4.3 - A Multichannel IR Sensor System for Condition Moni¬toring of Technical Fluids

Event
SENSOR+TEST Conferences 2011
2011-06-07 - 2011-06-09
Nürnberg
Band
Proceedings IRS² 2011
Chapter
I4 - Infrared Spectroscopy
Author(s)
T. Bley - Zentrum für Mechatronik und Automatisierungs¬technik GmbH, Saarbrücken (Germany), A. Schütze - Universität des Saarlandes, Saarbrücken (Germany)
Pages
94 - 99
DOI
10.5162/irs11/i4.3
ISBN
978-3-9810993-9-3
Price
free

Abstract

Determination of the current fluid condition is of interest in many applications making use of technical fluids. In order to avoid machine downtime due to excessive deterioration, oil changes are often made well before reaching a critical state based on a fixed number of operating hours or, alternatively, analyzing oil samples in the lab. However, oil sample analysis is rather costly and some uncertainty concerning the machine condition remains during and between sampling. This problem is especially relevant in applications, where complex systems depend on the correct function of a critical component, i.e. a transformer. With the focus on saving cost through better resource management and the reduction of machine downtimes, exact condition monitoring of technical fluids is becoming increasingly important. In addition to the economic advantages a reduction of the environmental impact of technical systems is highly desirable.
We realized a miniaturized infrared (IR) multichannel sensor system for continuous condition monitoring of technical fluids, e.g. to determine oil deterioration online in hydraulic systems, motors, gears etc. The system is based on a miniaturized measurement cell combined with a commercial IR light source and four thermopile IR detectors with different narrow bandwidth optical filters. The IR emitter sends a broad IR spectrum through the measurement cell with an optical path length of 0.2 mm to the quadruple thermopile detector. The detector signals are amplified and registered for evaluation. Using a quadruple thermopile detector provides four specific filter wavelengths which can be chosen for evaluation of the oil degradation. One filter is required as reference for the signal intensity to suppress the influence of broadband contaminations like soot or degradation of the IR source. The measurement of the grade of degradation of technical fluids like hydraulic oils can be achieved by
analyzing the oil in the near infrared spectrum. The presentation will show the sensor system and measurement set-up as well as results for native and synthetic fluids, e.g. taken from the engine of a communal heating/ power station.

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