VVP10 HART
HART
®
VALVE POSITIONER
INSTALLATION, OPERATION, CONFIGURATION AND MAINTENANCE MANUAL
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If the system is double acting, the only graphic change will be in the pressure curve, which will portray the difference
between OUT2 and OUT1 output pressures, resulting in a more horizontal curve. However, the hysteresis and settling
characteristics will be observed in the same way.
Figure 3.25 – Example of FST in a single action system Figure 3.26 – Example of FST in single action system
for a model with pressure sensors.
for a model without pressure sensors.
The test stores all measured Setpoint, Position and Output Pressure points (for compatible models), allowing the user
to save the complete graph in a personal file for future comparison.
Partial Stroke Test
Test that verifies the performance in safety systems, where the actuator/valve set remains fully open or closed most
of the working time, which may cause stuckness in the seating. Thus, the test performs a partial opening or closing
(configured by the user) to ensure that the system is responding as expected.
It is similar to Valve Signature, with the difference that it does not completely open or close the system, requiring
several configurations by the user. These settings are described below.
In addition to the previously mentioned statuses for the PST, there is also the
PST SP Changed
status, which indicates
a change in the Setpoint during the test (which will affect the control desired by the user) and, consequently, priority in
relation to the test. In this case, the test will also be aborted.
HINT
Use the Valve Signature test right after valve maintenance and good tuning of the PID parameters in order
to obtain an optimal reference graph. Periodically, to analyze the need for maintenance, perform the test
again and compare the graph of the new data obtained with the ideal reference recorded previously. Analyze
the Hysteresis of the system and look for points of friction/stuckness, as exemplified above.
Parameter
Description
PST Type
Sets the test movement type, opening or closing. If the system is not positioned according to
this configuration at the beginning of the test, it will be aborted and the
PST Aborted
status
will be activated.
PST Offset
Sets the test offset (in percentage) – 5% minimum.
PST Pause
Sets the time (in seconds) to wait between the end of opening and the beginning of closing
in the test.
PST Timeout
Configures the maximum time for performing the complete test. If the test exceeds this time,
it will be canceled and the
PST Timeout
status will be activated.
PST Breakout Limit
Sets the maximum time for valve initial movement (
Breakout
). If this time is exceeded, the
test will be canceled and the
PST Breakout
status will be activated.
PST Cycle Time
It configures the period (in hours) for the automatic execution of the test. Set this parameter
to zero to perform the test manually only. A performed tests counter (
PST Execution Counter
)
and a test failure counter (
PST Failure Counter
) are recorded with each new test.
