Abstract: The corrosion detection sensor detects corrosion to an electrical apparatus caused by a corrosive gas. The corrosion detection sensor includes a metal thin film to be corroded by the corrosive gas, a resistive element connected in series to the metal thin film, a resistance measuring instrument that measures a combined resistance of the metal thin film and the resistive element, and a notification unit that outputs a detection result indicating that the combined resistance measured by the resistance measuring unit is greater than a predetermined reference resistance. The reference resistance is determined according to a danger level indicating that the electrical apparatus is corrosively damaged by the corrosive gas.

Abstract: The corrosion detection sensor detects corrosion to an electrical apparatus caused by a corrosive gas. The corrosion detection sensor includes a metal thin film to be corroded by the corrosive gas, a resistive element connected in series to the metal thin film, a resistance measuring instrument that measures a combined resistance of the metal thin film and the resistive element, and a notification unit that outputs a detection result indicating that the combined resistance measured by the resistance measuring unit is greater than a predetermined reference resistance. The reference resistance is determined according to a danger level indicating that the electrical apparatus is corrosively damaged by the corrosive gas.

Abstract: The liquid-quality adjusting apparatus of the present invention includes: a water purifying part that deionizes a machining liquid; an anticorrosive part that exchanges ions in the machining liquid with anticorrosive ions; a conductivity measuring part that measures a measured value of conductivity of the machining liquid; a storage part that stores in advance a first reference value and a second reference value which are an upper limit value and a lower limit value of conductivity applicable to machining, respectively, and a third reference value which is between the first reference value and the second reference value; and a control part that performs control on the basis of the reference values stored in the storage part and the measured value of the conductivity of the machining liquid measured by the conductivity measuring part.

Abstract: A corrosion preventing apparatus including: a water purifying part that includes a hydrogen-ion form resin and a hydroxy-ion form resin; an anticorrosive part that includes a cation form resin and an anion form resin having anticorrosive ions supported thereon; a conductivity measuring part that measures a measured value of conductivity of a machining liquid; and a control part that controls a flow of the machining liquid to the water purifying part and the anticorrosive part on the basis of the conductivity measuring part; wherein the control part performs control on the basis of predetermined first and second conductivities and the measured value measured by the conductivity measuring part.

Abstract: The liquid-quality adjusting apparatus of the present invention includes: a water purifying part that deionizes a machining liquid; an anticorrosive part that exchanges ions in the machining liquid with anticorrosive ions; a conductivity measuring part that measures a measured value of conductivity of the machining liquid; a storage part that stores in advance a first reference value and a second reference value which are an upper limit value and a lower limit value of conductivity applicable to machining, respectively, and a third reference value which is between the first reference value and the second reference value; and a control part that performs control on the basis of the reference values stored in the storage part and the measured value of the conductivity of the machining liquid measured by the conductivity measuring part.

Abstract: A corrosion preventing apparatus including: a water purifying part that includes a hydrogen-ion form resin and a hydroxy-ion form resin; an anticorrosive part that includes a cation form resin and an anion form resin having anticorrosive ions supported thereon; a conductivity measuring part that measures a measured value of conductivity of a machining liquid; and a control part that controls a flow of the machining liquid to the water purifying part and the anticorrosive part on the basis of the conductivity measuring part; wherein the control part performs control on the basis of predetermined first and second conductivities and the measured value measured by the conductivity measuring part.

Abstract: A method allowing an accurate diagnosis of a failure of an oil-filled electrical apparatus resulting from production of copper sulfide even with a small amount of an insulating oil is implemented. A diagnostic method for an oil-filled electrical apparatus for diagnosing a failure of the oil-filled electrical apparatus having a copper part disposed in an insulating oil is implemented by detecting at least one compound of bibenzyl and dibenzyl sulfide in the oil of the oil-filled electrical apparatus, to diagnose a failure of the oil-filled electrical apparatus in accordance with the detected amount of the compound. It is configured such that a failure of the oil-filled electrical apparatus resulting from production of copper sulfide can be diagnosed by detecting a specified substance, which allows an accurate diagnosis of a failure even with a small amount of the insulating oil.

Abstract: Target fluid is made into electrolyte solution when measured fluid-quality value is lower than a first condition value, by substituting an impurity anion contained in the target fluid with a predetermined anion and substituting an impurity cation contained in the target fluid with a predetermined cation, and purified when the fluid-quality value is higher than a second condition value. The above procedures are repeated, so that the fluid-quality value of the target fluid falls within a predetermined range, to make the target fluid into electrolyte solution with a correlation between pH and conductivity.

Abstract: An electrical-discharge machining apparatus for machining a workpiece using an aqueous machining fluid includes an insulator for electrically insulating a machine platen from the workpiece where the workpiece is placed. A machining-fluid-property measuring instrument measures the state of the machining fluid; and a machining-fluid-property controller maintains the pH of the machining fluid so as to be kept within 8.5 through 10.5.

Abstract: In an electric discharge machining apparatus that machines a workpiece (1) by using a water-based dielectric fluid as a dielectric fluid while a voltage is being applied to a machining gap between an electrode (2) and the workpiece (1), the electric discharge machine includes: an anticorrosive power source section (26) that applies a predetermined voltage by taking the workpiece (1) as a cathode and taking as an anode an anticorrosive electrode (25) opposing the workpiece (1) with an insulator (24) therebetween; a dielectric fluid quality measuring instrument (22) that measures a quality of the dielectric fluid; and a dielectric fluid quality control section (16, 17, 18, 19, 20, 21, 23) that controls a pH level of the dielectric fluid to be within a range from 8.5 to 10.5 on the basis of the measured result of the dielectric fluid quality measuring instrument (22).

Abstract: Target fluid is made into electrolyte solution when measured fluid-quality value is lower than a first condition value, by substituting an impurity anion contained in the target fluid with a predetermined anion and substituting an impurity cation contained in the target fluid with a predetermined cation, and purified when the fluid-quality value is higher than a second condition value. The above procedures are repeated, so that the fluid-quality value of the target fluid falls within a predetermined range, to make the target fluid into electrolyte solution with a correlation between pH and conductivity.

Abstract: A method allowing an accurate diagnosis of a failure of an oil-filled electrical apparatus resulting from production of copper sulfide even with a small amount of an insulating oil is implemented. A diagnostic method for an oil-filled electrical apparatus for diagnosing a failure of the oil-filled electrical apparatus having a copper part disposed in an insulating oil is implemented by detecting at least one compound of bibenzyl and dibenzyl sulfide in the oil of the oil-filled electrical apparatus, to diagnose a failure of the oil-filled electrical apparatus in accordance with the detected amount of the compound. It is configured such that a failure of the oil-filled electrical apparatus resulting from production of copper sulfide can be diagnosed by detecting a specified substance, which allows an accurate diagnosis of a failure even with a small amount of the insulating oil.

Abstract: A water purifying unit generates pure water by eliminating impurity ions from dielectric fluid. A corrosion-protection-ion generating unit generates corrosion protection ions, substitutes predetermined cations for impurity cations contained in the dielectric fluid, and substitutes the corrosion protection ions for impurity anions contained in the dielectric fluid. A switching unit switches a supply of the dielectric fluid between the water purifying unit and the corrosion-protection-ion generating unit. A switching control unit controls the switching unit based on a conductivity of the dielectric fluid measured by a conductivity measuring unit.

Abstract: An electrical-discharge machining apparatus for machining a workpiece (1), using an aqueous machining fluid as a machining fluid, while applying voltage across a machining gap formed between an electrode (2) and the workpiece (1), includes: an insulating means (12) for electrically insulating from the workpiece (1) a machine platen (11) where the workpiece is placed; a machining-fluid-property measuring instrument (22) for measuring a state of the machining fluid; and a machining-fluid-property control means (106,107,108,109,110,111,113) for controlling, based on a measured result from the machining-fluid-property measuring instrument (112), the pH of the machining fluid so as to be kept within 8.5 through 10.5.

Abstract: In an electric discharge machining apparatus that machines a workpiece (1) by using a water-based dielectric fluid as a dielectric fluid while a voltage is being applied to a machining gap between an electrode (2) and the workpiece (1), the electric discharge machine includes: an anticorrosive power source section (26) that applies a predetermined voltage by taking the workpiece (1) as a cathode and taking as an anode an anticorrosive electrode (25) opposing the workpiece (1) with an insulator (24) therebetween; a dielectric fluid quality measuring instrument (22) that measures a quality of the dielectric fluid; and a dielectric fluid quality control section (16, 17, 18, 19, 20, 21, 23) that controls a pH level of the dielectric fluid to be within a range from 8.5 to 10.5 on the basis of the measured result of the dielectric fluid quality measuring instrument (22).

Abstract: A water purifying unit generates pure water by eliminating impurity ions from dielectric fluid. A corrosion-protection-ion generating unit generates corrosion protection ions, substitutes predetermined cations for impurity cations contained in the dielectric fluid, and substitutes the corrosion protection ions for impurity anions contained in the dielectric fluid. A switching unit switches a supply of the dielectric fluid between the water purifying unit and the corrosion-protection-ion generating unit. A switching control unit controls the switching unit based on a conductivity of the dielectric fluid measured by a conductivity measuring unit.