Differential inductive ratio transducer with short-circuiting ring for displacement measurement

This paper describes a differential inductive ratio transducer (DIRT) with a short-circuiting ring (SCR) which is smaller in size, lighter in weight, has 500 turns in each coil, has a laminated core of mumetal, is rugged in construction, and is lower in cost. It has linear and hysteresis-free response with immunity to undesirable variations in excitation conditions and influencing parameters. Due to the differential ratio mode of operation, there is a cancellation of common factors in the numerator and denominator. These factors have the terms containing the influence of constant errors due to leakage flux and finite resistance of the SCR, and variable errors due to changes in the excitation conditions and temperature. This process makes the transducer smart in its behavior. It has a full range of displacement up to /spl plusmn/37.5 mm, sensitivity of 0.0933 V/spl middot/mm/sup -1/, resolution of 0.1 /spl mu/m, temperature drift of 4.6 ppm//spl deg/C for a change in temperature from 30 to 70/spl deg/C, stability within /spl plusmn/0.09% for an excitation variation from 1 to 5 V, and within /spl plusmn/0.015% for a frequency variation from 1 to 10 kHz. It is suitable for use in all types of environments, including hostile conditions.<
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