recesses

41 and 42 at the separating place 40, in which are guided

flange rings

43 and 44 secured at the outwardly bent edge of the housing shells 30 and 31 and are threadably secured with the

insulating casing portions

38 and 39 by means of screws or

bolts

45 and 46 distributed over the circumference. The

insulating casing portions

38 and 39 are connected with each other in a gas-tight manner by sealing rings (not shown) with the use of bolts or screws 49 mounted at the

projections

47 and 48. The separating place 40 is surrounded by an annular screening electrode 50. The

tubular support members

27 and 28 consist each of two

portions

51, 52 and 53, 54 whereby the

separating places

55 and 56 are provided in proximity of the tapering ends of the conically shaped supporting-

type bushings

34 and 35. Threaded

pins

57 and 58 secured at the end of the shorter partial tubular members 52 and 54 disposed on the inside of the auxiliary electrode 29 serve as connecting means of the

tubular support portions

51, 52 and 53, 54. As a result thereof, temperature-conditioned changes in length of the

tubular support members

27 and 28 have no influence on the main capacity of the condenser conditioned by the

electrodes

25 and 26 with different coefficients of expansion between the

tubular support members

27, 28 and the insulating casing 21. Thus, a matching of the coefficients of expansion which is possible as such, of the

tubular support members

27 and 28 to the insulating casing 21 can therefore be dispensed with. The auxiliary electrode 29 is filled with an electro-negative gas, preferably sulfur hexafiuoride. The pressure of the insulating gas lies preferably again withinthe range of between about 1 and atm. Also. the space(lead-in space) located on the outside of the auxiliary electrode 29 and surrounded by the insulating casing 21 can be filled with an electro-negative gas, however, having a lower pressure, for example, about I ata. Also mixtures of electro-negative gases with other inert gases can be used both in the measurement condenser space as also in the lead-in space. A relatively high pressure on the inside of the measurement condenser space makes it possible that with a predetermined rated voltage, the electrode surfaces F can be increased and the electrode spacing A can be decreased, which brings about a higher capacity as is desirable for various measurements. On the other hand, with an unchanged electrode surface F and electrode spacing A, and with a higher insulating gas pressure in the auxiliary electrode 29, the condenser could be loaded with a higher voltage. An increase of the pressure P, on the inside of the auxiliary electrode 29 requires as a rule no increase of the pressure P of the space surrounded by the insulating casing 21 on the outside of the auxiliary electrode 29. Instead, a gas pressure P of preferably about 1 ata suffices even with high up to very high voltages in the lead-in space if also this pressure space is filled with an inert, preferably electro-negative gas.

The auxiliary electrode 29 need not necessarily be located completely on the inside of the insulating casing 21. For example, the insulating

casing portions

38 and 39 could also be secured at the support rings 36 and 37 whereby the diameter of the insulating

casing portions

38 and 39 would be considerably reduced. The

electrodes

25 and 26 may also have a shape different from that shown on the drawing, for example, the shape of a ball, of a mushroom or of an elipsoid. Instead of cone-disk-shaped supporting-type bushings, also disk-shaped or funnel-shaped supporting type bushings can be used.

A further significant advantage of the present invention resides in that both in the embodiment according to FIG. 1 as also in the embodiment according to FIG. 2, the gas pressure in the space constituted by the high voltage electrode and the low voltage electrode or/and the auxiliary electrode and the gas pressure in the space or spaces between these electrodes and the insulating casing housing can be so adjusted in each case that the product of gas volumes and gas pressure in both pressure spaces is so selected that the condenser can be shipped in the ready-to-use condition (with gas filling) taking into consideration the applicable safety rules and requirements. As a result thereof, condensers, preferably pressure gas condensers up to the highest occurring voltage planes can be shipped ready for use whereby considerable costs can be saved for the discharge and refilling of the insulating gas as well as for the preparation thereof at the location of use of the condenser.

While I have shown and described two embodiments in accordance with the present invention, it is understood that the same is not limited thereto but is susceptible of numerous changes and modifications as known to those skilled in the art, and I therefore do not wish to be limited to the details shown and described herein but intend to cover all such changes and modifications as are encompassed by the scope of the appended claims.

What I claim is:

l. A condenser, especially for measurement purposes, comprising an insulating casing housing means, electrode means including a high voltage electrode means and a low voltage electrode means arranged on the inside of said insulating casing housing means filled with a gas, characterized in that a first space is formed between the high voltage electrode means and the low voltage electrode means and is closed off insulating gas-tight, and in that the pressure of the gas in said first space which does not extend beyond the electrode means is higher than the pressure of the gas in a second gas-tight space formed between said high voltage electrode means and the insulating casing housing means.

2. A condenser, especially for measurement purposes, comprising an insulating casing housing means, electrode means including a high voltage electrode means, a low voltage electrode means and an auxiliary electrode means arranged on the inside of said insulating casing housing means filled with a gas, characterized in that a first space is delimited between said high voltage and low voltage electrode means, on the one hand, and said auxiliary electrode means, on the other and is closed off insulating gas-tight, and in that the pressure of the gas in said first space is higher than the pressure of the gas in a second gas-tight space formed between said auxiliary electrode means and said insulating casing housing means.

3. A condenser according to claim 1, characterized in that one supporting-type bushing means is provided as closure for the first space.

4. A condenser according to claim 3, characterized in that said bushing means is of a disk-shape.

5. A condenser according to claim 3, characterized in that said bushing means is of cone-disk shape.

6. A condenser according to claim 3, characterized in that said bushing means is funnel shaped.

7. A condenser according to claim 1, characterized in that the first space is filled with an inert gas.

8. A condenser according to claim 7, characterized in that said inert gas is nitrogen.

9. A condenser according to claim 1, characterized in that the first space is filled with an electro-negative gas in that said electro-negative gas is sulfur hexafluoride.

11. A condenser according to claim 1, characterized in that the high voltage and low voltage electrode means are constructed as electrodes disposed coaxial to one another.

10. A condenser according to claim 9, characterized 12. A condenser according to claim 1, characterized in that the gas pressure in the first space amounts to about 1 to about 10 atm.,.

13. A condenser according to claim 1, characterized in that the gas pressure in the first space and in the second space is so adjusted that the product of gas volumes and gas pressure in both pressure spaces is so selected that the condenser can be shipped in the readyto-use conditiontaking into consideration the applicable safety regulations.

14. A condenser according to claim 13, character ized in that the space is the first space enclosed by the high voltage electrode means and the low voltage electrode means.

15. A condenser according to claim 13, characterized in that at least one lead-in insulator is provided as closure for the first space.

16. A condenser according to claim 15, characterized in that the space is the first space enclosed by the high voltage electrode means and the low voltage electrode means.

17. A condenser, especially for measurement purposes, in which a high voltage electrode means and a low voltage electrode means are surrounded at least far-reachingly by an auxiliary electrode means which is at approximately half the high voltage potential, and in which the auxiliary electrode means is arranged at least partially on the inside of an insulating casing housing means filled with a gas, characterized in that the space between the high voltage electrode means and the low voltage electrode means, on the one hand, and between the low voltage electrode means and the auxiliary electrode means, on the other, is closed insulatingly gastight, and in that the pressure of the gas in the space constituted by the high voltage electrode means, the low voltage electrode means, and the auxiliary electrode means is higher than the pressure of the gas in the space between said electrode means and the insulating casing housing means.

18. A condenser according to claim 17, characterized in that the auxiliary electrode means is arranged completely on the inside of the insulating casing housing means filled with a gas.

19. A condenser according to claim 17, characterized in that the high voltage electrode means and the low voltage electrode means are constructed as electrodes disposed one above the other in the axial direction of the insulating casing housing means.

20. A condenser according to claim 17, characterized in that said electrodes have relatively large radii of curvature on the sides facing one another.

21. A condenser according to claim 17, characterized in that said electrodes are plate-shaped.

22. A condenser according to claim 17, characterized in that two supporting-type bushing means are provided as closure for the first space.

23. A condenser according to claim 22, characterized in that said bushing means is of disk-shape.

24. A condenser according to claim 22, characterized in that said bushing means is of cone-disk shape.

25. A condenser according to claim 22, characterized in that said bushing means is funnel shaped.

26.A condenser according to claim 17, characterized in that the first space is filled with an inert gas.

27. A condenser according to claim 26, characterized in that said inert gas is nitrogen.

28. A condenser according to claim 17, characterized in that the first space is filled with an electronegative gas.

29. A condenser according to claim 28, characterized in that said electro-negative gas is sulfer hexafluoride.

30. A condenser according to claim 17, characterized in that the gas pressure in the first space amounts to about 1 to about 10 ata.

31. A condenser according to claim 17, characterized in that the gas pressure in the first space and in the second space is so adjusted that the product of gas volumes and gas pressure in both pressure spaces is so se lected that the condenser can be shipped in the readyto-use condition taking into consideration the applicable safety regulations.

32. A condenser according to claim 31, characterized in that several lead-in insulators are provided as closure for the first space.

33. A condenser according to claim 31, character! ized in that the first space is enclosed by said auxiliary electrode means.

34. A condenser according to claim 32, characterized in that the first space is enclosed by said auxiliary electrode means.

Claims

1. A condenser, especially for measurement purposes, comprising an insulating casing housing means, electrode means including a high voltage electrode means and a low voltage electrode means arranged on the inside of said insulating casing housing means filled with a gas, characterized in that a first space is formed between the high voltage electrode means and the low voltage electrode means and is closed off insulating gas-tight, and in that the pressure of the gas in said first space which does not extend beyond the electrode means is higher than the pressure of the gas in a second gas-tight space formed between said high voltage electrode means and the insulating casing housing means.

9. A condenser according to claim 1, characterized in that the first space is filled with an electro-negative gas.

10. A condenser according to claim 9, characterized in that said electro-negative gas is sulfur hexafluoride.

12. A condenser according to claim 1, characterized in that the gas pressure in the first space amounts to about 1 to about 10 ata.

13. A condenser according to claim 1, characterized in that the gas pressure in the first space and in the second space is so adjusted that the product of gas volumes and gas pressure in both pressure spaces is so selected that the condenser can be shipped in the ready-to-use condition taking into consideration the applicable safety regulations.

14. A condenser according to claim 13, characterized in that the space is the first space enclosed by the high voltage electrode means and the low voltage electrode means.

17. A condenser, especially for measurement purposes, in which a high voltage electrode means and a low voltage electrode means are surrounded at least far-reachingly by an auxiliary electrode means which is at approximately half the high voltage potential, and in which the auxiliary electrode means is arranged at least partially on the inside of an insulating casing housing means filled with a gas, characterized in that the space between the high voltage electrode means and the low voltage electrode means, on the one hand, and between the low voltage electrode means and the auxiliary electrode means, on the other, is closed insulatingly gas-tight, and in that the pressure of the gas in the space constituted by the high voltage electrode means, the low voltage electrode means, and the auxiliary electrode means is higher than the pressure of the gas in the space between said electrode means and the insulating casing housing means.

26. A condenser according to claim 17, characterized in that the first space is filled with an inert gas.

28. A condenser according to claim 17, characterized in that the first space is filled with an electro-negative gas.

31. A condenser according to claim 17, characterized in that the gas pressure in the first space and in the second space is so adjusted that the product of gas volumes and gas pressure in both pressure spaces is so selected that the condenser can be shipped in the ready-to-use condition taking into consideration the applicable safety regulations.

33. A condenser according to claim 31, characterized in that the first space is enclosed by said auxiliary electrode means.