EP0085966A1 - Bushing for gas-insulated electrical equipment - Google Patents
Bushing for gas-insulated electrical equipment Download PDFInfo
- Publication number
- EP0085966A1 EP0085966A1 EP83101074A EP83101074A EP0085966A1 EP 0085966 A1 EP0085966 A1 EP 0085966A1 EP 83101074 A EP83101074 A EP 83101074A EP 83101074 A EP83101074 A EP 83101074A EP 0085966 A1 EP0085966 A1 EP 0085966A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- bushing
- main electrode
- end part
- main
- conductor
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B17/00—Insulators or insulating bodies characterised by their form
- H01B17/26—Lead-in insulators; Lead-through insulators
- H01B17/28—Capacitor type
Definitions
- This invention relates to a bushing for use in the lead-out portion of tank type electrical equipment such as transformers and gas-insulated electrical equipment.
- a bushing for use in the lead-out portion of tank type electrical equipment is a condenser bushing provided with a condenser core which has a sheet material, such as insulating paper, wound round a central conductor and in which a plurality of cylindrical electrodes conforming with a working voltage are arranged at suitable positions in the shape of concentric cylinders so that the electric field distributions inside and outside the bushing may become uniform.
- Figure 1 shows a prior-art condenser bushing.
- numeral 1 designates a central conductor, round which an insulating sheet member 2 such as insulating paper and syntheric resin film is wound.
- cylindrical main electrodes 3 are inserted at suitable positions in the shape of concentric cylinders so as to make uniform the distribution of electric fields inside and outside the bushing.
- a condenser core 4 is formed.
- Numeral 5 designates a fitting flange, numeral 6 a lower porcelain tube, and numeral 7 a lower terminal with which the lower end part of the central conductor 1 is held in threadable engagement.
- Numeral 8 designates an upper porcelain tube
- numeral 9 a head fixture which receives therein a compression spring (not shown) that serves to fix the upper porcelain tube 8, fitting flange 5 and lower procelain tube 6 by utilizing the central conductor 1 as a tensible strength member.
- Shown at numeral 10 is an upper terminal.
- a space surrounding the condenser core 4 is filled with an insulating medium 11.
- the condenser core 4 is so constructed that, in the course of winding the insulating sheet material 2, the main electrodes 3 made of an electrically conductive material and each being in the form of a sheet cut to a predetermined size are inserted and wound at predetermined suitable positions in the shape of concentric cylinders.
- each main electrode 3 is sandwiched between the layers of the insulating sheet material 2, and its end part as viewed in section is pointed.
- the distribution of electric fields when a voltage is applied to the bushing becomes such that equipotential surfaces 20 crowd on the electrode ends as illustrated in an enlarged sectional view of the end parts of the main electrodes 3 in Figure 2.
- the field intensity of the crowded parts needs to be designed to a value which the surrounding insulating material can endure.
- the electric field at the end of main electrode 3 can amount to several times of that at the middle part, so that the utilization rate is not very good. If the electric field crowding at the end part of the main electrode 3 can be moderated, the utilization rate of the insulating portion will be enhanced, and enhancement of the dielectric strength of condenser core 4 or reduction in the diameter thereof will become possible.
- the end part of the main electrode 3 is put into a shape that is bent in parallel with the equipotential surfaces.
- An alternative measure moderates the electric field crowding by disposing a rounded ring.
- these measures have been put into practical use in an epoxy-injection resin bushing, and it has been difficult to shape the end of the main electrode 3 in parallel with the equipotential surfaces in the bushing in which the condenser core 4 is formed of the insulating sheet material.
- the invention is intended to remedy these drawbacks and to eliminate the disadvantages described above. Accordingly, the invention provides a bushing which is easy fo fabricate wherein annular auxiliary electrodes which are electrically connected with corresponding main electrodes and the external shape of which have a curved surface, are arranged at the end parts of the main electrodes, whereby electric fields near the end parts of the main electrodes are moderated to enhance the dielectric strength of an insulating portion
- Figure 3 is a sectional view showing one embodiment according to the present invention
- Figure 4 is an enlarged sectional view of the end parts of electrodes.
- an insulating sheet member 2 is worked stepwise at the end parts of main electrodes 3 so as to expose the end parts of these main electrodes 3.
- annular auxiliary electrodes 12 formed of wire rods circular in section are fixed to each end part of each main electrode 3 and are electrically connected with the main electrode 3 by means of electrically-conductive supporters 13 which are arranged in a number of 3 - 4 at equal intervals in the peripheral direction of the main electrode 3.
- an insulating film 14 is disposed on the outer periphery of each auxiliary electrode 12 in such a way that a tape type insulating material is wound to a suitable thickness. Owing to such structure, electric fields at the end part of the main electrode 3 are moderated by the diameter of the auxiliary electrodes 12, and the dielectric strength of the bushing is sharply increased.
- the design of the electrode arrangement of the condenser bushing is determined by the field strength of that end part of the main electrode 3 at which the electric fields crowd. Therefore, the attachment of the auxiliary electrodes 12 as described above allows reduction in the insulation thickness of the middle part of the main electrode 3 of a condenser core 4. It is also possible to design the maximum field strength at a lower value in consideration of the combination between the dimensions of the main electrode 3 and the auxiliary electrodes 12. Another effect is that reliability is enhanced.
- the auxiliary electrode 12 is surrounded with the insulating film 14 obtained by winding the insulating tape material to a suitable thickness.
- the dielectric constant of the insulating film 14 is greater than that of an insulating medium 11 surrounding the film 14, the field strength of the surface electric fields of the auxiliary electrode 12 is lowered in inverse proportion to the former dielectric constant, so that the dielectric strength of the bushing is more enhanced conjointly with the dielectric strength of the insulating film 14.
- the insulating film 14 on the surface of the auxiliary electrode 12 may well be formed by a method in which the epoxy resin powder or the like, in a semi-hardened state, is applied on the surface by a swing coating process or the like and is then hardened. With this method, the insulating job for the auxiliary electrode 12 is facilitated, and an effect equivalent to that in the case of taping is attained.
- Figure 5 shows another embodiment of this invention applied to a bushing in which a conical spacer 15 is disposed in the lower part thereof.
- Figure 6 shows another embodiment of this invention.
- an auxiliary electrode 16 is so constructed that an elastic material such as electrically-conductive rubber and electrically-conductive synthetic resin is put into a sectional shape, such as an elliptical or oval shape, causing no electric field crowding and into a diameter somewhat smaller than that of the main electrode 3, the diameters being taken with respect to the axis of the bushing.
- the auxiliary electrode 16 is arranged at the end part of the main electrode 3 in a manner to abut on this main electrode 3.
- the auxiliary electrode 16 of the smaller diameter is attached to the condenser core 4 by utilizing its elasticity, whereby the attachment job is very easily performed.
- Figure 8 shows another embodiment of this invention wherein an auxiliary electrode 16 having elasticity is disposed on the main electrode 3 of a bushing which is equipped with a conical spacer 15 in the lower part thereof.
- the end part of a main electrode is exposed a predetermined length from an insulating member, and an annular electrode which is electrically connected with the main electrode and the external shape of which has a curved surface is arranged at the end part of the main electrode, whereby the electric fields crowding in the vicinity of the end part of the main electrode can be readily moderated, and the dielectric strength can be enhanced.
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Insulators (AREA)
Abstract
Description
- This invention relates to a bushing for use in the lead-out portion of tank type electrical equipment such as transformers and gas-insulated electrical equipment.
- In general, a bushing for use in the lead-out portion of tank type electrical equipment is a condenser bushing provided with a condenser core which has a sheet material, such as insulating paper, wound round a central conductor and in which a plurality of cylindrical electrodes conforming with a working voltage are arranged at suitable positions in the shape of concentric cylinders so that the electric field distributions inside and outside the bushing may become uniform.
- Figure 1 shows a prior-art condenser bushing. Referring to the figure, numeral 1 designates a central conductor, round which an
insulating sheet member 2 such as insulating paper and syntheric resin film is wound. In themember 2, cylindricalmain electrodes 3 are inserted at suitable positions in the shape of concentric cylinders so as to make uniform the distribution of electric fields inside and outside the bushing. Thus, acondenser core 4 is formed. Numeral 5 designates a fitting flange, numeral 6 a lower porcelain tube, and numeral 7 a lower terminal with which the lower end part of the central conductor 1 is held in threadable engagement. Numeral 8 designates an upper porcelain tube, and numeral 9 a head fixture which receives therein a compression spring (not shown) that serves to fix theupper porcelain tube 8, fittingflange 5 and lower procelain tube 6 by utilizing the central conductor 1 as a tensible strength member. Shown atnumeral 10 is an upper terminal. A space surrounding thecondenser core 4 is filled with aninsulating medium 11. - The
condenser core 4 is so constructed that, in the course of winding theinsulating sheet material 2, themain electrodes 3 made of an electrically conductive material and each being in the form of a sheet cut to a predetermined size are inserted and wound at predetermined suitable positions in the shape of concentric cylinders. Thus, eachmain electrode 3 is sandwiched between the layers of theinsulating sheet material 2, and its end part as viewed in section is pointed. For this reason, the distribution of electric fields when a voltage is applied to the bushing becomes such thatequipotential surfaces 20 crowd on the electrode ends as illustrated in an enlarged sectional view of the end parts of themain electrodes 3 in Figure 2. The field intensity of the crowded parts needs to be designed to a value which the surrounding insulating material can endure. The electric field at the end ofmain electrode 3 can amount to several times of that at the middle part, so that the utilization rate is not very good. If the electric field crowding at the end part of themain electrode 3 can be moderated, the utilization rate of the insulating portion will be enhanced, and enhancement of the dielectric strength ofcondenser core 4 or reduction in the diameter thereof will become possible. - In order to moderate the electric field crowding at the end part of the
main electrode 3, the end part of themain electrode 3 is put into a shape that is bent in parallel with the equipotential surfaces. An alternative measure moderates the electric field crowding by disposing a rounded ring. However, these measures have been put into practical use in an epoxy-injection resin bushing, and it has been difficult to shape the end of themain electrode 3 in parallel with the equipotential surfaces in the bushing in which thecondenser core 4 is formed of the insulating sheet material. - The invention is intended to remedy these drawbacks and to eliminate the disadvantages described above. Accordingly, the invention provides a bushing which is easy fo fabricate wherein annular auxiliary electrodes which are electrically connected with corresponding main electrodes and the external shape of which have a curved surface, are arranged at the end parts of the main electrodes, whereby electric fields near the end parts of the main electrodes are moderated to enhance the dielectric strength of an insulating portion
- Further features and advantages of the invention will be explained in detail below with reference to the drawings illustrating various embodiments, wherein
- Figure 1 is a sectional view of a prior-art bushing;
- Fig. 2 is an explanatory view showing electric field distributions at the end parts of main electrodes in Figure 1;
- Figure 3 is a sectional view of an embodiment of this invention;
- Figure 4 is an enlarged sectional view of the vicinities of the end parts of main electrodes in Figure 3;
- Figure 5 is a sectional view of another embodiment of this invention;
- Figure 6 is a sectional view of still another embodiment of this invention;
- Figure 7 is an enlarged sectional view of the vicinities of the end parts of main electrodes in Figure 6; and
- Figure 8 is a sectional view of yet another embodiment of this invention.
- In the drawings, the same symbols indicate the same or corresponding parts.
- Now, an embodiment of this invention will be concretely described with reference to Figures 3 and 4. Figure 3 is a sectional view showing one embodiment according to the present invention, while Figure 4 is an enlarged sectional view of the end parts of electrodes. In the embodiment of this invention, as illustrated in the figures, an
insulating sheet member 2 is worked stepwise at the end parts ofmain electrodes 3 so as to expose the end parts of thesemain electrodes 3. Further, annularauxiliary electrodes 12 formed of wire rods circular in section are fixed to each end part of eachmain electrode 3 and are electrically connected with themain electrode 3 by means of electrically-conductive supporters 13 which are arranged in a number of 3 - 4 at equal intervals in the peripheral direction of themain electrode 3. In addition, aninsulating film 14 is disposed on the outer periphery of eachauxiliary electrode 12 in such a way that a tape type insulating material is wound to a suitable thickness. Owing to such structure, electric fields at the end part of themain electrode 3 are moderated by the diameter of theauxiliary electrodes 12, and the dielectric strength of the bushing is sharply increased. - The design of the electrode arrangement of the condenser bushing is determined by the field strength of that end part of the
main electrode 3 at which the electric fields crowd. Therefore, the attachment of theauxiliary electrodes 12 as described above allows reduction in the insulation thickness of the middle part of themain electrode 3 of acondenser core 4. It is also possible to design the maximum field strength at a lower value in consideration of the combination between the dimensions of themain electrode 3 and theauxiliary electrodes 12. Another effect is that reliability is enhanced. - The
auxiliary electrode 12 is surrounded with theinsulating film 14 obtained by winding the insulating tape material to a suitable thickness. In this regard, since the dielectric constant of theinsulating film 14 is greater than that of aninsulating medium 11 surrounding thefilm 14, the field strength of the surface electric fields of theauxiliary electrode 12 is lowered in inverse proportion to the former dielectric constant, so that the dielectric strength of the bushing is more enhanced conjointly with the dielectric strength of theinsulating film 14. - The
insulating film 14 on the surface of theauxiliary electrode 12 may well be formed by a method in which the epoxy resin powder or the like, in a semi-hardened state, is applied on the surface by a swing coating process or the like and is then hardened. With this method, the insulating job for theauxiliary electrode 12 is facilitated, and an effect equivalent to that in the case of taping is attained. - Figure 5 shows another embodiment of this invention applied to a bushing in which a
conical spacer 15 is disposed in the lower part thereof. - Figure 6 shows another embodiment of this invention. In the embodiment shown in Figure 6, an
auxiliary electrode 16 is so constructed that an elastic material such as electrically-conductive rubber and electrically-conductive synthetic resin is put into a sectional shape, such as an elliptical or oval shape, causing no electric field crowding and into a diameter somewhat smaller than that of themain electrode 3, the diameters being taken with respect to the axis of the bushing. As shown in Figure 7, theauxiliary electrode 16 is arranged at the end part of themain electrode 3 in a manner to abut on thismain electrode 3. Theauxiliary electrode 16 of the smaller diameter is attached to thecondenser core 4 by utilizing its elasticity, whereby the attachment job is very easily performed. - Figure 8 shows another embodiment of this invention wherein an
auxiliary electrode 16 having elasticity is disposed on themain electrode 3 of a bushing which is equipped with aconical spacer 15 in the lower part thereof. - As set forth above, according to this invention, the end part of a main electrode is exposed a predetermined length from an insulating member, and an annular electrode which is electrically connected with the main electrode and the external shape of which has a curved surface is arranged at the end part of the main electrode, whereby the electric fields crowding in the vicinity of the end part of the main electrode can be readily moderated, and the dielectric strength can be enhanced.
Claims (5)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP18525/82 | 1982-02-05 | ||
JP57018525A JPS58135518A (en) | 1982-02-05 | 1982-02-05 | Bushing |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0085966A1 true EP0085966A1 (en) | 1983-08-17 |
EP0085966B1 EP0085966B1 (en) | 1986-10-08 |
Family
ID=11974043
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP83101074A Expired EP0085966B1 (en) | 1982-02-05 | 1983-02-04 | Bushing for gas-insulated electrical equipment |
Country Status (5)
Country | Link |
---|---|
EP (1) | EP0085966B1 (en) |
JP (1) | JPS58135518A (en) |
KR (1) | KR880000078B1 (en) |
CA (1) | CA1210466A (en) |
DE (1) | DE3366770D1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3846182A1 (en) * | 2019-12-30 | 2021-07-07 | ABB Power Grids Switzerland AG | Condenser bushing |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100357404B1 (en) * | 2000-02-22 | 2002-11-07 | 김영일 | shoehorn-possessed shoes |
KR200483720Y1 (en) | 2016-01-05 | 2017-06-15 | 정운용 | Shoe Inserts Including Shoe Lift |
Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB612061A (en) * | 1945-11-16 | 1948-11-08 | Giuseppe Scarpa | Insulators for high tension transformers |
DE1800667A1 (en) * | 1967-10-18 | 1969-05-08 | Elek Scher App Sprecher & Schu | Outdoor implementation with pressurized gas filling for maximum voltage |
US3538241A (en) * | 1967-10-18 | 1970-11-03 | Elektrisitetsforsyning | Arrangement for capacitive control of the voltage distribution on electrical insulators |
US3849590A (en) * | 1972-11-01 | 1974-11-19 | Hitachi Ltd | Gas filled electrical bushing with concentric intermediate electrodes |
AT345368B (en) * | 1975-07-03 | 1978-09-11 | Haefely & Cie Ag Emil | OUTDOOR HIGH VOLTAGE FEEDTHROUGH FOR SF6 COMPRESSED GAS ISOLATED ELECTRICAL SYSTEMS |
US4159401A (en) * | 1977-11-01 | 1979-06-26 | Tokyo Shibaura Kenki K.K. | Gas filled bushings with potential shields |
WO1980000762A1 (en) * | 1978-10-10 | 1980-04-17 | Bbc Brown Boveri & Cie | Compact sulfur hexafluoride-filled insulator bushing with reduced gas-filled volume |
EP0044179A1 (en) * | 1980-07-03 | 1982-01-20 | Ngk Insulators, Ltd. | Gaseous insulating bushing |
-
1982
- 1982-02-05 JP JP57018525A patent/JPS58135518A/en active Pending
- 1982-10-20 KR KR8204719A patent/KR880000078B1/en active
-
1983
- 1983-02-03 CA CA000420833A patent/CA1210466A/en not_active Expired
- 1983-02-04 DE DE8383101074T patent/DE3366770D1/en not_active Expired
- 1983-02-04 EP EP83101074A patent/EP0085966B1/en not_active Expired
Patent Citations (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB612061A (en) * | 1945-11-16 | 1948-11-08 | Giuseppe Scarpa | Insulators for high tension transformers |
DE1800667A1 (en) * | 1967-10-18 | 1969-05-08 | Elek Scher App Sprecher & Schu | Outdoor implementation with pressurized gas filling for maximum voltage |
US3538241A (en) * | 1967-10-18 | 1970-11-03 | Elektrisitetsforsyning | Arrangement for capacitive control of the voltage distribution on electrical insulators |
US3849590A (en) * | 1972-11-01 | 1974-11-19 | Hitachi Ltd | Gas filled electrical bushing with concentric intermediate electrodes |
AT345368B (en) * | 1975-07-03 | 1978-09-11 | Haefely & Cie Ag Emil | OUTDOOR HIGH VOLTAGE FEEDTHROUGH FOR SF6 COMPRESSED GAS ISOLATED ELECTRICAL SYSTEMS |
US4159401A (en) * | 1977-11-01 | 1979-06-26 | Tokyo Shibaura Kenki K.K. | Gas filled bushings with potential shields |
WO1980000762A1 (en) * | 1978-10-10 | 1980-04-17 | Bbc Brown Boveri & Cie | Compact sulfur hexafluoride-filled insulator bushing with reduced gas-filled volume |
EP0044179A1 (en) * | 1980-07-03 | 1982-01-20 | Ngk Insulators, Ltd. | Gaseous insulating bushing |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP3846182A1 (en) * | 2019-12-30 | 2021-07-07 | ABB Power Grids Switzerland AG | Condenser bushing |
WO2021136730A1 (en) | 2019-12-30 | 2021-07-08 | Abb Power Grids Switzerland Ag | Condenser bushing |
Also Published As
Publication number | Publication date |
---|---|
JPS58135518A (en) | 1983-08-12 |
CA1210466A (en) | 1986-08-26 |
DE3366770D1 (en) | 1986-11-13 |
KR880000078B1 (en) | 1988-02-22 |
KR840002149A (en) | 1984-06-11 |
EP0085966B1 (en) | 1986-10-08 |
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