Dielectric Thermoscopy Characterization of Water Contaminated Grease

Dittes, Nicholas; Pettersson, Anders; Marklund, Pär; Lang, Defeng; Lugt, Piet M.

doi:10.1080/10402004.2017.1333664

Cited by 5 publications

(6 citation statements)

References 14 publications

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“…Low frequencies have an advantage of having an e ' value of orders of magnitude higher than the typical higher frequencies used in dielectric measurements, in addition to the temperature dependence used in this dielectric thermoscopy method. A brief background was further described in a previous paper (7). As a further observation in Fig.…”

Section: Greasementioning

confidence: 94%

“…The theoretical performance of the sensor is given next. A similar derivation is given in (7); however, the theory has since then been further modified in this article to accommodate estimating the difference due to a thin coating with a different dielectric constant in between the traces and on top. This could be useful if it is found that coatings of a different hydrophobicity help improve the performance or behavior of the sensor with different greases.…”

Section: Sensor Designmentioning

confidence: 99%

“…For the purposes of attempting to acquire a correlation with water content, only the capacitance at 90 Hz is used. This frequency was used because it was shown in previous research to have less noise than lower frequencies, to provide a useful correlation with water content, and to not be a multiple of 50-or 60-Hz line frequencies, which could likely cause problems with electrical noise (7). The other frequencies are used only to show the frequency dependence to better understand the behavior of the sensor.…”

Section: Temperature and Capacitance Data Acquisitionmentioning

confidence: 99%

“…The dashed lines represent the fit according to Eq. [7], and the slope of the line fit represents the capacitance temperature slope: dC/dT (Farads/ C). Hysteresis is initially present but is practically absent after time has passed or several subsequent measurements are made.…”

Section: Temperature and Capacitance Data Acquisitionmentioning

confidence: 99%

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Automated Dielectric Thermoscopy Characterization of Water-Contaminated Grease

Dittes

Sjödahl

Pettersson

et al. 2019

Tribology Transactions

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Machine maintenance is important for improving machine uptime and reliability, and for reducing costs. Grease is used in most rolling element bearings, and one common failure criterion is water contamination, so developing a sensor that can detect water content automatically without human input could be a useful endeavor. The temperature dependence on the dielectric properties of water-contaminated grease is investigated in this article with computer logged instrumentation. This method has been termed dielectric thermoscopy (DT). Several off-the-shelf (two lithium, one lithium complex, and two calcium sulfonate complex) and one unadditivized lithium grease are tested with varying amounts of water contamination from 0% to approximately 5%. Another grease is tested with small increments of added water from 0% to 0.97% to test the resolution of the measurement. The purpose is to use the capacitance temperature slope (termed dielectric thermoscopy) to show correlations to the water content of the grease sample and investigate whether any grease types will pose problems in the measurement. A small, custom-made fringe field capacitance sensor with an integrated temperature sensor has been used for this characterization, and data are logged automatically with laboratory equipment and a personal computer (PC). A useable and positive correlation to water content and the DT measurement of roughly 0.5 pF per 10 C and percentage of water was found, although it was found that some greases have different behavior than others.

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Section: Greasementioning

confidence: 94%

Section: Sensor Designmentioning

confidence: 99%

Section: Temperature and Capacitance Data Acquisitionmentioning

confidence: 99%

Section: Temperature and Capacitance Data Acquisitionmentioning

confidence: 99%

See 2 more Smart Citations

Automated Dielectric Thermoscopy Characterization of Water-Contaminated Grease

Dittes

Sjödahl

Pettersson

et al. 2019

Tribology Transactions

Self Cite

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“…Furthermore, they use hazardous chemical reagents and fragile glass vessels. Beyond conventional grease-water content determination methods, there are also some novel approaches that have not yet been widely exploited, such as dielectric thermoscopy (Dittes et al, 2018). This method applies the temperature dependence of the dielectric properties of water-contaminated grease inside a test cell to estimate its water content by quantifying the change in the dielectric constant over a temperature change within a certain frequency range.…”

Section: Introductionmentioning

confidence: 99%

Laboratory robustness validation of a humidity sensor system for the condition monitoring of grease-lubricated components for railway applications

Dubek,

Schneidhofer,

Dörr

et al. 2024

J. Sens. Sens. Syst.

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Abstract. The condition monitoring of the health status of lubricating greases used in axle box bearings can be realized by applying well-established electrical or optical measurement principles. Furthermore, some novel methods have been reported that make use of humidity sensors or of dielectric thermoscopy. One of the most important grease condition parameters is the water content of the lubricating grease, as water can degrade grease to the point that it is no longer able to provide suitable lubrication and can also damage the bearing due to corrosion and cavitation. In this study, a new approach for water detection in lubricated wagon components is presented that is based on commercially available humidity sensors. The core element of this sensor system is a robust humidity sensor mounted in the immediate atmosphere of the grease-lubricated wagon axle bearing. In the case of water intake, the humidity of the gaseous atmosphere above the grease increases and can be detected by the customized sensor concept Humidity Sensor in Axle Bearings (HSAB). As this sensor system has to be sufficiently robust, it must be able to withstand environmental impact factors. The most important of these factors are temperature, relative humidity, and mechanical load, like vibrations and shocks, depending on the relevant railway application. To mimic these field effects under controlled laboratory conditions, the “lab-to-field” approach was set up and employed. Of the utmost importance was the installation of a development environment for the sensors that enabled the transfer of laboratory results to the respective rail field application. As a result, the HSAB system shows promise with respect to enhancing the reliability of railway wagons and decreasing maintenance costs, thereby reducing the downtime of railway wagons significantly.

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