CA1149602A - Non-toxic impregnant for electrical capacitors - Google Patents
Non-toxic impregnant for electrical capacitorsInfo
- Publication number
- CA1149602A CA1149602A CA000374173A CA374173A CA1149602A CA 1149602 A CA1149602 A CA 1149602A CA 000374173 A CA000374173 A CA 000374173A CA 374173 A CA374173 A CA 374173A CA 1149602 A CA1149602 A CA 1149602A
- Authority
- CA
- Canada
- Prior art keywords
- capacitor
- soybean oil
- dielectric
- toxic
- impregnant
- 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
- H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES OR LIGHT-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
Abstract
NON-TOXIC IMPREGNANT FOR
ELECTRICAL CAPACITORS
Abstract of the Invention Soybean oil is used as a non-toxic dielectric fluid for a-c electrical capacitors. An additive of a phenolic antioxidant is added to the fluid to gel it in place in the capacitor.
ELECTRICAL CAPACITORS
Abstract of the Invention Soybean oil is used as a non-toxic dielectric fluid for a-c electrical capacitors. An additive of a phenolic antioxidant is added to the fluid to gel it in place in the capacitor.
Description
~9602 This invention relates to a dielectric liquid impregnant for electrical devices and more particularly to an electrical capacitor utilizing an improved non-toxic dielectric liquid impregnant theretofore.
Liquid impregnants for electrical capacitors should have a high dielectric constant, maintain a low dissipation factor, and be compatible with the other materials utilized in capacitor structure. At the same time, the impregnant must withstand elevated and fluctuating temperature, pressure, and voltage stress conditions with excellent electrical characteristics for a long operative life of the capacitor.
The polycholorinated biphenyls as capacitor impregnants meet these requirements and they were eminently satisfactory for several decades.
The polychlorinated biphenyls are broadly referred to as PCBs. The poly-chlorinated biphenyls have recently been associated with ecological problems, restrictive use limitations, and rising costs. These problems have spurred the search for a suitable non-toxic replacement capacitor impregnant which would have some advantageous impregnant characteristics comparable to those of the chlorinated diphenyls, and still provide outstanding electrical and compat;bility performance with the two most important present day capacitor solid dielectrics, paper and polypropylene.
It has been found that soybean oil provides good electrical characteristics as a dielectric fluid impregnant as well as being non-toxic.
A useful soybean oil for example, would be of a refined, low acid grade with a flash point of about 325C, which is available in commercial quantities. However, one of the problems of using soybean oil is its fluidity or its otherwise mobility. More specifically the mobility of any conductive ions or impurities of the soybean oil could coat the metal foil in capacitors or cause hot spots in the capacitor.
~ ~9~(~2 FEATURES OR OB~ECTS OF THE INVENIION
_ . _ It is, therefore, a feature of the ;nvention to pr~vide a dielectriC
impregnating fluid that is non-toxic. Another feature of the invention is to provide such an impregnating flud that includes soybean oil. Another feature of the invention is the provision of such a dielectric impregnating fluid that includes an additive which causes the soybean oil to gel. Still another feature is the provision of such an additive ~ihich includes a phenolic antioxidant. Another feature of the invention is the provision of such a dielectric impregnating fluid that includes an antioxidant compound of alkylhydroxyphenylalkanoyl-hydrazine. These and other features of the invention will become apparent from the following description taken in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
Generally speaking, the present invention pertains to an a-c capacitor having a dielectric fluid including soybean oil and an additive of an alkylhydroxyphenylalkanoyl-hydrazine compound in an amount of from 0.1% to 10% by weight of the total weight of the dielectric fluid to gel the soybean^oil.
BRIEF DESCRIPTION OF THE DRA~IINGS
FIGURE 1 of the drawing illustrates a convolutely wound a-c capacitor body partially unwound to show the dielectric plastic film and foil electrode structure.
FIGURE 2 of the drawing illustrates the convolutely wound a-c capacitor body of FIGURE 1 to which leads are attached.
FIGURE 3 of the drawing illustrates the a-c capacitor body suitably encased and sealed in a housing.
DISCUSSION OF THE INYENTION
Referring now to Figure 1 of the drawing, there is illustrated a convolutely wound a-c capacitor body 10. The capacitor body 10 includes a pair of dielectric film layers 11 and 12 and overlying electrodes 13 and 14 _ c _ t ~
respectively. Electrodes 13 and 14 are of a suitable metal such as aluminum for example. Margins 15 and 16 are provided for preventing electrical short circuit between the electrodes. As shown in Figure 2, suitable terminal leads 23 and 24 are attached to the electrodes 13 and 14 from opposite ends 21 and 22 of the capacitor body 10. Suitable lead material could be solder coated copper for example.
The dielectric plastic films or layers 11 and 12 should have high dielectric strength, low dissipation factor to prevent thermal runaway, broad temperature range capabilities, resistance to the dielectric fluid7 and freedom from pinholes and conductive particles. Suitable dielectric film layers 11 and 12 may be paper, a paper and polymeric film combination, or polymeric films.
In Figures 2 and 3, a capacitor body 10 is preferable sealed to a can or housing 40 to form a capacitor 41. Capacitor 41 includes the metal housing or can 40 and terminals 42 and 43. The capacitor body 10 is contained within the housing 40 and terminal lead 23 makes electrical contact with terminal 42 and the remaining terminal lead 24 makes electrical contact with terminal 43.
As noted previously, fluid or liquid dielectric impregnants for electrical capacitors should have a high dielectric constant, maintain a low dissipation factor and be compatible with the other materials used in capacitor structure. According to the present invention, the dielectric fluid which is used to impregnate capacitor body 10 not only satisfies these requirements, but is substantially non-toxic. The dielectric fluid of the present invention includes refined soybean oil with an additive which when the soybean oil is cool, gels the soybean oil to arrest its fluidity or mobility. It has been found that phenolic antioxidant compounds of alkylhydroxyphenylalkanoyl-hydrazine are useful in gelling _ _ , . . . . . .. . .. . .
~9602 soybean oil. Such compounds are described in U.S. patent 3,773,722 issued November 20, 1973 to Martin Dexter. A useful compound is sold in commercial TM
quantities from Ciba-Geigy Co. under the brand name of Irganox MD-1024 and bears the chemical name rl, r M -bis ~3-(3',5'-di-tert-butyl-~'-hydroxyphenyl) propionyl~ hydrazine.
Over 50 additives were evaluated at high temperatures. The types of additives used for gelation were: Phenylamines; Napthylamines; An-inophenols;
Monophenols; Polyphenols; Pulyhydroxbenzenes; Quinones; Thiobisphenols:
Epoxides and others.
From 0.1 to 10% by weight of the total weight of the soybean oil of TM
such additives, including Irganox MD-1024, were added to soybean oil and heated in an air circulated oven at 125C or higher for 16 hours or longer.
At all stages, with elevated temperatures, soybean oil and any of the additives were in a liquid form. After heating, the samples were cooled to room temperature. All remained in a liquid state except those which TM
contained Irganox ~1~-1024. These haa gelled.
TM
These Irganox MD-1024 soybean gel samples were set back in the oven and heated for a short time. The gel converted to a liquid. They were again cooled to room temperature and again, the l;quid was converted to a 0 gel. Repeated heating and cooling produced the same results. Several TM
samples with Irganox MD-1024 were set in a vacuum at 130C overnight, then the heat was shut off with the vacuum still on. When these samples were cooled to approximately 55C under vacuum, the soybean oil converted to a gel. Thus, the rreSence of oxygen does not appear tc ir.fluer.ce sc'a'ion.
This phenomena is due to a physical reaction and partially responsible to Van Der Walls forces.
When used as an additive in a dielectric fluid for capacitors of the type described in Figures 1-3, the additive is mixed as a liquid with liquid soybean oil at temperatures above about ~35C and then impregnated into the B
~9602 capacitor. Upon cooling, the soybean oil gels in situ. The soybean oil will remain a gel since there is very seldom, if any, prolonged capacitor use above 85C.
On thousand hour life tests were perfonned on 4 electrical capacitors of the type described in Figures 1-3 using soybean oil as a dielectric fluid impregnant with an additive of 1.0% by weight of the total weight of the dielectric fluid of Irganox MD-1024. The results are shown in Table II
which presents average capacity and dissipation -Factors.
Table I
ELECTRICAL CAPACITOR PROPERTIES
CAPACITANCE AND % DISSIPATION FACTOR (DF) STABILITY
DURING LIFE TEST
25uF 370VAC rated capacitor operated at 459VAC
DIELECTRIC-2 layers x 0.45 Mils + 2 layers x 0.40 Mil PAPER
CAPACITANCE-uF INITIAL 500 HRS 1000 HRS
25C 18.1 18.2 18.1 65C 17.8 17.9 17.9 85C 17.7 17.8 17.8 20DISSIPATION FACTOR ,0 25C 0.172 0.196 0.195 65C 0.212 0.288 0.304 85C 0.308 0.408 0.427 It is seen that over a life test of 1000 hours, the capacitor exhibited good stability. There was no evidence of "hot spots" or other failures.
Liquid impregnants for electrical capacitors should have a high dielectric constant, maintain a low dissipation factor, and be compatible with the other materials utilized in capacitor structure. At the same time, the impregnant must withstand elevated and fluctuating temperature, pressure, and voltage stress conditions with excellent electrical characteristics for a long operative life of the capacitor.
The polycholorinated biphenyls as capacitor impregnants meet these requirements and they were eminently satisfactory for several decades.
The polychlorinated biphenyls are broadly referred to as PCBs. The poly-chlorinated biphenyls have recently been associated with ecological problems, restrictive use limitations, and rising costs. These problems have spurred the search for a suitable non-toxic replacement capacitor impregnant which would have some advantageous impregnant characteristics comparable to those of the chlorinated diphenyls, and still provide outstanding electrical and compat;bility performance with the two most important present day capacitor solid dielectrics, paper and polypropylene.
It has been found that soybean oil provides good electrical characteristics as a dielectric fluid impregnant as well as being non-toxic.
A useful soybean oil for example, would be of a refined, low acid grade with a flash point of about 325C, which is available in commercial quantities. However, one of the problems of using soybean oil is its fluidity or its otherwise mobility. More specifically the mobility of any conductive ions or impurities of the soybean oil could coat the metal foil in capacitors or cause hot spots in the capacitor.
~ ~9~(~2 FEATURES OR OB~ECTS OF THE INVENIION
_ . _ It is, therefore, a feature of the ;nvention to pr~vide a dielectriC
impregnating fluid that is non-toxic. Another feature of the invention is to provide such an impregnating flud that includes soybean oil. Another feature of the invention is the provision of such a dielectric impregnating fluid that includes an additive which causes the soybean oil to gel. Still another feature is the provision of such an additive ~ihich includes a phenolic antioxidant. Another feature of the invention is the provision of such a dielectric impregnating fluid that includes an antioxidant compound of alkylhydroxyphenylalkanoyl-hydrazine. These and other features of the invention will become apparent from the following description taken in conjunction with the accompanying drawings.
SUMMARY OF THE INVENTION
Generally speaking, the present invention pertains to an a-c capacitor having a dielectric fluid including soybean oil and an additive of an alkylhydroxyphenylalkanoyl-hydrazine compound in an amount of from 0.1% to 10% by weight of the total weight of the dielectric fluid to gel the soybean^oil.
BRIEF DESCRIPTION OF THE DRA~IINGS
FIGURE 1 of the drawing illustrates a convolutely wound a-c capacitor body partially unwound to show the dielectric plastic film and foil electrode structure.
FIGURE 2 of the drawing illustrates the convolutely wound a-c capacitor body of FIGURE 1 to which leads are attached.
FIGURE 3 of the drawing illustrates the a-c capacitor body suitably encased and sealed in a housing.
DISCUSSION OF THE INYENTION
Referring now to Figure 1 of the drawing, there is illustrated a convolutely wound a-c capacitor body 10. The capacitor body 10 includes a pair of dielectric film layers 11 and 12 and overlying electrodes 13 and 14 _ c _ t ~
respectively. Electrodes 13 and 14 are of a suitable metal such as aluminum for example. Margins 15 and 16 are provided for preventing electrical short circuit between the electrodes. As shown in Figure 2, suitable terminal leads 23 and 24 are attached to the electrodes 13 and 14 from opposite ends 21 and 22 of the capacitor body 10. Suitable lead material could be solder coated copper for example.
The dielectric plastic films or layers 11 and 12 should have high dielectric strength, low dissipation factor to prevent thermal runaway, broad temperature range capabilities, resistance to the dielectric fluid7 and freedom from pinholes and conductive particles. Suitable dielectric film layers 11 and 12 may be paper, a paper and polymeric film combination, or polymeric films.
In Figures 2 and 3, a capacitor body 10 is preferable sealed to a can or housing 40 to form a capacitor 41. Capacitor 41 includes the metal housing or can 40 and terminals 42 and 43. The capacitor body 10 is contained within the housing 40 and terminal lead 23 makes electrical contact with terminal 42 and the remaining terminal lead 24 makes electrical contact with terminal 43.
As noted previously, fluid or liquid dielectric impregnants for electrical capacitors should have a high dielectric constant, maintain a low dissipation factor and be compatible with the other materials used in capacitor structure. According to the present invention, the dielectric fluid which is used to impregnate capacitor body 10 not only satisfies these requirements, but is substantially non-toxic. The dielectric fluid of the present invention includes refined soybean oil with an additive which when the soybean oil is cool, gels the soybean oil to arrest its fluidity or mobility. It has been found that phenolic antioxidant compounds of alkylhydroxyphenylalkanoyl-hydrazine are useful in gelling _ _ , . . . . . .. . .. . .
~9602 soybean oil. Such compounds are described in U.S. patent 3,773,722 issued November 20, 1973 to Martin Dexter. A useful compound is sold in commercial TM
quantities from Ciba-Geigy Co. under the brand name of Irganox MD-1024 and bears the chemical name rl, r M -bis ~3-(3',5'-di-tert-butyl-~'-hydroxyphenyl) propionyl~ hydrazine.
Over 50 additives were evaluated at high temperatures. The types of additives used for gelation were: Phenylamines; Napthylamines; An-inophenols;
Monophenols; Polyphenols; Pulyhydroxbenzenes; Quinones; Thiobisphenols:
Epoxides and others.
From 0.1 to 10% by weight of the total weight of the soybean oil of TM
such additives, including Irganox MD-1024, were added to soybean oil and heated in an air circulated oven at 125C or higher for 16 hours or longer.
At all stages, with elevated temperatures, soybean oil and any of the additives were in a liquid form. After heating, the samples were cooled to room temperature. All remained in a liquid state except those which TM
contained Irganox ~1~-1024. These haa gelled.
TM
These Irganox MD-1024 soybean gel samples were set back in the oven and heated for a short time. The gel converted to a liquid. They were again cooled to room temperature and again, the l;quid was converted to a 0 gel. Repeated heating and cooling produced the same results. Several TM
samples with Irganox MD-1024 were set in a vacuum at 130C overnight, then the heat was shut off with the vacuum still on. When these samples were cooled to approximately 55C under vacuum, the soybean oil converted to a gel. Thus, the rreSence of oxygen does not appear tc ir.fluer.ce sc'a'ion.
This phenomena is due to a physical reaction and partially responsible to Van Der Walls forces.
When used as an additive in a dielectric fluid for capacitors of the type described in Figures 1-3, the additive is mixed as a liquid with liquid soybean oil at temperatures above about ~35C and then impregnated into the B
~9602 capacitor. Upon cooling, the soybean oil gels in situ. The soybean oil will remain a gel since there is very seldom, if any, prolonged capacitor use above 85C.
On thousand hour life tests were perfonned on 4 electrical capacitors of the type described in Figures 1-3 using soybean oil as a dielectric fluid impregnant with an additive of 1.0% by weight of the total weight of the dielectric fluid of Irganox MD-1024. The results are shown in Table II
which presents average capacity and dissipation -Factors.
Table I
ELECTRICAL CAPACITOR PROPERTIES
CAPACITANCE AND % DISSIPATION FACTOR (DF) STABILITY
DURING LIFE TEST
25uF 370VAC rated capacitor operated at 459VAC
DIELECTRIC-2 layers x 0.45 Mils + 2 layers x 0.40 Mil PAPER
CAPACITANCE-uF INITIAL 500 HRS 1000 HRS
25C 18.1 18.2 18.1 65C 17.8 17.9 17.9 85C 17.7 17.8 17.8 20DISSIPATION FACTOR ,0 25C 0.172 0.196 0.195 65C 0.212 0.288 0.304 85C 0.308 0.408 0.427 It is seen that over a life test of 1000 hours, the capacitor exhibited good stability. There was no evidence of "hot spots" or other failures.
Claims (3)
1. In an a-c capacitor, a dielectric fluid including soybean oil and an additive of an alkylhydroxyphenylalkanoyl-hydrazine compound in an amount of from 0.1% to 10% by weight of the total weight of the dielectric fluid.
2. In a capacitor according to claim 1 wherein said additive is N,N'-bis [3-(3',5'-di-tert-butyl-4'-hydroxyphenyl) propionyl] hydrazine.
3. In a capacitor according to claim 2 wherein said additive is in an amount of about 1% by weight of the total weight of the fluid.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US18912680A | 1980-09-22 | 1980-09-22 | |
| US06/189,126 | 1980-09-22 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1149602A true CA1149602A (en) | 1983-07-12 |
Family
ID=22696041
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000374173A Expired CA1149602A (en) | 1980-09-22 | 1981-03-30 | Non-toxic impregnant for electrical capacitors |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS5763825A (en) |
| CA (1) | CA1149602A (en) |
| DE (1) | DE3117318A1 (en) |
| SE (1) | SE8105267L (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5939017A (en) * | 1982-08-27 | 1984-03-03 | 信越半導体株式会社 | Oil-immersed condenser |
| FR2759198B1 (en) * | 1997-01-31 | 1999-03-26 | Atochem Elf Sa | METHOD FOR IMPREGNATING ELECTRIC CAPACITORS |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| NL99615C (en) * | 1955-05-18 | |||
| NL126252C (en) * | 1961-07-28 | 1900-01-01 | United States Rubber Co | |
| US3773722A (en) * | 1969-03-28 | 1973-11-20 | Ciba Geigy Corp | Synthetic organic polymeric substances stabilized with alkylhydroxyphenyl-alkanoyl-hydrazines |
| IT1009956B (en) * | 1973-06-12 | 1976-12-20 | Gen Electric | IMPREGNATING LIQUID CONSISTING OF A STABILIZED ESTER |
| DE2446422A1 (en) * | 1973-10-05 | 1975-04-17 | Gen Electric | LIQUID DIELECTRIC IMPRAEGNATION PREPARATION FOR ELECTRICAL APPARATUS |
-
1981
- 1981-03-30 CA CA000374173A patent/CA1149602A/en not_active Expired
- 1981-04-30 DE DE19813117318 patent/DE3117318A1/en not_active Withdrawn
- 1981-05-21 JP JP7732681A patent/JPS5763825A/en active Pending
- 1981-09-04 SE SE8105267A patent/SE8105267L/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5763825A (en) | 1982-04-17 |
| SE8105267L (en) | 1982-03-23 |
| DE3117318A1 (en) | 1982-04-08 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4420791A (en) | Dielectric fluid | |
| CA1154503A (en) | Electrical capacitors | |
| US4536331A (en) | Non-toxic impregnant for electrical capacitors | |
| US4744000A (en) | Electrical capacitor having improved dielectric system | |
| CA2443621C (en) | Dielectric fluid | |
| US2456381A (en) | Electric capacitor | |
| CA1149602A (en) | Non-toxic impregnant for electrical capacitors | |
| US4521826A (en) | Dielectric fluid for a compacitor | |
| US2166180A (en) | Electrolytic condenser | |
| CA1070102A (en) | Electrical capacitor having an improved dielectric system and method of processing the capacitor | |
| US3588644A (en) | Electrical apparatus and stabilized dielectric therefor | |
| US4538208A (en) | Alternating current capacitor | |
| US4679119A (en) | Dielectric fluid for electrical capacitors | |
| US4110496A (en) | Dielectric system for an electrical apparatus | |
| US4476516A (en) | Dielectric fluid for electrical capacitors | |
| CA1153193A (en) | Non-toxic impregnant for electrical capacitors | |
| US4330439A (en) | Electric device comprising impregnated insulating materials and electric elements | |
| CA1153194A (en) | Non-toxic impregnant for electrical capacitors | |
| US4097912A (en) | Electrical capacitor having an impregnated dielectric | |
| US3025440A (en) | Electrical device and dielectric material therefor | |
| US3509425A (en) | Electrolytic capacitor and electrolyte material therefor | |
| US2940025A (en) | Electrical capacitor | |
| US2196057A (en) | Electric capacitor | |
| US3619745A (en) | Capacitor having an impregnated dielectric | |
| KR830002522B1 (en) | Electrical apparatus consisting of electrical elements impregnated with insulating material |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |