Samson 3730-3 Operating Instructions Manual page 77

Test cancellation conditions
Various cancellation conditions provide ad-
ditional protection against the valve slam-
ming shut or moving past the end position.
The positioner cancels the partial stroke test
when one of the following cancellation con-
ditions is fulfilled:
− 'Max. test duration': The test is canceled
when the maximum permissible test du-
ration is reached.
− 'Max. breakaway time' (Types 3730-4/-
5 only): The test is canceled when the
valve position has reached less than
10 % of the PST target travel after the de-
fined time has elapsed. This cancellation
condition only becomes effective after it
has been activated ("Activation 'Max.
breakaway time'" = Yes).
Cancellation condition - valve position x (to
check the valve position)
− 'x control value': The test is canceled as
soon as the valve position falls below the
adjusted value.
This cancellation condition only becomes
effective after it has been activated ('Ac-
tivation x control' = Yes).
Cancellation condition - drive signal y (to
monitor the friction of the plug)
A higher drive signal from the positioner is
caused by increased plug friction and the re-
sulting increased breakaway torque. This
may result in overshooting. To prevent this,
the drive signal y can be monitored and the
test canceled in the event that an error is de-
tected.
EB 8389 EN
− 'delta y-monitoring value': The test is
canceled as soon as the drive signal y
falls below or exceeds the reference val-
ue. The reference value is made up of the
diagnostic parameters 'delta y-monitor-
ing reference value' and 'delta y-moni-
toring value'.
The 'delta y-monitoring value' is entered
in % and is based on the entire drive sig-
nal range (10000
This cancellation condition only becomes
effective after it has been activated ('Ac-
tivation delta y-monitoring' = Yes).
This cancellation condition (drive signal
y) is not suitable if the full actuator thrust
is required to move the valve due to the
process conditions.
Note
− The partial stroke test must be performed
with deactivated cancellation conditions for
valves with double-acting actuator and
pneumatic booster as well as for valves
that have been initialized using the SUB
mode (substitute calibration).
− Excessive overshooting may occur in valves
fitted with boosters. In this case, the can-
cellation conditions must be adapted ac-
cordingly.
Additionally, the partial stroke test is can-
celed when one of the following events aris-
es:
− 'Aborted by int. solenoid valve/forced
venting': The test was canceled by the
activation of the solenoid valve/forced
venting function.
Tests
).
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