Abstract: A Dielectric Energy Storage System (DESS) and method that stores energy for a wide variety of applications.

Abstract: A method and apparatus for storing energy. An apparatus comprises a first plate, a second plate, and a spacer. The spacer comprises a material having a plurality of pores, being open pores. The spacer is located between the first plate and the second plate. The apparatus further includes an enclosure, the first plate, the second plate, and the spacer located within the enclosure, the enclosure defining a volume, wherein the enclosure further defines a wall, and further comprising a second spacer disposed between the wall and one of the first plate and the second plate.

Abstract: A two-phase mixed media insulator having a dielectric fluid filling the interstices between macro-sized dielectric beads packed into a confined volume, so that the packed dielectric beads inhibit electro-hydrodynamically driven current flows of the dielectric liquid and thereby increase the resistivity and breakdown strength of the two-phase insulator over the dielectric liquid alone. In addition, an electrical apparatus incorporates the two-phase mixed media insulator to insulate between electrical components of different electrical potentials. And a method of electrically insulating between electrical components of different electrical potentials fills a confined volume between the electrical components with the two-phase dielectric composite, so that the macro dielectric beads are packed in the confined volume and interstices formed between the macro dielectric beads are filled with the dielectric liquid.

Abstract: A fluid cooled electrical capacitor assembly (10) includes a stack of honeycomb sheet-like structures (12) of dielectric material with an electrode (16) between each pair of honeycomb sheet-like structures. Alternate electrodes are electrically coupled together to each other and may be coupled to respective terminals of an electrical circuit. Fluid passages (20) in the honeycomb sheet-like structures provide a place for fluid (20a) to affect electrical characteristics of the capacitor assembly and/or to provide for cooling while preventing the fluid from contacting the electrodes. A method of assembling a capacitor assembly includes placing capacitor subunits including a dielectric honeycomb sheet-like structure and an electrode in parallel planar, overlying relation with the honeycomb. A method of cooling a capacitor assembly of dielectric honeycomb structure and electrodes includes directing a fluid through flow channels in the honeycomb structure.

Abstract: An embodiment relates to a liquid composite dielectric material (LCDM) comprising a metal-containing dispersed phase material in an organic liquid phase material, wherein the liquid composite dielectric material has a dielectric permittivity (?r) of 10000 or more at 40 Hz and a dielectric loss (tan ?) of 1 or less at 40 Hz.

Abstract: A method is provided for making a high permittivity dielectric material for use in capacitors. Several high permittivity materials in an organic nonconductive media with enhanced properties and methods for making the same are disclosed. A general method for the formation of thin films of some particular dielectric material is disclosed, wherein the use of organic polymers, shellac, silicone oil, and/or zein formulations are utilized to produce low conductivity dielectric coatings. Additionally, a method whereby the formation of certain transition metal salts as salt or oxide matrices is demonstrated at low temperatures utilizing mild reducing agents. Further, a circuit structure and associated method of operation for the recovery and regeneration of the leakage current from the long-term storage capacitors is provided in order to enhance the manufacturing yield and utility performance of such devices.

Abstract: An electronic component (2) for application in high pressure environments has a casing (4) entirely filled with an electrically insulating first fluid (F1), whereby the casing (4) exhibits or connects to a volume compensation unit for compensating a volume change of the first fluid (F1). An electric device (1) has at least one such electronic component (2) in a device housing (10), whereby the device housing (10) is filled with a second fluid (F2).

Abstract: A connector assembly utilizes capacitive coupling for connecting two substrates. The connector assembly includes first and second connector frames which may be respectively attached to first and second substrates. The first connector frame includes a plurality of first conductors connected to circuits on the first circuit substrate and these conductors have exposed contact surfaces with a dielectric material disposed thereon. The first conductors and associated dielectric material confront second, opposing conductors supported by the second connector frame when the connector frames are engaged together. The first connector frame has a recess formed therein so that its conductors and dielectric material are arranged at a level beneath the top surface of the first connector frame.

Abstract: At least one wound film/foil or metalized film capacitor is sealed between its electrodes to form a sealed enclosed annular region between the interior of the enclosure, the electrodes and the exterior of the wound capacitor to form a sealed capacitor assembly. A fluid dielectric can be introduced into the sealed enclosed annular region under a vacuum to form a sealed and impregnated wound capacitor assembly.

Abstract: A molten dielectric capacitor energy storage system for storing and providing power to an electric motorized vehicle. The molten dielectric capacitor energy storage system has an outer shell defining a hollow interior, a first conductive electrode with at least one first conductive plate, a second conductive electrode with at least one second conductive plate, and a dielectric material made of at least opal and sodium nitrite located in the hollow interior of the outer shell said. The first and second conductive plates are located in the hollow interior of the outer shell adjacent to each other defining a gap therebetween and are immersed in the dielectric material. A heating element is used to maintain the dielectric material in a molten phase.

Abstract: At least one wound film/foil or metalized film capacitor is sealed between its electrodes to form a sealed enclosed annular region between the interior of the enclosure, the electrodes and the exterior of the wound capacitor to form a sealed capacitor assembly. A fluid dielectric can be introduced into the sealed enclosed annular region under a vacuum to form a sealed and impregnated wound capacitor assembly.

Abstract: A dielectric fluid that provides improved resistance to device failure in capacitors comprising combinations of certain anthraquinone compounds and scavengers. Capacitors including the dielectric fluid can have a higher discharge inception voltage and can have increased failure threshold voltages in comparison to capacitors made without the combination. Therefore, these capacitors are more resistant to failures.

Abstract: A method is provided for making a high permittivity dielectric material for use in capacitors. Several high permittivity materials in an organic nonconductive media with enhanced properties and methods for making the same are disclosed. A general method for the formation of thin films of some particular dielectric material is disclosed, wherein the use of organic polymers, shellac, silicone oil, and/or zein formulations are utilized to produce low conductivity dielectric coatings. Additionally, a method whereby the formation of certain transition metal salts as salt or oxide matrices is demonstrated at low temperatures utilizing mild reducing agents. Further, a circuit structure and associated method of operation for the recovery and regeneration of the leakage current from the long-term storage capacitors is provided in order to enhance the manufacturing yield and utility performance of such devices.

Abstract: A high voltage capacitor includes multiple conductive strips on each side of a dielectric layer. The conductive strips on one side of the dielectric layer partially overlap conductive strips on the opposite side of the dielectric layer, in effect forming a series combination of subcapacitors. Insulating layers may overlay the conductive strips, sandwiching the strips between one of the insulating layers and the dielectric layer. To decrease the magnitude of the electric field between adjacent conductive strips on the same side of the dielectric layer, the gaps between the adjacent strips are filled with a dielectric liquid during the manufacturing process. The dielectric liquid may be, for example, aromatic oil, silicone oil, mineral oil, synthetic oil, a mixture of different oils, or a mixture of oil or oils with another substance. The resulting decrease in the magnitude of the electric field within the gaps reduces partial discharge in the capacitor.

Abstract: Capacitors (10,20,40,50,70,80) having a fluid dielectric material that is transported or undergoes a phase change are disclosed. The dielectric medium change results in a change in the total dielectric constant of the material between the electrodes (12, 14, 72, 74, 81, 82), thus changing the capacitance of the capacitors. Transporting or phase changing the dielectric fluids into and out of a the electric field of the capacitor, changes the effective dielectric constant and the capacitance of the capacitor.

Abstract: Based on the discovery that the melting point and solubility of onium salts are affected by the asymmetry of the substitution on cation, and that the branched substituents effectively shield onium cations from electrochemical reduction, new onium salts are synthesized and high performance electrolytes based on these salts for electrochemical capacitor are provided. The composition of the new electrolyte comprises an onium salt or mixture of such onium salts dissolved in aprotic, non-aqueous solvents or mixture of such solvents. The electrolyte is able to perform at high rate of charge/discharge, at low ambient temperatures, and within wide operating voltage, due to the high solubility, low melting temperature, and the improved reduction stability of the new onium cations, respectively.

Abstract: The present invention concerns the field of solid state capacitors and relates particularly to massed production methods for manufacturing solid state capacitors.

Abstract: The present invention is a module insertion tool. The module insertion tool has two drivers on either side that operate independently of each other, and help in anchoring the module to a motherboard. There is a knob that is connected to a chain that turns the drivers until a preset torque value is reached. Since the two drivers are independent of each other, each driver turns until the preset torque value on its side is reached. This preset torque value can be obtained by either manually turning the knob, or by attaching an electric source to a socket built into the knob. There are three locators on a bottom plate that help in the alignment of the module, and there are locking pins on each driver that hold the module stationary while it is being anchored to the motherboard.

Abstract: A desired performance characteristic of an electrical circuit employing a strip conductor is achieved by placing a fluid having a selected dielectric property in contact with at least a portion of the strip conductor, such that the dielectric property of the fluid effects one or more transmission characteristics of the conductor. In one embodiment, the circuit performance is measured and the dielectric property of the fluid adjusted, e.g., in an iterative process, until the desired performance characteristic of the circuit is achieved.

Abstract: A power transfer device adapted for interconnection with the electrical system of a building includes a cabinet, a set of switches mounted to the cabinet, and wires adapted to connect the switches to an electrical distribution panel associated with a building electrical system. The power transfer device includes a compartment associated with the cabinet, and a selectively configurable cover arrangement for interconnection with the cabinet so as to enclose the compartment. The cover arrangement varies according to the characteristics or parameters of the power transfer device, to provide an optional plug-type power input and an optional power input monitoring arrangement, either alone or in combination with each other, or to provide neither capability. The cover arrangement includes a series of differently configured cover sections which can be mounted to the cabinet in varying combinations, so as to vary the capability of the power transfer device.

Abstract: A new type of high-Q variable capacitor includes a substrate, a first electrically conductive layer fixed to the substrate, a dielectric layer fixed to a portion of the electrically conductive layer, and a second electrically conductive layer having an anchor portion and a free portion. The anchor portion is fixed to the dielectric layer and the free portion is initially fixed to the dielectric layer, but is released from the dielectric layer to become separated from the dielectric layer, and wherein an inherent stress profile in the second electrically conductive layer biases the free portion away from the dielectric layer. When a bias voltage is applied between the first electrically conductive layer and the second electrically conductive layer, electrostatic forces in the free portion bend the free portion towards the first electrically conductive layer, thereby increasing the capacitance of the capacitor.

Abstract: A vegetable oil-based electrically-insulating fluid. This fluid is environmentally-friendly and has a high flash point and a high fire point. The base oil is hydrogenated to produce maximum possible stability of the oil, or alternatively, is a higher oleic acid oil. The vegetable oils of the preferred embodiments are soybean or corn oils. The oil can be winterized to remove crystallized fats and improve the pour point of the base oil, without the necessity of heating the oil. The base oil can also be combined with an additive package containing materials specifically designed for improved pour point, improved cooling properties, and improved dielectric stability. The fluid is useful in electrical components such as transformers and transmission lines. The invention also provides methods for making the fluid and fluid-filled electrical components.

Abstract: A thixotropic dielectric fluid that includes vegetable oil, transformer oil, and a clay material. The thixotropic dielectric fluid is particularly suited for use in a capacitor.

Abstract: A vegetable oil-based electrically-insulating fluid. This fluid is environmentally-friendly and has a high flash point and a high fire point. The base oil is hydrogenated to produce maximum possible stability of the oil, or alternatively, is a higher oleic acid oil. The vegetable oils of the preferred embodiments are soybean or corn oils. The oil can be winterized to remove crystallized fats and improve the pour point of the base oil, without the necessity of heating the oil. The base oil can also be combined with an additive package containing materials specifically designed for improved pour point, improved cooling properties, and improved dielectric stability. The fluid is useful in electrical components such as transformers and transmission lines. The invention also provides methods for making the fluid and fluid-filled electrical components.

Abstract: The invention concerns ionic compounds in which the anionic load has been delocalized. A compound disclosed by the invention is comprised of an amide or one of its salts, including an anionic portion combined with at least one cationic portion M+m in sufficient numbers to ensure overall electronic neutrality; the compound is further comprised of M as a hydroxonium, a nitrosonium NO+, an ammonium —NH4+, a metallic cation with the valence m, an organic cation with the valence m, or an organometallic cation with the valence m. The anionic portion matches the formula RF—SOx—N−Z, wherein RF is a perfluorinated group, x is 1 or 2, and Z is an electroattractive substituent. The compounds can be used notably for ionic conducting materials, electronic conducting materials, colorants, and the catalysis of various chemical reactions.

Abstract: High oleic acid triglyceride compositions that comprise fatty acid components of at least 75% oleic acid, less than 10% diunsaturated fatty acid component; less than 3% triunsaturated fatty acid component; and less than 8% saturated fatty acid component; and having the properties of a dielectric strength of at least 35 KV/100 mil gap, a dissipation factor of less than 0.05% at 25° C., acidity of less than 0.03 mg KOH/g, electrical conductivity of less than 1 pS/m at 25° C., a flash point of at least 250° C. and a pour point of at least —15° C. are disclosed. Electrical insulation fluids comprising the triglyceride composition are disclosed. Electrical insulation fluids that comprise the triglyceride composition and a combination of additives are disclosed. Electrical apparatuses comprising the electrical insulation fluids and the use of electrical insulation fluids to provide insulation in electrical apparatuses are disclosed.

Abstract: A soybean oil based electrically insulating fluid with a high flash point and a high fire point. The base oil is hydrogenated to produce maximum possible stability of the soybean oil, and can be winterized to remove crystallized fats and improve the pour point of the base oil without the necessity of heating the oil. The base oil can also be combined with an additive package containing materials specifically designed for improved pour point, improved cooling properties, and improved dielectric stability.

Abstract: An environmentally prefered biobased soybean oil based electrically insulating fluid with a high flash point and a high fire point. The base oil is hydrogenated to produce maximum possible stability of the soybean oil, and can be winterized to remove crystallized fats and improve the pour point of the base oil without the necessity of heating the oil. The base oil can also be combined with an additive package containing materials specifically designed for improved pour point, improved cooling properties, and improved dielectric stability. The base oil is capable of conforming to the President's executive order 13101 of Sep. 14, 1998 for “Greening the Government Through Waste Prevention, Recycling, and Federal Acquisition.

Abstract: A thixotropic dielectric fluid that includes vegetable oil, transformer oil, and a clay material. The thixotropic dielectric fluid is particularly suited for use in a capacitor.

Abstract: A biodegradable soybean oil based electrically insulating fluid. The base oil is hydrogenated to produce maximum possible stability of the soybean oil, and can be winterized to remove crystallized fats and improve the pour point of the base oil without the necessity of heating the oil. The base oil can also be combined with an additive package containing materials specifically designed for improved pour point, improved cooling properties, and improved dielectric stability.

Abstract: A biodegradable soybean oil based electrically insulating fluid. The base oil is hydrogenated to produce maximum possible stability of the soybean oil, and can be winterized to remove crystallized fats and improve the pour point of the base oil without the necessity of heating the oil. The base oil can also be combined with an additive package containing materials specifically designed for improved pour point, improved cooling properties, and improved dielectric stability.

Abstract: An electrolytic capacitor of the present invention is so constituted that a capacitor element steeped with an electrolytic solution containing quaternary ammonia salts is accommodated in an armor case of which aperture is sealed with a sealing body. To achieve the above object, an external terminal of the electrolytic capacitor has a contact surface contacting with the sealing body and being coated by a ceramic coating layer.

Abstract: A metalized film capacitor has a plurality of electrodes separated by dielectric spacers and contains a dielectric fill system including 1 to 50 wt % of calcium oxide scavenger. This dielectric fill system is especially useful in aluminum metalized film capacitors for AC service.

Abstract: There is proposed an electrolytic solution having a low specific resistance, a high sparking voltage and a stable sparking property. This electrolytic solution contains a quaternary ammonium salt of cyanic acid, at least one phosphorus compound selected from an organic phosphorus acid compound, phosphoric acid and salts thereof, water and an organic solvent.

Abstract: Material for winding high voltage capacitors is prepared by evaporating polyfunctional acrylate monomer having a molecular rate in the range of from 150 to 600 and condensing the acrylate as a monomer film on a dielectric substrate. The acrylate is polymerized by irradiation by ultraviolet or electrons. Sometimes both faces of the dielectric are coated to protect the thermoplastic dielectric from swelling when exposed to dielectric liquid. The metallized layer provides an electrode of the capacitor. A polymerized acrylate layer may be applied over the metal layer. Electrical contact can be made to the metal layer by Schooping even though the metallized layer is covered by a layer of acrylate. Low oxygen permeability polypropylene, polyester or nylon sheet has a layer of crosslinked acrylate and an oxygen barrier layer formed of silicon oxide, aluminum oxide or metal. Adhesion is enhanced by plasma or corona treatment of a surface immediately before deposition.

Abstract: A process and apparatus for controlled continuous microwave digestion of samples of materials to prepare them for subsequent analyses or other chemical operations. The material to be analyzed, in finely divided form and mixed with digesting liquid, such as a strong acid, is charged as a slug into a flowing liquid carrier stream, usually water, which stream, containing the slug, is passed in a tube through a zone in which the tube and contents are subjected to microwave radiation, to heat the digesting liquid and the material to be digested to promote the digestion. The process and apparatus are modified by inclusion of detecting and controlling steps and corresponding apparatus components to detect a condition of the flowing liquid without physically contacting it, as by determining the dielectric constant of contents of the tube, or a related property of such contents at one or more locations of the tube, usually outside the microwave zone, and controlling operations of the process and apparatus accordingly.

Abstract: Dielectric materials having a high dipole moment density are provided. The high dipole moment density is achieved by the use of a substituted .alpha.-amino acid, such as N-trimethyl glycine and related homologues having nonpolar sidechain groups, with three alkyl substitutions on the nitrogen of the .alpha.-amino group. These molecules have a high dipole moment and small volume, allowing rapid rotation around the .alpha.-amino, carboxyl dipole. N-trimethyl glycine alone or in combination with one or more homologues is preferably provided as a solute in a liquid dielectric solution. Alternatively, these molecules are provided as substituents on a linear polymer.

Abstract: An electrical film capacitor in which a pair of metal film electrodes and a porous layer are wound into an assembly, and in which the porous layer serves to wick a liquid dielectric into the wound assembly. The liquid dielectric is an adipic acid ester such as di-isononyl adipate. Mono-isopropyl biphenyl can be added as well.

Abstract: A liquid filled variable capacitor or PFL which provides variable frequen impedance, and pulse length without changing the capacitor or PFL hardware. The capacitor is constructed from two or more conducting surfaces. A dielectric fluid mixture separates the conductors. A fluid supply system furnishes the dielectric fluid mixture to the conductors and provides for varying of the dielectric constant of the fluid and thus the capacitor operating characteristics, by varying the mixture composition. The fluid supply system has a mixing tank connected to both a supply of high dielectric constant fluid and a supply of low dielectric constant fluid. The high dielectric constant fluid and low dielectric constant fluid are mixed proportionally to obtain a dielectric fluid having the desired dielectric constant. A pump conveys the dielectric fluid between the mixing tank and the conductors while a heat exchanger controls the temperature of the dielectric fluid.

Abstract: A new electrical insulating oil composition having improved low temperature characteristics which composition comprises a mixture of 40% by weight or more of benzyltoluene and the remainder of alkyl substituted diphenylmethane having 15 to 17 carbon atoms which is represented by the following general formula: ##STR1## wherein R.sub.1 and R.sub.2 are C.sub.1 to C.sub.4 alkyl groups and the total number of carbon atoms in R.sub.1 and R.sub.2 is 1 to 4, with the proviso that R.sub.1 and R.sub.2 may not simultaneously be methyl groups and the proportion of the total quantity of solid phase calculated according to the following general solid-liquid equilibrium equation is 45% by weight or less relative to the total quantity of said composition at -40.degree. C.: ##EQU1## where X.sub.i is the equilibrium mole fraction of a component i, in the liquid phase, .DELTA.H.sub.i.sup.f is the heat of fusion (cal.mol.sup.-1), T.sub.i.sup.

Abstract: A circuit component 100 or (200) comprising typically of a hollow body 101 (201) and a plurality of solderable terminations (102 and 103 (202 and 203) is being disclosed. Internal to said circuit component 100 (200) is a plurality of electrodes 104 and 106 (204 and 206). A filling point 108 (208) is provided so as to fill the volume of said circiut component (100 (200 ) with a specific compound 114 (214) having a desired electrical characteristics including dielectric constant. A method for manufacturing said circuit component 100 (200) is disclosed.

Abstract: An electrical insulating oil composition which comprises 45% by weight or more of at least 2 members selected from the group consisting of (a) m-ethylbiphenyl, (b) p-ethylbiphenyl, (c) o-benzyltoluene, (d) m-benzyltoluene, (e) p-benzyltoluene, and (f) 1,1-diphenylethane; and the remainder of non-condensed bicyclic aromatic hydrocarbons having not more than 17 carbon atoms besides the above 6 components; and is characterized in that, when the temperature of the composition is -40.degree. C., (I) the total quantity of solid phase obtained by calculating according to the following solid-liquid equilibrium equation is 45% by weight or less relative to the total quantity of the composition, and (II) in the liquid phase composition calculated by the following solid-liquid equilibrium equation, the total quantity of the compounds (a) to (f) is 40% by weight or more and the viscosity of this liquid phase is 500 cSt or lower, ##EQU1## wherein X.sub.

Abstract: An electrical insulating oil composition having good low temperature characteristics which comprises at least 4 members selected from the group consisting of (a) m-ethylbiphenyl, (b) p-ethylbiphenyl, (c) o-benzyltoluene, (d) m-benzyltoluene, (e) p-benzyltoluene, (f) 1,1-diphenylethane, and (g) 1,1-diphenylethylene; and is characterized in that the proportion of solid phase at a temperature of -40.degree. C. of the electrical insulating oil composition is not more than 45% by weight and the proportion of the total quantity of solid phase is calculated according to the following general equation of solid-liquid equilibrium: ##EQU1## wherein X.sub.i is the equilibrium mole fraction of a component i in the liquid phase of the composition, .DELTA.H.sub.i.sup.f is the heat of fusion (cal.mol.sup.-1), T.sub.i.sup.f is the melting point (K), t is the temperature (K), and R is the gas constant (cal.mol.sup.-1.K.sup.-1).

Abstract: The present invention relates to an improved electrical insulating oil composition which has excellent electrical characteristics and is suitable for use in impregnating electrical appliances in which plastic dielectric material is used, and further relates to electrical appliances impregnated with such a composition. The electrical insulating oil composition is produced by bringing a by-product oil fraction mainly containing components having boiling points in the range of 260.degree. to 330.degree. C. (atmospheric pressure basis) into liquid-liquid contact with an organic polar solvent; said by-product oil fraction being formed by alkylating benene or toluene with ethylene in the presence of an alkylation catalyst and then distilling the alkylation product; and said electrical insulating oil composition being characterized in that the ratio of the integrated intensity as chemical shift at 120 to 155 ppm of the spectrum measured by .sup.

Abstract: A three-terminal capacitor having high and low voltage electrodes coaxially aligned in a housing which serves as a ground plane includes a non-gaseous dielectric material filling the cavity of the housing. In the preferred embodiments, the dielectric is either a suitable oil or plastic. A source of voltage, that can be used to power for example an external electrical measuring device, can be generated by arranging a tertiary electrode proximate to the high voltage electrode and suitably selecting the ratio of surface areas of the tertiary and high voltage electrodes to produce sufficient current to power the device. Various embodiments of the capacitor also include and internal current transformer which provides a current signal indicative of series current flow through the capacitor. This current signal and the signal appearing on the low voltage electrode can be used to readily provide an indication of the amount of power supplied by a power transmission line to a load situated downstream of the capacitor.

Abstract: The invention relates to the use of certain aromatic compounds of the formula ##STR1## in which R', R" and X have the meaning given in the description,as dielectric liquids for high-energy voltage-storage capacitors, and to dielectric liquids containing these aromatic compounds, for these high-power capacitors.

Abstract: A three-terminal capacitor having high and low voltage electrodes coaxially aligned in a housing which serves as a ground plane includes a non-gaseous dielectric material filling the cavity of the housing. In the preferred embodiments, the dielectric is either an oil or plastic. A source of power voltage can be generated by arranging a tertiary electrode proximate to the high voltage electrode and selecting the ratio of surface areas to produce sufficient current to power an external device.

Abstract: An electrical capacitor is built into a metallic housing, the capacitor having end contact layers and being fixed in the housing with the assistance of pressure ribs arranged at an outside edge of an insulating cap. The insulating cap has an inner space in which a terminal element is arranged. The other terminal element is insulated from the differently polarized end contact layer by a connector or sleeve arranged in the insulating cap. The housing the filled with an insulating oil up to a defined level. Aeration holes are arranged at an upper side of is insulating cap to prevent gas bubbles from arising under the insulating cap.

Abstract: An insulating oil containing N,N-bis(2-hydroxyethyl)-N-cyclohexylamine at 0.5 mg/l or more. An electrical apparatus is filled with the insulating oil in which a copper component is immersed. During operation of the apparatus for a long period of time, the tan .delta. of the insulating oil does not increase so that deterioration of the insulating oil is deferred, thereby substantially extending the life of the insulating oil.

Abstract: An electrical insulating oil composition which is excellent in low temperature characteristics and suitable for use in impregnating capacitors, and comprises (a) m-ethylbiphenyl, (b) p-ethylbiphenyl, (c) m-isopropylbiphenyl and (d) p-isopropylbiphenyl, and is characterized in that the total amount of the ethylbiphenyls is not less than 40% by weight and the proportion of solid phase in the composition at a temperature of -40.degree. C. is not more than 45% by weight, the solid quantity of each component being calculated according to the following equation of solid-liquid equilibrium: ##EQU1## wherein X.sub.1 is the equilibrium mole fraction of a component i in the liquid phase of the composition, .DELTA.H.sub.i.sup.f is the heat of fushion (cal.mol.sup.-1) of the component i, T.sub.i.sup.f is the melting point (K) of the component i, T is the temperature (K) of the system, and R is the gas constant (cal.mol.sup.-1.K.sup.-1).