2015 年 23 巻 3 号 p. 448-453
Eddy-current (EC) displacement sensors are used in devices for measuring the shaft vibration of turbines. An EC displacement sensor is composed of a coil, a coaxial cable and an impedance / output voltage (Z /V) converter. The state of coaxial cable may change according to the situation, which is problematic because the sensitivity of the eddy-current (EC) displacement sensor changes when the state of the coaxial cable changes. The output voltage and sensitivity depend on the impedance of the EC displacement sensor because it is used as part of an oscillation circuit in impedance/voltage (Z/ V) converter. The impedance due to torsion of the coaxial cable of the EC displacement sensor due to frequency was measured. In addition, the impedance, change including the oscillation circuit of the EC displacement sensor due to torsion of coaxial cable, was measured. The oscillation frequency was optimized such that a reduction in change of sensitivity is possible.
