Mitsubishi Electric Corporation

Fukutaro Kato

Satoru Toyama

Kota Mizuno

Eiichi Nagao

Tsuyoshi Amimoto

Ryota Kuriyama

Shiki Hayamizu

Ryuichi Nishiura

Junji Tanimura

Noboru Hosokawa

Yoshio Kimura

The present invention is directed to a method of estimating an overheating temperature of an oil-immersed electric appliance in which ester oil is used as insulating oil. The overheating temperature is estimated based on a first concentration ratio representing a concentration ratio between two types of gas components contained in the ester oil and a second concentration ratio representing a concentration ratio between other two types of gas components contained in the ester oil. The first concentration ratio and the second concentration ratio are selected from a concentration ratio between acetylene and ethane, a concentration ratio between acetylene and hydrogen, a concentration ratio between acetylene and methane, and a concentration ratio between acetylene and ethylene.

Method of estimating overheating temperature of oil-immersed electric appliance

The present invention is a diagnosis method for internal fault of an oil-immersed electric apparatus using a silicone oil as an insulating oil. The method diagnoses an internal fault of the oil-immersed electric apparatus based on a first concentration ratio that is a concentration ratio between two gases selected from an analysis gas group consisting of hydrogen gas, methane gas, ethane gas, and ethylene gas contained in the, silicone oil, and a second concentration ratio that is a concentration ratio between the other two gases selected from the analysis gas group. A combination of the two gases and a combination of the other two gases are a combination of ethylene gas and hydrogen gas, a combination of ethane gas and hydrogen gas, a combination of ethylene gas and methane gas, or a combination of methane gas and ethane gas.

Diagnosis method for internal fault of oil-immersed electric apparatus

The method for diagnosing the oil-filled electrical apparatus in the present invention is a method for diagnosing whether or not discharge has occurred inside the oil-filled electrical apparatus. The diagnosing method includes: an in-oil gases analyzing step of analyzing hydrogen gas and a gas selected from the group consisting of methane, ethane, ethylene, acetylene, hydrocarbon having a carbon number of 3 or 4, carbon monoxide, carbon dioxide, oxygen, and nitrogen, contained in an insulating oil used inside the oil-filled electrical apparatus; a step of analyzing a causative substance serving as a cause of generation of hydrogen in the insulating oil irrespective of whether or not the discharge has occurred; and a step of diagnosing whether or not the discharge has occurred based on an analysis result of the in-oil gases analyzing step and an analysis result of the step of analyzing the causative substance.

Method for diagnosing oil-filled electrical apparatus

The present invention is a method for preventing copper sulfide generation in oil-filled electrical equipment having an inhibitor of copper sulfide generation in insulating oil, and the method is characterized in monitoring characteristics of the insulating oil and performing re-addition of the inhibitor at an appropriate moment in accordance with a result of the monitoring.

Method for suppressing copper sulfide generation in oil-filled electrical equipment

The present invention relates to an electric insulating oil inspection method for determining whether or not an inhibitor-consuming substance is present in an electric insulating oil. The inhibitor-consuming substance is such a substance that causes to decrease over time a concentration of an inhibitor which is added to the electric insulating oil to inhibit copper sulfide from being generated on an insulating paper immersed in the electric insulating oil. The electric insulting oil inspection method includes steps of: preserving the electric insulating oil at a predetermined condition, measuring a concentration of the inhibitor, and determining that the inhibitor-consuming substance is present upon condition that a decrement of the concentration of the inhibitor relative to an initial concentration of the inhibitor becomes not less than a specified amount within a predetermined period.

Electric insulating oil inspection method, electric insulating oil treatment method, and oil-filled electric device maintenance method

The present invention provides a method for inhibiting production of copper sulfide in an electrical insulating oil inside an oil-filled electrical apparatus, including adding a benzotriazole compound not having a long-chain alkyl group when the oil-filled electrical apparatus is an open-type oil-filled electrical apparatus, or adding a benzotriazole compound having a long-chain alkyl group when the oil-filled electrical apparatus is a closed-type oil-filled electrical apparatus.

Method for inhibiting generation of copper sulfide

An initial concentration of the residual concentration of a causative substance contained in an insulating oil is compared with a reference value. The causative substance reacts with a conductor forming a winding of an oil-filled electrical device to generate an electrically conductive compound. The reference value is defined as a value for determining whether a main determinant that determines the lifetime of the oil-filled electrical device is generation of the electrically conductive compound or degradation of insulating paper. Based on the initial concentration of the causative substance and the reference value, the lifetime of the oil-filled electrical device is assessed.

Lifetime assessment apparatus and method for oil-filled electrical device, and degradation suppression apparatus and method for oil-filled electrical device

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Chiyoda-ku, Japan

Fukutaro Kato