CONTROL VALVE POSITIONERS HAVING IMPROVED OPERATING CHARACTERISTICS

摘要

A control assembly includes a positioner/actuator and a control valve. The positioner/actuator includes a valve actuator and a positioner for controlling actuator position and speed in response to a control signal. The control valve has a characteristic flow rate as a function of time. The positioner may include an electronic control circuit for modifying the travel speed of the actuator to produce a desired flow rate as a function of time. The positioner may determine an error between a desired actuator position and an actual actuator position and apply a correction signal to reduce the error. The correction signal is asymmetric with respect to error polarity.