Abstract: The water-concentration detection device for detecting a water concentration of insulating gas filled in a gas-insulated device includes: porous electrodes having porous properties that are arranged to face each other in the insulating gas; a solid electrolyte membrane that is sandwiched between and fixedly attached to the electrodes and has hydrogen-ion conductivity; a voltage application unit that applies an alternating-current voltage at a frequency of 325 Hz or a frequency of 10 Hz or lower to the electrodes; an impedance measurement unit that measures an alternating-current impedance between the electrodes in a state in which the alternating-current voltage is applied to the electrodes; and a water-concentration detection unit that detects the water concentration of the insulating gas based on the alternating-current impedance measured by the impedance measurement unit.

Abstract: A water-concentration detection device is configured to detect a water concentration of insulating gas filled in a gas-insulated device. The water-concentration detection device includes: a gas chamber in which the insulating gas introduced from the gas-insulated device is enclosed; electrodes that are porous and are arranged to face each other within the gas chamber; a solid electrolyte membrane that is hydrogen-ion conductive and is held between and fixedly attached to the electrodes; an impedance measurement unit that measures an alternating-current impedance between the electrodes by applying an alternating-current voltage to the electrodes; a water-concentration detection unit that detects the water concentration of the insulating gas based on the alternating-current impedance measured by the impedance measurement unit; and a drying unit that removes water from an atmosphere in the gas chamber before the insulating gas is introduced into the gas chamber from the gas-insulated device.

Abstract: The water-concentration detection device for detecting a water concentration of insulating gas filled in a gas-insulated device includes: porous electrodes having porous properties that are arranged to face each other in the insulating gas; a solid electrolyte membrane that is sandwiched between and fixedly attached to the electrodes and has hydrogen-ion conductivity; a voltage application unit that applies an alternating-current voltage at a frequency of 325 Hz or a frequency of 10 Hz or lower to the electrodes; an impedance measurement unit that measures an alternating-current impedance between the electrodes in a state in which the alternating-current voltage is applied to the electrodes; and a water-concentration detection unit that detects the water concentration of the insulating gas based on the alternating-current impedance measured by the impedance measurement unit.

Abstract: A water-concentration detection device is configured to detect a water concentration of insulating gas filled in a gas-insulated device. The water-concentration detection device includes: a gas chamber in which the insulating gas introduced from the gas-insulated device is enclosed; electrodes that are porous and are arranged to face each other within the gas chamber; a solid electrolyte membrane that is hydrogen-ion conductive and is held between and fixedly attached to the electrodes; an impedance measurement unit that measures an alternating-current impedance between the electrodes by applying an alternating-current voltage to the electrodes; a water-concentration detection unit that detects the water concentration of the insulating gas based on the alternating-current impedance measured by the impedance measurement unit; and a drying unit that removes water from an atmosphere in the gas chamber before the insulating gas is introduced into the gas chamber from the gas-insulated device.

Abstract: A gas sensor which can be used for measuring a low concentration repeatedly, which has a quick response and which can be used for a long time with high stability is provided. The gas sensor comprises a solid electrolyte, a detecting electrode provided in contact with one of the surfaces of the solid electrolyte and exposed to a gas to be detected, a counter electrode, provided in contact with the other surface of the solid electrolyte, and lead wires to place an electric voltage across both electrodes or to take out electric signals, wherein an inactive substance which is hard to form a reaction product with the gas to be detected is used as a material to constitute both electrodes.