Detection of broken rotor bars in induction motors using stator current measurements

This work proved the feasibility of an interferometric, high pressure sensor. A pressure measurement system based on a birefringent, compact, Fabry-Perot etalon was selected and designed. The temperature response of the reflectivity of the etalon was calibrated; a 1 C change in temperature was equivalent to a 1000 psi pressure change. Efficient coupling of the key components was demonstrated using a monolithic, single-frequency, diode-pumped ring laser (developed at Lightwave Electronics Corp. based on Stanford University research), a single-mode optical fiber, and a sapphire etalon. Successful experimental results demonstrated that an optical pressure transducer can be made that has the properties of compactness, wide pressure range, immunity to electro-magnetic interference, and low cost. Keywords: Pressure measurement, Fiber optics, Lasers, Etalon. (JHD)