Analysis of the effect of lubrication performance on motor operated valve actuator output thrust

In this study, we performed theoretical analysis and test to identify an effect that lubricant performance has on actuator output thrust of MOV. Particularly, we introduced Stem Friction Coefficient (SFC) concept that means friction coefficient between a stem nut and a stem screw. By using SFC concept, an effect of lubricant performance on the actuator output thrust was analyzed quantitatively. The first phase test was performed to compare the lubrication performance between new lubricant and old lubricant and the second phase test was performed to compare the lubrication performance for the three kinds of representative lubricants (EP0, EP1, EP2) being used in Korea nuclear power plants. According to the test results, SFC value of old lubricant appeared higher than that of new lubricant and a old lubricant at TST point generated lower thrust value than a new lubricant at the same torque value. We can verify that the effect of lubrication performance has on power generated in an actuator was very large and SFC was a very useful variable in analyzing lubrication performance quantitatively.