Study on static characteristics of array electrode capacitance control rod position measurement sensor

•The control rod position measurement method of double capacitance values is proposed.•The structure of array electrode capacitance control rod position measurement sensor is proposed.•The static characteristic experiments and finite element model analyses are carried out.•The maximum measurement error can be limited to ± 4 mm within the measurement range of 840 mm. Control rod position measurement sensor is the key measurement component of the nuclear reactor. For the capacitance control rod position measurement sensor (CCRPMS), a new method of measuring the control rod position with double capacitance values is proposed. In order to realize this method, the array electrode CCRPMS is designed. For the array electrode CCRPMS, the static characteristic experiments are carried out, the finite element model is established. The relationship between the electrode arrangement method and the “eccentricity inconsistency” effect is analyzed. The function between double capacitance values with rod positions is fitted. For tilt states and different deflection angles of the measuring rod, the applicability of the function is evaluated. Static measurement errors of the sensor are systematically analyzed. Results show that the maximum measurement error of the array electrode CCRPMS can be limited within ±4 mm.