US 12,135,321 B2
Oil deterioration detection device, oil deterioration detection system, and oil deterioration detection method
Ikumi Watanabe, Tokyo (JP); Toshiyasu Kiyabu, Tokyo (JP); and Akihiko Yano, Tokyo (JP)
Assigned to MITSUBISHI HEAVY INDUSTRIES, LTD., Tokyo (JP)
Filed by MITSUBISHI HEAVY INDUSTRIES, LTD., Tokyo (JP)
Filed on Oct. 4, 2022, as Appl. No. 17/959,723.
Claims priority of application No. 2021-168376 (JP), filed on Oct. 13, 2021.
Prior Publication US 2023/0112726 A1, Apr. 13, 2023
Int. Cl. G01N 33/28 (2006.01); G01N 27/02 (2006.01)
CPC G01N 33/2888 (2013.01) [G01N 27/02 (2013.01)] 10 Claims
OG exemplary drawing
 
1. An oil deterioration detection device comprising a processor configured to:
perform an analysis based on impedances at at least three first specific frequencies selected from a first frequency range to calculate an arc of impedance on a Nyquist diagram, the impedances being measured by applying an AC voltage at the at least three first specific frequencies to counter electrodes when oil to be evaluated passes between the counter electrodes, and
when the calculated arc is larger than a reference arc calculated in advance of the oil to be evaluated by a predetermined value or larger, determine that moisture is mixed and calculate an amount of moisture based on a shape of the calculated arc,
wherein the oil deterioration detection device configured to obtain impedances measured by applying an AC voltage at at least two second specific frequencies selected from a second frequency range lower than the first frequency range to the counter electrodes, perform an analysis based on a maximum value of a real axis of a first arc of impedance serving as the arc of impedance based on the first specific frequencies and on the measured impedances at the at least two second specific frequencies, to calculate a second arc of impedance on a Nyquist diagram, and determine whether an impurity is mixed by comparing the second arc with a reference arc calculated in advance of the oil to be evaluated.