During the test, the valve no longer follows the external setpoint value. Changing the valve’s position
can impair the process.
Menu option Description
PST state Information about PST state is displayed in this area
è
Informa-
tion on the PST state.
PST execution The Partial Stroke Test can be started in this area.
Tab. 81: ‘Partial stroke test’ menu
Information on the PST state
PST state Description
PST Initialization Initialised, not initialised
Successful initialisation is a prerequisite for executing the Partial
Stroke Test.
Time since last PST Time since last Partial Stroke Test in hours.
Last PST result Result of the last Partial Stroke Test: not initialised, running, success-
fully completed, termination with cause.
Tab. 82: Information on the PST state
Messages in connection with PST abort
The following diagram illustrates the relationship between setpoint position and waiting time (T_wait)
for the PST version:
–
Continuous line: current position
–
Dashed line: target position
Fig. 32:
Movement with PST execution
If the characteristics lie above or below the user-defined thresholds, a message is generated and the
Partial Stroke Test is aborted.
The following diagram shows the tolerance range of the position limitation:
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