VALVE POSITIONER

摘要

PROBLEM TO BE SOLVED: To provide a valve positioner having improved control performance while reducing a long wasteful time resulting from a great hysteresis of a control valve body portion by arranging an additional compensation element therein with a pressure control system granted to a position control system to secure the follow-up performance of an operating pneumatic pressure to a control signal. SOLUTION: The valve positioner comprises the pressure control system for fetching an output signal from the position control system as a pressure set value and controlling the operating pneumatic pressure of a control valve drive part, added to the position control system for controlling a stem position of the control valve body portion, wherein a hysteresis compensator is provided for applying to the output signal from the position control system a hysteresis compensation signal equivalent to the hysteresis of the control valve body portion.