Numerical Research on LVDT Sensor for Electromagnet Rigidity Measurement of Bottom Mounted CRDM

The stepping motor directly drives the ball screw, and the nut of the ball screw makes the electromagnet move up and down along the guide tube. At this time the higher force of an electromagnet will greatly result in less position fluctuation of the armature for a given variation of loadings. The magnetic rigidity represents one of the most important characteristics of the electromagnet. For this reason, it is necessary to measure control rod position including sagging rate due to loadings exactly. Therefore, KAERI has developed electromagnet rigidity measuring sensor using LVDT. This paper presents the case numerical research of prototyping a LVDT sensor for BMCRDM. The results of a FEM in this work lead to the following conclusions: The FEM result for LVDT shows good linearity of dIsplacement vs. induced voltage between 0[mm] and ±15[mm] intervals. For the extension of linearity interval, additional research work is necessary for the configuration and arrangement of primary and secondary coils