CA1135495A - Capacitor having dielectric fluid with high di-isopropyl biphenyl content - Google Patents
Capacitor having dielectric fluid with high di-isopropyl biphenyl contentInfo
- Publication number
- CA1135495A CA1135495A CA000333948A CA333948A CA1135495A CA 1135495 A CA1135495 A CA 1135495A CA 000333948 A CA000333948 A CA 000333948A CA 333948 A CA333948 A CA 333948A CA 1135495 A CA1135495 A CA 1135495A
- Authority
- CA
- Canada
- Prior art keywords
- isopropyl biphenyl
- weight
- biphenyl
- isopropyl
- mono
- 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.)
- Expired
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
- H01B3/00—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties
- H01B3/18—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances
- H01B3/20—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils
- H01B3/22—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of organic substances liquids, e.g. oils hydrocarbons
-
- 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
- H01G4/221—Dielectrics using combinations of dielectrics from more than one of groups H01G4/02 - H01G4/06 impregnated characterised by the composition of the impregnant
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2203/00—Organic non-macromolecular hydrocarbon compounds and hydrocarbon fractions as ingredients in lubricant compositions
- C10M2203/06—Well-defined aromatic compounds
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
- C10M2207/02—Hydroxy compounds
- C10M2207/023—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings
- C10M2207/026—Hydroxy compounds having hydroxy groups bound to carbon atoms of six-membered aromatic rings with tertiary alkyl groups
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2207/00—Organic non-macromolecular hydrocarbon compounds containing hydrogen, carbon and oxygen as ingredients in lubricant compositions
- C10M2207/08—Aldehydes; Ketones
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
- C10M2209/02—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10M—LUBRICATING COMPOSITIONS; USE OF CHEMICAL SUBSTANCES EITHER ALONE OR AS LUBRICATING INGREDIENTS IN A LUBRICATING COMPOSITION
- C10M2209/00—Organic macromolecular compounds containing oxygen as ingredients in lubricant compositions
- C10M2209/10—Macromolecular compoundss obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2040/00—Specified use or application for which the lubricating composition is intended
- C10N2040/14—Electric or magnetic purposes
- C10N2040/16—Dielectric; Insulating oil or insulators
-
- C—CHEMISTRY; METALLURGY
- C10—PETROLEUM, GAS OR COKE INDUSTRIES; TECHNICAL GASES CONTAINING CARBON MONOXIDE; FUELS; LUBRICANTS; PEAT
- C10N—INDEXING SCHEME ASSOCIATED WITH SUBCLASS C10M RELATING TO LUBRICATING COMPOSITIONS
- C10N2040/00—Specified use or application for which the lubricating composition is intended
- C10N2040/14—Electric or magnetic purposes
- C10N2040/17—Electric or magnetic purposes for electric contacts
Landscapes
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Chemical & Material Sciences (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Manufacturing & Machinery (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Fixed Capacitors And Capacitor Manufacturing Machines (AREA)
- Organic Insulating Materials (AREA)
- Laminated Bodies (AREA)
Abstract
47,971 ABSTRACT OF THE DISCLOSURE
A capacitor is disclosed of layers of metal foil alternating with insulating sheets impregnated with a di-electric fluid. The dielectric fluid contains concentra-tions of di-isopropyl biphenyl of at least 25 percent. The dielectric fluid may also contain smaller percentages of mono-isopropyl biphenyl and tri-isopropyl biphenyl.
A capacitor is disclosed of layers of metal foil alternating with insulating sheets impregnated with a di-electric fluid. The dielectric fluid contains concentra-tions of di-isopropyl biphenyl of at least 25 percent. The dielectric fluid may also contain smaller percentages of mono-isopropyl biphenyl and tri-isopropyl biphenyl.
Description
3 ~
47,971 CAPACITOR HAVING DIELECTRIC FLUID
WITH HIGH DI-ISOPROPYL ~IPHENYL CONTENT
BACKGROUND OF THE INVENTION
Recent developments of hydrocarbon dielectric fluids ~or high voltage stress lnsulation~ such as capaci-tors, were based on the use of high levels of aromaticity to resist the e~fects of corona generating overvoltages. These flulds are essentlally alkylated aromatics, such as i80-propyl blphenyl, or solutions of an aromatlc in an alkyl-aromatic e~ter, such as di-isononylphthalate. The alkyl substitutes glve the fluid a large temperature range of ~luidlty, particularly at low temperatures and in low vapor processes; however, they cause the corona reslstance to be poor wlth respect to aromatlc substltutes because hydrogen is generated and persists, whlch causes ~urther discharges.
Thls ls probably because the hydrogen is not stron~ly bound in the dielectric fluid~ and is therefore more easily and coplously generated. Moreover, those flulds do not absorb hydrogen as aromatics apparently do. The alkyl content o~ a hydrocarbon dielectric fluid should therefore be ~ust high enough to achieve the necessary fluid properties, but should .
not adversely affect the electrical properties. ~he tendency, therefore, is to favor fluids with low amounts of alkyl and with high amounts of aromatic. In optimizing isopropyl biphenyl dielectric fluid for capacitors, 20% di-isopropyl biphenyl with the remalnder mono~isopropyl biphenyl was believed to be the maximum tolerable amount of alkyl. (See U.S. Patent 4,054 2 937.) T~e corona extinctlon voltage at low temperatures was found to begin to decrease at a di-iso-propyl biphenyl content of about 20 percent. Also, the pour :, ,, 3 ~ ~g ~ 47,971
47,971 CAPACITOR HAVING DIELECTRIC FLUID
WITH HIGH DI-ISOPROPYL ~IPHENYL CONTENT
BACKGROUND OF THE INVENTION
Recent developments of hydrocarbon dielectric fluids ~or high voltage stress lnsulation~ such as capaci-tors, were based on the use of high levels of aromaticity to resist the e~fects of corona generating overvoltages. These flulds are essentlally alkylated aromatics, such as i80-propyl blphenyl, or solutions of an aromatlc in an alkyl-aromatic e~ter, such as di-isononylphthalate. The alkyl substitutes glve the fluid a large temperature range of ~luidlty, particularly at low temperatures and in low vapor processes; however, they cause the corona reslstance to be poor wlth respect to aromatlc substltutes because hydrogen is generated and persists, whlch causes ~urther discharges.
Thls ls probably because the hydrogen is not stron~ly bound in the dielectric fluid~ and is therefore more easily and coplously generated. Moreover, those flulds do not absorb hydrogen as aromatics apparently do. The alkyl content o~ a hydrocarbon dielectric fluid should therefore be ~ust high enough to achieve the necessary fluid properties, but should .
not adversely affect the electrical properties. ~he tendency, therefore, is to favor fluids with low amounts of alkyl and with high amounts of aromatic. In optimizing isopropyl biphenyl dielectric fluid for capacitors, 20% di-isopropyl biphenyl with the remalnder mono~isopropyl biphenyl was believed to be the maximum tolerable amount of alkyl. (See U.S. Patent 4,054 2 937.) T~e corona extinctlon voltage at low temperatures was found to begin to decrease at a di-iso-propyl biphenyl content of about 20 percent. Also, the pour :, ,, 3 ~ ~g ~ 47,971
-2~
points were ~ound to increase at a di~isopropyl biphenyl content of about 20 percent.
PRIOR AR~
U.S. Patent 4,054,937 discloses a capacitor con-taining 20% di-isopropyl biphenyl and 80% mono-isopropyl biphenyl.
U.S. Patent 2,837,724 discloses a dielectric fluid for transformers which can be a methyl tertiary butyl biphenyl.
~ electric fluid sold under the trade designation "MCS1238" was analyzed as containing 17% sulfone and the rest isopropyl biphenyl, of which 31.1% was di-isopropyl biphenyl and the rest was mono-isopropyl biphenyl. The fluid is covered by U.S. Patent 3,796,934.
~UMMARY OF THE INVENTION
Contrary to the implications of U.S. Patent 4,05~,937, we ha~e found that high concentration~ of di isopropyl biphenyl in an isopropyl biphenyl dielectric fluid ~or capacitors is not as harmful to electrical properties as was expected. Specifically, the overvoltage propertles and the corona resistance, while not as good as in dielectric fluids containing large amounts of mono-isopropyl biphenyl, is nevertheless within acceptable commercial limits.
In addition, isopropyl biphenyl dielectric fluids with high concentrations of di isopropyl biphenyl resist crystallization at low temperatures better than do isopropyl biphenyl dielectric fluids ~ith high concentrations of mono-isopropyl biphenyl unless the meta isomer content in the mono-isopropyl biphenyl ls also high.
Finally, isopropyl biphenyl dielectric fluids with 47~971 --3~
high concenkrations o~ dt-i~opropyl blphenyl are les~ expen-sive than are isopropyl blphenyl dielectric fluids with high concentratlons of mono isopropyl biphenyl~
DESCRIPTION OF THE INVENTION
The aGcompanying drawing is a partial isometric sectional ~iew o~ a certain presently preferred capacitor winding according to this lnvention.
In the drawing, a container 1 which is hermetic-ally sealed, holds one or more windings containing strai~ht conducting foll 2 and a conducting foil 3 which is narrower and has rounded edges. These foils alternake with layers of insulatlon 4, here shown as film 5, paper 69 and film 7. A
dielectric ~luid 8, accordin~ to this invention~
container 1 and impregnates the winding. Electrode termina~
tions may be provided in accordanc~e with conventional prac-tice. Also, the dlelectric layers will tend to conform to the spaces available so that in practice a large Bpace RS
shown ln the drawing wlll be substantially reduced.
The dielectric ~luid of thi~ invention con~i~$s ~ `
20 essentially o~ about 25% to about 100% ~all percentage3 herein are by weight ba~ed on the dielectric fluid wel~ht, unless otherwise lndicated) of di-isopropyl biphenyl, up to o about ~ mono~isopropyl biphenyl, and up to about 20~ tri-i opropyl biphenyl. Preferably, the dielectric f~uid con-sists essentially o~ about 25% to about 80% dl-isopropyl biphenyl, about 20% to about 7~% mono-l~opropyl biphenyl, and up to àbout 15% tri isopropyl biphenyl. The dielectric fluid may also comprise about 35% to about 100% di~ opropyl biphenyl, up to about 65% mono isopropyl biphenyl and up to about 20% tri~isopropyl biphenyl. Preferably, the dielec-
points were ~ound to increase at a di~isopropyl biphenyl content of about 20 percent.
PRIOR AR~
U.S. Patent 4,054,937 discloses a capacitor con-taining 20% di-isopropyl biphenyl and 80% mono-isopropyl biphenyl.
U.S. Patent 2,837,724 discloses a dielectric fluid for transformers which can be a methyl tertiary butyl biphenyl.
~ electric fluid sold under the trade designation "MCS1238" was analyzed as containing 17% sulfone and the rest isopropyl biphenyl, of which 31.1% was di-isopropyl biphenyl and the rest was mono-isopropyl biphenyl. The fluid is covered by U.S. Patent 3,796,934.
~UMMARY OF THE INVENTION
Contrary to the implications of U.S. Patent 4,05~,937, we ha~e found that high concentration~ of di isopropyl biphenyl in an isopropyl biphenyl dielectric fluid ~or capacitors is not as harmful to electrical properties as was expected. Specifically, the overvoltage propertles and the corona resistance, while not as good as in dielectric fluids containing large amounts of mono-isopropyl biphenyl, is nevertheless within acceptable commercial limits.
In addition, isopropyl biphenyl dielectric fluids with high concentrations of di isopropyl biphenyl resist crystallization at low temperatures better than do isopropyl biphenyl dielectric fluids ~ith high concentrations of mono-isopropyl biphenyl unless the meta isomer content in the mono-isopropyl biphenyl ls also high.
Finally, isopropyl biphenyl dielectric fluids with 47~971 --3~
high concenkrations o~ dt-i~opropyl blphenyl are les~ expen-sive than are isopropyl blphenyl dielectric fluids with high concentratlons of mono isopropyl biphenyl~
DESCRIPTION OF THE INVENTION
The aGcompanying drawing is a partial isometric sectional ~iew o~ a certain presently preferred capacitor winding according to this lnvention.
In the drawing, a container 1 which is hermetic-ally sealed, holds one or more windings containing strai~ht conducting foll 2 and a conducting foil 3 which is narrower and has rounded edges. These foils alternake with layers of insulatlon 4, here shown as film 5, paper 69 and film 7. A
dielectric ~luid 8, accordin~ to this invention~
container 1 and impregnates the winding. Electrode termina~
tions may be provided in accordanc~e with conventional prac-tice. Also, the dlelectric layers will tend to conform to the spaces available so that in practice a large Bpace RS
shown ln the drawing wlll be substantially reduced.
The dielectric ~luid of thi~ invention con~i~$s ~ `
20 essentially o~ about 25% to about 100% ~all percentage3 herein are by weight ba~ed on the dielectric fluid wel~ht, unless otherwise lndicated) of di-isopropyl biphenyl, up to o about ~ mono~isopropyl biphenyl, and up to about 20~ tri-i opropyl biphenyl. Preferably, the dielectric f~uid con-sists essentially o~ about 25% to about 80% dl-isopropyl biphenyl, about 20% to about 7~% mono-l~opropyl biphenyl, and up to àbout 15% tri isopropyl biphenyl. The dielectric fluid may also comprise about 35% to about 100% di~ opropyl biphenyl, up to about 65% mono isopropyl biphenyl and up to about 20% tri~isopropyl biphenyl. Preferably, the dielec-
3 S ~ 5 47~971 tric ~luid comprises about 35~ to about 80~ di~isopropyl biphen~l~ about 20% to about ~5% mono-isopropyl bip'len~l~
and~up to about 15% tri~isopropyl biphenyl. Xf less than isopropyl biphenyl ls used, ~he ~ielectrlc fluid may become impractical for low cost capacitors. Isoprop~l biphenyl dielectric fluids having about 25% to about ]00~
di~isopropyl blphenyl have very good low temperature proper-. tles.
Due to the method of p-reparation (alkylation of biphenyl); the dielectric fluid may contain some biphenyl.
Biphenyl is irritatln~ and volatile, and there~ore it ls desirable that it not be presènt a~ more ~han 1%. Its concentration would be considerably below this when the level of diisopropyl biphenyl is high, because biphen~l would be greatly con~erted in the first p].ace at a high degree of alkylation o~ blphenyl, and it would be further reduced on fractio~ation of the dialkyl constituent because o~ its considerably greater volatllity.
The dielectric fluid preferably includes up to about 1% o~ an antioxidant for thermal stability. The pre~erred amount is about 0.01% to about 0.2%, and the pre~erred antioxidants are di-t-butyl-paracresol, di-t-butyl~pherlol, or mixtures thereofO
~he fluid also pre.~erably contains llp to about 2~ -and preferably about 0~1% to about 0.5% of a hy~rogen accep-tor for imp-roved corona resistance. An anthraqulnone~ such as B-methylanthraqulnone, anthraqulrlone, or ~chloroanthra~
quinone may be used. Because it ls more readil~ a~ailable and more soluble~ ~methylant~raquinone is pre~erred.
The antioxldants and h~drogen acceptors seem to .
3 ~ ~`9 ~
47~971 ~5 lnteract to produce a loss of corona re~isGance wherl eithe one i3 used in high concentrat:l.ons ~ ThereI'ore 3 preferabl~
neither one ls used at more than ].~. A compositlon in whlch both are effective contains about 0.2% dl--tertlary butyl paracresol and about 0O5% ~ methylanthraquinone. Although not necessarlly preferred3 the fluid may include up to about 2% and pref'erabl.y about 0.05% to about 2% of an epoxy~ such as glycidyl phenyl ether, for corona resista.nce~
The capacitors are preferably film (e.~.~ poly~
propylene)-paper or 100% fil.m because a hi~h level of di~
electric constant of the fluid ls not important in these types of' capacitors, but may also be 100% paper.
The followin~ e~amples ~urther i.:Llustrlte thls lnvention~ , Tests were made with sma.11. lmpregnat,ed capacitors o~ abou-t 12 microfarads containing polypropylene film and paper, the same dielectric used in high volt,age power capa cltorsO The windings consisted of 75 gauge ~llm and 45 gauge paper in a film-paper-film conflguration with one of the foils narrower than the other a.nd foldecL at the edges.
tWith this foil arrangement~ the stress on the foil edge is less than wlth the usual one of two equal widths and sharp edged foils.) A severe overvoltage ~est was applied to the capacitors, in which the~ were contl}luously ener~ized at 2.7 kV, 10% above rated vc)ltage~ and sub~ected to 5 c~cles of 8.1 kV, 3~3 tlmes rated every three mirltltec. t~ne hlghest over~oltage such a cap2citor would encourlter ln ser-rlce ls three tlmes rated, and this would occur very rare:L.y~) The following table give~s the results o:E' this test on such , 3.~ ~ 47,971 ~6--capacitors impregnated with the ~luid containlng 80% di-isopropyl biphenyl and wlth the presently accepted one whlch contains less than 5% di--isopropyl biphenyl and more than 95% mono-isopropyl biphenyl. lncluded in this table are also results for capacltors impregnated with tri-chloro-biphenyl which was u~ed until recently and mineral oil~ with about 80% aliphatic type carbon3.
re~nt 80% di-isopropyl biphenyl 14% tri isopropyl biphenyl and about 5% mono isopropyl 603~ 700 ,i biphenyl + .2% dl-teriary-butyl ~:
paracresol + 0.5%~methyl ; anthraquinone 96% mono-isopropyl biphenyl, 3% dl~isopropyl biphenyl >1005,~1475, 1058,~1430, 0.2% di-tertiary-butyl paracresol, 0.5%~imethyl anthraquinone trichlorobiphenyl ~ 0.3%~-methyl anthraquinone 170, 240, mineral 0.1 ~ 0.2~ di-tert-butyl paracresol + 0.5% B-methYl anthra-qulnone (not rounded ~oil) 9, 23-; In regard to the above results, the high di-i~opropyl biphenyl, although not performing as well as the high mono-isopropyl biphenyl, did perform better than the . ~ . tri-chlorobiphenyl, and is satlsfactory ~or commercial high voltage capacitors.
This example shows that isopropyl biphenyl dielec-tric fluids containlng high concentrations of dl-isopropyl biphenyl are more fire resistant than those containing hlgh conc~ntrations of mono~isopropyl biphenyl. The following table gives the results of a Cleveland Open Cup Test for ~lash and fire points for various mixtures of mono- and di-isopropyl biphenyl.
~3971 uid Composition C`~ 3~n~æ_C
Flash Point Plre Point 80% di-, 14% tri-, 5% mono-isopropyl biphenyl 180 186 53% di-, 10% tri-, 36% mono-lsopropyl blphenyl 160 170 27% di-, 5% tri-, 65% mono-isopropyl blphenyl 157 171 1% di~, 95~ mono-isopropyl biphenyl 150 160 Tests were performed to determlne the low tempera-ture stability of di~isopropyl biphenyl dielectrlc flulds containing various amounts of di~lsopropyl biphenyl.
A series of test tubes containing fluids of vary-ing amounts of mono- and di-isopropyl biphenyl were sub-~ected to six repeated cycles of two hours at -3~C and two hours at -60C and observed for the development of opaque crystals. Resistalloe to crystallization, by remaining transparent in a glassy state, is necessary for low temper-ature ~luid stability because gas-filled voids can develop on crystallization that break down with high voltage. The -30C and -60C cycling accelerates crystallization e~fects in such fluids that are prone to this. For the solutionS
one of two stock ~luids contained 97.2% mono~isopropyl biphenyl, with 54.8% para and 42.4% meta isomers which cause it to be easily crystallized because of the greater fraction of the para isomer. The other consisted of 80% dl-, 14%
tri and 5% mono-isopropyl biphenyl. The following table gives the observation made of these solutions after the si~
low temperature cycles.
117~971 Fluid Composition % mono- % di~ % tri- Appearance at -30C'and at ~60C a~er i~gg~ ~=~b99o_ _ 6 cYcles at these tempera~ures 97.2 2 all opaque 88 10 - lower 2/3 opaque~ top transparent 79 17.5 3 lower 1/3 opaque, top transparent 61 34 5 all transparent 24.5 64.5 11 all transparent 6 80 14 all transparent It can be seen that low temperature crystalli~a-tion of mono-isopropyl biphenyl i6 e~fectively inhibited wlth about 25% or more di-isopropyl biphenyl, and that the composition with 80% dl-isopropyl biphenyl continues to resist crystallization.
~ .
. , ~
, :
and~up to about 15% tri~isopropyl biphenyl. Xf less than isopropyl biphenyl ls used, ~he ~ielectrlc fluid may become impractical for low cost capacitors. Isoprop~l biphenyl dielectric fluids having about 25% to about ]00~
di~isopropyl blphenyl have very good low temperature proper-. tles.
Due to the method of p-reparation (alkylation of biphenyl); the dielectric fluid may contain some biphenyl.
Biphenyl is irritatln~ and volatile, and there~ore it ls desirable that it not be presènt a~ more ~han 1%. Its concentration would be considerably below this when the level of diisopropyl biphenyl is high, because biphen~l would be greatly con~erted in the first p].ace at a high degree of alkylation o~ blphenyl, and it would be further reduced on fractio~ation of the dialkyl constituent because o~ its considerably greater volatllity.
The dielectric fluid preferably includes up to about 1% o~ an antioxidant for thermal stability. The pre~erred amount is about 0.01% to about 0.2%, and the pre~erred antioxidants are di-t-butyl-paracresol, di-t-butyl~pherlol, or mixtures thereofO
~he fluid also pre.~erably contains llp to about 2~ -and preferably about 0~1% to about 0.5% of a hy~rogen accep-tor for imp-roved corona resistance. An anthraqulnone~ such as B-methylanthraqulnone, anthraqulrlone, or ~chloroanthra~
quinone may be used. Because it ls more readil~ a~ailable and more soluble~ ~methylant~raquinone is pre~erred.
The antioxldants and h~drogen acceptors seem to .
3 ~ ~`9 ~
47~971 ~5 lnteract to produce a loss of corona re~isGance wherl eithe one i3 used in high concentrat:l.ons ~ ThereI'ore 3 preferabl~
neither one ls used at more than ].~. A compositlon in whlch both are effective contains about 0.2% dl--tertlary butyl paracresol and about 0O5% ~ methylanthraquinone. Although not necessarlly preferred3 the fluid may include up to about 2% and pref'erabl.y about 0.05% to about 2% of an epoxy~ such as glycidyl phenyl ether, for corona resista.nce~
The capacitors are preferably film (e.~.~ poly~
propylene)-paper or 100% fil.m because a hi~h level of di~
electric constant of the fluid ls not important in these types of' capacitors, but may also be 100% paper.
The followin~ e~amples ~urther i.:Llustrlte thls lnvention~ , Tests were made with sma.11. lmpregnat,ed capacitors o~ abou-t 12 microfarads containing polypropylene film and paper, the same dielectric used in high volt,age power capa cltorsO The windings consisted of 75 gauge ~llm and 45 gauge paper in a film-paper-film conflguration with one of the foils narrower than the other a.nd foldecL at the edges.
tWith this foil arrangement~ the stress on the foil edge is less than wlth the usual one of two equal widths and sharp edged foils.) A severe overvoltage ~est was applied to the capacitors, in which the~ were contl}luously ener~ized at 2.7 kV, 10% above rated vc)ltage~ and sub~ected to 5 c~cles of 8.1 kV, 3~3 tlmes rated every three mirltltec. t~ne hlghest over~oltage such a cap2citor would encourlter ln ser-rlce ls three tlmes rated, and this would occur very rare:L.y~) The following table give~s the results o:E' this test on such , 3.~ ~ 47,971 ~6--capacitors impregnated with the ~luid containlng 80% di-isopropyl biphenyl and wlth the presently accepted one whlch contains less than 5% di--isopropyl biphenyl and more than 95% mono-isopropyl biphenyl. lncluded in this table are also results for capacltors impregnated with tri-chloro-biphenyl which was u~ed until recently and mineral oil~ with about 80% aliphatic type carbon3.
re~nt 80% di-isopropyl biphenyl 14% tri isopropyl biphenyl and about 5% mono isopropyl 603~ 700 ,i biphenyl + .2% dl-teriary-butyl ~:
paracresol + 0.5%~methyl ; anthraquinone 96% mono-isopropyl biphenyl, 3% dl~isopropyl biphenyl >1005,~1475, 1058,~1430, 0.2% di-tertiary-butyl paracresol, 0.5%~imethyl anthraquinone trichlorobiphenyl ~ 0.3%~-methyl anthraquinone 170, 240, mineral 0.1 ~ 0.2~ di-tert-butyl paracresol + 0.5% B-methYl anthra-qulnone (not rounded ~oil) 9, 23-; In regard to the above results, the high di-i~opropyl biphenyl, although not performing as well as the high mono-isopropyl biphenyl, did perform better than the . ~ . tri-chlorobiphenyl, and is satlsfactory ~or commercial high voltage capacitors.
This example shows that isopropyl biphenyl dielec-tric fluids containlng high concentrations of dl-isopropyl biphenyl are more fire resistant than those containing hlgh conc~ntrations of mono~isopropyl biphenyl. The following table gives the results of a Cleveland Open Cup Test for ~lash and fire points for various mixtures of mono- and di-isopropyl biphenyl.
~3971 uid Composition C`~ 3~n~æ_C
Flash Point Plre Point 80% di-, 14% tri-, 5% mono-isopropyl biphenyl 180 186 53% di-, 10% tri-, 36% mono-lsopropyl blphenyl 160 170 27% di-, 5% tri-, 65% mono-isopropyl blphenyl 157 171 1% di~, 95~ mono-isopropyl biphenyl 150 160 Tests were performed to determlne the low tempera-ture stability of di~isopropyl biphenyl dielectrlc flulds containing various amounts of di~lsopropyl biphenyl.
A series of test tubes containing fluids of vary-ing amounts of mono- and di-isopropyl biphenyl were sub-~ected to six repeated cycles of two hours at -3~C and two hours at -60C and observed for the development of opaque crystals. Resistalloe to crystallization, by remaining transparent in a glassy state, is necessary for low temper-ature ~luid stability because gas-filled voids can develop on crystallization that break down with high voltage. The -30C and -60C cycling accelerates crystallization e~fects in such fluids that are prone to this. For the solutionS
one of two stock ~luids contained 97.2% mono~isopropyl biphenyl, with 54.8% para and 42.4% meta isomers which cause it to be easily crystallized because of the greater fraction of the para isomer. The other consisted of 80% dl-, 14%
tri and 5% mono-isopropyl biphenyl. The following table gives the observation made of these solutions after the si~
low temperature cycles.
117~971 Fluid Composition % mono- % di~ % tri- Appearance at -30C'and at ~60C a~er i~gg~ ~=~b99o_ _ 6 cYcles at these tempera~ures 97.2 2 all opaque 88 10 - lower 2/3 opaque~ top transparent 79 17.5 3 lower 1/3 opaque, top transparent 61 34 5 all transparent 24.5 64.5 11 all transparent 6 80 14 all transparent It can be seen that low temperature crystalli~a-tion of mono-isopropyl biphenyl i6 e~fectively inhibited wlth about 25% or more di-isopropyl biphenyl, and that the composition with 80% dl-isopropyl biphenyl continues to resist crystallization.
~ .
. , ~
, :
Claims
47,971 We claim:
1. A capacitor comprising layers of metal foil alternating with a dielectric spacer impregnated with a dielectric fluid which comprises about 35% to about 100% by weight di-isopropyl biphenyl, up to about 65% by weight mono-isopropyl biphenyl a and up to about 20% by weight tri-isopropyl biphenol, . 2. A capacitor according to Claim 1 wherein said dielectric fluid contains up to about 1% by weight of an antioxidant and up to about 1% by weight of a hydrogen acceptor compound.
3. A capacitor according to Claim 2 wherein said antioxidant is di-tert-butyl-paracresol and said hydrogen acceptor is di-methyl anthraquinone.
4. A capacitor according to Claim l wherein said dielectric fluid includes about 0.05 to about 2% of an epoxy.
5. A capacitor according to Claim 1 wherein said dielectric spacer consists of paper and film, 100% film, or 100% paper.
6. A capacitor according to Claim 1 wherein every other layer of said metal foil is narrower and has rounded edges.
7. A capacitor according to Claim 1 wherein the amount of said di-isopropyl biphenyl is about 35% to about 80% by weight, the amount of said mono-isopropyl biphenyl is about 20% to about 65% by weight, and the amount of said tri-isopropyl biphenyl is up to about 15% by weight.
8. A capacitor comprising layers of metal foil alternating with a dielectric spacer impregnated with a di-47,971 electric fluid which consists essentially of about 25% to about 100% by weight di-isopropyl biphenyl, up to about 75%
by weight mono-isopropyl biphenyl, and up to about 20% by weight tri-isopropyl biphenyl.
9. A capacitor according to Claim 8 wherein the amount of di-isopropyl biphenyl is about 25% to about 80% by weight, the amount of mono-isopropyl biphenyl is about 20%
to 75% by weight, and the amount of tri-isopropyl biphenyl is up to about 15% by weight.
10. A capacitor according to Claim 8 wherein said dielectric fluid contains up to about 1% of an antioxidant and up to about 1% by weight of a hydrogen acceptor com-pound.
1. A capacitor comprising layers of metal foil alternating with a dielectric spacer impregnated with a dielectric fluid which comprises about 35% to about 100% by weight di-isopropyl biphenyl, up to about 65% by weight mono-isopropyl biphenyl a and up to about 20% by weight tri-isopropyl biphenol, . 2. A capacitor according to Claim 1 wherein said dielectric fluid contains up to about 1% by weight of an antioxidant and up to about 1% by weight of a hydrogen acceptor compound.
3. A capacitor according to Claim 2 wherein said antioxidant is di-tert-butyl-paracresol and said hydrogen acceptor is di-methyl anthraquinone.
4. A capacitor according to Claim l wherein said dielectric fluid includes about 0.05 to about 2% of an epoxy.
5. A capacitor according to Claim 1 wherein said dielectric spacer consists of paper and film, 100% film, or 100% paper.
6. A capacitor according to Claim 1 wherein every other layer of said metal foil is narrower and has rounded edges.
7. A capacitor according to Claim 1 wherein the amount of said di-isopropyl biphenyl is about 35% to about 80% by weight, the amount of said mono-isopropyl biphenyl is about 20% to about 65% by weight, and the amount of said tri-isopropyl biphenyl is up to about 15% by weight.
8. A capacitor comprising layers of metal foil alternating with a dielectric spacer impregnated with a di-47,971 electric fluid which consists essentially of about 25% to about 100% by weight di-isopropyl biphenyl, up to about 75%
by weight mono-isopropyl biphenyl, and up to about 20% by weight tri-isopropyl biphenyl.
9. A capacitor according to Claim 8 wherein the amount of di-isopropyl biphenyl is about 25% to about 80% by weight, the amount of mono-isopropyl biphenyl is about 20%
to 75% by weight, and the amount of tri-isopropyl biphenyl is up to about 15% by weight.
10. A capacitor according to Claim 8 wherein said dielectric fluid contains up to about 1% of an antioxidant and up to about 1% by weight of a hydrogen acceptor com-pound.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US93862978A | 1978-08-31 | 1978-08-31 | |
| US938,629 | 1992-09-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1135495A true CA1135495A (en) | 1982-11-16 |
Family
ID=25471702
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000333948A Expired CA1135495A (en) | 1978-08-31 | 1979-08-14 | Capacitor having dielectric fluid with high di-isopropyl biphenyl content |
Country Status (18)
| Country | Link |
|---|---|
| JP (1) | JPS5536996A (en) |
| AR (1) | AR219995A1 (en) |
| AU (1) | AU522462B2 (en) |
| BE (1) | BE878499A (en) |
| BR (1) | BR7905515A (en) |
| CA (1) | CA1135495A (en) |
| CH (1) | CH642768A5 (en) |
| DE (1) | DE2934103A1 (en) |
| FR (1) | FR2435113A1 (en) |
| GB (1) | GB2029444B (en) |
| IN (1) | IN152902B (en) |
| IT (1) | IT1122918B (en) |
| MX (1) | MX153377A (en) |
| NO (1) | NO150257C (en) |
| PH (1) | PH14798A (en) |
| SE (1) | SE7907274L (en) |
| YU (1) | YU42953B (en) |
| ZA (1) | ZA794372B (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2926609A1 (en) * | 1979-07-02 | 1981-01-08 | Bayer Ag | IMPREGNANT AND ITS USE |
| US4320034A (en) * | 1979-10-12 | 1982-03-16 | Mcgraw-Edison Company | Electrical capacitor having an improved dielectric system |
| US4348713A (en) * | 1980-05-07 | 1982-09-07 | General Electric Company | Impregnants for metallized paper electrode capacitors |
| US4344105A (en) * | 1980-12-12 | 1982-08-10 | Westinghouse Electric Corp. | Power capacitor structure and method of assembly |
| US4813116A (en) * | 1981-08-18 | 1989-03-21 | Westinghouse Electric Corp. | Method of making a multi-section power capacitor with all-film dielectric |
| US4467397A (en) * | 1981-08-18 | 1984-08-21 | Westinghouse Electric Corp. | Multi-section power capacitor with all-film dielectric |
| GB8329134D0 (en) * | 1983-11-01 | 1983-12-07 | Exxon Research Engineering Co | Dielectric fluid |
| DE3432746A1 (en) * | 1984-09-06 | 1986-03-13 | Chemische Fabrik Wibarco GmbH, 4530 Ibbenbüren | INSULATING OIL FOR ELECTRICAL MEDIUM AND HIGH VOLTAGE DEVICES |
| JP3117892B2 (en) * | 1995-03-03 | 2000-12-18 | シャープ株式会社 | Fixing device |
| US5790931A (en) * | 1995-10-26 | 1998-08-04 | Sharp Kabushiki Kaisha | Fixing device |
| JP3158030B2 (en) * | 1995-12-14 | 2001-04-23 | シャープ株式会社 | Fixing device |
| JPH09166935A (en) * | 1995-12-18 | 1997-06-24 | Sharp Corp | Fixing device |
| JP3153754B2 (en) * | 1995-12-26 | 2001-04-09 | シャープ株式会社 | Fixing device |
| JP3192362B2 (en) * | 1995-12-27 | 2001-07-23 | シャープ株式会社 | Fixing device |
| JPH09185279A (en) * | 1995-12-28 | 1997-07-15 | Sharp Corp | Fixing device and manufacturing method thereof |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5086700A (en) | 1973-12-06 | 1975-07-12 | ||
| US4054937A (en) * | 1976-04-28 | 1977-10-18 | Westinghouse Electric Corporation | Capacitor |
| DE2926609A1 (en) * | 1979-07-02 | 1981-01-08 | Bayer Ag | IMPREGNANT AND ITS USE |
| JPS6170075A (en) * | 1984-09-12 | 1986-04-10 | 水島 繁三郎 | Shape memory silk yarn and its production |
-
1979
- 1979-08-14 CA CA000333948A patent/CA1135495A/en not_active Expired
- 1979-08-15 GB GB7928428A patent/GB2029444B/en not_active Expired
- 1979-08-15 MX MX178923A patent/MX153377A/en unknown
- 1979-08-17 IN IN855/CAL/79A patent/IN152902B/en unknown
- 1979-08-17 PH PH22922A patent/PH14798A/en unknown
- 1979-08-20 ZA ZA00794372A patent/ZA794372B/en unknown
- 1979-08-23 AU AU50242/79A patent/AU522462B2/en not_active Ceased
- 1979-08-23 DE DE19792934103 patent/DE2934103A1/en not_active Withdrawn
- 1979-08-27 YU YU2089/79A patent/YU42953B/en unknown
- 1979-08-28 FR FR7921586A patent/FR2435113A1/en active Granted
- 1979-08-28 JP JP10871879A patent/JPS5536996A/en active Pending
- 1979-08-28 BR BR7905515A patent/BR7905515A/en unknown
- 1979-08-29 BE BE0/196938A patent/BE878499A/en not_active IP Right Cessation
- 1979-08-30 CH CH787279A patent/CH642768A5/en not_active IP Right Cessation
- 1979-08-30 IT IT25396/79A patent/IT1122918B/en active
- 1979-08-30 NO NO792821A patent/NO150257C/en unknown
- 1979-08-30 AR AR277903A patent/AR219995A1/en active
- 1979-08-31 SE SE7907274A patent/SE7907274L/en not_active Application Discontinuation
Also Published As
| Publication number | Publication date |
|---|---|
| BE878499A (en) | 1980-02-29 |
| IT7925396A0 (en) | 1979-08-30 |
| GB2029444B (en) | 1983-01-06 |
| NO150257B (en) | 1984-06-04 |
| IN152902B (en) | 1984-04-28 |
| IT1122918B (en) | 1986-04-30 |
| NO150257C (en) | 1984-09-12 |
| MX153377A (en) | 1986-10-07 |
| PH14798A (en) | 1981-12-09 |
| NO792821L (en) | 1980-03-03 |
| CH642768A5 (en) | 1984-04-30 |
| BR7905515A (en) | 1980-05-20 |
| AU522462B2 (en) | 1982-06-10 |
| YU42953B (en) | 1989-02-28 |
| ZA794372B (en) | 1980-11-26 |
| FR2435113A1 (en) | 1980-03-28 |
| SE7907274L (en) | 1980-03-01 |
| JPS5536996A (en) | 1980-03-14 |
| DE2934103A1 (en) | 1980-03-13 |
| YU208979A (en) | 1983-04-30 |
| GB2029444A (en) | 1980-03-19 |
| FR2435113B1 (en) | 1985-03-01 |
| AU5024279A (en) | 1980-03-06 |
| AR219995A1 (en) | 1980-09-30 |
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