Analysis of Calibration Error of NPP Shutoff Valve Electric Drive

The results of research aimed at developing a portable complex for carrying out the online non-disassembly field diagnostics and calibration of torque limiters of electric drive valves (EDV) at the place of EDV operation are presented (EDVTL PC). The concept and methodology of calibration of an electric drive at the place of its installation on the EDV are described. A description of the software and hardware complex implementing this concept is given. The main results of testing the complex are described, which showed its applicability for performing the EDV diagnostics at NPPs. Statistical tests were performed to develop and certify measurement procedures. For this purpose, the uncertainty of the result of electric drive calibration, which is introduced by the calibration procedure itself, was analyzed. It is shown that an effect of the torque sensor, which is installed using the specially designed equipment between the valves and the electric drive, is insignificant and affects only the secondary diagnostic parameters. Thus, the possibility of combining operations of the basic testing of electric drive and the technical diagnosing of EDV is confirmed. The obtained test results were used to compile and metrologically certify the methodology for direct and indirect measurements of the torque of EDV at the place of its operation.