| 摘要 |
PROBLEM TO BE SOLVED: To suppress an adverse influence on a plant due to unnecessary PST(Partial Stroke Test) activation.SOLUTION: A safety instrumentation system comprises: a positioner 2 for controlling the aperture of an emergency shutoff valve installed in the piping of a plant; and a host system 3 for managing the PST of the emergency shutoff valve. The positioner 2 includes: a PST execution part 22 for executing the PST of the emergency shutoff valve in response to an activation command from the host system 3 or an activation command from a control panel at a job site where the positioner 2 is installed; a timer 20 for measuring a lapsed time since the PST of the emergency shutoff valve is completed; and a PST activation inhibition determination part 21 for, when receiving the activation command of the PST from the host system 3 or the control panel, comparing the previous lapsed time from the PST with a preliminarily specified PST minimum frequency to determine the acceptance/rejection of the PST activation. |
