GB2173041A - High tension capacitor - Google Patents
High tension capacitor Download PDFInfo
- Publication number
- GB2173041A GB2173041A GB08526979A GB8526979A GB2173041A GB 2173041 A GB2173041 A GB 2173041A GB 08526979 A GB08526979 A GB 08526979A GB 8526979 A GB8526979 A GB 8526979A GB 2173041 A GB2173041 A GB 2173041A
- Authority
- GB
- United Kingdom
- Prior art keywords
- capacitor
- high tension
- insulating material
- dielectric layers
- solid
- 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
Links
- 239000003990 capacitor Substances 0.000 title claims abstract description 106
- 229920003002 synthetic resin Polymers 0.000 claims abstract description 16
- 239000000057 synthetic resin Substances 0.000 claims abstract description 16
- 239000007787 solid Substances 0.000 claims abstract 15
- 238000001816 cooling Methods 0.000 claims abstract 8
- 239000011810 insulating material Substances 0.000 claims description 18
- 239000007788 liquid Substances 0.000 claims description 11
- 239000013013 elastic material Substances 0.000 claims description 4
- 229920005989 resin Polymers 0.000 claims description 4
- 239000011347 resin Substances 0.000 claims description 4
- 238000000034 method Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 claims description 2
- 238000004519 manufacturing process Methods 0.000 claims 5
- 239000000463 material Substances 0.000 claims 4
- 239000011148 porous material Substances 0.000 claims 4
- 230000001419 dependent effect Effects 0.000 claims 2
- 239000003989 dielectric material Substances 0.000 abstract description 2
- 239000012774 insulation material Substances 0.000 abstract 1
- 239000011159 matrix material Substances 0.000 abstract 1
- 238000009413 insulation Methods 0.000 description 7
- 238000004880 explosion Methods 0.000 description 4
- 239000011521 glass Substances 0.000 description 4
- 230000002159 abnormal effect Effects 0.000 description 3
- 239000004744 fabric Substances 0.000 description 3
- 238000005470 impregnation Methods 0.000 description 3
- 229910018503 SF6 Inorganic materials 0.000 description 2
- 229910000831 Steel Inorganic materials 0.000 description 2
- 239000007799 cork Substances 0.000 description 2
- 238000005336 cracking Methods 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000005096 rolling process Methods 0.000 description 2
- 239000010959 steel Substances 0.000 description 2
- 229920013646 Hycar Polymers 0.000 description 1
- 239000004743 Polypropylene Substances 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 239000003822 epoxy resin Substances 0.000 description 1
- 230000017525 heat dissipation Effects 0.000 description 1
- 239000012212 insulator Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 230000002093 peripheral effect Effects 0.000 description 1
- 239000002985 plastic film Substances 0.000 description 1
- 229920006255 plastic film Polymers 0.000 description 1
- 229920000647 polyepoxide Polymers 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- -1 polypropylene Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- SFZCNBIFKDRMGX-UHFFFAOYSA-N sulfur hexafluoride Chemical compound FS(F)(F)(F)(F)F SFZCNBIFKDRMGX-UHFFFAOYSA-N 0.000 description 1
- 229960000909 sulfur hexafluoride Drugs 0.000 description 1
- 238000001291 vacuum drying Methods 0.000 description 1
- 238000009423 ventilation Methods 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/32—Wound capacitors
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G2/00—Details of capacitors not covered by a single one of groups H01G4/00-H01G11/00
- H01G2/08—Cooling arrangements; Heating arrangements; Ventilating arrangements
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G2/00—Details of capacitors not covered by a single one of groups H01G4/00-H01G11/00
- H01G2/12—Protection against corrosion
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/002—Details
- H01G4/018—Dielectrics
- H01G4/20—Dielectrics using combinations of dielectrics from more than one of groups H01G4/02 - H01G4/06
- H01G4/22—Dielectrics using combinations of dielectrics from more than one of groups H01G4/02 - H01G4/06 impregnated
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
- H01G4/00—Fixed capacitors; Processes of their manufacture
- H01G4/38—Multiple capacitors, i.e. structural combinations of fixed capacitors
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Manufacturing & Machinery (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
Abstract
In a high-tension capacitor comprising a plurality of elements (A) each of which is a rolled laminate of alternate electrodes and dielectrics, the porous dielectric layers are impregnated with synthetic resin. The capacitor elements (A) are insulated by impregnating a surrounding porous insulation material (B) with the same synthetic resin. The solid insulating matrix thus formed may be provided with a plurality of air ducts (10) for cooling. <IMAGE>
Description
SPECIFICATION
High tension capacitor
The present invention relates to a high-tension capacitor.
Conventional high-tension capacitors have so far been manufactured in the manner described below with reference to Fig. 1. Firstly, capacitor elements A are formed by overlapping alternately electrode layers and dielectric layers made from insulating paper or plastic film and rolling the laminated sheet. A plurality of such capacitor elements are housed in a steel casing 4 and are connected to one another and to high-tension bushings 7 through lead wires 6. Finally they are vacuumimpregnated with a high-tension insulating oil 8 and azure sealed.
In such high-tension capacitors, the dielectric layers must have a high degree of insulation property because it greatly effects the life of capacitor. In conventional high-tension capacitors, the dielectric layers are impregnated with a high-tension insulating oil to form insulation layers between the electrode layers. However, even with such measure, they were not completely free from insulation breakdown or abnormal temperature rise.
Should such a trouble occur, the temperature of the capacitor itself rises to an abnormal level and the capacitor elements and the insulating oil expand by heat. This can induce breakage or explosion of the steel casing and environmental pollution with splashed insulating oil. Further, fire can be induced since an insulating oil is a combustible liquid with a flashing point between 130 and 200"C.
Should a fire break out at a crowded place such as high-rise buildings, underground streets, hospitals, and schools, life of a great nuniber of people may be lost. Therefore, non-combustible and explosion-proof properties are required for any electrical equipments.
Oilless arrangement has been completed for all electrical equipments except for high-tension capacitors.
In view of the above, the applicant of the present invention proposed in Japanese Patent
Application No. 59-3993 a high-tension capacitor comprising capacitor elements having dielectrics disposed between the electrode layers and impregnated with synthetic resin, the capacitor elements being housed in a sealed container molded of synthetic resin, and sulfur hexafluoride gas (SF6) being filled into the container as an insulator. Even with such a capacitor, gas pressure might increase and the explosion of the container be induced, if the protective device should fail to operate so that the capacitor itself heats up to an abnormal level.
It is an object of the present invention to provide a high-tension capacitor which can be manufactured easily and is free from hazard of fire and explosion.
It is another object of the present invention to provide a high-tension capacitor which provides good heat dissipation.
In accordance with the present invention, no gas or liquid is used as insulating medium.
Instead, not only the dielectric layers in the capacitor elements are impregnated with synthetic resin to increase the insulation strength, but also the capacitor elements are insulated with synthetic resin by having their outer periphery molded of synthetic resin. This provides high-tension capacitors having no fear of fire or explosion due to insulation failure.
Further, in accordance with the present invention, relaxation layers made of an elastic material are provided at regular radial spacings in each capacitor element to prevent cracking of the dielectric layers and the peeling at the boundary between the electrode layers and the dielectric layers.
Still further, in accordance with the present invention, a plurality of air ducts are formed in the insulating layer around the capacitor elements to dissipate heat from each of the capacitor elements and prevent the temperature of the capacitor elements from rising abnormally.
According to the present invention, without using any liquid or gaseous insulating material, high-quality, explosion-proof, non-inflammable high-tension capacitors are provided.
Other objects and features of the present invention will become apparent from the following description taken with references to the accompanying drawings, in which:
Fig. 1 is a sectional view of a conventional high-tension capacitor;
Fig. 2 is a sectional view of a high-tension capacitor embodying the present invention;
Fig. 3 is a horizontal sectional view taken along the line X-X of Fig. 2;
Fig. 4 is a view similar to Fig. 3 of another embodiment;
Fig. 5 to Fig. 8 are plan views of examples of capacitor elements;
Fig. 9 is a sectional view of the dielectric layer;
Fig. 10 is a sectional view of the capacitor element not rolled.
Fig. 11 is a sectional view of a further embodiment similar to the embodiment of Fig. 3 but having a plurality of air ducts; and
Fig. 12 is a sectional view of a still further embodiment similar to the embodiment of Fig.
4 but having a plurality of air ducts.
Referring now to the drawings, Fig. 9 shows a dielectric layer a which comprises an easily impregnated and porous insulating material 2 such as non-woven or woven cloth attached to both sides of a film 1 of synthetic resin such as polyester or polypropylene. The capacitor elements A shown in Figs. 5 and 6 are made by overlapping the dielectric layers a and the electrode layers b alternately as shown in Fig. 10 and rolling the laminate.
A plurality of the capacitor elements A are arranged along wiring 6' as shown in Fig. 2.
The gap C and the periphery B are filled with an easily impregnated electrical insulating material such as glass tape, glass cloth, glass mat, glass chop, non-woven cloth or paper to a predetermined peripheral shape. The assembly of capacitor elements is then put into a- metal die as shown in Fig. 2 and is subjected to heat drying and vacuum drying and then to impregnation with a synthetic resin such as epoxy resin under high vacuurn. The porous part of the dielectric layers a and the insulating material are impregnated with the same resin at one time. For better impregnation, the temperature of synthetic resin should be kept at 1009C and its viscosity be lowered to about 20 cp, and high vacuum be kept for over three -6hours.This ensures that the dielectric layers a have good insulation. Further, the outer covering is molded of synthetic resin together with the capacitor elements.
Although in the preferred embodiment the impregnation of the capacitor elements and the formation of the insulating layer around the capacitor elements are performed simultaneously, the capacitor elements may be im pregnated and mounted in a metal mold, and an insulating layer may be formed around the capacitor elements. This method has an advantage that different synthetic resins can be used, namely, resin having a good impregnability and low viscosity for the capacitor elements, and a resin having a good strength and high viscosity for the insulating layer.
In forming a capacitor element A by overlapping the electrode layers b and the dielectric layers a, as shown in Figs. 7 and 8, relaxation layers 9 made of an elastic material such as Hycar cork, cork sponge and press board should be interposed at regular intervals t.
The layers between the relaxation layers 9 are electrically connected in parallel with each other. The relaxation layers absorb the shrinking force upon hardening of the synthetic resin, preventing the cracking of the dielectric layers and the peeling at the boundary between the electrode layer and the dielectric layer and thus precluding the decrease of the insulation strength. The distance t between the relaxation layers 9 may be determined suitably. If the thickness T of the capacitor element is e.g. 50 mm, the distance t should be 10-20 mm for greater workability, though the smaller, the better.
Referring to Fig. 11, this embodiment is the same as that of Fig. 3 except-that a plurality of square or rectangular air ducts 10 are formed in the insulating layer around the capacitor elements to extend axially. Similarly, the embodiment of Fig. 12 is the same as that of
Fig. 4 except that a plurality of air ducts 10' of an elongate cross-section are formed in the insulating layer to extend axially. The air ducts may be of any desired section.
The air ducts 10 or 10' may be formed at the same time as the molding of the insulating layer. As shown in Fig. 11, the air ducts may be formed so that part of the outer periphery of the capacitor elements will be exposed to the air duct to cause the capacitor element to be directly air-cooled. Air may be passed through the air duct by natural or forced ventilation. The air ducts air-cool the capacitor elements, thus prolonging the life of the capacitor elements.
The present invention is particularly but not exclusively applicable to the design and construction of high tension power capacitors rated at 5 to 100kVA. Typical rated working voltages are of the order of 1 to 10kV, e.-g.
3.3kV or 6.6kV.
Claims (18)
1. A capacitor having a plurality of capacitor elements each comprising electrode layers and dielectric layers overlapped alternately and rolled, said capacitor elements being covered with an electrical insulating material impregnated with synethic resin and said dielectric layers being impregnated with synthetic resin.
2. A capacitor as claimed in claim 1, wherein said cpacitor elements each have a plurality of relaxation layers made of an elastic material and arranged at a regular radial distance therebetween.
3. A capacitor comprising a plurality of capacitor units spaced apart and housed in a common housing, each capacitor unit comprising a rolled laminate of alternate electrode and dielectric layers, wherein the spaces between said capacitor units within said housing are substantially filled with solid insulating material.
4. A capacitor as claimed in claim 3, wherein said dielectric layers are composed of porous material impregnated with solid insulating material.
5. A capacitor as claimed in claim 4 wherein the solid insulating material which impregnates said porous material is of the same composition as the solid insulating material within said spaces.
6. A capacitor as claimed in any preceding claim, incorporating at least one cooling duct.
7. A capacitor as claimed in claim 6, wherein at least one capacitor element is exposed within said cooling duct.
8. A capacitor as claimed in claim 6 or claim 8, wherein said duct is substantially parallel to the axis of a said capacitor element.
9. A capacitor as claimed in claim 8, incoporating a plurality of parallel cooling ducts.
10. A capacitor as claimed in any of claims 6 to 9 as dependent on claim 3, wherein said duct is formed within said solid insulating material.
11. A capacitor as claimed in any of claims 6 to 10 in combination with means for forcing air through said cooling duct.
12. A capacitor as claimed in any preceding claim which is a high tension power capacitor rated at between 5 and 100kVA.
13. A method of making a capacitor of the type comprising a plurality of capacitor units located within a common housing, each capacitor unit being in the form of a rolled laminate of alternate electrode layers and porous spacing material, said method including the steps of impregnating said porous spacing material with a liquid, causing said liquid to solidify to form a solid dielectric, introducing a liquid into said housing around said capacitor units and causing the introduced liquid to solidify to a solid body of insulating material.
14. A capacitor substantially as described hereinabove with reference to Figures 2 to 10 of the accompanying drawings.
15. A capacitor substantially as described hereinabove with reference to Figure 11 or
Figure 12 of the accompanying drawings.
16. A high tension capacitor according to any one of claims 1 to 11, 14 or 15.
17. A method of making a capacitor substantially as described hereinabove.
18. A method of making a high tension capacitor according to claim 13 or 17.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60059228A JPS61216417A (en) | 1985-03-22 | 1985-03-22 | High voltage capacitor |
| JP60215919A JPS6276513A (en) | 1985-09-27 | 1985-09-27 | High voltage capacitor |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8526979D0 GB8526979D0 (en) | 1985-12-04 |
| GB2173041A true GB2173041A (en) | 1986-10-01 |
| GB2173041B GB2173041B (en) | 1989-04-12 |
Family
ID=26400282
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8526979A Expired GB2173041B (en) | 1985-03-22 | 1985-11-01 | High-tension capacitor |
Country Status (4)
| Country | Link |
|---|---|
| KR (1) | KR890005359B1 (en) |
| DE (1) | DE3539691A1 (en) |
| FR (1) | FR2579365B1 (en) |
| GB (1) | GB2173041B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2622345A1 (en) * | 1987-10-23 | 1989-04-28 | Risho Kogyo Kk | MOLDED CAPACITOR |
| DE19814700A1 (en) * | 1998-04-01 | 1999-10-07 | Vishay Electronic Gmbh | Power capacitor |
| WO2006048431A1 (en) * | 2004-11-05 | 2006-05-11 | Siemens Aktiengesellschaft | Energy store composed of double-layer capacitors, use of such an energy store in railway vehicles, and associated railway vehicle |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6276513A (en) * | 1985-09-27 | 1987-04-08 | 利昌工業株式会社 | High voltage capacitor |
| DE102010012949A1 (en) * | 2010-03-26 | 2011-09-29 | Siemens Aktiengesellschaft | Capacitor module, has control unit for controlling temperature of cells, where control unit includes phase change material, which is in contact with cells to absorb heat delivered by cells and located on surface of cooling body |
| DE102012201753A1 (en) * | 2012-02-07 | 2013-08-08 | Zf Friedrichshafen Ag | Capacitor used in power electronic circuit of hybrid vehicle, has case that is arranged for fastening capacitor between coils, such that longitudinal extension axis of case and winding axis of coils are aligned parallel to each other |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2007432A (en) * | 1977-11-08 | 1979-05-16 | Fribourg Condensateurs | High Voltage Condenser |
| GB1567519A (en) * | 1976-06-02 | 1980-05-14 | Licentia Gmbh | Electrical capacitor |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US2107423A (en) * | 1933-03-09 | 1938-02-08 | Products Prot Corp | Electric condenser construction |
| US3363156A (en) * | 1966-10-19 | 1968-01-09 | Gen Electric | Capacitor with a polyolefin dielectric |
| DE2519559C3 (en) * | 1975-05-02 | 1981-10-29 | Messerschmitt-Bölkow-Blohm GmbH, 8000 München | Paint structure for metallic or non-metallic substrates, in particular for the outer skins of aircraft |
| DE2641182C2 (en) * | 1976-09-13 | 1982-10-21 | Siemens AG, 1000 Berlin und 8000 München | Regenerative, electrical winding capacitor divided into several partial capacities and the use of two such capacitors when building a voltage multiplier cascade |
-
1985
- 1985-11-01 GB GB8526979A patent/GB2173041B/en not_active Expired
- 1985-11-08 DE DE19853539691 patent/DE3539691A1/en active Granted
- 1985-11-13 FR FR8516739A patent/FR2579365B1/en not_active Expired - Lifetime
-
1986
- 1986-03-18 KR KR1019860001973A patent/KR890005359B1/en not_active IP Right Cessation
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1567519A (en) * | 1976-06-02 | 1980-05-14 | Licentia Gmbh | Electrical capacitor |
| GB2007432A (en) * | 1977-11-08 | 1979-05-16 | Fribourg Condensateurs | High Voltage Condenser |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2622345A1 (en) * | 1987-10-23 | 1989-04-28 | Risho Kogyo Kk | MOLDED CAPACITOR |
| GB2211663A (en) * | 1987-10-23 | 1989-07-05 | Risho Kogyo Kk | Common casing for multiple capacitor |
| BE1002865A3 (en) * | 1987-10-23 | 1991-07-09 | Risho Kogyo Kk | COATED CAPACITOR. |
| GB2211663B (en) * | 1987-10-23 | 1992-03-04 | Risho Kogyo Kk | Molded capacitor |
| DE19814700A1 (en) * | 1998-04-01 | 1999-10-07 | Vishay Electronic Gmbh | Power capacitor |
| US6212058B1 (en) | 1998-04-01 | 2001-04-03 | Vishay Electronic Gmbh | Power capacitor |
| WO2006048431A1 (en) * | 2004-11-05 | 2006-05-11 | Siemens Aktiengesellschaft | Energy store composed of double-layer capacitors, use of such an energy store in railway vehicles, and associated railway vehicle |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2173041B (en) | 1989-04-12 |
| FR2579365A1 (en) | 1986-09-26 |
| FR2579365B1 (en) | 1993-09-24 |
| DE3539691C2 (en) | 1991-04-11 |
| KR890005359B1 (en) | 1989-12-23 |
| DE3539691A1 (en) | 1986-10-02 |
| GB8526979D0 (en) | 1985-12-04 |
| KR870003524A (en) | 1987-04-18 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4654751A (en) | High-tension capacitor | |
| RU2473997C2 (en) | High-voltage bushing insulator for outdoor installation | |
| KR100579257B1 (en) | Outdoor dry transformer having shielding means comprising high-functional fiber materials | |
| US4670814A (en) | High-tension capacitor | |
| US3244799A (en) | Electrical cable with cable core wrap | |
| US4500745A (en) | Hybrid electrical insulator bushing | |
| DE69004484T2 (en) | Dense coating based on a fibrous wrap and composite lightning rod as an application. | |
| CN1129995C (en) | Conductor winding arrangement for heavy electric machine | |
| EP3576108B1 (en) | Capacitive graded high voltage bushing | |
| GB2173041A (en) | High tension capacitor | |
| US3801791A (en) | Ozone generator | |
| US3585278A (en) | Electrical bushings having insulating means including a cured elastomer containing mineral oil | |
| CA1178674A (en) | Tape-wound insulation sheath or jacket for an electrical conductor and method of making same | |
| US3440587A (en) | Electrical induction apparatus construction | |
| US3594489A (en) | Extra high voltage cables | |
| US4031311A (en) | Electrical bushing | |
| JP4386382B2 (en) | Dry metallized film capacitor | |
| US1948506A (en) | By-pass condenser | |
| US4472702A (en) | Wedging device and transformer including same | |
| US11469014B2 (en) | Electrical device having an insertable high-voltage bushing | |
| KR100644732B1 (en) | High-voltage power supply unit | |
| EP3544032A1 (en) | Electrical device with gel composite insulation | |
| EP0610589B1 (en) | Electrical capacitor with overpressure cut-off means | |
| JPH08115625A (en) | Lighting arrestor | |
| EP4345854A1 (en) | Transformer coil |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PE20 | Patent expired after termination of 20 years |
Effective date: 20051031 |