Method and device for the activation of an electropneumatic valve of a pressure medium-actuated position controller

A device for the activation of an electropneumatic valve of a pressure medium-operated position controller, the electropneumatic valve being configured to be activated by an electrical signal constituting a manipulated variable within a process regulation and control loop, to act with a pilot control pressure upon a booster stage downstream of the electropneumatic valve to actuate an acutating drive, the device being configured to achieve a blocking fail-safe behavior as a result of the failure of a pressure medium, the device comprising:

• detecting means for detecting a current position of the booster stage after action with the pilot control pressure and assigning the manipulated variable to correspond to the detected current position;
• sensor means for continuously measuring at least one of a regulation variable and a process variable to be influenced by the position controller;
• evaluation means for determining an expected directional reaction of the at least one of the regulation variable and process variable to the assigned manipulated variable, and to compare the expected directional reaction with the measured actual directional reaction of the at least one of the regulation variable and process variable;
• determining means for determining existence of a pressure medium failure upon the evaluation means determining that the expected directional reaction does not coincide with the actual directional reaction;
• and
• assigning means for assigning an electrical emergency signal generating a blocking fail-safe behavior of the electropneumatic valve as a new manipulated variable for the electropneumatic valve.

A device configured to activate an electropneumatic valve of a pressure medium-operated position controller, the electropneumatic valve being configured to be activated by an electrical signal constituting a manipulated variable within a process regulation and control loop, to act with a pilot control pressure upon a booster stage downstream of the electropneumatic valve to actuate an acutating drive, the device being configured to achieve a blocking fail-safe behavior as a result of the failure of a pressure medium, the device comprising:

• a detector configured to detect a current position of the booster stage after action with the pilot control pressure and assign the manipulated variable to correspond to the detected current position;
• a sensor configured to continuously measure at least one of a regulation variable and a process variable to be influenced by the position controller;
• and
• an evaluation unit configured to determine an expected directional reaction of the at least one of the regulation variable and process variable to the assigned manipulated variable, to compare the expected directional reaction with the measured actual directional reaction of the at least one of the regulation variable and process variable, to determine existence of a pressure medium failure upon the evaluation unit determining that the expected directional reaction does not coincide with the actual directional reaction, and to assign an electrical emergency signal generating a blocking fail-safe behavior of the electropneumatic valve as a new manipulated variable for the electropneumatic valve.