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Optical Fiber Fabry-Perot Current Sensor Based On Giant Magnetostrictive Materials

Posted on:2008-04-08Degree:MasterType:Thesis
Country:ChinaCandidate:X F YaoFull Text:PDF
GTID:2178360215490567Subject:Instrument Science and Technology
Abstract/Summary:PDF Full Text Request
Electric power industry is the foundation one of national economic development. It is significant in the country economic construction, so current measurement is quite important in the power industry. At present the current transformer is widely used in electric power systems. But it has many disadvantages, such as big volume, heavy weight, hard installation, liable to electromagnetic interference and poor insulation. Because of these, it can not meet industry needs. Optical fiber Fabry-Perot sensors have many advantages, such as good insulation, without electromagnetic interference, small volume ,light weight ,and the reference and sensor signals share the same fiber, so it can inhibit the negative effects that inner birefringence of fiber ,environmental temperature and vibration have on the sensor. It has wide development and application prospect in power system. This thesis gives one new type fiber current sensor which is based on fiber Fabry-Perot sensor and giant magnetostrictive materials.This thesis introduces research of fiber current sensor at home and abroad and gives the design method of the fiber Fabry-Perot current sensor. The measurement principle is analyzed, which includes from current to magnetic field, then to magnetostriction and at last to the gap changes of F-P sensors. Magnetostrictive materials and optical fiber F-P sensor are key parts for current measurement. The magnetostrictive phenomena,principle and material characteristics of the magnetostrictive material are studied. After comparison of advantages and disadvantages of giant magnetostrictive materials and PZT, magnetostrictive material is chosen as sensor medium of optical fiber F-P sensor in this paper. It analyzes the basic principle of Fabry-Perot interferometer and compares manufacturing processes and measurement precision. Then extrinsic Fabry-Perot interferometer is chosen to measure distortion of magnetostrictive material.Based on operating principle analysis, current measurement theory is analyzed. After comparison, Tb0 . 3Dy0.7Fe1.95provided by Rare Earths Institute in Baotou is used as core material. It also studies prestressing force effects, offset magnetic field effects and temperature effects on giant magnetostrictive materials. The solenoid which is used to change the measured current into magnetic field is designed and produced and also emulation is done to show that magnetic field uniformity can meet our needs. From demodulation principle of the optical fiber F-P gap changes, advantages and disadvantages of various methods are analyzed. DGT is chosen and its light path to realization is studied. At last fiber strain-measured instrument is chosen to measure the changes of gap in fiber Fabry-Perot sensor.At last the experiment table is built up, and prestressing calibration is done. Prestressing force effect, offset magnetic field effect and temperature effect on the sensor system are analyzed through experiments. Then the conclusion is reached that performance of sensor is optimal when prestressing force is 470N and offset current is 1A.
Keywords/Search Tags:Fiber Current Sensor, Current Measurement, Giant Magnetostrictive Materials, Fabry-Perot Interferometer
PDF Full Text Request
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