Fig. 1. The CCS construction: (a) 3-D cross section; (b) construction details.

Fig. 2. Existing two CCS’s: (a) the four-segment CCS; (b) the eight-segment CCS.

Fig. 3. Simple model for guard gap corrections.

Fig. 4. FE model of CCS with the circumferential gap: (a) a CCS model for the FE analysis; (b) FE meshing results.

Fig. 5. Equipotential contour of the FE analysis results: (a) air and narrow gap; (b) epoxy and narrow gap; (c) epoxy and wide gap.

Fig. 6. Variations of the equivalent length extension due to various effects: (a) effect of the sensor thickness and the circumferential gap width; (b) effect of the air gap and the epoxy relative permittivity.

Fig. 7. Schematic diagram of the CCS with circumferential gaps.

Fig. 8. EAF variations according to circumferential gap widths.

Fig. 9. Analytical orbit measurement simulation of CCSs with narrow and wide circumferential gaps: (a) 1 mm circumferential gap; (b) 3.3 mm circumferential gap.

Fig. 10. Analytical orbit measurement simulation of the test rotor: (a) with the uncompensated CCS; (b) with the compensated CCS.

Fig. 11. Comparison of the expected harmonic error magnitudes.

Fig. 12. The experimental setup: (a) schematic diagram of the experimental setup; (b) the flexible rotor test rig; (c) the CCS housing.

Fig. 13. Fast beat phenomenon: (a) orbit plot; (b) time plot.

Fig. 14. The experimental results of orbit measurement of the test rotor: (a) with the uncompensated CCS; (b) with the compensated CCS.

Fig. 15. Fourier transformation of the experimental results: (a) large radius orbit in X direction; (b) large radius orbit in Y direction; (c) small radius orbit in X direction; (d) small radius orbit in Y direction.

Fig. A.1. Variables for the CCS mathematical model: (a) variables for a rotor and a sensor; (b) variables for a rotor position with roundness errors.

Fig. A.2. The EAF of the eight-segment CCS.

Fig. B.1. Test target rotor: (a) shape; (b) magnitudes of harmonic geometric errors.