A high-resolution tilt sensor is developed, which is composed of a pair of optical fiber collimators and a simple pendulum with an F-P filter. The tilt angle is measured by demodulating the shift of center wavelength of F-P filter, which is caused by incidence angle changing. The relationship between tilted angle and the center wavelength is deduced. Calibration experiment results also confirm the deduction, and show that it is easy to obtain a high resolution. Setting the initial angle to 6degree, the measurement range is ±3degree, its average sensitivity is 1104pm/degree, and its average resolution is as high as 0.0009degree.
Real-time, on-line measurement of key physical parameters as well as their variations is the most crucial problem for
safety running of reciprocating compressors in petrochemical plants. In this paper, a method for condition monitoring
and fault diagnosis of reciprocating compressor based on FBG sensors is proposed. A fiber optic accelerometer is
demonstrated, which is used for detecting the vibration of crankcase, crosshead and cylinder of the compressor. FBGbased
temperature sensors are used to monitor the variation of the suction/vent valve temperature. A monitoring system
included hardware and software for the reciprocating compressors is developed and applied in a petrochemical plant.
Currently, the vibration measurement and monitoring of the rotating machines has become the primary means of fault
diagnosis. This paper proposed to develop a magnetic coupling non-contact machinery vibration detection sensor based
on fiber Bragg grating (FBG). The magnetic coupling technology and elastic diaphragm are adopted to achieve the
vibration detection by changing the axial strain of optical fiber. Theoretical analysis and static experiment show that the
function of output wavelength and the measured spacing is exponential decrease. Dynamic vibration measurement shows
that the proposed FBG diaphragm accelerometer provides a wide frequency response range (0-90Hz), identifying it as a
good candidate for machinery health monitoring.
KEYWORDS: Sensors, Demodulation, Fiber optics sensors, Reflectivity, Fiber Bragg gratings, Electromagnetism, Temperature metrology, Capillaries, Signal detection, Chemical elements
The author in the paper fabricates a novel type of chirped fiber Bragg grating (CFBG) vibration sensor with symmetrical
push-pull configuration. It is a typical mass-spring system mainly made up of CFBG, steel tube, mass block. A push-pull
configuration design makes it have not only high sensitivity but also function of temperature self-compensation. Using
CFBG instead of FBG as a sensing element makes its measuring range increase by a big margin. Adopting matching
demodulation technology solves availably the problem of demodulation speed. The sensor has excellent sensing
properties and been successfully applied to vibration monitoring and fault diagnosis on large rotating machinery.
Vibration monitoring is one of important technology means for large electromechanical equipment's safety-alert
and malfunction-diagnosis, and also a hot problem studied for a long time at home and abroad. Vibration sensor is key
part for the technology means, but traditional electromagnetic vibration sensors are restricted for use in the field due to
their weak competence to anti-electromagnetic interference. It is inevitable and imminent to develop novel type of
vibration sensors instead of them. Aiming at the above-mentioned demand, the authors in the paper fabricate a push-pull
type of chirped fiber Bragg grating (CFBG) vibration sensor based on matching demodulation. The authors, at first, set
up mechanical model of the sensor, then analyze the principle of CFBG matching demodulation and get the relation
between acceleration and output voltage at last. The sensor has such functions as anti-electromagnetic interference,
temperature self-compensation and combining vibration sensing and dynamic wavelength demodulation. Moreover,
some experiments are done to study its sensing properties and the results indicate that its sensitivity is 369mv/g, linearity
degree is over 99.9%, repeatability is superior to 2%, measurement bandwidth is from 10Hz to 400Hz, acceleration
measurement range is 8g, and the minimal cross-axis anti-interference is 30dB. To sum up, the sensor is competently
used for monitoring the vibration of large electromechanical equipment.
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